Primary Progenitor Muscle Cells for Regenerative Medicine: Standardization of Therapeutic Protocols and Optimized In Vivo Murine Model For Volumetric Muscle Loss

Skeletal muscle tissue engineering constitutes an emerging therapeutic repair strategy aiming for structural and functional restoration following traumatic injury, deep burns, congenital malformation or surgical tumor removal. As for similar musculoskeletal acute and degenerative affections, allogenic progenitor cell therapy represents a promising clinical approach to synergistically supplement traditional surgical care. Preliminary studies have established the adequation of primary human fetal muscle progenitors (hFMPs) for applications in regenerative medicine. Such therapeutic cell sources combined with bioresorbable scaffolds optimally integrate in murine muscle injury models without causing immune rejection. The present work aimed at functional recovery assessment following standardized application of hFMPs in an optimized murine skeletal muscle wound model. Cryopreserved hFMPs were initiated and culture-expanded before seeding in equine collagen scaffolds. Gastrocnemius muscles of C57BL/6 mice were injured following a standardized protocol. Resulting volume defects were treated with collagen constructs yielding marked hFMPs (105 cells/construct), constructs alone or remained untreated, assorted to appropriate internal controls. Histological and biomechanical analysis of muscle tissue and integrated therapeutic constructs were performed at the time of surgery and during the following 8 weeks. Both therapeutic protocols and in vivo models were optimized and standardized, based on internal experience concerning progenitor cell therapies for cutaneous reconstruction. Results indicated significantly improved function in all study groups treated with hFMPs. In particular, absolute peak twitch tensions measured on injured muscles were relatively superior in value at different time points after progenitor cell therapy application. Engraftment of hFMPs in murine wounded muscle enabled xenogeneic tissue repair stimulation and overall improvement of functional recovery. The combination of murine muscle wound model and therapeutic cell delivery method was determined as optimal for assessing muscle functional characteristic evolution notwithstanding severe tissue injury by volume loss. Such data support further translational investigation of allogenic progenitor cell therapy for human muscle defects and injuries