Compelling in vitro and in vivo data demonstrated a novel formulation of strontium substituted-hydroxyapatite nanoparticles (Sr-nHap) promotes bone remodeling and exert a potent anabolic effect (1). Gelatin sponges such as Gelfoam are FDA-approved medical devices currently used as hemostatic application on bleeding surfaces (2). Because of their porous structure, they are attractive in the orthopedic field as suitable carriers of other components (such as ceramics and hydroxyapatite) (3). In this study, Gelfoam was used as a carrier for Sr-nHap and its ability to promote bone formation was assessed. We first abiotically characterized both the Gelfoam and Gelfoam associated with Sr-nHap, highlighting the microscopic structures and the time-dependent strontium release. The osteogenic capacity of the Sr-nHap loaded-Gelfoam was then examined in vivo by implanting on the femoral periosteal surface of a mouse model. Gelfoam alone was used as control and bone morphogenetic protein 2 (BMP2) loaded-Gelfoam served as positive control. Histological observations and gene expression evaluation of the samples at different time points showed strong endochondral bone formation response on the periosteal surface while the surrounding connective and muscular tissues remained unaffected. Furthermore, while stem cell recruitment and osteogenesis processes were favored, osteoclastogenesis was down-regulated in contrast to sponges containing BMP2. These results suggest the use of Sr-NPs loaded-Gelfoam as bone graft substitutes might provide better outcomes for complex fractures, avoiding the commonly experienced BMP2 side-effects in which high levels of osteolytic coupled remodeling occur. These grafts could become a novel therapeutic option for people suffering from trauma, osteoporosis, bone defects or severe bone injuries.
- Cornaglia AI, Bruni G, Sglavo VM, Visai L, Cristofaro F, Dirè S, Ceccato R, Frasnelli M, Callone E. Synthesis and characterization of strontium-substituted hydroxyapatite nanoparticles for bone regeneration. Mater. Sci. Eng. C [Internet]. Elsevier B.V.; 2016;71:653–62. Available from: http://dx.doi.org/10.1016/j.msec.2016.10.047
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