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It's still a long way off to see culturing organs for use in transplants. The work of Prof. Jacob Hanna on stem cells is paving the way for this to become a reality.
A team from the Weizmann Institute of Science's Molecular Genetics Department has found a way to culture human stem cells in a much earlier state than was previously possible. Stem cells created by them are far more competent and can integrate more efficiently with their host environment. This improves the chances of getting a cross-species chimera, which allows cells from one creature to play a significant role in the development of another.
The recent findings show that early human cells can be integrated into mice, due to their undifferentiated state, and that they can develop into any type of cell in the body, including other stem cells. The researchers have a protocol for increasing efficiency with which these cells can integrate. If we could improve our ability to create and study these cell types, we could transfer cells from one animal to another.
The first stem cell injection into a mouse and show that they can successfully integrate into the latter's developing embryo broke ground in the lab. Eight years after this study was first published, the team felt they could go one step further and produce a fully nave form of stem cells for use in similar procedures. As they pondered the idea, they knew that it was almost impossible to achieve. "Our experience with producing similar cells in mice has taught us to expect challenging obstacles along the way."
These cells don't differentiate as well as they should because of genetic and epigenetic instability, which is a requirement for their integration into another animal's embryo. Only a small percentage of cells that have been transferred between species actually contribute to development.
The ability to differentiate perfectly is one of the things that the researchers in the new study were able to boost these numbers with. Stem cells that can integrate well without causing damage to the host are a result of the researchers' alterations to an important gene that contributes to genome stability. "We found a way to make human stem cells more competent, and competitive, increasing the chances for a successful transfer by about fivefold compared to what we were able to do in the past."
The present study shows that human nave stem cells can differentiate into primordial germ cells, the progenitors of egg or sperm cells, and also into extraembryonic tissues, such as the placenta and yolk sac cells. Such cells could be used as a source for developing synthetic embryos without the need for donor eggs. "Reaching this state with mouse stem cells is very difficult, because human cells are apparently different," he said.
The researchers found that the behavior of human and mouse stem cells were different. The work that still needs to be done in making the dream of developing "made-to-order" organs a reality is exposed by the differences.
Understanding these differences will be crucial for overcoming issues still facing the field of stem cell research and application, for example, if we want to grow a pancreas in pigs for human transplantation. It would appear that the team has taken a step in the right direction.
The principles of signaling pathway modulation for enhancing human naive pluripotency are described in Cell Stem Cell. There is an article in the journal Stem.
The journal contains information about cell stem cell.
A new study brings us one step closer to growing human organs for transplantation.
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