Inorganic Reacted Matrix Disperses Myogenic Stem Cells In Vivo

Background: Cellular therapy is a promising treatment for musculoskeletal injury and disease, with the potential to replace the exhausted stem cell pool, differentiating into mature cells. However, significant challenges regarding ischemic pocketing of the injected stem cells resulting in acute stem cell death remains. Inorganic matrices can promote cellular adhesion and dispersion, with fibronectin acting as the primary junction binding matrix to cells. Therefore, the purpose of this study was to investigate the potential of a novel inorganic biomaterial, Reacted Matrix (RM), to disperse myogenic stem cells within the injected mouse myofascial compartment. Hypothesis: 24 hours post injection of stem cells with RM (SCRM) in NOD.Cg-PrkdcSCID (SCID) mice, RM will prevent pocketing (ischemic pockets greater than 200 μm in diameter) and promote dispersion of myogenic stem cells in injured tibialis anterior (TA) muscles. Methods: The left TA muscles of adult 3-month-old SCID mice were injured with 1.2% BaCl2 (50 µl). Following the acute inflammatory phase post-BaCl2 (3 days post injury), mice were injected with either stem cells alone (SC) or SCRM, resuspended in sterile saline (50 µl) with 0.05% sodium alginate in the previously injured TA muscle. MyoK9 cells and RM (250 µg) were combined 30 minutes prior to injection to allow for adherence. ~1,000,000 cells were delivered in each intramuscular injection. The SCID mouse is immunodeficient and readily accepts MyoK9 cells without rejection. 24 hours following injection, TA muscles were harvested and immunostained for SV40 (identifies MyoK9), laminin (myofiber borders), and DAPI (nuclei) to analyze histological localization of stem cells within cross-section. Results: TA muscles injected with SCRM decreased the diameter of pocketed stem cells by 66% (means ± SEM: SCRM, 92.7 ± 7.8 µm; SC, 272.7 ± 10.9 µm; P < 0.01). SCRM reduced the area of the largest stem cell pocket by 78% compared to SC alone (SCRM, 0.028 ± 0.002 mm2; SC, 0.127 ± 0.003 mm2; P < 0.01). Total area of stem cells dispersed in cross-section increased by 35% following injection of SCRM (SCRM, 0.172 ± 0.017 mm2; SC, 0.127 ± 0.003 mm2; P = 0.07). Conclusion: Results support the hypothesis that 24 hours post injection of SCRM into the injured TA of SCID mice, myogenic stem cells show marked dispersion throughout the implantation site, preventing the pocketing observed in myogenic stem cells alone. Support: Advancing Discovery to Market Award from Texas A&M University (A.B.M., P.P.N.) and NIH LRP Award from NIAMS (A.B.M.) This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.