Embryonic and patient-specific induced pluripotent stem cells (iPSCs) hold great potential for cell-based therapies due to their ability to generate the tissues and cell types of developing organs.
In addition to embryonic stem cells (ESCs), some adult tissue-specific stem cells can also be potentially utilized for organ repair and therapeutic applications.
The continued advance of stem cell therapy in clinical medicine will require robust and renewable sources of stem cells. The origin of this source could be from ESCs, tissue-specific stem cells, or iPSCs. Since the only current source for the derivation of human embryonic stem cells (hESCs) remains discarded human tissue from in vitro fertilization (IVF) clinics, there is a close relationship between reproductive medicine and the field of stem cell biology. A continual supply of normal hESCs lines and iPSCs are essential to developing cell-based therapies to address general health concerns as well as those in reproductive medicine. Some of the potential target therapeutic applications in reproductive medicine include advancing treatments for oocyte development atresia diminishing gonadal function and urinary tract disorders associated with aging or premature ovarian failure.
In addition, there are less well-defined sources of stem cells from reproductive tissue such as ovarian stem cells and fetal stem cells that persist in maternal blood during fetal microchimerism, that might prove useful for cell-based therapies in health and reproductive function. In this chapter we briefly discuss some of the available types of stem cells and the clinical potential of this field.
ESCs were originally isolated from mouse, and hESCs are now derived from discarded human embryos from assisted reproductive technology (ART) clinics. The hallmark of hESCs is their ability to self-renew, proliferate on mitotically inactivated mouse embryonic fibroblast (MEF) feeders, and differentiate under permissive culture conditions into virtually any cell type of the human body. In the mouse model, the transfer of ESCs into a gestational carrier has demonstrated the ability of these cells to contribute to several tissue types as reflected by the birth of resultant chimeric mice, which can then go on to reproduce demonstrating germline contribution of these ESCs.
ESCs give rise to variety of cell types of the adult organism (ectoderm, mesoderm, and endoderm). Thus the potential applications of hESCs has captured the imagination of scientists and the medical community with the hope of developing cell-based therapies for diseases involving degenerative cellular mechanisms. The challenges to be met before achieving these hopes include (1) ethical issues, (2) evidence of chromosomal instability in culture, (3) concerns about antigen matching of donor cells, (4) concerns about possible teratoma formation post-transplant, and (5) concern for zoonoses given culturing techniques.
Adult Tissue-Specific Stem Cells
While the current literature has significantly concentrated on the potential of ESCs, there is a ...