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Archive for the ‘MicroEngineering Cell-Tissue & Systems’ Category


Fibrin-coated Electrospun Polylactide Nanofibers Potential Applications in Skin Tissue Engineering

Reported by: Irina Robu, PhD

 

Fibrin plays an essential role during wound healing and skin regeneration and is often applied for the treatment of skin injuries. Fibrin is formed after thrombin cleavage of fibrinopeptide A from fibrinogen Aalpha-chains, thus initiating fibrin polymerization. Double-stranded fibrils form through end-to-middle domain (D:E) associations, and concomitant lateral fibril associations and branching create a clot network. In addition, its primary role is to provide scaffolding for the intravascular thrombus.

Dr. Lucie Bacakova and her colleagues from Department of Biomaterials and Tissue engineering at Czech Academy of Sciences prepared electrospun nanofibrious membranes made from poly(L-lactide) modified with a thin fibrin nanocoating. The cell-free fibrin nanocating remained stable in cell culture medium for 14 days and did not change its morphology. The rate of fibrin degradation is correlated to the degree of cell proliferation on membrane populated with human dermal fibroblasts. It was shown that the cell spreading, mitochondrial activity and cell population density were higher on membranes coated with fibrin than on nonmodified membranes. The cell performance was improved by adding ascorbic acid in the cell culture medium. At the same time, fibrin stimulated the expression and synthesis of collagen I in human dermal fibroblasts. The expression of beta-integrins was improved by fibrin. And it is shown that the combination of nanofibrous membranes with a fibrin nanocoating and ascorbic acids is beneficial to tissue engineering.

Source

https://www.dovepress.com/articles.php?article_id=25743#

 

 

 

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3-D Printed Liver

Curator: Larry H. Bernstein, MD, FCAP

 

 

3D-printing a new lifelike liver tissue for drug screening

Could let pharmaceutical companies quickly do pilot studies on new drugs
February 15, 2016    http://www.kurzweilai.net/3d-printing-a-new-lifelike-liver-tissue-for-drug-screening

Images of the 3D-printed parts of the biomimetic liver tissue: liver cells derived from human induced pluripotent stem cells (left), endothelial and mesenchymal supporing cells (center), and the resulting organized combination of multiple cell types (right). (credit: Chen Laboratory, UC San Diego)

 

University of California, San Diego researchers have 3D-printed a tissue that closely mimics the human liver’s sophisticated structure and function. The new model could be used for patient-specific drug screening and disease modeling and could help pharmaceutical companies save time and money when developing new drugs, according to the researchers.

The liver plays a critical role in how the body metabolizes drugs and produces key proteins, so liver models are increasingly being developed in the lab as platforms for drug screening. However, so far, the models lack both the complex micro-architecture and diverse cell makeup of a real liver. For example, the liver receives a dual blood supply with different pressures and chemical constituents.

So the team employed a novel bioprinting technology that can rapidly produce complex 3D microstructures that mimic the sophisticated features found in biological tissues.

The liver tissue was printed in two steps.

  • The team printed a honeycomb pattern of 900-micrometer-sized hexagons, each containing liver cells derived from human induced pluripotent stem cells. An advantage of human induced pluripotent stem cells is that they are patient-specific, which makes them ideal materials for building patient-specific drug screening platforms. And since these cells are derived from a patient’s own skin cells, researchers don’t need to extract any cells from the liver to build liver tissue.
  • Then, endothelial and mesenchymal supporting cells were printed in the spaces between the stem-cell-containing hexagons.

The entire structure — a 3 × 3 millimeter square, 200 micrometers thick — takes just seconds to print. The researchers say this is a vast improvement over other methods to print liver models, which typically take hours. Their printed model was able to maintain essential functions over a longer time period than other liver models. It also expressed a relatively higher level of a key enzyme that’s considered to be involved in metabolizing many of the drugs administered to patients.

“It typically takes about 12 years and $1.8 billion to produce one FDA-approved drug,” said Shaochen Chen, NanoEngineering professor at the UC San Diego Jacobs School of Engineering. “That’s because over 90 percent of drugs don’t pass animal tests or human clinical trials. We’ve made a tool that pharmaceutical companies could use to do pilot studies on their new drugs, and they won’t have to wait until animal or human trials to test a drug’s safety and efficacy on patients. This would let them focus on the most promising drug candidates earlier on in the process.”

The work was published the week of Feb. 8 in the online early edition of Proceedings of the National Academy of Sciences.


Abstract of Deterministically patterned biomimetic human iPSC-derived hepatic model via rapid 3D bioprinting

The functional maturation and preservation of hepatic cells derived from human induced pluripotent stem cells (hiPSCs) are essential to personalized in vitro drug screening and disease study. Major liver functions are tightly linked to the 3D assembly of hepatocytes, with the supporting cell types from both endodermal and mesodermal origins in a hexagonal lobule unit. Although there are many reports on functional 2D cell differentiation, few studies have demonstrated the in vitro maturation of hiPSC-derived hepatic progenitor cells (hiPSC-HPCs) in a 3D environment that depicts the physiologically relevant cell combination and microarchitecture. The application of rapid, digital 3D bioprinting to tissue engineering has allowed 3D patterning of multiple cell types in a predefined biomimetic manner. Here we present a 3D hydrogel-based triculture model that embeds hiPSC-HPCs with human umbilical vein endothelial cells and adipose-derived stem cells in a microscale hexagonal architecture. In comparison with 2D monolayer culture and a 3D HPC-only model, our 3D triculture model shows both phenotypic and functional enhancements in the hiPSC-HPCs over weeks of in vitro culture. Specifically, we find improved morphological organization, higher liver-specific gene expression levels, increased metabolic product secretion, and enhanced cytochrome P450 induction. The application of bioprinting technology in tissue engineering enables the development of a 3D biomimetic liver model that recapitulates the native liver module architecture and could be used for various applications such as early drug screening and disease modeling.

Fernando

I wonder how equivalent are these hepatic cells derived from human induced pluripotent stem cells (hiPSCs) compared with the real hepatic cell populations.
All cells in our organism share the same DNA info, but every tissue is special for what genes are expressed and also because of the specific localization in our body (which would mean different surrounding environment for each tissue). I am not sure about how much of a step forward this is. Induced hepatic cells are known, but this 3-D print does not have liver shape or the different cell sub-types you would find in the liver.

I agree with your observation that having the same DNA information doesn’t account for variability of cell function within an organ. The regulation of expression is in RNA translation, and that is subject to regulatory factors related to noncoding RNAs and to structural factors in protein folding. The result is that chronic diseases that are affected by the synthetic capabilities of the liver are still problematic – toxicology, diabetes, and the inflammatory response, and amino acid metabolism as well. Nevertheless, this is a very significant step for the testing of pharmaceuticals. When we look at the double circulation of the liver, hypoxia is less of an issue than for heart or skeletal muscle, or mesothelial tissues. I call your attention to the outstanding work by Nathan O. Kaplan on the transhydrogenases, and his stipulation that there are significant differences between organs that are anabolic and those that are catabolic in TPNH/DPNH, that has been ignored for over 40 years. Nothing is quite as simple as we would like.

