Stem cells are part of every living organisms' physical form. During a lifetime, they differentiate into a wide range of special cell types that keep getting more and more complex. Its initial research and findings are credited to Ernest A. McCulloch and James E. Till.
This 1960 study revealed the fact that mammalian stem cells are of two types. In the case of the first type, the embryonic stem cells, they are isolated from the blastocyst cell mass and in case of second category, the adult stem cells, they are found only in adult tissues.
Their development begins from the time of conception. In case of a developing embryo, ones that are inherited gradually, differentiate into embryonic tissues. Adult organisms display cells that act as a repair mechanism for the body, along with the progenitor.
Their basic functions include:
- Generating a repair system for the body.
- Replenishing special cells.
- Maintaining the turnover of organs that are regenerative in nature.
The process is used to aid the need to generate the cells of various muscles and nerve tissues. A number of therapies use elastic adult stem cells from bone marrow and umbilical cord. Research is also being conducted on embryonic cell lines that are autologous in nature, to aid the creation of a therapeutic cloning base for future therapies.
The fact that some cells could help to generate other cells, made the rounds within the medical fraternity during the 1800s. In the early 1900s, the discovery of the first 'real' stem cell led to the discovery that these cells could generate blood cells.
Initially, the animal and human stem cells were classified into:
- Totipotent type found in embryos.
- Pluripotent type that exists in blastocyst cell mass.
- Multipotent type derived from adult stem cells, fetal tissue, and cord blood.
In the 1900s, physicians experimented with an oral bone marrow transfer to patients with leukemia. The unsuccessful therapy led to dedicated laboratory experiments to try to infuse healthy cells into organisms with defective marrow. This rippled on in the experiment with bone marrow transplants between humans.
This kind of allogeneic transplant was first carried out in France in the 1950s. In 1958, the identification of histocompatibility antigens by Jean Dausset, highlighted the fact that proteins found on cell surfaces are leukocyte or HLA antigens.
Further research revealed that the HLA antigens help the immune system to determine the cells that are healthy and which belong to the body and successfully create a series of antigens for those that spell destruction. In the 1960s, physicians experimented a lot on HLA compatibility and cell transplants between siblings.
In 1973, the first 'unrelated' marrow transplant was conducted that culminated in the National Organ Transplant Act in 1984. The National Marrow Donor Program or NDWP followed soon in 1990.
During this decade, the bone marrow program was at its helm and has on record above 16,000 transplants. These transplants basically addressed cures for immunodeficiencies, hemophilia, and blood cancer which is also called leukemia.
James Thompson from the University of Wisconsin, isolated cells from embryo cell mass in 1998. The study and research resulted in the development of embryonic stem cell lines. A little later, in the same year, John Gearhart was successful in deriving germ cells from fetal gonadal tissue.
The march towards a better understanding of stem cells and their role in increasing longevity continues till today. Cell biology has interested man since the advent of microscopes. The latter helped us recognize stem cells as blocks of human development.
A number of controversies in the research have made the rounds with regards to its history and the applications in place today. Ethics of the research, especially embryonic stem cell research are being questioned.
The advantages and disadvantages of this form of research, the techniques used, and ultimate usage of the extracted stem cells are highly controversial issues. The controversies spring from the facts that highlight the destruction of the embryo to initiate a stem cell line. The process also calls for therapeutic cloning.