Particle systems for stem cell applications

Stem cells have been widely investigated for regeneration of aged, injured, or diseased tissues. Although they have remarkable potential in clinical applications, some critical issues must be addressed, one of which being the poor control of their fates in vivo. A variety of particles, typically the organic and inorganic materials, liposomes, and polyplexes, provides multiple functionalities of labeling and tracking of the transplanted stem cells, and versatile capabilities of intracellular delivery of biomolecules for stem cell control in vivo. In this report, major applications of different particle systems are reviewed on the topics of tracking transplanted stem cells and labeling of endogenous stem cells in vivo. Detailed discussions are provided on recent advances of the particle-assisted intracellular delivery of biomolecules to stem cells for in vivo applications. Some novel particle-carriers are reported on stem cell transplantation and drug delivery for cancer therapy. Also discussed are critical challenges and future directions in the development of particle carriers for stem cell applications.