ECRUITING ENDOGENOUS STEM CELLS: THE “BUILT-IN REPAIR KIT”
I foresee a day when the disadvantages and limitations of exogenously administered stem cell transplantation may be overcome, to a major degree, by techniques to mobilize endogenous adult stem cells (multipotent progenitor cells) and assist them in their recruitment and use by diseased and ailing tissue. In simplistic terms, this process is the “built-in repair kit” of animals. Modern science may be approaching a circumstance where the stimulation of endogenous stem cells could be a viable treatment option. There are several drugs or candidate compounds that are known to promote the proliferation and mobilization of adult stem cells, e.g. human granulocyte-macrophage colony-stimulating factor (hGM-CSF), but these agents possess disadvantages and limitations, including occasional onerous side effects and great expense. Frenetic interest has been shown in commercial processes that can harvest adult stem cells and transform them into differentiated, somatic cells that can provide structures and functions that are compromised by incurable diseases (e.g. Dopamine-producing cells for Parkinson’s Disease, motor nerves for Amyotrophic Lateral Sclerosis and Islet cells for Diabetes mellitus). While a number of studies show an ability for many agents to mobilize human adult stem cells, uncertainty remains concerning the recruitment and function of these endogenous-stimulated progenitor cells. A variety of cytokines are known to promote the self renewal and stimulate the growth and maturation of stem cells leading to a possibility that mixtures of cytokines could be given to patients during treatments that mobilize endogenous stem cells to obtain the desired therapeutic outcome of tissue engraftment and function of endogenous progenitor cells. An further attractive approach to stem cell mobilization is the synergistic use of a variety of nutrients or botanicals, such as anthocyanidins (e.g. blueberry), green tea catechins, carnosine, blue-green algae and vitamin D3. Although much of this research on proliferation of adult stem cells has been performed in vitro, early studies imply that these natural compounds may have a dose-related effect on the proliferation of human bone marrow stem cells, as measured in sequential blood samples, following ingestion of these natural substances. I believe that the healing benefits of many nutritional, botanical or herbal agents could operate through a mechanism of the stimulation of endogenous stem cells that are involved in healing and regeneration. I have postulated that the practice of live cell therapy, involving the injection of animal fetal tissue, may provide signals to promote human stem cell migration and implantation in diseased or ailing tissues. Certainly, this proposal fits with the knowledge that live cell therapy does not result in the engraftment of xenotransplants from animals. There appears to be enough good scientific agreement that complex combinations of selected botanicals and nutrients may promote healing and perhaps longevity by interaction with stem cell populations that occupy niches in tissues of many organs of the body. The idea of mobilizing stem cells, facilitating their transformation and assisting in their recruitment by damaged tissue seems within our reach in the next few years.