Extracellular Matrix-Derived Modular Bioscaffolds for Soft Connective Tissue Regeneration
Abstract
Human decellularized adipose tissue (DAT) represents a promising extracellular matrix (ECM) source for the development of biomaterials, with its properties conductive of angiogenesis, adipogenesis, and scaffold remodelling. This thesis sought to provide new fundamental insight into the design of ECM-derived bioscaffolds by developing novel modular biomaterials for soft connective tissue regeneration and by studying the effects of ECM composition on cell function and fate.
Initial studies explored the effects of ECM composition of pre-assembled bead foams derived from DAT or commercially-sourced bovine collagen (COL) on human wound edge dermal fibroblasts (weDFs) sourced from chronic wounds. In vitro testing under conditions simulating chronic wound stresses and in vivo investigation in a murine subcutaneous implantation model indicated that weDF survival and angiogenic marker expression were significantly enhanced in the DAT bead foams as compared to the COL bead foams. These results confirmed DAT as an ECM source with pro-regenerative properties.
Building from this work, a novel scaffold format comprised of fused networks of ECM-derived beads was generated through a “cell-assembly” approach using human adipose-derived stromal cells (ASCs) seeded on DAT beads. The cell-assembled bead foams, stabilized by the synthesis of new ECM, were structurally robust, easily handled, and contained a high density of viable ASCs distributed throughout the scaffold. Within a murine subcutaneous implantation model, the cell-assembled DAT bead foams showed enhanced early cell retention using a non-invasive in vivo cell tracking approach, along with increased detection of CD31+ endothelial cells within the implant at day 28, relative to ASC-seeded pre-assembled DAT bead foams. Overall, it was found that the novel cell-assembled DAT bead foams represented a promising pro-regenerative cell-delivery system.
The novel cell-assembly methods were extended to produce tissue-specific cell-assembled bead foams derived from decellularized trabecular bone (DTB) and COL. Preliminary findings indicated that the DAT and COL scaffold groups provided a highly supportive microenvironment for adipogenic differentiation in culture. Results also suggested that the DTB group may have inhibitory effects on ASC adipogenesis. Overall, this work established that the cell-assembly approach can be used to generate platforms for exploring the effects of ECM composition on stem cell differentiation.