An important step has been accomplished in the possibility of growing human organs in animals. The organs would be created from stem cells derived from the future recipient’s skin so that the issue of rejection is minimized. Scientists at Salk Institute announced that undifferentiated human stem cells have survived for four weeks in a mother pig. Undifferentiated cells have the potential to become specialized to create specific human tissue and organs in the presence of the right chemical cocktail, rather the right sequence of chemicals.
Scientists have attempted growth of human tissue in glass tubes, but do not have the recipes for the chemical cocktails for different organs. Now here comes something I don’t understand. By genetically engineering an embryo to be unable to create a certain type of organ, somehow the embryo’s chemical cocktail might use the inserted human cells to make the organ. What I don’t get is if the master gene for a liver, say, has been removed, then how does the embryo know to make one from the human cells? Whether I understand it or not, the procedure has worked for rats and mice. A rat’s master gene for a pancreas has been removed causing the embryo to create one from implanted mouse cells. The pancreas then has been transplanted into a mouse suffering from diabetes.
In the pig experiment, the pig’s genes were not modified, and when the embryos were withdrawn after four weeks, the surviving human cells had become precursors of human muscle, heart, pancreas, liver and spinal cord tissue. Rats and mice are more closely related than humans and pigs, which makes the success less expected. Hmm, I know some humans . . . The goal is to control the development of the human cells into the intended organ. The rat/mice experiment shows promise. Some research has been banned in the past because of perceived risk to human cells developing into cells of the brain or reproductive organs of the animals. The removal of the embryos after four weeks is intended to respect ethical concerns.
Scientists say that even if organs are not developed for transplant, the tissue could be useful for testing drugs and treatment for disease in place of or before human trials as well as for learning more about embryo development.
We are said to think with our guts or emotions rather than our brains. I admit to feeling uneasy about this experimentation, but in reading the articles and learning that 76,000 people per year are in need of transplants, I understand I need to weigh the idea with my brain cells.