Fernando commented on 3-D printed liver

3-D printed liver Larry H. Bernstein, MD, FCAP, Curator LPBI 3D-printing a new lifelike liver tissue for drug …

I wonder how equivalent are these hepatic cells derived from human induced pluripotent stem cells (hiPSCs) compared with the real hepatic cell populations.
All cells in our organism share the same DNA info, but every tissue is special for what genes are expressed and also because of the specific localization in our body (which would mean different surrounding environment for each tissue). I am not sure about how much of a step forward this is. Induced hepatic cells are known, but this 3-D print does not have liver shape or the different cell sub-types you would find in the liver.

 

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Lifelong Contraceptive Device for Men: Mechanical Switch to Control Fertility on Wish

Reporter and Curator: Dr. Sudipta Saha, Ph.D.

There aren’t many options for long-term birth control for men. The most common kinds of male contraception include

  • condoms,
  • withdrawal / pulling out,
  • outercourse, and
  • vasectomy.

But, other than vasectomy none of the processes are fully secured, comfortable and user friendly. Another solution may be

  • RISUG (Reversible Inhibition of Sperm Under Guidance, or Vasalgel)

which is said to last for ten years and no birth control pill for men is available till date.

VIEW VIDEO

http://www.mdtmag.com/blog/2016/01/implanted-sperm-switch-turns-mens-fertility-and?et_cid=5050638&et_rid=461755519&type=cta

Recently a German inventor, Clemens Bimek, developed a novel, reversible, hormone free, uncomplicated and lifelong contraceptive device for controlling male fertility. His invention is named as Bimek SLV, which is basically a valve that stops the flow of sperm through the vas deferens with the literal flip of a mechanical switch inside the scortum, rendering its user temporarily sterile. Toggled through the skin of the scrotum, the device stays closed for three months to prevent accidental switching. Moreover, the switch can’t open on its own. The tiny valves are less than an inch long and weigh is less than a tenth of an ounce. They are surgically implanted on the vas deferens, the ducts which carry sperm from the testicles, through a simple half-hour operation.

The valves are made of PEEK OPTIMA, a medical-grade polymer that has long been employed as a material for implants. The device is patented back in 2000 and is scheduled to undergo clinical trials at the beginning of this year. The inventor claims that Bimek SLV’s efficacy is similar to that of vasectomy, it does not impact the ability to gain and maintain an erection and ejaculation will be normal devoid of the sperm cells. The valve’s design enables sperm to exit the side of the vas deferens when it’s closed without any semen blockage. Leaked sperm cells will be broken down by the immune system. The switch to stop sperm flow can be kept working for three months or 30 ejaculations. After switching on the sperm flow the inventor suggested consulting urologist to ensure that all the blocked sperms are cleared off the device. The recovery time after switching on the sperm flow is only one day, according to Bimek SLV. However, men are encouraged to wait one week before resuming sexual activities.

Before the patented technology can be brought to market, it must undergo a rigorous series of clinical trials. Bimek and his business partners are currently looking for men interested in testing the device. If the clinical trials are successful then this will be the first invention of its kind that gives men the ability to control their fertility and obviously this method will be preferred over vasectomy.

 

References:

 

https://www.bimek.com/this-is-how-the-bimek-slv-works/

 

http://www.mdtmag.com/blog/2016/01/implanted-sperm-switch-turns-mens-fertility-and?et_cid=5050638&et_rid=461755519&type=cta

 

http://www.telegraph.co.uk/news/worldnews/europe/germany/12083673/German-carpenter-invents-on-off-contraception-switch-for-sperm.html

 

http://www.discovery.com/dscovrd/tech/you-can-now-turn-off-your-sperm-flow-with-the-flip-of-a-switch/

 

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Contribution to Inflammatory Bowel Disease (IBD) of bacterial overgrowth in gut on a chip

Larry H. Bernstein, MD, FCAP, Curator

LPBI

 

Contributions of microbiome and mechanical deformation to intestinal bacterial overgrowth and inflammation in a 

human gut-on-a-chip 
Gut-On-a-Chip Holds Clues for Treating Inflammatory Bowel Diseases
Greg Watry
Human intestinal epithelial cells cultured in the Wyss Institute's human gut-on-a-chip form differentiated intestinal villi when cultured in the presence of lifelike fluid flow and rhythmic, peristalsis-like motions. Here the villi are visible using a traditional microscope (left) or a confocal microscope (right); when the same villi are stained with fluorescent antibodies, it clearly reveals the nuclei in the intestinal cells (blue) and their specialized apical membranes when they contact the intestinal lumen (green). Credit: Wyss Institute at Harvard University
Human intestinal epithelial cells cultured in the Wyss Institute’s human gut-on-a-chip form differentiated intestinal villi when cultured in the presence of lifelike fluid flow and rhythmic, peristalsis-like motions. Here the villi are visible using a traditional microscope (left) or a confocal microscope (right); when the same villi are stained with fluorescent antibodies, it clearly reveals the nuclei in the intestinal cells (blue) and their specialized apical membranes when they contact the intestinal lumen (green). Credit: Wyss Institute at Harvard University

Roughly the size of a computer memory stick and made of clear flexible polymer, the human gut-on-a-chip was created by Harvard Univ.’s Wyss Institute in 2012. Three years later, researchers are utilizing the technology in hopes of creating new therapies for inflammatory bowel diseases (IBD).

The Centers for Disease Control and Prevention estimates that between 1 and 1.3 million people suffer from IBD, including such diseases as ulcerative colitis and Crohn’s disease. With origins still mysterious, IBD is currently incurable.

“It has not been possible to study…human intestinal inflammatory diseases, because it is not possible to independently control these parameters in animal studies or in vitro models,” wrote the researchers in Proceedings of the National Academy of the Sciences. “In particular, given the recent recognition of the central role of the intestinal microbiome in human health and disease, including intestinal disorders, it is critical to incorporate commensal microbes into experimental models, however, this has not been possible using conventional culture systems.”

Additionally, static in vitro methods fail to replicate the pathophysiology of human IBD.

But the hollow-channeled microfluidic gut-on-a-chip successfully simulates the human intestine’s physical structure, microenvironment, peristalsis-like motion, and fluid flow.

“With our human gut-on-a-chip, we can not only culture the normal gut microbiome for extended times, but we can also analyze contributions of pathogens, immune cells, and vascular and lymphatic endothelium, as well as model specific diseases to understand the complex pathophysiological responses of the intestinal tract,” said Donald Ingber, founding director of the Wyss Institute.

The device was “used to co-culture multiple commensal microbes in contact with living human intestinal epithelial cells for more than a week in vitro and to analyze how gut microbiome, inflammatory cells, and peristalsis-associated mechanical deformations independently contribute to intestinal bacterial overgrowth and inflammation,” the researchers wrote.

Thus far, use of the device has yielded two interesting observations.

Four proteins—called cytokines—work together to trigger an inflammatory responses that exacerbate the bowel, the researchers found. Potentially, this new discovery could lead to the development of treatments that block the cytokine interaction.

Another observation, the researchers noted, is that “by ceasing peristalsis-like motions while maintaining luminal flow, lack of epithelial deformation was shown to trigger bacterial overgrowth similar to that observed in patients with ileus and inflammatory bowel disease,” according to the researchers.

The researchers believe the micro-device may one day be applicable to precision medicine. Eventually, a custom treatment may arise from scientists using a patient’s gut microbiota and cells on a human gut-on-a-chip.

