Modification of Nano-calcium Sulfate Scaffold for Bone Regeneration

Objectives: The goal of this study was to modify a nanocalcium sulfate material (nCS) that has properties of an osteoconductive scaffold. This nCS has recently been shown to have surface characteristics favorable for osteoblastic cell growth, but optimization of its bone regenerative performance is still necessary for critical size defects. Since fibrin gels have been shown in some studies to enhance bone formation, the specific aim was to assess mesenchymal stem cells (MSCs) growth and differentiation on nCS (control) vs. nCS with fibrin gel formed with various concentrations of fibrinogen and thrombin. In some groups, alginate, a well-characterized porogen, was added to allow more favorable migration of cells into the scaffold’s interior.
Methods: Rat MSCs that have been previously isolated and characterized in Dr. Yang’s lab using well-established techniques and protocols approved by the University’s IACUC were used. Cells were cultured either on tissue culture wells or on disks prepared from nCS with or without alginate (10%) and fibrinogen & thrombin at a range of concentrations. Cell growth/viability was studied using a MTT assay and differentiation using a biochemical assay for alkaline phosphatase (ALP). All statistical analyses were conducted via ANOVA.
Results: The MTT assay revealed significant increases (p<0.05), compared to controls, in cell activity of MSCs cultured in nCS+ alginate alone without fibrinogen and thrombin. ALP studies indicated significantly (p<0.05) increased cell differentiation for all groups compared to controls, with the highest increase (p<0.05) occurring in the nCS groups+ alginate.
Conclusions: These studies suggest that addition of a fibrin network to nCS, although not toxic, does not yield a more optimal scaffold for MSCs growth and differentiation than what can be attained with alginate. Use of alginate with nCS appears to provide a well-fabricated scaffold for MSCs growth and differentiation.