Saturday, March 13, 2010

Artificial Organs

For the thousands of people that suffer from organ failure there may be a new hope on the horizon. Today doctors and and biomedical scientists have developed a way to actually regrow healthy tissue. Researchers at the Wake Forest Institute for Regenerative Medicine have successfully grown hearts, kidneys, parts of fingers, and ears. However the most successful organ to be generated artificially has been the bladder. Every organ has its own special stem cells specifically unique to that body part. When scientists are able to isolate the cells, the cells begin to multiply. Meanwhile, the scientists create an exact mold of the bladder. Once the scientists have grown a sufficient number of bladder cells from the stem cells they begin to layer the cells onto the mold. The mold dissolves over time as the cells continue to grow. One amazing thing about artificial organs is that because they are made from the patients own cells there is much less of a change that they body will reject the organ. Rejection can often be a major problem with transplant that often requires drugs that take a harsh toll on the body. There is a special "pixie dust" found in pigs bladders called ecm or extracellular matrix that when placed that encourage grow of healthy tissues. It has been used to regrew muscle and to ensure the sucess of hands transplants.
People die every single day waiting for an organ and this could potentially give them an organ mere weeks that they discover that they need the new organ. The biggest problem with regenerative medicine is that there is still a huge question mark next to it. There are so many trials to be done and the bladder has really been the only successful human transplant of an artificial organ. Scientists still worry about how to control growth of the new tissues within the body etc, and many still question man's right to "play god". However, in the case of regenerative medicine, the promise seems to far outweigh the problems.

Tuesday, March 2, 2010

Stem Cells

Embryonic stem cells are stem cells derived from embryos. Stem cells are usually extracted during the blastocyst stage of development. In essence, a blasotcyst is a hollow ball of cells. The out most part of the blastocyst, called the trophoblast, will eventually become the placenta. A cluster of cells inside the trophoblast, called the inner cell mass, is composed of the stem cells or the cells that will eventually become the fetus. Embryonic stem cells are undifferentiated cells that have the potential to become any cell needed in the body. In this undifferentiated state they can multiply and self renew almost indefinitely. In a lab setting, the trophoblast would be destroyed and the stem cells would placed in in small groups into petri dishes. Scientists are still trying to perfect ways of differentiating these cells, but growth factors like sonic hedgehog and activin are sometimes used to instruct the stem cells on what specific cells to differentiate into. One problem with embryonic stem cell research is that it has caused quite a moral debate. Many feel that even though embryonic stem cells have the potential to save lives, it is not humane to destroy a life to do so. However a Japanese doctor, Shinya Yamanaka, seems to have found a solution. He is able to take adult skin cells and insert four genes that reprogram the skin cells into embryonic stem cells. These cell are called IPS or induced pluripotent stem cells. Though there are still a few kinks to be worked out these cells present great promise. Another less controversial alternative to embryonic stem cells are adult stem cells. Adult stem cells are found in certain organs and tissues in the body. The cells can differentiate themselves into most parts of that particular organ or tissue. These cells however do not divide nearly as readily as embryonic stem cells.

Doctors and scientists have devised many different ways of using stem cells to treat various diseases. For instance, stem cells in bone marrow transplants help the body to produce blood and immune cells which is very helpful for people with diseases like leukemia. Stem cells taken from a patient's umbilical cord can also be used in bone marrow transplants. Scientists have also grown stem cells found in the hair follicles that can help grow skin grafts for burn victims. In horses, cells are also used to promote growth and healing in injured muscles or ligaments. The hope is that in humans stem cells can be used to regrow areas of the brain that have been damaged by degenerative neural disorders, to help patients with sickle cell anemia grow healthy blood cells, and help diabetics grows blood cells that produce more insulin.