Stem cells are primal cells common to all multi-cellular organisms that retain the ability to renew themselves through cell division and can differentiate into a wide range of specialized cell types.
The three broad categories of mammalian stem cells exist: embryonic stem cells, derived from blastocysts, adult stem cells, which are found in adult tissues, and cord blood stem cells, which are found in the umbilical cord.
In a developing embryo, stem cells are able to differentiate into all of the specialized embryonic tissues.
In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells.
As stem cells can be readily grown and transformed into specialised cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed.
In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates.
Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues.
Also known as somatic stem cells, they can be found in children, as well as adults. A great deal of adult stem cell research has focused on clarifying their capacity to divide or self-renew indefinitely and their differentiation potential.
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Stem cells: n. Undifferentiated, primitive cells with the ability both to multiply and to differentiate into specific kinds of cells.
Stem cells hold the promise of allowing researchers to grow specialized cells or tissue, which could be used to treat injuries or disease.
Stem cell research is controversial because the best source of stem cells is human fetal tissue.
Harvesting the stem cells destroys the embryo, which many see as morally problematic.
Purpose of this Site: to serve as a starting point for learning about the ethical debate over stem cell research. To engage in this debate in a thoughtful and respectful way requires that we understand the science of stem cells, the regulatory context, and the key ethical arguments that have already been made.
Life Legal Defense Foundation supports ethical stem cell research, such as stem cell research using adult and umbilical cord stem cells, which have already produced many cures and therapies.
Embryonic stem cell lines (ES cell lines) are cultures of cells derived from the epiblast tissue of the inner cell mass (ICM) of a blastocyst. A blastocyst is an early stage embryo - approximately 4 to 5 days old in humans and consisting of 50-150 cells. ES cells are pluripotent, and give rise during development to all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm. In other words, they can develop into each of the more than 200 cell types of the adult body when given sufficient and necessary stimulation for a specific cell type. They do not contribute to the extra-embryonic membranes or the placenta.
When given no stimuli for differentiation, ES cells will continue to divide in vitro and each daughter cell will remain pluripotent. The pluripotency of ES cells has been rigorously demonstrated in vitro and in vivo, thus they can be indeed classified as stem cells.
Because of their unique combined abilities of unlimited expansion and pluripotency, embryonic stem cells are a potential source for regenerative medicine and tissue replacement after injury or disease. To date, no approved medical treatments have been derived from embryonic stem cell research. This is not surprising considering that many nations currently have moratoria on either ES cell research or the production of new ES cell lines.
Research in the human stem cell field grew out of findings by Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s
Stem cell treatments
Medical researchers believe that stem cell therapy has the potential to radically change the treatment of human disease.
A number of adult stem cell therapies already exist, particularly bone marrow transplants that are used to treat leukaemia.
In the future, medical researchers anticipate being able to use technologies derived from stem cell research to treat a wider variety of diseases including cancer, parkinson's disease, spinal cord injuries, and muscle damage, amongst a number of other impairments and conditions.
However, there still exists a great deal of social and scientific uncertainty surrounding stem cell research, which could possibly be overcome through public debate and future research.
Stem cells, however, are already used extensively in research, and some scientists do not see cell therapy as the first goal of the research, but see the investigation of stem cells as a goal worthy in itself.
