Stem cell research is being hailed to answer many unanswered questions in modern medicine. The regenerative ability of stem cells brought a revolution in the world of medicine, in re-formation of many organs like heart, kidney, lungs, etc. But there is a dispute going on this regeneration process as the stem cells used for this process are derived from human embryo cells. The culturing and using of such stem cells is considered as unethical by many.
What are stem cells?
Stem cells are unspecialized cells that have two defining properties: the ability to differentiate into other cells and the ability to self-regeneration. The ability to develop into other cell types is called as totipotency which gives rise to a complete organ from a single cell. There are many types of stem cells depending upon the ability to differentiate into other cell types. There are totipotent stem cells, pluripotent stem cells, oligopotent stem cells, bi-potent stem cells, uni-potent stem cells, etc. The virtuous character of stem cells is self- regeneration; the ability to divide and produce more stem cells.
Role of stem cells in organ generation:
Stem cells have many applications in the medical science. One of the important clinical applications is regeneration of organs. A number of progenitor stem cells been identified which play a major role in organ regeneration. Progenitor cells are formed from the germ layer during the process of embryonic development. Progenitor cells are also known as precursor cells. The available literature says that the progenitor cells are formed as a result of asymmetrical division of the stem cells.
Stem cells are plenty during the developmental stages, but as most of the stem cells have differentiated and multiplied, there number falls in adults. This makes it extremely difficult to isolate stem cells from an adult organism, which is why scientists hope to use embryonic stem cells for therapy because embryonic stem cells are much easier to obtain.
Organ regeneration has long been believed to be through organ-specific and tissue-specific stem cells. Hematopoietic stem cells were believed to replenish blood cells, stem cells of the gut to replace cells of the gut and so on. Recently, using cell lineage tracking, stem cells from one organ have been discovered that divide to form cells of another organ. Hematopoietic stem cells can give rise to liver, brain and kidney cells. This plasticity of adult stem cells has been observed not only under experimental conditions, but also in people who have received bone marrow transplants. Thus it is likely that organ-specific progenitors and hematopoietic stem cells are involved in repair, even for other organ repair.