Embryonic stem cells clinical potential

Embryonic stem cells (ESCs) are cells isolated from the inner mass of blastocysts." The mechanisms by which ESCs maintain self-renewal and pluripotency are still not yet fully understood. Many reports highlight the involvement of miRNAs as crucial players in ESCs regulation and ESCs development. In fact ESCs lose their self-renewal differentiation capacity, following alterations in the machineiy involved in miRNAs processing, maintenance and activity. Potential clinical applications of ES cells raise many practical and ethical concerns. Many nations currently have moratoria on either ES cell research or the production of new ES cell lines. Because of their combined abilities of unlimited expansion and pluripotency, embiyonic stem cells remain a theoretically potential source for regenerative medicine and tissue replacement after injuiy or disease. 

Trachea TE has been one of the most promising approaches to providing a potential clinical application for the treatment of long-segment tracheal stenosis. The sources of the cells are particularly important as the primary factor for TE. Besides autologous mature cells, various stem cells, including bone marrow-derived mesenchymal stem cells (MSCs), adipose tissue—derived stem cells, umbilical cord blood—derived mesenchymal stem cells, amniotic fluid stem cells, embryonic stem cells, and induced pluripotent stem cells, have received extensive attention in trachea TE [118]. 

Embryonic stem cells (ESCs) are isolated during embryonic development from the inner cell mass of the blastocyst. ESCs can differentiate into any cell lineage of the three germ layers, and can proliferate undifferentiated indefinitely in vitro. As a result of their limitless differentiation and proliferation capacities, ECSs are attractive for use in cartilage tissue engineering apphcations. However, ethical issues and scientific hurdles such as efficient differentiation of a homogenous cell population, immunorejection, and tumourigenicity have left the clinical potential of the field unrealized [64]. 

Stem cells offer unprecedented opportunities and potentials for regenerative medicine. Bone marrow transplantation is an established clinical procedure, and the transplant of blood stem cells separated from umbilical cord blood, has also been established. It is, however, the potential of using embryonic and adult stem cells to regenerate all the tissues and organs in the body that has attracted attention and imagination all over the world. If stem cell potentials materialize, or even a fraction of their potentials are materialized, the health care industry will be revolutionized. 

Stem cells from a number of sources have been explored for regenerating the myocardium. Both multi-potent adult stem cells and pluripotent embryonic stem (ES) cells have been used to generate vascular cells and cardiac myocytes for therapy (Figure 34.3). A number of clinical studies have explored adult stem cells for their therapeutic potential in treating ischemic heart disease. While ES cells have only been investigated to date in preclinical models, a new clinical study is expected to assess safety of ES cell transplantation (Alper, 2009). In addition to stem cells, adult skeletal muscle cells have also been explored for clinical cardiac cell therapy. Each cell type is briefly reviewed in the context of myocardium regeneration. 

Embryonic stem (ES) cells can indefinitely self-renew and have the potential to differentiate to every cell in the body (Sato et al. 2003), including hematopoietic cells. ES cells were first isolated from the inner cell mass of developing mouse blastocysts (Sukoyan et al. 1993). Because of their renewal in the undifferentiated state and pluripotent properties, ES cells are a prospective cell source for clinical therapies (Kaji and Leiden 2001). 

---