Tissue-specific extracellular matrix promotes myogenic differentiation of human muscle progenitor cells on gelatin and heparin conjugated alginate hydrogels.

Myogenic differentiation, cell fusion, and myotube formation of skeletal muscle progenitor cells (SMPCs) have key roles during skeletal muscle development and repair. However, after isolation from living tissue and transition to culture dishes, SMPCs gradually lose their function and stop propagating due to the absence of extracellular matrix (ECM). Despite encouraging results of experiments using ECM components in cell culture for maintenance and propagation of some tissue types, the benefits of this approach on SMPC culture are limited, because the bioactive molecules and proteins instantly release and are degraded during culture. In this study, we developed a novel approach to enhance the proliferation and differentiation of human skeletal muscle progenitor cells (hSMPCs) in vitro with skeletal muscle ECM in combination with a modified alginate hydrogel conjugated with gelatin and heparin (Alg-G-H) as a substrate. This Alg-G-H substrate, together with skeletal muscle ECM, significantly enhanced cell expansion, differentiation, and maturation of hSMPCs compared with individual substrata (i.e. gelatin, Matrigel®, or ECM alone). In Western-blot and immunocytochemical analyses, the Alg-G-H-ECM predominantly enhanced expression of skeletal myogenesis markers (MyoD, Myf5, Myogenin, Desmin and Myosin) and myotube formation in hSMPCs. This study demonstrated that combining Alg-G-H substrates with skeletal muscle ECM modulated homeostasis of cell proliferation, differentiation, and maturation of hSMPCs by releasing signaling molecules and growth factors. This technique could be a cost-effective tool for in vitro skeletal muscle cell differentiation and maturation, with potential applications in tissue regeneration and drug development. STATEMENT OF SIGNIFICANCE: Alginate based biomaterials are commonly used in tissue engineering and regenerative medicine field, however, the inefficient sequestration of growth factors restricted its utilization. In this study, a novel alginate based substrates was produced covalently modified with gelatin and heparin, in order to capture more effective cytokines and proteins in the culture milieu, keep homeostasis for cell survival and tissue regeneration with growth factor sequestration and long-term release capacities. Combining with skeletal muscle derived ECM, the modified Alginate-Gelatin-Heparin gel could most effectively mimic the tissue specific microenvironment to support skeletal muscle progenitor cells proliferation, differentiation and myotube formation. Additionally, the economical and practical features will make it more promising in high-throughput application for regenerative medicine research.