Long-term longitudinal study on swine VML model.

Background: Volumetric Muscle Loss (VML), resulting from severe trauma or surgical ablation, is a pathological condition preventing myofibers regeneration, since skeletal muscle owns the remarkable ability to restore tissue damage, but only when limited in size. The current surgical therapies employed in the treatment of this pathology, which particularly affects military personnel, do not yet provide satisfactory results. For this reason, more innovative approaches must be sought, specifically skeletal muscle tissue engineering seems to highlight promising results obtained from preclinical studies in VML mouse model. Despite the great results obtained in rodents, translation into human needs a comparable animal model in terms of size, in order to validate the efficacy of the tissue engineering approach reconstructing larger muscle mass (human-like). In this work we aim to demonstrate the validity of a porcine model, that has underwent a surgical ablation of a large muscle area, as a VML damage model.
Results: For this purpose, morphological, ultrasound, histological and fluorescence analyses were carried out on the scar tissue formed following the surgical ablation of the peroneus tertius muscle of Sus scrofa domesticus commonly called mini-pig. In particular, the replenishment of the damaged area, the macrophage infiltration and the vascularization at different time-points were evaluated up to the harvesting of the scar upon six months.
Conclusion: Here we demonstrated that following VML damage, there is an extremely poor regenerative process in the swine muscle tissue, while the formation of fibrotic, scar tissue occurs. The analyses performed up to 180 days after the injury revealed the development of a stable, structured and cellularized tissue, provided with vessels and extracellular matrix acquiring the status of granulation tissue like in human.
(© 2023. The Author(s).)