Optimizing Mesenchymal Stromal Cells Delivery: Present Status and New Frontiers in Regenerative Medicine

Purpose of Review Multipotent Mesenchymal stromal cells (MSCs) have recently risen to prominence in regenerative medicine for their powerful intrinsic properties of self-regeneration, immunomodulation, and multi-potency. They exhibited an excellent safety profile in early-phase clinical trials. Nevertheless, MSCs-based therapy suffers reduced efficacy in randomized clinical trials due to a poor understanding of their proper delivery modalities. Here, we intend to explore the current application of MSCs after tissue injuries. We specifically focus on tissue source, delivery routes, metabolic fitness, and cell dose. We further discuss potential approaches to optimize in vivo engraftment. Recent findings MSCs therapeutic effect mediates by paracrine and contact factors, which are cells' intrinsic physiological processes. The cell culture expansion process does not destroy MSCs' intrinsic properties. In vivo persistence of administered MSCs determines their therapeutic potency. Cell viability, fitness, immune match, and delivery route meticulously regulate their in vivo persistency. Different genetic or chemical modification strategies are currently applied to extend their in vivo lifespan and boost their pharmaceutical effect. Summary Improving the in vivo persistence of implanted MSCs could facilitate its clinical translation. This review highlights the pros and cons of different MSCs’ delivery strategies used in clinical or preclinical studies, emphasizing various modification approaches. These can promote prolonged graft cell survival.