Combination therapy with BMP-2 and a systemic RANKL inhibitor enhances bone healing in a mouse critical-sized femoral defect

Abstract

Recombinant human BMP-2 (rhBMP-2) is a potent osteoinductive agent, but has been associated not only with bone formation, but also osteoclastogenesis and bone resorption. Osteoprotegerin (OPG) is a RANKL inhibitor that blocks differentiation and function of osteoclasts. We hypothesized that the combination of local BMP-2 (recombinant protein or a product of gene therapy) plus systemic OPG-Fc is more effective than BMP-2 alone in promoting bone repair. To test this hypothesis we used a mouse critical-sized femoral defect model. Col2.3eGFP (osteoblastic marker) male mice were treated with rhBMP-2 (group I), rhBMP-2 and systemic OPG (group II), rhBMP-2 and delayed administration of OPG (group III), mouse BM cells transduced with a lentiviral vector containing the BMP-2 gene (LV-BMP-2; group IV), LV-BMP-2 and systemic OPG (group V), a carrier alone (group VI) and administration of OPG alone (group VII). All bone defects treated with BMP-2 (alone or combined with OPG) healed, whereas minimal bone formation was noted in animals treated with the carrier alone or OPG alone. MicroCT analysis showed that bone volume (BV) in rhBMP-2 + OPG and LV-BMP-2 + OPG groups was significantly higher compared to rhBMP-2 alone (p < 0.01) and LV-BMP-2 alone (p < 0.001). Similar results were observed in histomorphometry, with rhBMP-2 alone defects exhibiting significantly lower bone area (B.Ar) compared to rhBMP-2 + OPG defects (p < 0.005) and LV-BMP-2 defects having a significantly lower B.Ar compared to all BMP-2 + OPG treated groups (p ≤ 0.01). TRAP staining demonstrated a major osteoclast response in the groups that did not receive OPG (rhBMP-2, LV-BMP-2 and sponge alone) beginning as early as 7 days post-operatively. In conclusion, we demonstrated that locally delivered BMP-2 (recombinant protein or gene therapy) in combination with systemically administered OPG improved bone healing compared to BMP-2 alone in a mouse critical-sized bone defect. These data indicate that osteoclasts can diminish healing responses to BMP-2 and that RANKL inhibition may thus accentuate BMP-2 efficacy.

Micro-computed tomography in murine models of cerebral cavernous malformations as a paradigm for brain disease

“…With the advent of different potential therapeutic agents (Gibson et al, 2015; Li and Whitehead, 2010) along with a handful of genes implicated in CCM signaling (Zhou et al, 2015) and phenotypic variations (Choquet et al, 2014), a sensitive, reliable and rapid way of determining their impact on CCM genesis and progression is desirable. The use of the micro-CT technique to assess therapeutic interventions is already being applied in other disease states (Bougioukli et al, 2015; Rusckowski et al, 2016). Similarly, micro-CT imaging is already being relied on in pre-clinical transgenic models involving genetic alterations and transcriptional modifications (Huesa et al, 2015; Keller et al, 2013).…”

Bone Pain and Muscle Weakness in Cancer Patients

“…[3, 62] OPG has been shown to have inhibitory potential in breast cancer-induced bone destruction. [63]…”

Bone morphogenetic protein 2 alleviated intervertebral disc degeneration through mediating the degradation of ECM and apoptosis of nucleus pulposus cells via the PI3K/Akt pathway

“…BMP2 was also suggested to protect the growth and decrease the apoptosis of NP cells (22), but the exact mechanism remains unclear. An animal model demonstrated that combination therapy of BMP2 and a receptor activator of nuclear factor κB ligand inhibitor promoted bone healing in a critical-sized femoral defect mouse model (23). Additionally, BMP2 inhibited the growth and metastasis of hepatocellular carcinoma by inhibiting the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway, which serves an important role in osteogenesis (24,25).…”