CD34 positive cells isolated from traumatized human skeletal muscle require the CD34 protein for multi-potential differentiation.

The CD34 protein is regarded as a marker of stem cells from multiple origins. Recently a mesenchymal progenitor CD34 positive cell identified from traumatized human skeletal muscle demonstrates differentiation capability into vascular endothelial cells, osteoblasts and adipocytes. Here they were treated with a small inhibitory RNA for CD34, which significantly reduced the cellular level of the CD34 protein. These treated cells had a reduced capacity to proliferate, and migrate. They were both unable to differentiation down multiple pathways and to undergo vascular endothelial differentiation as reflected by a lack of expression of VE cadherin, Tie 2 and CD31. Additionally the cells were unable to form tube-like structures in an endothelial tube assay. These treated cells were also unable to undergo osteogenesis, as revealed by lack of alizarin red and alkaline phosphatase staining and were unable to undergo adipogenesis as revealed by lack of oil red O staining. Finally, when CD34 was expressed in cells lacking this protein, the cells were able to undergo vascular endothelial differentiation as revealed by expression of Tie2, VE-cadherin and CD31. These data indicate that in cells derived from traumatized muscle the CD34 protein is required for enhanced proliferation, migration and differentiation down multiple pathways.