Endogenous bone marrow-derived stem cell mobilization and homing for in situ tissue regeneration.

In mammals, post-injury repair and regenerative events rely predominantly on stem cell function. Stem cell transplantation has achieved considerable success in animals but remains unfavorable for humans because of the unavoidable drawbacks. Nevertheless, substantial evidence suggests the regenerative potential of endogenous stem cells can be improved for functional and structural recovery of tissue damage or in diseases conditions. Endogenous stem cells are mostly quiescent under steady-state conditions and reside in their niche. Once faced with tissue injury, physiological and molecular changes within the niche or from distant tissues activate the migration, proliferation and differentiation of stem cells, contributing to tissue repair. Tissue regeneration is augmented by artificially amplifying the factors that promote stem cell mobilization or enhance the homing of endogenous stem cells. This cell-free strategy, known as "in situ tissue regeneration", represents a safer and more efficient means to conduct tissue regeneration. Bone marrow (BM) is considered the central niche and main reservoir of many types of stem cells. These stem cells hold great therapeutic potential for the regeneration of multiple injured tissues. Herein, we review recent strategies for promoting in situ tissue regeneration through BM-derived stem cell mobilization or homing in animal models as well as in human trials. With the advancement in biomaterial engineering, chemoattractant signals combined with functionalized bioscaffolds have accomplished sustained activation of endogenous BM-derived stem cells that can be used as an attractive strategy for efficient in situ tissue regeneration.