Differentiation potential of multipotent progenitor cells derived from war-traumatized muscle tissue

Background: Recent military conflicts have resulted in numerous extremity injuries requiring complex orthopaedic reconstructive procedures, which begin with a thorough debridement of all contaminated and necrotic tissue in the zone of injury. The site of injury is also the site of healing, and we propose that debrided muscle tissue contains cells with robust reparative and regenerative potential. Methods: Debrided muscle from soldiers who had sustained traumatic open extremity injuries was collected during surgical debridement procedures at Walter Reed Army Medical Center. With modifications to a previously described stem-cell-isolation protocol, mesenchymal progenitor cells were harvested from traumatized muscle, enriched, expanded in culture, and exposed to induction media for osteogenesis, adipogenesis, and chondrogenesis. Results: The isolated mesenchymal progenitor cells stained positive for cell-surface markers (CD73, CD90, CD105), which are characteristic of adult human mesenchymal stem cells. Histological identification of lineage-specific markers demonstrated the potential of these cells to differentiate into multiple mesenchymal lineages. Reverse transcription-polymerase chain reaction analysis confirmed multilineage mesenchymal differentiation at the gene-expression level. Conclusions: To our knowledge, the present report provides the first description of mesenchymal progenitor cell isolation from traumatized human muscle. These cells may play an integral role in tissue repair and regeneration and merit additional investigation as they could be useful in future cell-based tissue-engineering strategies. Clinical Significance: Mesenchymal progenitor cells isolated from war-traumatized tissues have the potential for applications in cell-based tissue engineering. Elucidating the cellular mechanisms regulating their differentiation activities may lead to the development of novel treatments for musculoskeletal trauma and pathological healing responses, such as heterotopic ossification.