Stem Cell Therapy Perspectives

Abstract

Stem cells have self-renewal potential and ability to differentiate into one or more specialized cell types. An ideal candidate for developing stem cell based therapies would be readily available, easy to expand in culture, possess an acceptable long term safety profile and be autologous in nature, in order to avoid the need to modulate the host immune response and prevent rejection. Unfortunately, a cell type that fulfils all these criteria remains elusive, however, current research is directed towards a limited number of cell types which themselves exhibit certain advantages or disadvantages. Such cell populations may be sourced from three broad categories: embryonic or foetal tissue, adult tissue and reprogrammed cells. There are two broad types of stem cells, embryonic stem cells (ESCs) and adult stem cells. ESCs are isolated from inner cell mass of blastocyst which can transdifferentiate into cells of all three germ layers. Unlike ESCs, adult stem cells show restricted proliferation and lineage differentiation. Embryonic and adult stem cells offer the opportunity to transplant a live source for self-regeneration. Bone marrow transplants (BMT) are a well-known clinical application of adult stem cell transplantation for cancer patients. BMTs can repopulate the marrow and restore the blood’s different cell types after high doses of chemotherapy and/or radiotherapy, which are used to eliminate cancer cells. An alternative for ESC are stem cells obtained from tissue after birth. Adult tissue-derived stem cells offer an alternative for the development of cell based therapies which circumvents the ethical controversies surrounding foetal and embryonic tissue. For instance, neural progenitor cells have been harvested from adult brain and spinal cord. However, adult stem cells are less plastic than ESCs and divide less frequently in culture. Also, their differentiation potential may decrease in time. This makes them a possible but somewhat limited alternative for ESCs. On the other hand, they offer the advantage that they can be transplanted without genetic modifications or pretreatments. The most common way of thinking about stem cells treating disease is through a stem cell transplant. Embryonic stem cells are differentiated into the necessary cell type, and then those mature cells replace tissue that is damaged by disease or injury. This type of treatment could be used to replace neurons damaged by spinal cord injury, stroke, Alzheimer’s disease, Parkinson’s disease, or other neurological problems. Cells grown to produce insulin could treat people with diabetes and heart muscle cells could repair damage after a heart attack. This list could conceivably include any tissue that is injured or diseased [1,2].