%0 Journal Article %T The role of resident monocytes and vascular pericytes in the stem cell niche %A Antonin Bukovsky %J Stem Cell Studies %D 2011 %I %R 10.4081/3157 %X The perivascular tissue-specific "stem cell niche" (SCN) determines nuclear reprogramming of multipotent stem cells into particular cell types in distinct tissues in vivo. It represents a morphostatic (homeostatic) mechanism executed by the so called tissue control system (TCS), which is associated with postcapillary venules and consists of vascular pericytes regulated by the autonomic nervous system and of resident perivascular monocyte-derived cells. Tissue morphostasis executed by the TCS is a complex procedure consisting of three processes: (1) stem cell and tissue renewal by asymmetric division of stem cells, (2) maintenance of tissue quantity, and (3) preservation of tissue cells in a properly differentiated (functional) state. The TCS-mediated functional preservation of tissue-specific cells is established during the fetal adaptive period as a "stop effect" at the level of resident self-renewing tissue monocyte-derived cells (MDC), and its function declines with advancing age. Inhibition or acceleration of certain tissue differentiation during fetal adaptation can result in persistent functional immaturity or premature tissue aging. A promising approach in regenerative medicine is a chemical approach, such as the combination of sex steroids stimulating growth of endogenous stem cells for neuronal, vascular, and cardiac repair. Sex steroid combinations and doses for clinical applications are suggested. Regenerative medicine may be more successful in acute/traumatic disorders with intact morphostatic SCN compared to the chronic and degenerative diseases caused by an altered SCN. If we attain the capacity to repair the function of altered SCN and the tissue-specific "stop effect" by trascriptional therapy, we may be able to provide novel treatments for early postnatal tissue disorders, improve regenerative medicine, and delay aging. %K stem cell niche %K pericytes %K monocyte-derived cells %U http://www.pagepress.org/journals/index.php/scs/article/view/3157