Where are stem cells located in the adult body?
Adult stem cell
Early regenerative applications of adult stem cells has focused on intravenous delivery of blood progenitors known as Hematopetic Stem Cells (HSC's). CD34+ hematopoietic  Stem Cells have been clinically applied to treat various diseases including spinal cord injury,[48] liver cirrhosis [49] and Peripheral Vascular disease.[50] Research has shown that CD34+ hematopoietic Stem Cells are relatively more numerous in men than in women of reproductive age group among spinal cord Injury victims.[51] Other early commercial applications have focused on Mesenchymal Stem Cells (MSCs). For both cell lines, direct injection or placement of cells into a site in need of repair may be the preferred method of treatment, as vascular delivery suffers from a "pulmonary first pass effect" where intravenous injected cells are sequestered in the lungs.[52]  Clinical case reports in orthopedic applications have been published.  Wakitani has published a small case series of nine defects in five knees involving surgical transplantation of mesenchymal stem cells with coverage of the treated chondral defects.[53]  Centeno et al. have reported high field MRI evidence of increased cartilage and meniscus volume in individual human clinical subjects as well as a large n=227 safety study.[54][55][56][57] Many other stem cell based treatments are operating outside the US, with much controversy being reported regarding these treatments as some feel more regulation is needed as clinics tend to exaggerate claims of success and minimize or omit risks.[58]