QS6: Collagen-glycosaminoglycans Scaffold Can Improve Muscle Function Recovery After Volumetric Muscle Loss Injury in Rat Model

PROPOSE: Skeletal muscle regenerative capacity fails in restoring muscle function following major injuries in which significant skeletal muscle is lost or damaged. As such, volumetric muscle loss (VML), ultimately results in permanent disability. Therapeutic options are limited in VML and currently no standard of care exists. Biodegradable scaffolds hold great potentials in the regeneration of lost muscle tissue by replacing the lost structural framework of the defect. In this study we aim to evaluate the effects of a porous collagen-glycosaminoglycans scaffold (CGS) on muscle function recovery following VML injury in a rat model. METHODS: Fifteen male 12-week old Sprague-Dawley rats were randomly divided into three groups of 5 rats in each: 1) Sham group, 2) VML Untreated (control) group, and 3) VML+CGS group. A standard model of VML injury was performed to bilateral Tibialis Anterior (TA) muscles in VML Untreated and VML+CGS groups. The muscle defect in VML+CGS group was filled with 3 sheets of CGS cuts while the muscle defects in VML control group left untreated. Animals in Sham group underwent the same surgical procedure (skin and fascia opening and closure) but without any muscle injury. Pick isometric twitch and tetanus forces of foot dorsiflexion were measured in vivo prior, immediately after, and four weeks post injury using a dual mode muscle lever system. In situ TA muscle twitch and tetanic contraction strengths were also determined six weeks after injury. RESULTS: Prior, and immediately after injury no statistically significant differences was seen between VML Untreated and VML+CGS groups in terms of the means of twitch and tetanus foot isometric dorsiflexion forces. Four weeks after injury, TA of VML+ CGS group showed significant functional recovery as compared with VML Untreated group in twitch (76 ± 22.7% vs 51.3 ± 22.3%, p<0.01) and tetanus (77.4 ± 22.1% vs 59.8 ± 22.4%, p<0.05) foot dorsiflexion forces. In situ muscle strength measurements of TA at six weeks post injury, also showed significantly higher twitch (35.2 ± 12.5 mN/mm(2) vs 23.7 ± 6.9 mN/mm(2), p<0.05) and tetanus (115.0 ± 35.3 mN/mm(2) vs 87.9 ± 20 mN/mm(2), p<0.05) forces in TA of VML+CGS group when compared with the VML Untreated group. On histology of the TA performed six weeks following initial injury, placement of CGS decreased fibrosis across the injury, as defined as percentage of positive area in trichrome staining compared with VML Untreated group (1.3 ± 0.1% vs. 7.1 ± 1.3%, p<0.01). In addition, immunofluorescence tissue staining confirmed positive myosin heavy chain staining within the scaffold, indicating the formation of nascent myofibers within the area of injury. CONCLUSIONS: Application of CGS to the muscle defect following VML injury can improve muscle function recovery, limit fibrosis, and promote muscle regeneration in rodent model. These findings can foster future research in larger animals and human subjects.*p<0.05, **p<0.01. Error bars: Standard Deviations.