Osteostatin-loaded onto mesoporous ceramics improves the early phase of bone regeneration in a rabbit osteopenia model

Parathyroid hormone-related protein (PTHrP) is an important modulator of bone formation. Recently, we reported that PTHrP (107–111) (osteostatin) coating onto mesoporous ceramics confers osteogenic activity to these materials. Bone repair is dramatically compromised in osteopenia/osteoporosis. Thus, we examined the efficacy of unmodified and organically modified SBA15 ceramics loaded with osteostatin in promoting bone repair in an osteoporotic rabbit model. Osteoporosis was induced in New Zealand rabbits by methylprednisolone administration, and healthy rabbits were used as controls. Tested materials were implanted into a femoral cavitary defect, and animals were sacrificed at 2 weeks post-implantation. At this time, implants were encapsulated by a variable layer of fibrotic tissue with no evidence of inflammation. Similarly to observations in normal rabbits, both types of osteostatin-loaded bioceramics induced tissue regeneration associated with increased staining for PCNA, Runx2, osteopontin, and/or vascular endothelial growth factor in osteoporotic rabbits. Our present findings demonstrate that these osteostatin-bearing bioceramics increase the early repair response not only in normal bone but also in osteoporotic bone after a local injury.

Runx 2 and PCNA immunostaining in the vicinity of the implanted materials (SBA15 and SBA15+C8) within a cavitary defect in the femur of control and osteoporotic rabbits at 2 weeks. Corresponding score values (mean ± SD; n = 4) are shown. ∗p < 0.01 vs. corresponding unloaded material. The image shows abundant positivity for Runx2 in the newly formed bone area in a control rabbit with osteostain-containing SBA15+C8 implant.Figure optionsDownload high-quality image (127 K)Download as PowerPoint slide