Functional Recovery in Volumetric Muscle Loss After Receiving a Minced Muscle Transplant

Volumetric muscle loss (VML) refers to the traumatic or surgical loss of a substantial portion of skeletal muscle, which lacks the ability to regenerate naturally, leading to chronic functional deficits. Current therapeutic interventions have shown limited success in restoring both muscle structure and function, highlighting the need for novel regenerative approaches. Purpose: This study aimed to enhance muscle regeneration and functional recovery following VML injury through the use of a minced muscle transplant (MMT), designed to restore the structural and cellular components lost during the injury. Methods: Eight rats received a full-thickness, 6 mm VML injury in the left tibialis anterior (TA) muscle, with the right TA serving as an uninjured intra-animal control. A subset of the rats received a MMT from a GFP-expressing donor, aimed at replacing 100% of the muscle mass lost during the VML procedure. Neuromuscular testing of the anterior compartment of both legs was performed after 3 weeks using a force-frequency protocol (10-200 Hz), with peak force measured at 200 Hz. Force measurements were compared among the MMT-treated, untreated (NT), and uninjured control limbs. Results: The MMT group exhibited a peak force of 11.157±2.182 mN-m in the injured leg, which was not significantly different from the NT group (6.965±0.805 mN-m; p=0.1188). Both groups, however, showed significantly reduced force compared to the uninjured control limbs (22.545±0.241 mN-m; p=0.0028). Conclusion: This study underscores the profound loss of muscle function following VML injury, as evidenced by the marked reduction in strength in the injured limbs. While no significant difference in force generation was observed between the MMT and NT groups at 3 weeks, early indications suggest that MMT may contribute to the regeneration of new tissue. We hypothesize that with extended recovery time, MMT-treated muscles could exhibit greater improvements in strength and functional capacity.