Decellularized tissues represent promising biomaterials, which harness the innate capacity of the tissue-specific extracellular matrix (ECM) to direct cell functions including stem cell proliferation and lineage-specific differentiation. However, bioscaffolds derived exclusively from decellularized ECM offer limited versatility in terms of tuning biomechanical properties, as well as cell–cell and cell–ECM interactions that are important mediators of the cellular response. As an alternative approach, in the current chapter we describe methods for incorporating cryo-milled decellularized tissues as a cell-instructive component within a hydrogel carrier designed to crosslink under mild conditions. This composite strategy can enable in situ cell encapsulation with high cell viability, allowing efficient seeding with a homogeneous distribution of cells and ECM. Detailed protocols are provided for the effective decellularization of human adipose tissue and porcine auricular cartilage, as well as the cryo-milling process used to generate the ECM particles. Further, we describe methods for synthesizing methacrylated chondroitin sulphate (MCS) and for performing UV-initiated and thermally induced crosslinking to form hydrogel carriers for adipose and cartilage regeneration. The hydrogel composites offer great flexibility, and the hydrogel phase, ECM source, particle size, cell type(s) and seeding density can be tuned to promote the desired cellular response. Overall, these systems represent promising platforms for the development of tissue-specific 3-D in vitro cell culture models and in vivo cell delivery systems.
Cell delivery vehicle Cell therapy Cell-instructive biomaterials Composite scaffolds Decellularization Extracellular matrix (ECM) Hydrogels In vitro In vivo Methacrylated chondroitin sulphate Stem cells
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Scholarship funding to support this work was provided by the NSERC CREATE CONNECT! Program and Western’s Collaborative Graduate Training Program in Musculoskeletal Health Research (CMHR). Operational grant funding support was provided by NSERC. The authors would like to thank Cody Brown for technical assistance with the SEM imaging and the Western Nanofabrication facility for access to their imaging equipment. Finally, we would like to acknowledge Drs. Aaron Grant, Brian Evans and Robert Richards for their clinical collaborations in providing human adipose tissue samples, as well as the Mount Brydges abattoir for providing the porcine auricular cartilage tissue.
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