Effects of Bioactive-Glass Containing rh-BMP-2 on Growth/Proliferation of Rat Pre-osteoblasts

Bioactive glasses promote bone formation in vivo and show great potential for use as bone tissue-engineering scaffolds. This study investigated using these materials to deliver recombinent human Bone Morphogenic Protein-2(rhBMP2), a growth factor with osteogenic potential. Objectives: This project compared in vitro cell growth on disks of sol-gel bioactive glass with and without rhBMP2. We assessed the effect of this composite on pre-osteoblast attachment, proliferation, and differentiation. Methods: Uniform discs of sol-gel bioactive glass (85% SiO2, 11% CaO, and 4% P2O5), 1mm x 15.5mm, were prepared by grinding and pressing the glass. 100ng of rhBMP2, in solution, was applied to each glass disk(GBMP) and allowed to adsorb. Cell culture-treated polystyrene wells(PS), additional glass disks without rhBMP(GD), and grit-blasted acid etched titanium disks(TD) served as controls. A primary cell culture, rich in pre-osteoblasts was obtained from 19 day-old fetal rat calvariae. Disks were plated in standard 24-well culture plates and each well received 10,000 cells. Viable cells at hallmark times for attachment (4 and 24 hrs), proliferation (48, 96, and 120 hrs), and differentiation (216 and 288 hrs), were counted using 10% alamarBlue nuclear dye and a fluorescent colorimeter. Alkaline phosphatase(Apase) was measured to assess differentiation. Significance was determined using Students t-test with a=0.05 Results: At attachment and proliferation times, TD, GBMP, and GD cell counts were equivalent. All material disks had fewer cells than PS controls. At differentiation times, TD and GD disks remained equal and had fewer cells than PS wells. However, GBMP had significantly more (nearly 6X as many) cells than the PS. Apase levels were greater in GBMP than the other three groups. Conclusions: Sol-gel bioactive glass provides a substrate for cell growth which is similar to grit-blasted acid etched titanium, and may serve as a delivery scaffold for rhBMP. Supported by: Medical Research Foundation of Oregon.