The effects of 3D bioactive glass scaffolds and BMP-2 on bone formation in rat femoral critical size defects and adjacent bones

Abstract

Reconstruction of critical size defects in the load-bearing area has long been a challenge in orthopaedics. In the past, we have demonstrated the feasibility of using a biodegradable load-sharing scaffold fabricated from poly(propylene fumarate)/tricalcium phosphate (PPF/TCP) loaded with bone morphogenetic protein-2 (BMP-2) to successfully induce healing in those defects. However, there is limited osteoconduction observed with the PPF/TCP scaffold itself. For this reason, 13-93 bioactive glass scaffolds with local BMP-2 delivery were investigated in this study for inducing segmental defect repairs in a load-bearing region. Furthermore, a recent review on BMP-2 revealed greater risks in radiculitis, ectopic bone formation, osteolysis and poor global outcome in association with the use of BMP-2 for spinal fusion. We also evaluated the potential side effects of locally delivered BMP-2 on the structures of adjacent bones. Therefore, cylindrical 13-93 glass scaffolds were fabricated by indirect selective laser sintering with side holes on the cylinder filled with dicalcium phosphate dehydrate as a BMP-2 carrier. The scaffolds were implanted into critical size defects created in rat femurs with and without 10 μg of BMP-2. The x-ray and micro-CT results showed that a bridging callus was found as soon as three weeks and progressed gradually in the BMP group while minimal bone formation was observed in the control group. Degradation of the scaffolds was noted in both groups. Stiffness, peak load and energy to break of the BMP group were all higher than the control group. There was no statistical difference in bone mineral density, bone area and bone mineral content in the tibiae and contralateral femurs of the control and BMP groups. In conclusion, a 13-93 bioactive glass scaffold with local BMP-2 delivery has been demonstrated for its potential application in treating large bone defects.

Rapid bone regeneration by Escherichia coli -derived recombinant human bone morphogenetic protein-2 loaded on a hydroxyapatite carrier in the rabbit calvarial defect model

“…For space maintenance during wound healing, biphasic calcium phosphate with a high proportion of HA may be a more appropriate rhBMP-2 carrier [ 20 ]. Bioactive glass fabricated with dicalcium phosphate dehydrate is not suitable as a BMP-2 carrier; a previous study showed that the bone mineral density, bone area, and bone mineral content of tibiae and contralateral femurs did not differ between control and BMP-treated groups [ 21 ]. The goals of this study were to evaluate the effect of HAP on bone regeneration and to determine the efficacy of HAP as a carrier for ErhBMP-2 in a rabbit calvarial intraosseous defect model.…”

Bone grafts and biomaterials substitutes for bone defect repair: A review

“…Like the other ceramics, the mechanical properties of bioglass were reported to be brittle and weak. Therefore, it has been mainly applied in the reconstruction of facial defects [155] , [156] when combined with growth factors [157] , [158] .…”

Angiogenesis Assays for the Evaluation of Angiogenic Properties of Orthopaedic Biomaterials – A General Review

“…Following an injury to the bone, the disruption of blood vessels activates the coagulation cascade and formation of a hematoma. A sequential overview of the biological events of osteogenesis and angiogenesis during bone healing with implantation of a scaffold is presented in Figure . Not only does the formation of new blood vessels bring in osteoblast and osteoclast precursors along with other growth factors and cytokines, ECs and their precursors can also express factors to directly act on osteogenesis (as seen in Figure ) .…”