Fig. 1

Factors that hinder MSC-based therapies. a The small amount of MSCs inoculated. Additionally, although MSCs are easily trapped in pulmonary capillaries after systemic administration, there is no long-term retention. Thus, the amount of restorative factors is progressively reduced. b MSCs are vulnerable to the toxicity of inflamed microenvironments, resulting in low survival rates in vivo. The few remaining viable MSCs might not be enough to exert adequate therapeutic effect. c Although viable and in adequate numbers, MSCs may still have low potency, i.e., lack activity or effectiveness to attenuate inflammation or repair injured tissue