Soluble factors and remodeling in a synthetic stem cell niche

Hematopoietic stem cells produce the body’s entire complement of blood and immune cells, in a process known as hematopoiesis. Producing half a trillion cells daily, this rare population (<0.01% of human bone marrow) possess the ability to produce multiple cell lines (differentiation) and stem cell daughters (self-renewal). HSCs are found throughout the body but primarily reside in the adult bone marrow, in specialized compartments termed the niche. Within the niche is a host of biophysical, cellular, and soluble factor cues that combine in temporally and spatially organized zones which elicit distinct responses from resident HSCs. Clinically, HSC transplants are the most widely used regenerative therapy, treating disorders of the blood and immune system e.g., anemias, leukemias, and myelo-ablative chemoradiation treatments. However, the rarity of the cells and scarcity of appropriately matched donors (