Development and characterization of a novel meniscal extracellular matrix-derived scaffold
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Musculoskeletal injuries are a common and significant problem in orthopaedic practice. Despite advances in orthopaedic surgery, effective treatments for injuries to the knee meniscus remain a common and significant clinical challenge. Tissue engineering is a developing field that aims to regenerate injured tissues with a combination of cells, scaffolds, and signals. Many natural and synthetic scaffold materials have been developed and tested for the repair and restoration of a number of musculoskeletal tissues. Among these, biological scaffolds derived from extracellular matrix (ECM) have been developed and tested given the critical role of the ECM for maintaining the biological and biomechanical properties, structure, and function of native tissues. Decellularized scaffolds composed of ECM hold promise for repair and regeneration of the meniscus given the potential for ECM-based biomaterials to aid in cell recruitment, infiltration, and differentiation. The objectives of this research were to decellularize canine menisci in order to fabricate a micronized, ECM-derived scaffold, and to determine the cytocompatibility and repair potential of the scaffold ex vivo by developing an in vitro model for meniscal repair. In the first series of experiments, menisci were decellularized with a combination of physical agitation and chemical treatments. For scaffold fabrication, decellularized menisci were cryoground into a powder and the size and morphology of the ECM particles were evaluated using scanning electron microscopy. Histologic and biochemical analyses of the scaffold confirmed effective decellularization with loss of proteoglycan from the tissue but no significant reduction in collagen content. When washed effectively, the decellularized scaffold was cytocompatible to meniscal fibrochondrocytes, synoviocytes, and whole meniscal tissue based on the resazurin reduction assay, fluorescent live/dead staining, and histologic evaluation. Further, the scaffold supported cellular attachment and proliferation when combined with platelet rich plasma, and promoted an upregulation of genes associated with meniscal ECM synthesis and tissue repair. In an ex vivo model for meniscal repair, radial tears repaired and augmented with the scaffold demonstrated increased cellular proliferation and tissue repair compared to non-augmented repairs. Therefore, a micronized scaffold derived from decellularized meniscus may be a viable biomaterial for promoting avascular meniscal healing. However, further studies are necessary to determine an optimal carrier for delivery of the scaffold, and to examine the potential for the scaffold to induce cellular differentiation and functional meniscal fibrochondrogenesis.