Mesenchymal stem cells and exosomes in tissue regeneration and remodeling: characterization and therapy

Abstract There are increasing reports on adult mesenchymal stem cells (MSCs) in vivo and in vitro studies that have provided new insights for MSC potential clinical applications in tissue regeneration and remodeling. MSCs are ubiquitous component of tissue stroma, which constitute the intrinsic structural barriers onto parenchyma of tissues and organs. The recent paradigm on biology of MSCs suggests that they can also employ/express/implement diverse mechanisms to mediate remodeling of the stroma and parenchyma in response to stress and/or damage. Currently, many clinical trials are ongoing. This review includes these advances, ranging from the context of characterizing MSCs, self-renewal for tissue repair, recovery after diseases, to the possible use of exosomes. In human clinical cases and experimental animal models, MSCs have been widely characterized and exhibited mitigation and therapy on different diseases. MSC-based technologies for treating various diseases alone or in combination with adjuvants are under studies. There are challenges in MSC therapy including the need to overcome cell purity, bioengineering difficulties for tissue structures, optimal MSC sources, optimal MSC administration protocols, termination of MSC activation after repair and regeneration accomplished, and safety of long-term presence of MSCs in the body. Exosomes derived from MSCs are studied extensively and demonstrate equal efficacy as MSCs. Treatment with exosomes may avoid the concerns mentioned above.