 

 

Contributions of microbiome and mechanical deformation to intestinal bacterial overgrowth and inflammation in a human gut-on-a-chip
Hyun Jung Kima,1, Hu Lia,2, James J. Collinsa,b,c,d,e,f,3, and Donald E. Ingbera,g,h,
http://www.pnas.org/content/early/2015/12/09/1522193112.full.pdf

A human gut-on-a-chip microdevice was used to coculture multiple commensal microbes in contact with living human intestinal epithelial cells for more than a week in vitro and to analyze how gut microbiome, inflammatory cells, and peristalsis-associated mechanical deformations independently contribute to intestinal bacterial overgrowth and inflammation. This in vitro model replicated results from past animal and human studies, including demonstration that probiotic and antibiotic therapies can suppress villus injury induced by pathogenic bacteria. By ceasing peristalsis-like motions while maintaining luminal flow, lack of epithelial deformation was shown to trigger bacterial overgrowth similar to that observed in patients with ileus and inflammatory bowel disease. Analysis of intestinal inflammation on-chip revealed that immune cells and lipopolysaccharide endotoxin together stimulate epithelial cells to produce four proinflammatory cytokines (IL-8, IL-6, IL-1β, and TNF-α) that are necessary and sufficient to induce villus injury and compromise intestinal barrier function. Thus, this human gut-on-a-chip can be used to analyze contributions of microbiome to intestinal pathophysiology and dissect disease mechanisms in a controlled manner that is not possible using existing in vitro systems or animal models.

 

Significance The main advance of this study is the development of a microengineered model of human intestinal inflammation and bacterial overgrowth that permits analysis of individual contributors to the pathophysiology of intestinal diseases, such as ileus and inflammatory bowel disease, over a period of weeks in vitro. By studying living human intestinal epithelium, with or without vascular and lymphatic endothelium, immune cells, and mechanical deformation, as well as living microbiome and pathogenic microbes, we identified previously unknown contributions of specific cytokines, mechanical motions, and microbiome to intestinal inflammation, bacterial overgrowth, and control of barrier function. We provide proof-of-principle to show that the microfluidic gut-on-a-chip device can be used to create human intestinal disease models and gain new insights into gut pathophysiology.

 

Various types of inflammatory bowel disease (IBD), such as Crohn’s disease and ulcerative colitis, involve chronic inflammation of human intestine with mucosal injury and villus destruction (1), which is believed to be caused by complex interactions between gut microbiome (including commensal and pathogenic microbes) (2), intestinal mucosa, and immune components (3). Suppression of peristalsis also has been strongly associated with intestinal pathology, inflammation (4, 5), and small intestinal bacterial overgrowth (5, 6) in patients with Crohn’s disease (7) and ileus (8). However, it has not been possible to study the relative contributions of these different potential contributing factors to human intestinal inflammatory diseases, because it is not possible to independently control these parameters in animal studies or in vitro models. In particular, given the recent recognition of the central role of the intestinal microbiome in human health and disease, including intestinal disorders (2), it is critical to incorporate commensal microbes into experimental models; however, this has not been possible using conventional culture systems. Most models of human intestinal inflammatory diseases rely either on culturing an intestinal epithelial cell monolayer in static Transwell culture (9) or maintaining intact explanted human intestinal mucosa ex vivo (10) and then adding live microbes and immune cells to the apical (luminal) or basolateral (mucosal) sides of the cultures, respectively. These static in vitro methods, however, do not effectively recapitulate the pathophysiology of human IBD. For example, intestinal epithelial cells cultured in Transwell plates completely fail to undergo villus differentiation, produce mucus, or form the various specialized cell types of normal intestine. Although higher levels of intestinal differentiation can be obtained using recently developed 3D organoid cultures (11), it is not possible to expose these cells to physiological peristalsis-like motions or living microbiome in long-term culture, because bacterial overgrowth occurs rapidly (within ∼1 d) compromising the epithelium (12). This is a major limitation because establishment of stable symbiosis between the epithelium and resident gut microbiome as observed in the normal intestine is crucial for studying inflammatory disease initiation and progression (13), and rhythmical mechanical deformations driven by peristalsis are required to both maintain normal epithelial differentiation (14) and restrain microbial overgrowth in the intestine in vivo (15).

Thus, we set out to develop an experimental model that would overcome these limitations. To do this, we adapted a recently described human gut-on-a-chip microfluidic device that enables human intestinal epithelial cells (Caco-2) to be cultured in the presence of physiologically relevant luminal flow and peristalsislike mechanical deformations, which promotes formation of intestinal villi lined by all four epithelial cell lineages of the small intestine (absorptive, goblet, enteroendocrine, and Paneth) (12, 16). These villi also have enhanced barrier function, drug-metabolizing cytochrome P450 activity, and apical mucus secretion compared with the same cells grown in conventional Transwell cultures, which made it possible to coculture a probiotic gut microbe (Lactobacillus rhamnosus GG) in direct contact with the intestinal epithelium for more than 2 wk (12), in contrast to static Transwell cultures (17) or organoid cultures (11) that lose viability within hours under similar conditions. In the present study, we leveraged this human gut-on-a-chip to develop a disease model of small intestinal bacterial overgrowth (SIBO) and inflammation. We analyzed how probiotic and pathogenic bacteria, lipopolysaccharide (LPS), immune cells, inflammatory cytokines, vascular endothelial cells and mechanical forces contribute individually, and in combination, to intestinal inflammation, villus injury, and compromise of epithelial barrier function. We also explored whether we could replicate the protective effects of clinical probiotic and antibiotic therapies on-chip to demonstrate its potential use as an in vitro tool for drug development, as well as for dissecting fundamental disease mechanisms.

 

Fig. 1. The human gut-on-a-chip microfluidic device and changes in phenotype resulting from different culture conditions on-chip, as measured using genome-wide gene profiling. (A) A photograph of the device. Blue and red dyes fill the upper and lower microchannels, respectively. (B) A schematic of a 3D cross-section of the device showing how repeated suction to side channels (gray arrows) exerts peristalsis-like cyclic mechanical strain and fluid flow (white arrows) generates a shear stress in the perpendicular direction. (C) A DIC micrograph showing intestinal basal crypt (red arrow) and villi (white arrow) formed by human Caco-2 intestinal epithelial cells grown for ∼100 h in the gut-on-achip under medium flow (30 μL/h) and cyclic mechanical stretching (10%, 0.15 Hz). (Scale bar, 50 μm.) (D) A confocal immunofluorescence image showing a horizontal cross-section of intestinal villi similar to those shown in Fig. 1C, stained for F-actin (green) that labels the apical brush border of these polarized intestinal epithelial cells (nuclei in blue). (Scale bar, 50 μm.) (E) Hierarchical clustering analysis of genome-wide transcriptome profiles (Top) of Caco-2 cells cultured in the static Transwell, the gut-on-a-chip (with fluid flow at 30 μL/h and mechanical deformations at 10%, 0.15 Hz) (Gut Chip), or the mechanically active gut-on-a-chip cocultured with the VSL#3 formulation containing eight probiotic gut microbes (Gut Chip + VSL#3) for 72 h compared with normal human small intestinal tissues (Duodenum, Jejunum, and Ileum; microarray data from the published GEO database). The dendrogram was generated based on the averages calculated across all replicates, and all branches in the cluster have the approximately unbiased (AU) P value equal to 100. The y axis next to the dendrogram represents the metric for Euclidean distance between samples. Corresponding pseudocolored GEDI maps analyzing profiles of 650 metagenes between samples described above (Bottom).

