Effectiveness of BMP-2 and PDGF-BB Adsorption onto a Collagen/Collagen-Magnesium-Hydroxyapatite Scaffold in Weight-Bearing and Non-Weight-Bearing Osteochondral Defect Bone Repair: In Vitro, Ex Vivo and In Vivo Evaluation

Abstract

Despite promising clinical results in osteochondral defect repair, a recently developed bi-layered collagen/collagen-magnesium-hydroxyapatite scaffold has demonstrated less optimal subchondral bone repair. This study aimed to improve the bone repair potential of this scaffold by adsorbing bone morphogenetic protein 2 (BMP-2) and/or platelet-derived growth factor-BB (PDGF-BB) onto said scaffold. The in vitro release kinetics of BMP-2/PDGF-BB demonstrated that PDGF-BB was burst released from the collagen-only layer, whereas BMP-2 was largely retained in both layers. Cell ingrowth was enhanced by BMP-2/PDFG-BB in a bovine osteochondral defect ex vivo model. In an in vivo semi-orthotopic athymic mouse model, adding BMP-2 or PDGF-BB increased tissue repair after four weeks. After eight weeks, most defects were filled with bone tissue. To further investigate the promising effect of BMP-2, a caprine bilateral stifle osteochondral defect model was used where defects were created in weight-bearing femoral condyle and non-weight-bearing trochlear groove locations. After six months, the adsorption of BMP-2 resulted in significantly less bone repair compared with scaffold-only in the femoral condyle defects and a trend to more bone repair in the trochlear groove. Overall, the adsorption of BMP-2 onto a Col/Col-Mg-HAp scaffold reduced bone formation in weight-bearing osteochondral defects, but not in non-weight-bearing osteochondral defects.

3D-Printed Magnesium Peroxide-Incorporated Scaffolds with Sustained Oxygen Release and Enhanced Photothermal Performance for Osteosarcoma Multimodal Treatments

“…In fact, researchers have used calcium peroxide to promote the survival, proliferation, and differentiation of transplanted seed cells to boost the efficiency of bone repair, while the present study used 3D printing technology to achieve a more sustained oxygen release and to secure the mechanical strength of the material . Using 3D-printed magnesium composite scaffolds, which have been presented as an important approach for bone defect repair, Xu et al found that both platelet-derived growth factor BB (PDGF-BB) and BMP2 expression were upregulated, thereby displaying excellent osteogenetic, angiogenetic, and mechanical properties . Besides, the alkaline environment formed during Mg 2+ release also increases osteoblast-mediated mineral deposition and inhibits osteoclast activity, thus accelerating bone regeneration .…”

“…27 Using 3D-printed magnesium composite scaffolds, which have been presented as an important approach for bone defect repair, Xu et al found that both platelet-derived growth factor BB (PDGF-BB) and BMP2 expression were upregulated, thereby displaying excellent osteogenetic, angiogenetic, and mechanical properties. 55 Besides, the alkaline environment formed during Mg 2+ release also increases osteoblast-mediated mineral deposition and inhibits osteoclast activity, thus accelerating bone regeneration. 56 Consequently, the oxygen and Mg 2+ released in response to MgO 2 implantation can effectively promote the subsequent bone defect repair process and play a dual synergistic role.…”