Bone Regenerative Engineering Using a Protein Kinase A-Specific Cyclic AMP Analogue Administered for Short Term

Small molecule-mediated bone regeneration is emerging as a promising strategy for replacing or enhancing the therapeutic protein-based growth factors. However, unknown non-specific toxicity of small molecules on non-target cells or organs due to the long-term exposure has been a concern. We previously demonstrated that the continuous treatment of osteoblast-like MC3T3-E1 cells with small molecule cyclic AMP analogue N6-benzoyladenosine-3′,5′-cyclic monophosphate (6-Bnz-cAMP) was capable of inducing in vitro osteogenesis via the protein kinase A (PKA) signaling pathway. In this study, we investigate the effect of short-term 6-Bnz-cAMP treatment, i.e., 1-day treatment, as compared to continuous treatment, on in vitro osteogenesis in osteoprogenitor cells. It is hypothesized that the proposed short-term 6-Bnz-cAMP treatment scheme would result in osteogenesis as in the case of continuous 6-Bnz-cAMP treatment. Our results showed that both short-term and continuous 6-Bnz-cAMP treatments elicited osteoblastic differentiation and mineralization of osteoblast-like MC3T3-E1 cells. Short-term treatment using small molecule 6-Bnz-cAMP can serve as a highly promising strategy for bone regeneration while mitigating potential non-specific side effect risks associated with small molecules. The goal of this work is to develop a simple, inexpensive, effective, and safe method to heal bone defect. We would like to treat the bone defects with a small molecule-based therapeutic agent in a short-term treatment so that undesirable side effects from the therapeutics would be significantly minimized. Our work may also result in novel bone graft materials that can potentially become a viable alternative to existing grafts.