Ex vivo expansion of human circulating myogenic progenitors on cluster-assembled nanostructured TiO2.

Ex vivo expansion of hematopoietic stem cells has been explored in the fields of stem cell biology, gene therapy and clinical transplantation. Recently, we demonstrated the existence of a circulating myogenic progenitor expressing the CD133 antigen. The relative inability of circulating CD133+ stem cells to reproduce themselves ex vivo imposes substantial limitations on their use for clinical applications in muscular dystrophies. Here we report that the use of cluster-assembled nanostructured titanium dioxide (ns-TiO(2)) substrates, in combination with cytokine enriched medium, enables high-level expansion of circulating CD133+ stem cells in vitro. Furthermore, we demonstrate that expanded circulating CD133+ stem cells retain their in vitro capacity to differentiate into myogenic cells. The exploitation of cluster-assembled ns-TiO(2) substrates for the expansion of CD133+ stem cells in vitro could therefore make the clinical application of these stem cells for the treatment of muscle diseases practical.