Pre-vascularized porous gelatin-coated β-tricalcium phosphate scaffolds for bone regeneration: an in vivo and in vitro investigation.

Vascularization is vital in bone tissue engineering, supporting development, remodeling, and regeneration. Lack of vascularity leads to cell death, necessitating vascularization strategies. Angiogenesis, forming new blood vessels, provides crucial nutrients and oxygen. Pre-vascularized gelatin-coated β-tricalcium phosphate (G/β-TCP) scaffolds show promise in bone regeneration and vascularization. Our study evaluates G/β-TCP scaffolds' osteogenic and angiogenic potential in vitro and a canine model with vascular anastomosis. Channel-shaped G/β-TCP scaffolds were fabricated using foam casting and sintering of a calcium phosphate/silica slurry-coated polyurethane foam, then coated with cross-linked gelatin. Buccal fat pad-derived stem cells (BFPdSCs) were seeded onto scaffolds and assessed over time for adhesion, proliferation, and osteogenic capacity using scanning electron microscopy (SEM), 4,6-diamidino-2-phenylindole (DAPI) staining, Alamar blue, and alkaline phosphatase (ALP) assays. Scaffolds were implanted in a canine model to evaluate osteogenesis and angiogenesis by histology and CT scans at 12 wk. Our studies showed preliminary results for G/β-TCP scaffolds supporting angiogenesis and bone regeneration. In vitro analyses demonstrated excellent proliferation/viability, with BFPdSCs adhering and increasing on the scaffolds. ALP activity and protein levels increased, indicating osteogenic differentiation. Examination of tissue samples revealed granulation tissue with a well-developed vascular network, indicating successful angiogenesis and osteogenesis was further confirmed by a CT scan. In vivo, histology revealed scaffold resorption. However, scaffold placement beneath muscle tissue-restricted bone regeneration. Further optimization is needed for bone regeneration applications.