Decellularized Muscle Supports New Muscle Fibers and Improves Function Following Volumetric Injury

Abstract

Current strategies to treat volumetric muscle loss use primarily pedicle or free muscle transfers, but these grafts fail to adequately regenerate functional tissue. Decellularized soft tissue grafts possess physical and chemical cues to promote muscle regeneration, suggesting their potential for use in large muscle defects. In this study, we developed a decellularized muscle matrix (DMM) graft using rat gastrocnemius. Anisotropy and chemical components of the extracellular matrix were retained, including laminin, fibronectin, and collagen. We compared the ability of DMM, autologous muscle grafts (clinical standard), and type I collagen plugs (negative control) to support muscle regeneration. DMM supported regeneration over a 56-day period in 1 × 1 cm and 1.5 × 1 cm gastrocnemius defects in rats. Muscle function tests demonstrated improved muscle recovery in rats with DMM grafts when compared to collagen. Histological sections were assessed using morphometrics and immunostaining. DMM supported muscle regeneration with less fibrosis and more de novo neuromuscular receptors than either autograft or collagen. Overall, our results indicate that DMM may be used as a muscle replacement graft based on its ability to improve muscle function recovery, promote muscle regeneration, and support new neuromuscular junctions.

Decellularized Tissue for Muscle Regeneration

“…Based on the above points, it is not surprising that acellular scaffolds derived form a range of different tissues have already been tested in animal models [20,21,22,23,24,25,26,27,28,29,30,31,32,33,34] and in small cohorts of patients affected by VML [35,36]. …”

“…Conversely, skeletal muscle scaffolds have only been used in animal models, and their preparation has been shown to be a more complex procedure, mainly due to tissue complexity and thickness. The main protocols applied to generate decellularized scaffolds from skeletal muscle are essentially of three types: enzymatic-not detergent [9,24,29], detergent [31,32,33,34], and detergent-enzymatic [33,45,46] treatments. In the literature such scaffolds are defined as decellularized; however, some of them would be better defined as “anucleated” rather than “acellular” scaffolds.…”

“…In the literature such scaffolds are defined as decellularized; however, some of them would be better defined as “anucleated” rather than “acellular” scaffolds. Indeed, together with the elimination of the nuclear content and the maintenance of the ECM, such treatments can partially preserve cytoplasmic components of the original tissue, in particular those belonging to myofibers [24,32,33,39,45,46]. …”

“…Both innervation and in vivo force production were enhanced when implantation of bioconstructs was followed by an exercise regimen [31]. Another study showed the ability of decellularized skeletal muscle to support functional muscle regeneration by host cells, with less fibrosis and more de novo neuromuscular receptors than either autograft or collagen implants in a rat model of gastrocnemius VML [32]. …”

“…More recently, a 13-patient cohort study was performed, using commercially available ECMs—BioDesign (SIS), Matristem (UBM), and Xenatrix (dermis-ECM)—to repair VML defects. The authors reported that in all cases the acellular scaffold facilitated functional tissue remodeling, thanks to the recruitment of myogenic progenitor cells and improved innervation [32]. These clinical results are in contrast with those obtained from studies performed in large animal models [27,30].…”