Long-Term Evaluation of Functional Outcomes Following Rat Volumetric Muscle Loss Injury and Repair


Tissue-engineered muscle repair (TEMR) technology is used to facilitate the regeneration of muscle by providing a favorable microenvironment for regenerative growth. This is done by seeding muscle progenitor cells (MPCs) onto a porcine bladder acellular matrix (BAM), which is then implanted into the animal. Although tissue-engineered constructs are a good restorative option for volumetric muscle loss (VML) injuries, the variability between different muscles poses a challenge in creating fully compatible constructs. This study focuses on improving the matching geometry of TEMR to the TA muscle, specifically, in the rat animal model. Using Aurora’s 1305A 3-in-1 Whole Animal System, an in vivo analysis of peak isometric torque was conducted. At 6 months post VML injury, 67% of TEMR-implanted rats showed significantly greater peak isometric torque compared to other treatment groups. Moreover, 38% of TEMR responders reached approximately 90% of the maximum force production, thus demonstrating near full recovery. In addition to functional assessment, the authors conducted histological and immunofluorescence analyses. Fiber cross sectional area (FCSA) was quantified in both the experimental and control TA muscles of maximum responder rats. It was found that the median FCSA was lower in the experimental TA muscles than in the TA muscles of the control leg. Vascularization and macrophage counts were also assessed, although no significant differences were found. This study highlights the importance of adapting and improving existing tissue engineering technology to allow for optimal treatment of VML injuries in various muscles.