Figure 5.

Assessment of orthotopic mineralization in femoral defects treated with alginate constructs. A) Femoral defects were treated with alginate constructs containing 1 mg of unloaded HMPs, 1 mg of HMPs loaded with 2.5 μg of BMP-2, or 2.5 μg of BMP-2 (n = 4–5). Representative radiographs of femurs at 2, 4, 8, and 12 weeks post-surgery. All of the defects treated with BMP-2 alone bridged (5/5), whereas only some of the defects containing HMP + BMP-2 bridged (3/5), and no defects containing unloaded HMPs bridged. Radiographs of femurs treated with BMP-2-loaded HMPs are representative of both bridging and non-bridging cases. White arrows indicate gaps in mineral formation in non-bridged defects. B) Micro-CT quantification of mineral volume in bone defects at 4, 8, and 12 weeks post-surgery. Both BMP-2 and BMP-2-loaded HMP treated femurs demonstrated greater bone formation than unloaded HMPs at each time point (* = p < 0.05 as indicated). BMP-2 treatment induced more bone formation than loaded HMPs overall (p < 0.001). C) Explanted femurs underwent torsion to failure after 12 weeks post-surgery (n = 3–4). No differences in maximum torque were observed between the BMP-2 treated groups or compared to intact femurs of age-matched rats (historical data [16]).