 

Fig. 2. Reconstitution of pathological intestinal injury induced by interplay between nonpathogenic or pathogenic enteroinvasive E. coli bacteria or LPS endotoxin with immune cells. (A) DIC images showing that the normal villus morphology of the intestinal epithelium cultured on-chip (Control) is lost within 24 h after EIEC (serotype O124:NM) are added to the apical channel of the chip (+EIEC; red arrows indicate bacterial colonies). (B) Effects of GFP-EC, LPS (15 μg/mL), EIEC, or no addition (Control) on intestinal barrier function (Left). Right shows the TEER profiles in the presence of human PBMCs (+PBMC). GFP-EC, LPS, and EIEC were added to the apical channel (intestinal lumen) at 4, 12, and 35 h, respectively, and PBMCs were subsequently introduced through the lower capillary channel at 44 h after the onset of experiment (0 h) (n = 4). (C) Morphological analysis of intestinal villus damage in response to addition of GFP-EC, LPS, and EIEC in the absence (−PBMC) or the presence of immune components (+PBMC). Schematics (experimental setup), phase contrast images (horizontal view, taken at 57 h after onset), and fluorescence confocal micrographs (vertical cross-sectional views at 83 h after onset) were sequentially displayed. F-actin and nuclei were coded with magenta and blue, respectively. (D) Quantification of intestinal injury evaluated by measuring changes in lesion area (Top; n = 30) and the height of the villi (Bottom; n = 50) in the absence (white) or the presence (gray) of PBMCs. Intestinal villi were grown in the gut-on-a-chip under trickling flow (30 μL/h) with cyclic deformations (10%, 0.15 Hz) during the preculture period for ∼100 h before stimulation (0 h, onset). Asterisks indicate statistical significance compared with the control at the same time point (*P < 0.001, **P < 0.05). (Scale bars, 50 μm.)

 

Recapitulating Organ-Level Intestinal Inflammatory Responses. During inflammation in the intestine, pathophysiological recruitment of circulating immune cells is regulated via activation of the underlying vascular endothelium. To analyze this organ-level inflammatory response in our in vitro model, a monolayer of human microvascular endothelial cells (Fig. 3 C and D and Fig. S6 A and C) or lymphatic endothelial cells (Fig. S6 B and C) was cultured on the opposite (abluminal) side of the porous ECM-coated membrane in the lower microchannel of the device to effectively create a vascular channel (Fig. 3C). To induce intestinal inflammatory responses, LPS (Fig. 3 C and D) or TNF-α (Fig. S6) was flowed through the upper epithelial channel for 24 h, and then PBMCs were added to the vascular channel for 1 h without flow (Fig. 3 C and D). Treatment with both LPS (or TNF-α) and PBMCs resulted in the activation of intercellular adhesion molecule-1 (ICAM-1) expression on the surface of the endothelium (Fig. 3 C and D, Left, and Fig. S6) and a significant increase (P < 0.001) in the number of PBMCs that adhered to the surface of the capillary endothelium compared with controls (Fig. 3D). These results are consistent with our qPCR results, which also showed up-regulation of genes involved in immune cell trafficking (Fig. S5). Neither addition of LPS nor PBMCs alone was sufficient to induce ICAM-1 expression in these cells (Fig. 3D), which parallels the effects of LPS and PBMCs on epithelial production of inflammatory cytokines (Fig. 3A) as well as on villus injury (Fig. 2 B and D).

Evaluating Antiinflammatory Probiotic and Antibiotic Therapeutics On-Chip. To investigate how the gut microbiome modulates these inflammatory reactions, we cocultured the human intestinal villi with the eight strains of probiotic bacteria in the VSL#3 formulation that significantly enhanced intestinal differentiation (Fig. 1E and Fig. S1B). To mimic the in vivo situation, we colonized our microengineered gut on a chip with the commensal microbes (VSL#3) first and then subsequently added immune cells (PBMCs), pathogenic bacteria (EIEC), or both in combination. The VSL#3 microbial cells inoculated into the germ-free lumen of the epithelial channel primarily grew as discrete microcolonies in the spaces between adjacent villi (Fig. 4A and Movie S3) for more than a week in culture (Fig. S7A), and no planktonic growth was detected. These microbes did not overgrow like the EIEC (Fig. 2A and Movie S2), although occasional microcolonies also appeared at different spatial locations in association with the tips of the villi (Fig. S7 B and C). The presence of these living components of the normal gut microbiome significantly enhanced (P < 0.001) intestinal barrier function, producing more than a 50% increase in TEER relative to control cultures (Fig. 4B) without altering villus morphology (Fig. 4C). This result is consistent with clinical studies suggesting that probiotics, including VSL#3, can significantly enhance intestinal barrier function in vivo (18).

To mimic the effects of antibiotic therapies that are sometimes used clinically in patients with intestinal inflammatory disease (29), we identified a dose and combination of antibiotics (100 units per mL penicillin and 100 μg/mL streptomycin) that produced effective killing of both EIEC and VSL#3 microbes in liquid cultures (Fig. S9) and then injected this drug mixture into the epithelial channel of guton-a-chip devices infected with EIEC. When we added PBMCs to these devices 1 h later, intestinal barrier function (Fig. 4B) and villus morphology (Fig. 4C) were largely protected from injury, and there was a significant reduction in lesion area (Fig. 4D). Thus, the gut-on-a-chip was able to mimic suppression of injury responses previously observed clinically using other antibiotics that produce similar bactericidal effects.

Analyzing Mechanical Contributions to Bacterial Overgrowth. Finally, we used the gut-on-a-chip to analyze whether physical changes in peristalsis or villus motility contribute to intestinal pathologies, such as the small intestinal bacterial overgrowth (SIBO) (5, 6) observed in patients with ileus (8) and IBD (7). When the GFPEC bacteria were cultured on the villus epithelium under normal flow (30 μL/h), but in the absence of the physiological cyclic mechanical deformations, the number of colonized bacteria was significantly higher (P < 0.001) compared with gut chips that experienced mechanical deformations (Fig. 5A). Bacterial cell densities more than doubled within 21 h when cultured under conditions without cyclic stretching compared with gut chips that experienced physiological peristalsis-like mechanical motions, even though luminal flow was maintained constant (Fig. 5B). Thus, cessation of epithelial distortion appears to be sufficient to trigger bacterial overgrowth, and motility-induced luminal fluid flow is not the causative factor as assumed previously (7).

 

Discussion One of the critical prerequisites for mimicking the living human intestine in vitro is to establish a stable ecosystem containing physiologically differentiated intestinal epithelium, gut bacteria, and immune cells that can be cultured for many days to weeks. Here we leveraged a mechanically active gut-on-a-chip microfluidic device to develop an in vitro model of human intestinal inflammation that permits stable long-term coculture of commensal microbes of the gut microbiome with intestinal epithelial cells. The synthetic model of the human living intestine we built recapitulated the minimal set of structures and functions necessary to mimic key features of human intestinal pathophysiology during chronic inflammation and bacterial overgrowth including epithelial and vascular inflammatory processes and destruction of intestinal villi.

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Surgical Separation of Conjoined Twins been Computer-Aided with CT and 3D BioPrinting

Reporter: Aviva Lev-Ari, PhD, RN

 

From: “PR Newswire for Journalists” <push_services@prnewswire.com>

Sent: Wednesday, December 02, 2015 4:04 PM

To: info@newmedinc.com

Subject: CT and 3-D Printing Aid Surgical Separation of Conjoined Twins

 

CT and 3-D Printing Aid Surgical Separation of Conjoined Twins

CHICAGO, Dec. 2, 2015 /PRNewswire-USNewswire/ — A combination of detailed CT imaging and 3-D printing technology has been used for the first time in the surgical planning for separation of conjoined twins, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA).

