Background: Polyhedral oligomeric silsesquioxane (POSS) is a monomer with silicon structure and an
internal nanometric cage.
Objective: The purpose of this study was to provide an injectable hydrogel that could be easily located in open or
closed bone fractures and injuries, and also to reduce the possible risks of infections caused by bone graft either
as an allograft or an autograft.
Methods: Various formulations of temperature sensitive hydrogels containing hydroxyapatite, Gelrite, POSS and
platelets rich plasma (PRP), such as the co-gelling agent and cell growth enhancer, were prepared. The hydrogels
were characterized for their injectability, gelation time, phase transition temperature and viscosity. Other physical
properties of the optimized formulation including compressive stress, compressive strain and Young’s modulus as
mechanical properties, as well as storage and loss modulus, swelling ratio, biodegradation behavior and cell toxicity
as rheometrical parameters were studied on human osteoblast MG-63 cells. Alizarin red tests were conducted
to study the qualitative and quantitative osteogenic capability of the designed scaffold, and the cell adhesion to
the scaffold was visualized by scanning electron microscopy.
Results: The results demonstrated that the hydrogel scaffold mechanical force and injectability were 3.34±0.44
Mpa and 12.57 N, respectively. Moreover, the scaffold showed higher calcium granules production in alizarin red
staining compared to the control group. The proliferation of the cells in G4.5H1P0.03PRP10 formulation was significantly
higher than in other formulations (p<0.05).
Conclusion: The optimized Gelrite/Hydroxyapatite/POSS/PRP hydrogel scaffold has useful impacts on osteoblasts
activity, and may be beneficial for local drug delivery in complications including a break or bone loss.