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Posts Tagged ‘human induced pluripotent stem cells’


Stem Cells Differentiated into Insulin-Producing Cells in Mice

Reported: Irina Robu, PhD

Dr. Douglas Melton team from Harvard University funded in part by NIH’s National Institute of Diabetes and Digestive and Kidney Diseases set out to transform stem cells into beta cells that have the potential to replace damaged beta cells. While scientists have been able to change stem cells into insulin-producing cells, these cells don’t have markers that indicate they are beta cells, and they aren’t responsive to glucose.

Since diabetes is a disorder of elevated blood sugars where the body does not harvest enough insulin to meet where the body does not harvest enough insulin to respond properly to the insulin being made. When blood glucose levels rise, beta cells in the pancreas normally make the hormone insulin. Insulin triggers cells throughout the body to take up sugar from the blood. In type 2 diabetes, the most common form, tissues in the body lose their sensitivity to insulin, and pancreatic beta cells can’t make enough insulin to keep glucose levels in check. In type 1 diabetes, the body’s own immune system attacks and destroys beta cells. High blood glucose levels can lead to heart disease, blindness, and other health problems over time.

One approach to treat diabetes is to replace destroyed beta cells. Transplanted human pancreatic cells from deceased donors have been successfully used to treat people with type 1 diabetes. But this method is restricted by the accessibility of donor cells and the side effects of immunosuppression. The other approach is to develop functioning beta cells from stem cells which have the potential to transform into many different cell types. These cells can grow indefinitely in the laboratory and can differentiate, into any cell type found in the body.
In this experiment, the researchers grew a human embryonic stem cell line and 2 human-induced pluripotent stem cell lines in a culture system that allowed them to produce large numbers of cells. The researchers tested more than 150 combinations of over 70 compounds to figure out a method to produce functional human beta cells from the cultured stem cells which when added in exact combinations over a period of several weeks, they transformed human pluripotent stem cells into beta cells that functioned similarly to normal adult beta cells.

The cultured beta cells had specific markers that were found on normal beta cells which displayed changes in calcium levels when exposed to glucose and packaged insulin into granules. However, when transplanted into mice these cells secreted insulin in response to glucose. However, when the cells were transplanted into diabetic mice, abnormally high blood glucose levels lowered. More work is needed to develop these cells for clinical use. However, at this point they can serve as a useful screening tool for diabetes drugs.

SOURCE
http://www.frontlinegenomics.com/news/26168/stem-cells-turned-into-insulin-producing-cells-in-mice/

 

 

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Functioning Human Neural Networks Grown in 3-D from Stem Cells

Reporter: Irina Robu, PhD

 

Researchers at Tuffs University developed three-dimensional human tissue model that mimics structural and functional features of the brain and were able to demonstrate sustained neural activity over several months. The 3D brain tissue models were the result of a collaborative effort between researchers from Tufts University School of Engineering, Tufts University School of Medicine, the Sackler School of Graduate Biomedical Sciences at Tufts, and the Jackson Laboratory.

 

These tissue models have the ability to populate a 3D matrix of silk protein and collagen with cells from patients with Parkinson’s disease, Alzheimer’s disease and the ability to

  • explore cell interactions,
  • disease progression and
  • response to treatment.

The 3D brain tissue models overcome a crucial challenge of previous models which is the availability of human source neurons due to the fact that neurological tissues are rarely removed from

  • healthy patients, and are usually available
  • post-mortem from diseased patients.

The 3D tissue models are populated with human induced pluripotent stem cells (iPSCs) that can be derived from several sources, including patient skin. The iPSCs are generated by turning back the clock on cell development to their embryonic-like precursors. They can then be dialed forward again to any cell type, including neurons. The porous structure of the 3D tissue cultures labeled in the research delivers sufficient oxygenation, access for nutrients and measurement of cellular properties. A clear window in the center of each 3D matrix allows researchers to visualize the

  • growth,
  • organization and
  • behavior of individual cells.

According to David L. Kaplan, “the silk-collagen scaffolds provide the right environment to produce cells with the genetic signatures and electrical signaling found in native neuronal tissues”. Compared to growing and culturing cells in two dimensions, the three-dimensional matrix yields a knowingly extra complete mix of cells found in neural tissue, with the appropriate morphology and expression of receptors and neurotransmitters. Other researchers have used iPSCs to create brain-like organoids, but can still make it difficult figuring out what individual cells are doing in real time. Likewise, cells in the center of the organoids may not obtain enough oxygen or nutrients to function in a native state.

However, the researchers can see a great advantage of the 3D tissue models with advanced imaging techniques, and the addition of cell types such as

  • microglia and
  • endothelial cells,

to create a more complete model of the brain environment and the complex interactions that are involved in

  • signaling,
  • learning and plasticity, and
  • degeneration.

 

SOURCE

https://www.rdmag.com/news/2018/10/scientists-grow-functioning-human-neural-networks-3d-stem-cells

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