Bone tissue engineering relies on the ability of osteoprogenitor cells to proliferate rapidly and populate an implantable scaffold prior to differentiation and mineralization. The quality of regenerated tissue achieved is in part governed by the number of cells available for tissue formation. It is therefore our goal to determine the effects of the material variables of a scaffold on growth kinetics, and to use that information to tune the material for rapid cell proliferation.

In the work presented, a material based in a sol-gel made of whey protein isolate (WPI) is designed for use as a scaffold for bone regeneration. We have previously demonstrated that these biopolymer gels support preosteoblast proliferation – an attribute vital to scaffold success. In order to optimize the composition of a WPI gel composite for this application, the growth curves of preosteoblast cells are constructed by culturing MC3T3-E1 cells on WPI gels of varying protein, polysaccharide, and salt concentrations. The curves are used to extract kinetic parameters, which are in-turn compared to one another to elucidate the influence of each component on the behavior of the preosteoblasts – leading to the material that supports the highest cell proliferation rate.

For this optimization study, MC3T3-E1 cells are cultured on WPI discs for different lengths of incubation. At each time point, the cells are harvested and their DNA is purified. The DNA is quantified using fluorescence, and used as a direct measure of cell number. Scanning electron micrographs validate the bulk kinetic data; images demonstrate that the proliferating cells exhibit the desired phenotype. The optimal gel composition and structure inferred from this study are a key in creating a material that will support the growth of new bone tissue in a clinical setting.