Conjoined twins, or twins whose bodies are connected, account for approximately one of every 200,000 live births. Survival rates are low and separating them through surgery is extremely difficult because they often share organs and blood vessels.

Specialists at Texas Children’s Hospital in Houston brought a new approach to these challenges when they set out to surgically separate Knatalye Hope and Adeline Faith Mata, conjoined twins from Lubbock, Texas. Knatalye and Adeline were born on April 11, 2014, connected from the chest all the way down to the pelvis.

“This case was unique in the extent of fusion,” said the study’s lead author, Rajesh Krishnamurthy, M.D., chief of radiology research and cardiac imaging at Texas Children’s Hospital. “It was one of the most complex separations ever for conjoined twins.”

To prepare for the separation surgery, Dr. Krishnamurthy and colleagues performed volumetric CT imaging with a 320-detector scanner, administering intravenous contrast separately to both twins to enhance views of vital structures and help plan how to separate them to ensure survival of both children. They used a technique known as target mode prospective EKG gating to freeze the motion of the hearts on the images and get a more detailed view of the cardiovascular anatomy, while keeping the radiation exposure low.

“The CT scans showed that the babies’ hearts were in the same cavity but were not fused,” Dr. Krishnamurthy said. “Also, we detected a plane of separation of the liver that the surgeons would be able to use.”

The team translated the CT imaging results into a color-coded physical 3-D model with skeletal structures and supports made in hard plastic resin, and organs built from a rubber-like material. The livers were printed as separate pieces of the transparent resin, with major blood vessels depicted in white for better visibility. The models were designed so that they could be assembled together or separated during the surgical planning process. The surgical team used the models during the exhaustive preparation process leading up to the surgery.

On February 17, a little more than 10 months after they were born, the Mata twins underwent surgical separation by a team of more than 26 clinicians, including 12 surgeons, six anesthesiologists and eight surgical nurses. The official separation took place approximately 18 hours into the 26-hour surgery.

The 3-D models proved to be an excellent source of information, as there were no major discrepancies between the models and the twins’ actual anatomy.

“The surgeons found the landmarks for the liver, hearts and pelvic organs just as we had described,” Dr. Krishnamurthy said. “The concordance was almost perfect.”

Dr. Krishnamurthy expects the combination of volumetric CT, 3-D modeling, and 3-D printing to become a standard part of preparation for surgical separation of conjoined twins, although barriers remain to its adoption.

“The 3-D printing technology has advanced quite a bit, and the costs are declining. What’s limiting it is a lack of reimbursement for these services,” he said. “The procedure is not currently recognized by insurance companies, so right now hospitals are supporting the costs.”

Besides assisting clinicians prepare for surgery, the 3-D model also served another important function: helping the twins’ parents, Elysse and John Eric Mata, understand the process.

“When I showed the mother the model and explained the procedure, she held my hand and thanked me,” Dr. Krishnamurthy recalled. “They said, ‘For the first time, we understand what is going to happen with our babies.'”

Knatalye Hope returned home in May 2015 and her sister Adeline Faith came home a month later. They are both doing well and have a Facebook page, “Helping Faith & Hope Mata,” with updates on their progress.

Co-authors on the study are Nicholas Dodd, B.S., Darrell Cass, M.D., Amrita Murali and Jayanthi Parthasarathy, B.D.S., M.S., Ph.D.

Note: Copies of RSNA 2015 news releases and electronic images will be available online at RSNA.org/press15 beginning Monday, Nov. 30.

RSNA is an association of more than 54,000 radiologists, radiation oncologists, medical physicists and related scientists, promoting excellence in patient care and health care delivery through education, research and technologic innovation. The Society is based in Oak Brook, Ill. (RSNA.org)

For patient-friendly information on CT, visit RadiologyInfo.org.

SOURCE Radiological Society of North America (RSNA)

Radiological Society of North America (RSNA)

CONTACT: RSNA Newsroom, 1-312-791-6610; Before 11/28/15 or after 12/3/15: RSNA Media Relations, 1-630-590-7762; Linda Brooks, 1-630-590-7738, lbrooks@rsna.org; Maureen Morley, 1-630-590-7754, mmorley@rsna.org

Web Site: http://www.rsna.org

SOURCE

From: “Dr. Katie Katie Siafaca” <info@newmedinc.com>

Reply-To: “Dr. Katie Katie Siafaca” <info@newmedinc.com>

Date: Thursday, December 3, 2015 at 2:00 PM

To: Aviva Lev-Ari <AvivaLev-Ari@alum.berkeley.edu>

Subject: fw: CT and 3-D Printing Aid Surgical Separation of Conjoined Twins

 

 

 

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FDA Guidance On Source Animal, Product, Preclinical and Clinical Issues Concerning the Use of Xenotranspantation Products in Humans – Implications for 3D BioPrinting of Regenerative Tissue

Reporter: Stephen J. Williams, Ph.D.

 

The FDA has submitted Final Guidance on use xeno-transplanted animal tissue, products, and cells into human and their use in medical procedures. Although the draft guidance was to expand on previous guidelines to prevent the introduction, transmission, and spread of communicable diseases, this updated draft may have implications for use of such tissue in the emerging medical 3D printing field.

This document is to provide guidance on the production, testing and evaluation of products intended for use in xenotransplantation. The guidance includes scientific questions that should be addressed by sponsors during protocol development and during the preparation of submissions to the Food and Drug Administration (FDA), e.g., Investigational New Drug Application (IND) and Biologics License Application (BLA). This guidance document finalizes the draft guidance of the same title dated February 2001.

For the purpose of this document, xenotransplantation refers to any procedure that involves the transplantation, implantation, or infusion into a human recipient of either (a) live cells, tissues, or organs from a nonhuman animal source, or (b) human body fluids, cells, tissues or organs that have had ex vivo contact with live nonhuman animal cells, tissues or organs. For the purpose of this document, xenotransplantation products include live cells, tissues or organs used in xenotransplantation. (See Definitions in section I.C.)

This document presents issues that should be considered in addressing the safety of viable materials obtained from animal sources and intended for clinical use in humans. The potential threat to both human and animal welfare from zoonotic or other infectious agents warrants careful characterization of animal sources of cells, tissues, and organs. This document addresses issues such as the characterization of source animals, source animal husbandry practices, characterization of xenotransplantation products, considerations for the xenotransplantation product manufacturing facility, appropriate preclinical models for xenotransplantation protocols, and monitoring of recipients of xenotransplantation products. This document recommends specific practices intended to prevent the introduction and spread of infectious agents of animal origin into the human population. FDA expects that new methods proposed by sponsors to address specific issues will be scientifically rigorous and that sufficient data will be presented to justify their use.

Examples of procedures involving xenotransplantation products include:

  • transplantation of xenogeneic hearts, kidneys, or pancreatic tissue to treat organ failure,
  • implantation of neural cells to ameliorate neurological degenerative diseases,
  • administration of human cells previously cultured ex vivo with live nonhuman animal antigen-presenting or feeder cells, and
  • extracorporeal perfusion of a patient’s blood or blood component perfused through an intact animal organ or isolated cells contained in a device to treat liver failure.

