Transplantation
Transplanting living tissue from person to person is a standard surgical procedure. Successful organ transplants between humans have created an increased demand for donor organs that has vastly outgrown supply. Closing the gap between supply and demand is not easy. The tissue of the donor and the recipient need to be compatible so that rejection does not occur, and the tissue needs to be able to be collected in a strict medical environment.
Around half of all people who need a transplant die whilst on waiting lists. This need for organs and tissues for transplantation increases the pressure on researchers to find other ways of providing the needed tissues. These include using human cells in tissue culture and using embryonic or other stem cells to grow new cell types.
Growing specialised human cells such as skin, blood and ligament cells is referred to as tissue culture. This is a very important method of providing healthy tissue for transplantation. It is a very useful technique because the tissue produced has developed from a patient's own cells – the body may try to reject cells from a different person.
For more than 25 years skin cells have been cloned to produce more healthy skin for people who require skin grafts after burns or accidents. Healthy cells are removed from the person who requires the cultured tissue, and then separated from each other, placed in a container of liquid nutrients and kept under conditions that enable them to multiply to make more skin cells.
Specialised adult cells can be cloned in this way but they usually stop dividing after about 20 cell divisions. Therefore, with current technology, very large patches of skin cannot be produced.
Increased understanding of the mechanisms of transplant organ rejection means that organs from other species may soon be used as an alternative to human tissues to help alleviate organ shortages.