Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
Induced pluripotent stem cells, commonly abbreviated as iPS cells or iPSCs are a type of pluripotent stem cell artificially derived from a non-pluripotent cell - typically an adult somatic cell - by inducing a "forced" expression of specific genes. Induced pluripotent stem cells are similar to natural pluripotent stem cells, such as embryonic stem (ES) cells, in many aspects, such as the expression of certain stem cell genes and proteins, chromatin methylation patterns, doubling time, embryoid body formation, teratoma formation, viable chimera formation, and potency and differentiability, but the full extent of their relation to natural pluripotent stem cells is still being assessed.
In humans, adipose tissue is located beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow (yellow bone marrow) and in breast tissue. Adipose tissue is found in specific locations, which are referred to as 'adipose depots.' Scientific interest in Adult Stem Cells from adipose tissue (fat) is focused on their ability to transform into many different cell types. Adipose (fat) Derived Adult Stem Cells are the most abundant type of Adult Stem Cells in the body. They are readily accessible and easy to collect. Adipose (fat) deposits contain vast amounts of Adult Stem Cells, which have the ability to divide, grow and transform into multiple tissues and organs within the body.
Current research focuses on differentiating hESC into a variety of cell types for eventual use as cell replacement therapies (CRTs). Some of the cell types that have or are currently being developed include cardiomyocytes (CM), neurons, hepatocytes, bone marrow cells, islet cells and endothelial cells. However, the derivation of such cell types from hESCs is not without obstacles and hence current research is focused on overcoming these barriers. For example, studies are underway to differentiate hESC in to tissue specific CMs and to eradicate their immature properties that distinguish them from adult CMs. Besides in the future becoming an important alternative to organ transplants, hESC are also being used in field of toxicology and as cellular screens to uncover new chemical entities (NCEs) that can be developed as small molecule drugs. Studies have shown that cardiomyocytes derived from hESC are validated in vitro models to test drug responses and predict toxicity profiles. hESC derived cardiomyocytes have been shown to respond to pharmacological stimuli and hence can be used to assess cardiotoxicity like Torsades de Pointes.
Adult stem cells are undifferentiated cells, found throughout the body after embryonic development, that multiply by cell division to replenish dying cells and regenerate damaged tissues. Also known as somatic stem cells they can be found in juvenile as well as adult animals and humans. Scientific interest in adult stem cells is centered on their ability to divide or self-renew indefinitely, and generate all the cell types of the organ from which they originate, potentially regenerating the entire organ from a few cells. Unlike embryonic stem cells, the use of adult stem cells in research and therapy is not considered to be controversial, as they are derived from adult tissue samples rather than destroyed human embryos.
Multipotent stem cells are also found in amniotic fluid. These stem cells are very active, expand extensively without feeders and are not tumorigenic. Amniotic stem cells are multipotent and can differentiate in cells of adipogenic, osteogenic, myogenic, endothelial, hepatic and also neuronal lines. All over the world, universities and research institutes are studying amniotic fluid to discover all the qualities of amniotic stem cells, and scientists such as Anthony Atalaand Giuseppe Simoni have discovered important results. Use of stem cells from amniotic fluid overcomes the ethical objections to using human embryos as a source of cells. Roman Catholic teaching forbids the use of embryonic stem cells in experimentation; accordingly, the Vatican newspaper "Osservatore Romano" called amniotic stem cells "the future of medicine". It is possible to collect amniotic stem cells for donors or for autologuous use: the first US amniotic stem cells bank was opened in 2009 in Medford, MA, by Biocell Center Corporation and collaborates with various hospitals and universities all over the world
Glenn Edwards McGee is an American bioethicist. He holds degrees in philosophy from Vanderbilt University and Baylor University and completed a post-doctoral fellowship in the Human Genome Project. He has been noted for his work on reproductive technology and genetics and for advancing a theory of pragmatic bioethics, as well as the role of ethicists in society and in local and state settings in particular.
Paul Knoepfler, PhD Associate Professor UC Davis School of Medicine. Member of CIRM-funded UC Davis Institute for Regenerative Cures, Institute for Pediatric Regenerative Medicine, Leader of UC Davis Cancer Center Cancer Stem Cell Initiative, Cancer survivor and patient advocate, writer, blogger. www.ipscell.com