The guidance addresses issues such as:

  1. Clinical Protocol Review
  2. Xenotransplantation Site
  3. Criteria for Patient Selection
  4. Risk/Benefit Assessment
  5. Screening for Infectious Agents
  6. Patient Follow-up
  7. Archiving of Patient Plasma and Tissue Specimens
  8. Health Records and Data Management
  9. Informed Consent
  10. Responsibility of the Sponsor in Informing the Patient of New Scientific Information

A full copy of the PDF can be found below for reference:

fdaguidanceanimalsourcesxenotransplatntation

An example of the need for this guidance in conjunction with 3D printing technology can be understood from the below article (source http://www.geneticliteracyproject.org/2015/09/03/pig-us-xenotransplantation-new-age-chimeric-organs/)

Pig in us: Xenotransplantation and new age of chimeric organs

David Warmflash | September 3, 2015 | Genetic Literacy Project

Imagine stripping out the failing components of an old car — the engine, transmission, exhaust system and all of those parts — leaving just the old body and other structural elements. Replace those old mechanical parts with a brand new electric, hydrogen powered, biofuel, nuclear or whatever kind of engine you want and now you have a brand new car. It has an old frame, but that’s okay. The frame wasn’t causing the problem, and it can live on for years, undamaged.

When challenged to design internal organs, tissue engineers are taking a similar approach, particularly with the most complex organs, like the heart, liver and kidneys. These organs have three dimensional structures that are elaborate, not just at the gross anatomic level, but in microscopic anatomy too. Some day, their complex connective tissue scaffolding, the stroma, might be synthesized from the needed collagen proteins with advanced 3-D printing. But biomedical engineering is not there yet, so right now the best candidate for organ scaffolding comes from one of humanity’s favorite farm animals: the pig.

Chimera alarmists connecting with anti-biotechnology movements might cringe at the thought of building new human organs starting with pig tissue, but if you’re using only the organ scaffolding and building a working organ from there, pig organs may actually be more desirable than those donated by humans.

How big is the anti-chimerite movement?

Unlike anti-GMO and anti-vaccination activists, there really aren’t too many anti-chemerites around. Nevertheless, there is a presence on the web of people who express concern about mixing of humans and non-human animals. Presently, much of their concern is focussed on the growing of human organs inside non-human animals, pigs included. One anti-chemerite has written that it could be a problem for the following reason:

Once a human organ is grown inside a pig, that pig is no longer fully a pig. And without a doubt, that organ will no longer be a fully human organ after it is grown inside the pig. Those receiving those organs will be allowing human-animal hybrid organs to be implanted into them. Most people would be absolutely shocked to learn some of the things that are currently being done in the name of science.

The blog goes on to express alarm about the use of human genes in rice and from there morphs into an off the shelf garden variety anti-GMO tirade, though with an an anti-chemeric current running through it. The concern about making pigs a little bit human and humans a little bit pig becomes a concern about making rice a little bit human. But the concern about fusing tissues and genes of humans and other species does not fit with the trend in modern medicine.

Utilization of pig tissue enters a new age 

pigsinus

A porcine human ear for xenotransplantation. source: The Scientist

For decades, pig, bovine and other non-human tissues have been used in medicine. People are walking around with pig and cow heart valves. Diabetics used to get a lot of insulin from pigs and cows, although today, thanks to genetic engineering, they’re getting human insulin produced by microorganisms modified genetically to make human insulin, which is safer and more effective.

When it comes to building new organs from old ones, however, pig organs could actually be superior for a couple of reasons. For one thing, there’s no availability problem with pigs. Their hearts and other organs also have all of the crucial components of the extracellular matrix that makes up an organ’s scaffolding. But unlike human organs, the pig organs don’t tend to carry or transfer human diseases. That is a major advantage that makes them ideal starting material. Plus there is another advantage: typically, the hearts of human cadavers are damaged, either because heart disease is what killed the human owner or because resuscitation efforts aimed at restarting the heart of a dying person using electrical jolts and powerful drugs.

Rebuilding an old organ into a new one

How then does the process work? Whether starting with a donated human or pig organ, there are several possible methods. But what they all have in common is that only the scaffolding of the original organ is retained. Just like the engine and transmission of the old car, the working tissue is removed, usually using detergents. One promising technique that has been applied to engineer new hearts is being tested by researchers at the University of Pittsburgh. Detergents pumped into the aorta attached to a donated heart (donated by a human cadaver, or pig or cow). The pressure keeps the aortic valve closed, so the detergents to into the coronary arteries and through the myocardial (heart muscle) and endocardial (lining over the muscle inside the heart chambers) tissue, which thus gets dissolved over the course of days. What’s left is just the stroma tissue, forming a scaffold. But that scaffold has signaling factors that enable embryonic stem cells, or specially programed adult pleuripotent cells to become all of the needed cells for a new heart.

Eventually, 3-D printing technology may reach the point when no donated scaffolding is needed, but that’s not the case quite yet, plus with a pig scaffolding all of the needed signaling factors are there and they work just as well as those in a human heart scaffold. All of this can lead to a scenario, possibly very soon, in which organs are made using off-the-self scaffolding from pig organs, ready to produce a custom-made heart using stem or other cells donated by new organ’s recipient.

David Warmflash is an astrobiologist, physician, and science writer. Follow @CosmicEvolution to read what he is saying on Twitter.

And a Great Article in The Scientist by Dr. Ed Yong Entitled

Replacement Parts

To cope with a growing shortage of hearts, livers, and lungs suitable for transplant, some scientists are genetically engineering pigs, while others are growing organs in the lab.

By Ed Yong | August 1, 2012

Source: http://www.the-scientist.com/?articles.view/articleNo/32409/title/Replacement-Parts/

.. where Joseph Vacanti and David Cooper figured that using

“engineered pigs without the a-1,3-galactosyltransferase gene that produces the a-gal residues. In addition, the pigs carry human cell-membrane proteins such as CD55 and CD46 that prevent the host’s complement system from assembling and attacking the foreign cells”

thereby limiting rejection of the xenotransplated tissue.

In addition to issues related to animal virus transmission the issue of optimal scaffolds for organs as well as the advantages which 3D Printing would have in mass production of organs is discussed:

To Vacanti, artificial scaffolds are the future of organ engineering, and the only way in which organs for transplantation could be mass-produced. “You should be able to make them on demand, with low-cost materials and manufacturing technologies,” he says. That is relatively simple for organs like tracheas or bladders, which are just hollow tubes or sacs. Even though it is far more difficult for the lung or liver, which have complicated structures, Vacanti thinks it will be possible to simulate their architecture with computer models, and fabricate them with modern printing technology. (See “3-D Printing,” The Scientist, July 2012.) “They obey very ordered rules, so you can reduce it down to a series of algorithms, which can help you design them,” he says. But Taylor says that even if the architecture is correct, the scaffold would still need to contain the right surface molecules to guide the growth of any added cells. “It seems a bit of an overkill when nature has already done the work for us,” she says.

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New FDA Draft Guidance On Homologous Use of Human Cells, Tissues, and Cellular and Tissue-Based Products – Implications for 3D BioPrinting of Regenerative Tissue

Reporter: Stephen J. Williams, Ph.D.

The FDA recently came out with a Draft Guidance on use of human cells, tissues and cellular and tissue-based products (HCT/P) {defined in 21 CFR 1271.3(d)} and their use in medical procedures. Although the draft guidance was to expand on previous guidelines to prevent the introduction, transmission, and spread of communicable diseases, this updated draft may have implications for use of such tissue in the emerging medical 3D printing field.

