Browsing by Subject "Skeletal muscle regeneration"

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Electrophoretically decellularized xenogeneic extracellular matrix for large volume skeletal muscle regeneration
(2015-08) Merscham, Melissa Marie; Farrar, Roger P.; Suggs, Laura; Thompson, Wesley; Brothers, Robert; Baker, Aaron
Large volume skeletal muscle injuries, such as those that occur through traumatic or surgical means, are complex injuries that are unable to repair through the body’s native repair processes. These injuries, termed volumetric muscle loss (VML), result in fibrotic scar tissue formation and functional impairments. Within the last decade, there has been an immense push towards bioscaffold research and development to regenerate functional skeletal muscle tissue in VML injuries. The most promising bioscaffold is the use of a decellularized skeletal muscle-derived extracellular matrix (ECM). However, the use of skeletal muscle derived ECMs to replace lost tissues is limited by the inability to produce ECMs of clinically relevant sizes and shapes. Therefore, the purpose of this study was to develop an electrophoresis-based decellularization method that can render large volumes of porcine skeletal muscle ECM acellular time while also retaining the native ECM ultrastructure. Analysis of the resulting decellularized porcine skeletal muscle ECM determined most soluble proteins and DNA were removed, and the collagen framework of the ECM resembled that of native skeletal muscle. The decellularized ECM was implanted into a rodent lateral gastrocnemius (LGAS) VML injury model previously developed in our lab. Repair of the VML injury with the electrophoretically decellularized porcine ECM improved morphology of the LGAS and resulted in myofiber, blood vessel, and nerve growth throughout the ECM implant in vivo, and promoted an M2 macrophage profile. Addition of mesenchymal stem cells (MSCs) to the implanted ECM increased functional recovery, myofiber and blood vessel infiltration, and reduced fibrosis within the ECM implant region compared to saline treated implants 84 days after injury. The direct contribution of the injected MSCs tagged with green fluorescent protein (GFP) to myofiber development was not detected. These data demonstrate an electrophoresis-based decellularization protocol may be a better alternative to produce clinically relevant ECMs that can be used to repair VML injuries, and resulting porcine ECMs serve as a viable platform for muscle regeneration. Additionally, injection of MSCs into the ECM improves myofiber ingrowth, vascularization, and function most likely through modulation of the tissue microenvironment rather than differentiation and fusion into skeletal muscle.
Functional recovery of a volumetric skeletal muscle loss injury using mesenchymal stem cells in a PEGylated fibrin gel seeded on an extracellular matrix
(2012-12) Merscham, Melissa Marie; Farrar, Roger P.; Suggs, Laura J
This study investigated the effect of bone marrow derived mesenchymal stem cells (MSCs) in a PEGylated fibrin gel (PEG) seeded into a decellularized extracellular matrix (ECM) on recovery of skeletal muscle following a volumetric muscle loss (VML) injury. Six to nine month old male Sprague-Dawley rats were used in this study. Approximately one-third of the skeletal muscle mass of the lateral gastrocnemius (LGAS) was removed from the LGAS, which was immediately replaced with an acellular ECM of the same dimensions. Seven days after injury, animals were injected with one of four solutions: saline (SAL), MSCs (MSC), PEGylated fibrin hydrogel (PEG), or MSCs in PEG (PEG+MSC). Maximal isometric tetanic tension (Po) of the LGAS was assessed fifty-six days after VML injury, followed by histological evaluation. VML injury resulted in a functional impairment of the LGAS capable of producing 76.1± 4.9% of the force generated in the non-injured contralateral LGAS. Tetanic tension of the PEG+MSC treated group was significantly higher compared to all other treatment groups (p < 0.05), although specific tension (N/cm2) in the PEG+MSC group (79.7±4.0%) was only significantly higher compared to SAL (58.2±3.0) and PEG (64.0±2.1%) treated groups (p < 0.05). However, LGAS mass was significantly higher in the PEG+MSC group compared to all other groups (p < 0.05). These findings suggest the combination of the PEG+MSC did not lead to a significant increase in muscle function compared to MSC treatment alone, and demonstrates the importance of MSCs in skeletal muscle regeneration in VML injury models. However, as evident by the significant increase in LGAS mass, PEG+MSC treatment may lead to histological differences not evaluated in this study. Gross morphology of the repaired gastrocnemius was indistinguishable from the contralateral control.
Repair of skeletal muscle transection injury with tissue loss
(2009-08) Merritt, Edward Kelly, 1979-; Farrar, Roger P.
A traumatic skeletal muscle injury that involves the loss of a substantial portion of tissue will not regenerate on its own. Little is understood about the ability of the muscle to recover function after such a defect injury, and few research models exist to further elucidate the repair and regeneration processes of defected skeletal muscle. In the current research, a model of muscle injury was developed in the lateral gastrocnemius (LGAS) of the rat. In this model, the muscle gradually remodels but functional recovery does not occur over 42 days. Repair of the defect with muscle-derived extracellular matrix (ECM), improves the morphology of the LGAS. Blood vessels and myofibers grow into the ECM implant in vivo, but functional recovery does not occur. Addition of bone marrow-derived mesenchymal stem cells (MSCs) to the implanted ECM in the LGAS increases the number of blood vessels and regenerating myofibers within the ECM. Following 42 days of recovery, the cell-seeded ECM implanted LGAS produces significantly higher isometric force than the non-repaired and non-cell seeded ECM muscles. These results suggest that the LGAS muscle defect is a suitable model for the study of traumatic skeletal muscle injury with tissue loss. Additionally, MSCs seeded on an implanted ECM lead to functional restoration of the defected LGAS.