When was the first human being cloned?


The goal of therapeutic cloning, too Research cloningcalled, is the extraction of embryonic stem cells that are genetically identical to the donor organism. The embryo created after the nuclear transfer is used in this procedure in the blastocyst stage to derive stem cells from it. These cells are pluripotent. This means that they can develop into all cell types in the body. They are of interest for therapeutic purposes because different tissues can be grown from them. This could cure diseases caused by the loss of certain types of cells or tissues. For example, heart muscle tissue that has died after a heart attack or nerve cells degenerated in Parkinson's disease could be replaced. Since the cloned stem cells are genetically identical to the donor organism, in this case to the patient to be treated, an immunological defense reaction is less likely with this method. This means that the cells and tissues introduced into the body would not be rejected or would be less rejected. Long-term treatment with drugs that suppress the function of the immune system after the transplant (immunosuppressants) would probably no longer be necessary. It is also hoped that tissues made from cloned stem cells will counteract the lack of organ transplants, which is due, among other things, to the incompatibility of most donor organs with the recipient.

For some years now, there has also been a method with which differentiated body cells can be restored to their original state. By adding certain genes, the cells are reprogrammed so that they have the properties of embryonic stem cells. They are pluripotent and can differentiate again into certain cell types. These cells are called induced pluripotent stem cells (iPS). The Japanese stem cell researcher Shin’ya Yamanaka received the Nobel Prize in Physiology or Medicine in 2012 for developing this process. The iPS cells have great medical potential, as they can also be used for cell replacement therapies, for example to treat degenerative diseases. Since no nucleus transfer or egg cell is required for their production, as is the case with therapeutic cloning, the use of iPS cells is far less problematic from an ethical and legal point of view.

However, routine use of both methods in medicine is not to be expected anytime soon. Stem cells have a potential for tumor formation that must be prevented. In addition, it must be possible to functionally integrate the cells into the respective tissues or organs. In addition, similar to organs, rejection reactions have also been demonstrated in transplanted replacement cells. When using cloned stem cells, which result from somatic nuclear transfer, mitochondrial differences between donor and egg cells are responsible. Mitochondria are organelles that produce energy in the cell. They also contain DNA, which differs from the genetic information of the donor cell and can lead to rejection reactions after the transplant.