Bone morphogenetic proteins (BMPs) have been widely used for bone repair in the craniofacial region. However, its high dose requirement in clinical applications revealed adverse effects and inefficient bone formation, along with high cost. Here, we report a novel osteoinductive strategy to effectively complement the osteogenic activity of BMP-2 using phenamil, a small molecule that can induce osteogenic differentiation via stimulation of BMP signaling. Treatment of adipose-derived stem cells (ASCs) with BMP-2 in combination with phenamil significantly promoted the in vitro osteogenic differentiation of ASCs. The efficacy of the combination strategy of phenamil + BMP-2 was further confirmed in a mouse calvarial defect model using scaffolds consisting of poly(lactic-co-glycolic acid) and apatite layer on their surfaces designed to slowly release phenamil and BMP-2. Six weeks after implantation, the scaffolds treated with phenamil + BMP-2 significantly promoted mouse calvarial regeneration as demonstrated by micro-computerized tomography and histology, compared with the groups treated with phenamil or BMP-2 alone. Moreover, the combination treatment reduced the BMP-2 dose without compromising calvarial healing efficacy. These results suggest promising complementary therapeutic strategies for bone repair in more efficient and cost-effective manners.
The direct use of adipose-derived stem cells (ASCs) alone has had limited success in the treatment of large bone defects. This study used an alternative approach that complements bone morphogenetic protein (BMP) activity to maximize the osteogenesis of ASCs by regulating levels of antagonists and agonists to BMP signaling. Findings indicate promising stem cell-based therapy for treating bone defects that can effectively complement or replace current osteoinductive therapeutics.
Growth factor-based therapeutics using bone morphogenetic protein 2 (BMP-2) presents a promising strategy to reconstruct craniofacial bone defects such as mandible. However, clinical applications require supraphysiological BMP doses that often increase inappropriate adipogenesis, resulting in well-documented, cyst-like bone formation. Here we reported a novel complementary strategy to enhance osteogenesis and mandibular bone repair by using small-molecule phenamil that has been shown to be a strong activator of BMP signaling. Phenamil synergistically induced osteogenic differentiation of human bone marrow mesenchymal stem cells with BMP-2 while suppressing their adipogenic differentiation induced by BMP-2 in vitro. The observed pro-osteogenic and antiadipogenic activity of phenamil was mediated by expression of tribbles homolog 3 (Trb3) that enhanced BMP-smad signaling and inhibited expression of peroxisome proliferator-activated receptor gamma (PPARγ), a master regulator of adipogenesis. The synergistic effect of BMP-2+phenamil on bone regeneration was further confirmed in a critical-sized rat mandibular bone defect by implanting polymer scaffolds designed to slowly release the therapeutic molecules. These findings indicate a new complementary osteoinductive strategy to improve clinical efficacy and safety of current BMP-based therapeutics.
Vascular regeneration is thought to be crucial in the repair of damaged vessels as well as nonvascular tissues. A healthy endothelial layer provides homeostasis and prevents thrombosis in blood vessels. The variety of cells such as hematopoietic stem cells (HSCs), endothelial progenitor
cells (EPCs), and mature endothelial cells (ECs), are revealed to play an important role in forming an endothelial layer. There are a number of biomolecules that have been identified to be capable of attacting these cells to participate in vascular repair. In terms of these findings, alternative
strategies through the biomolecule modification of scaffold have been recently established to enhance in situ endothelialization for vascular regeneration. This article mainly reviews current and developing biomolecules that can be immobilized onto biomaterial surfaces to accelerate
in situ endothelialization for vascular repair, providing potentials in further discovering novel tissue engineering therapeutics for the treatment of human vascular diseases.
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