A full copy of the PDF can be found here for reference but the following is a summary of points of the guidance.FO508ver – 2015-373 HomologousUseGuidanceFinal102715

In 21 CFR 1271.10, the regulations identify the criteria for regulation solely under section 361 of the PHS Act and 21 CFR Part 1271. An HCT/P is regulated solely under section 361 of the PHS Act and 21 CFR Part 1271 if it meets all of the following criteria (21 CFR 1271.10(a)):

  • The HCT/P is minimally manipulated;
  • The HCT/P is intended for homologous use only, as reflected by the labeling, advertising, or other indications of the manufacturer’s objective intent;
  • The manufacture of the HCT/P does not involve the combination of the cells or tissues with another article, except for water, crystalloids, or a sterilizing, preserving, or storage agent, provided that the addition of water, crystalloids, or the sterilizing, preserving, or storage agent does not raise new clinical safety concerns with respect to the HCT/P; and
  • Either:
  1. The HCT/P does not have a systemic effect and is not dependent upon the metabolic activity of living cells for its primary function; or
  2. The HCT/P has a systemic effect or is dependent upon the metabolic activity of living cells for its primary function, and:
  3. Is for autologous use;
  4. Is for allogeneic use in a first-degree or second-degree blood relative; or
  5. Is for reproductive use.

If an HCT/P does not meet all of the criteria in 21 CFR 1271.10(a), and the establishment that manufactures the HCT/P does not qualify for any of the exceptions in 21 CFR 1271.15, the HCT/P will be regulated as a drug, device, and/or biological product under the Federal Food, Drug and Cosmetic Act (FD&C Act), and/or section 351 of the PHS Act, and applicable regulations, including 21 CFR Part 1271, and pre-market review will be required.

1 Examples of HCT/Ps include, but are not limited to, bone, ligament, skin, dura mater, heart valve, cornea, hematopoietic stem/progenitor cells derived from peripheral and cord blood, manipulated autologous chondrocytes, epithelial cells on a synthetic matrix, and semen or other reproductive tissue. The following articles are not considered HCT/Ps: (1) Vascularized human organs for transplantation; (2) Whole blood or blood components or blood derivative products subject to listing under 21 CFR Parts 607 and 207, respectively; (3) Secreted or extracted human products, such as milk, collagen, and cell factors, except that semen is considered an HCT/P; (4) Minimally manipulated bone marrow for homologous use and not combined with another article (except for water, crystalloids, or a sterilizing, preserving, or storage agent, if the addition of the agent does not raise new clinical safety concerns with respect to the bone marrow); (5) Ancillary products used in the manufacture of HCT/P; (6) Cells, tissues, and organs derived from animals other than humans; (7) In vitro diagnostic products as defined in 21 CFR 809.3(a); and (8) Blood vessels recovered with an organ, as defined in 42 CFR 121.2 that are intended for use in organ transplantation and labeled “For use in organ transplantation only.” (21 CFR 1271.3(d))

Contains Nonbinding Recommendations
Draft – Not for Implementation

Section 1271.10(a)(2) (21 CFR 1271.10(a)(2)) provides that one of the criteria for an HCT/P to be regulated solely under section 361 of the PHS Act is that the “HCT/P is intended for homologous use only, as reflected by the labeling, advertising, or other indications of the manufacturer’s objective intent.” As defined in 21 CFR 1271.3(c), homologous use means the repair, reconstruction, replacement, or supplementation of a recipient’s cells or tissues with an HCT/P that performs the same basic function or functions in the recipient as in the donor. This criterion reflects the Agency’s conclusion that there would be increased safety and effectiveness concerns for HCT/Ps that are intended for a non-homologous use, because there is less basis on which to predict the product’s behavior, whereas HCT/Ps for homologous use can reasonably be expected to function appropriately (assuming all of the other criteria are also met).2 In applying the homologous use criterion, FDA will determine what the intended use of the HCT/P is, as reflected by the the labeling, advertising, and other indications of a manufacturer’s objective intent, and will then apply the homologous use definition.

FDA has received many inquiries from manufacturers about whether their HCT/Ps meet the homologous use criterion in 21 CFR 1271.10(a)(2). Additionally, transplant and healthcare providers often need to know this information about the HCT/Ps that they are considering for use in their patients. This guidance provides examples of different types of HCT/Ps and how the regulation in 21 CFR 1271.10(a)(2) applies to them, and provides general principles that can be applied to HCT/Ps that may be developed in the future. In some of the examples, the HCT/Ps may fail to meet more than one of the four criteria in 21 CFR 1271.10(a).

III. QUESTIONS AND ANSWERS

  1. What is the definition of homologous use?

Homologous use means the repair, reconstruction, replacement, or supplementation of a recipient’s cells or tissues with an HCT/P that performs the same basic function or functions in the recipient as in the donor (21 CFR 1271.3(c)), including when such cells or tissues are for autologous use. We generally consider an HCT/P to be for homologous use when it is used to repair, reconstruct, replace, or supplement:

  • Recipient cells or tissues that are identical (e.g., skin for skin) to the donor cells or tissues, and perform one or more of the same basic functions in the recipient as the cells or tissues performed in the donor; or,
  • Recipient cells that may not be identical to the donor’s cells, or recipient tissues that may not be identical to the donor’s tissues, but that perform one or more of the same basic functions in the recipient as the cells or tissues performed in the donor.3

2 Proposed Approach to Regulation of Cellular and Tissue-Based Products, FDA Docket. No. 97N-0068 (February. 28, 1997) page 19. http://www.fda.gov/downloads/biologicsbloodvaccines/guidancecomplianceregulatoryinformation/guidances/tissue/ ucm062601.pdf.

3“Establishment Registration and Listing for Manufacturers of Human Cellular and Tissue-Based Products” 63 FR 26744 at 26749 (May 14, 1998).

Contains Nonbinding Recommendations
Draft – Not for Implementation

1-1. A heart valve is transplanted to replace a dysfunctional heart valve. This is homologous use because the donor heart valve performs the same basic function in the donor as in the recipient of ensuring unidirectional blood flow within the heart.

1-2. Pericardium is intended to be used as a wound covering for dura mater defects. This is homologous use because the pericardium is intended to repair or reconstruct the dura mater and serve as a covering in the recipient, which is one of the basic functions it performs in the donor.

Generally, if an HCT/P is intended for use as an unproven treatment for a myriad of

diseases or conditions, the HCT/P is likely not intended for homologous use only.4

  1. What does FDA mean by repair, reconstruction, replacement, or supplementation of a recipient’s cells or tissues?

Repair generally means the physical or mechanical restoration of tissues, including by covering or protecting. For example, FDA generally would consider skin removed from a donor and then transplanted to a recipient in order to cover a burn wound to be a homologous use. Reconstruction generally means surgical reassembling or re-forming. For example, reconstruction generally would include the reestablishment of the physical integrity of a damaged aorta.5 Replacement generally means substitution of a missing tissue or cell, for example, the replacement of a damaged or diseased cornea with a healthy cornea or the replacement of donor hematopoietic stem/progenitor cells in a recipient with a disorder affecting the hematopoietic system that is inherited, acquired, or the result of myeloablative treatment. Supplementation generally means to add to, or complete. For example, FDA generally would consider homologous uses to be the implantation of dermal matrix into the facial wrinkles to supplement a recipient’s tissues and the use of bone chips to supplement bony defects. Repair, reconstruction, replacement, and supplementation are not mutually exclusive functions and an HCT/P could perform more than one of these functions for a given intended use.

