Harnessing Extracellular Vesicles for Regenerative Therapy

One approach used to promote tissue regeneration has been inoculation with mesenchymal stem cells: cells with the ability to differentiate into a variety of other cell types including bone, cartilage and muscle.

Such therapies have shown effectiveness in some pathologies, despite the fact that only a tiny fraction of the mesenchymal stem cells typically survive in damaged tissues after one week. This has lead scientists to suspect that the regenerative effects of mesenchymal stem cells may actually be due to a signal that they are releasing.

Several studies support this hypothesis, demonstrating that media derived from mesenchymal stem cell cultures can have equal or even greater regenerative effects than the stem cells themselves. This therapeutic effect is thought to be primarily due to signals carried by lipid-enclosed particles called extracellular vesicles. Many researchers and clinicians are now turning their attention towards vesicle -based therapies, as they have a number of advantages:

• More readily harvested than mesenchymal stem cells
• Can be stored until needed, and so do not need to be produced at the time of inoculation
• Can enter thin capillaries and reach sites that stem cells may be too large to reach
• Can cross the blood-brain barrier
• Are unlikely to be rejected by the immune system