One-day treatment of small molecule 8-bromo-cyclic AMP analogue induces cell-based VEGF production forin vitroangiogenesis and osteoblastic differentiation

Abstract

Small molecule based regenerative engineering is emerging as a promising strategy for regenerating bone tissue. Small molecule cAMP analogues have been proposed as novel biofactors for bone repair and regeneration, and while promising, the effect that these small molecules have on angiogenesis, a critical requirement for successful bone regeneration, is still unclear. Our previous research demonstrated that the small molecule cAMP analogue 8-bromoadenosine-3’,5’-cyclic monophosphate (8-Br-cAMP) was able to promote initial osteoblast adhesion on a polymeric scaffold via cAMP signaling cascades. Here, we report that 8-Br-cAMP is capable of inducing in vitro cell-based VEGF production for angiogenesis promotion. We first demonstrated that treating osteoblast-like MC3T3-E1 cells with 8-Br-cAMP for one day significantly increased VEGF production and secretion. We then demonstrated that 8-Br-cAMP induced cell-secreted VEGF is biologically active and may promote angiogenesis as evidenced by increased endothelial cells (HUVECs) migration and tubule formation. In addition, treatment of MC3T3-E1 cells with 8-Br-cAMP for as short as a single day resulted in enhanced ALP activity as well as matrix mineralization, demonstrating in vitro osteoblastic differentiation. A short term 8-Br-cAMP treatment also addresses the concern of non-specific cytotoxicity, as our data indicate that a one-day 8-Br-cAMP treatment scheme supports cellular proliferation of MC3T3-E1 cells as well as HUVECs. While the major concern associated with small molecule drugs is the risk of non-specific cytotoxicity, the short exposure treatment outlined in this paper provides a very promising strategy to mitigate the risk associated with small molecules.

The transcription factor cyclic adenosine 3′,5′‐monophosphate response element‐binding protein enhances the odonto/osteogenic differentiation of stem cells from the apical papilla

“…, Lo et al . ), and PKA activation induces in vitro osteogenesis and in vivo bone formation (Siddappa et al . ).…”

“…Some studies have suggested that this signalling contributes to osteogenesis. For example, the treatment of MSCs with a cAMP stimulator results in enhanced osteoblastic differentiation (Kim et al 2013, Lo et al 2016, and PKA activation induces in vitro osteogenesis and in vivo bone formation (Siddappa et al 2008). Other studies have proposed an inhibitory role of this signalling pathway in osteogenesis.…”

Small-molecule based musculoskeletal regenerative engineering

“…This coordination between timing and location of small molecules could be optimized for both specific tissue types and tissue interfaces (1). In addition, reducing the frequency of administration of small molecule drugs has been recently proposed as a promising strategy to minimize their side effects (22, 76). Nevertheless, more research work needs to be done to unravel the role of small molecules in musculoskeletal tissue regeneration prior to its clinical utility, including studying dosage requirements and effective delivery strategies (Box 3).…”

Pharmacological efficacy of a synergistic composition based on activators of cAMP accumulation as a wound healing agent

“…Thus, the ubiquitously present PDEs play a pivotal role in regulating cell signalling via the breakdown of cAMP and cGMP. PDE inhibitors are therapeutic agents which target PDE isoenzymes and inhibit the metabolism of the secondary messengers (cAMP, cGMP) thus, prolonging the biological effect determined by the type of cell involved [10,11].…”