The Use of Vinyl Styrene Microbeads (VSM) as Carriers of Growth Factors and Osteoblasts

In the field of craniofacial surgery, the need for porous alloplastic materials as bone filler is on the rise. Vinyl Styrene Microbeads (NRT Co. Bandera, Texas) are inert 500 micrometer beads that were shown to be non phagocytosable and compatible with osteogenesis. The long term objective of this study is to use microbeads as carrier for osteogenic cells and local growth factors. Objectives: to establish an osteoblast cell culture, to determine the functional characteristics of the cells, and to determine the possible adherence of the cells to microbeads in the absence or presence of local growth factors. Methods: rat osteoprogenitor cells were cultured from calvaria of fetal rats (day 15-17 gestation) for 10 days till confluency. Cells were processed by immunoperoxidase technique using mouse anti-osteocalcin and mouse anti-alkaline phosphatase antibodies (Zymed, CA) and stained by Von Kossa stain. Results: cells were found to acquire alkaline phosphatase, osteocalcin immunoreactivity and showed the presence of calcium phosphate deposits and therefore were characterized as osteoblasts. The osteoblasts were then harvested and cultured on the surface of VSM disc alone or in the presence of TGF-b, PDGF or both. The VSM plus cells were processed for scanning electron microscopy. The cells were found to adhere to the surface of the microbeads and also invade the macro pores between the beads. Conclusion: the local growth factors markedly enhanced the proliferation and adherence of the osteoblasts to the surface of the polymer. The results support the future testing of VSM plus cells and local growth factors as bone grafting materials in calvarial critical size defects animal model, supported by a grant from NRT Company Bandera, Texas.