  1. What does FDA mean by “the same basic function or functions” in the definition of homologous use?

For the purpose of applying the regulatory framework, the same basic function or functions of HCT/Ps are considered to be those basic functions the HCT/P performs in the body of the donor, which, when transplanted, implanted, infused, or transferred, the HCT/P would be expected to perform in the recipient. It is not necessary for the HCT/P in the recipient to perform all of the basic functions it performed in the donor, in order to

4 “Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing” 66 FR 5447 at 5458 (January 19, 2001).

5 “Current Good Tissue Practice for Human Cell, Tissue, and Cellular and Tissue-Based Product Establishments; Inspection and Enforcement” 69 FR 68612 at 68643 (November 24, 2004) states, “HCT/Ps with claims for “reconstruction or repair” can be regulated solely under section 361 of the PHS Act, provided the HCT/P meets all the criteria in § 1271.10, including minimal manipulation and homologous use.”

Contains Nonbinding Recommendations
Draft – Not for Implementation

meet the definition of homologous use. However, to meet the definition of homologous use, any of the basic functions that the HCT/P is expected to perform in the recipient must be a basic function that the HCT/P performed in the donor.

A homologous use for a structural tissue would generally be to perform a structural function in the recipient, for example, to physically support or serve as a barrier or conduit, or connect, cover, or cushion.

A homologous use for a cellular or nonstructural tissue would generally be a metabolic or biochemical function in the recipient, such as, hematopoietic, immune, and endocrine functions.

3-1. The basic functions of hematopoietic stem/progenitor cells (HPCs) include to form and to replenish the hematopoietic system. Sources of HPCs include cord blood, peripheral blood, and bone marrow.6

  1. HPCs derived from peripheral blood are intended for transplantation into an individual with a disorder affecting the hematopoietic system that is inherited, acquired, or the result of myeloablative treatment. This is homologous use because the peripheral blood product performs the same basic function of reconstituting the hematopoietic system in the recipient.
  2. HPCs derived from bone marrow are infused into an artery with a balloon catheter for the purpose of limiting ventricular remodeling following acute myocardial infarction. This is not homologous use because limiting ventricular remodeling is not a basic function of bone marrow.
  3. A manufacturer provides HPCs derived from cord blood with a package insert stating that cord blood may be infused intravenously to differentiate into neuronal cells for treatment of cerebral palsy. This is not homologous use because there is insufficient evidence to support that such differentiation is a basic function of these cells in the donor.

3-2. The basic functions of the cornea include protecting the eye by forming its outermost layer and serving as the refracting medium of the eye. A corneal graft is transplanted to restore sight in a patient with corneal blindness. This is homologous use because a corneal graft performs the same basic functions in the donor as in the recipient.

3-3. The basic functions of a vein or artery include serving as a conduit for blood flow throughout the body. A cryopreserved vein or artery is used for arteriovenous access during hemodialysis. This is homologous use because the vein or artery is supplementing the vessel as a conduit for blood flow.

3-4. The basic functions of amniotic membrane include covering, protecting, serving as a selective barrier for the movement of nutrients between the external and in utero

6 Bone marrow meets the definition of an HCT/P only if is it more than minimally manipulated; intended by the manufacturer for a non-homologous use, or combined with certain drugs or devices.

Contains Nonbinding Recommendations
Draft – Not for Implementation

environment, and to retain fluid in utero. Amniotic membrane is used for bone tissue replacement to support bone regeneration following surgery to repair or replace bone defects. This is not a homologous use because bone regeneration is not a basic function of amniotic membrane.

3-5. The basic functions of pericardium include covering, protecting against infection, fixing the heart to the mediastinum, and providing lubrication to allow normal heart movement within chest. Autologous pericardium is used to replace a dysfunctional heart valve in the same patient. This is not homologous use because facilitating unidirectional blood flow is not a basic function of pericardium.

  1. Does my HCT/P have to be used in the same anatomic location to perform the same basic function or functions?

An HCT/P may perform the same basic function or functions even when it is not used in the same anatomic location where it existed in the donor.7 A transplanted HCT/P could replace missing tissue, or repair, reconstruct, or supplement tissue that is missing or damaged, either when placed in the same or different anatomic location, as long as it performs the same basic function(s) in the recipient as in the donor.

4-1. The basic functions of skin include covering, protecting the body from external force, and serving as a water-resistant barrier to pathogens or other damaging agents in the external environment. The dermis is the elastic connective tissue layer of the skin that provides a supportive layer of the integument and protects the body from mechanical stress.

  1. An acellular dermal product is used for supplemental support, protection, reinforcement, or covering for a tendon. This is homologous use because in both anatomic locations, the dermis provides support and protects the soft tissue structure from mechanical stress.
  2. An acellular dermal product is used for tendon replacement or repair. This is not homologous use because serving as a connection between muscle and bone is not a basic function of dermis.

4-2. The basic functions of amniotic membrane include serving as a selective barrier for the movement of nutrients between the external and in utero environment and to retain fluid in utero. An amniotic membrane product is used for wound healing of dermal ulcers and defects. This is not homologous use because wound healing of dermal lesions is not a basic function of amniotic membrane.

4-3. The basic functions of pancreatic islets include regulating glucose homeostasis within the body. Pancreatic islets are transplanted into the liver through the portal vein,

7 “Human Cells, Tissues, and Cellular and Tissue-Based Products; Establishment Registration and Listing” 66 FR 5447 at 5458 (January 19, 2001).

6

Contains Nonbinding Recommendations
Draft – Not for Implementation

for preservation of endocrine function after pancreatectomy. This is homologous use because the regulation of glucose homeostasis is a basic function of pancreatic islets.

  1. What does FDA mean by “intended for homologous use” in 21 CFR 1271.10(a)(2)?

The regulatory criterion in 21 CFR 1271.10(a)(2) states that the HCT/P is intended for homologous use only, as reflected by the labeling, advertising, or other indications of the manufacturer’s objective intent.

Labeling includes the HCT/P label and any written, printed, or graphic materials that supplement, explain, or are textually related to the product, and which are disseminated by or on behalf of its manufacturer.8 Advertising includes information, other than labeling, that originates from the same source as the product and that is intended to supplement, explain, or be textually related to the product (e.g., print advertising, broadcast advertising, electronic advertising (including the Internet), statements of company representatives).9

An HCT/P is intended for homologous use when its labeling, advertising, or other indications of the manufacturer’s objective intent refer to only homologous uses for the HCT/P. When an HCT/P’s labeling, advertising, or other indications of the manufacturer’s objective intent refer to non-homologous uses, the HCT/P would not meet the homologous use criterion in 21 CFR 1271.10(a)(2).

  1. What does FDA mean by “manufacturer’s objective intent” in 21 CFR 1271.10(a)(2)?

A manufacturer’s objective intent is determined by the expressions of the manufacturer or its representatives, or may be shown by the circumstances surrounding the distribution of the article. A manufacturer’s objective intent may, for example, be shown by labeling claims, advertising matter, or oral or written statements by the manufacturer or its representatives. It may be shown by the circumstances that the HCT/P is, with the knowledge of the manufacturer or its representatives, offered for a purpose for which it is neither labeled nor advertised.

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