Abstract
BACKGROUND: Composite comprising bovine dermis-derived soluble collagen sponge and porous beta-tricalcium phosphate (β-TCP) small particles has the potential to combine favorable clinical handling properties, excellent osteoconductivity and biodegradation capability.
PURPOSE: The purpose of this study was to determine cell biological properties of the β-TCP-collagen composite and histologic characteristics during new bone formation using in vivo and in vitro experimental models.
MATERIALS AND METHODS: The β-TCP-collagen composite or control collagen sponge was implanted in rat calvarial defects with a 5.0-mm diameter. Histologic evaluation was performed at 2, 4 and 8 weeks postoperatively. Rat bone marrow-derived osteoblastic cells were co-cultured with the composite or control collagen sponge on a polystyrene plate without physical contact.
RESULTS: The composite initially underwent osteoblastic cellular invasion and connective-like tissue ingrowth from inside and outside the material together with biodegradation. Eventually, most parts of the composite were replaced with densely packed, thick and mature bone tissue without reduction in the size of the implantation site, whereas only thin, fibrous-like tissue formation was observed in the defect implanted with the control collagen sponge. ALP activity, von Kossa-positive mineralizing nodule area and intracellular calcium level were higher in osteoblastic culture under the composite than under the control collagen sponge.
CONCLUSIONS: The β-TCP-collagen composite allowed initial trabecular formation inside the material followed by replacement of the material with mature bone tissue during the healing process in rat calvarial criticalsize bone defect. Moreover, it was suggested that the composite stimulated osteoblastic cellular differentiation through supplementation of calcium. These observations supported the excellent osteoconductivity, biodegradation property and osteostimulating activity of the composite.
