Absorbable, Self-setting Bone Cement

DESCRIPTION (provided by applicant): Since early development of polymethyl methacrylate bone cement (PMMA-BC), there have been many efforts to develop alternative compositions to circumvent some of its clinical shortcomings, which include (1) monomer cytotoxicity; (3) inability to form strong joint at the tissue-cement interface; and (3) being a permanent, non-absorbable implant, which may induce infection. Among the major alternatives to PMMA-BC is the self-setting calcium phosphate bone cement (CPC), which suffers from being fragile and highly susceptible to fracture. Acknowledging PMMA-BC and CPC shortcomings and recent commercialization of absorbable cyanoacrylate tissue adhesive formulations prompted the pursuit of the proposed program. And its Phase I objective is to demonstrate the feasibility of developing a self-setting absorbable, bioactive, cyanoacrylate phosphate-based composite as a preferred alternative to non-absorbable PMMA-BC. Accordingly, Phase I plans entail (1) using initial results acquired in this laboratory on self-setting, absorbable, cyanoacrylate phosphate-based composites (SCC-P) to prepare five candidate systems and selecting the most promising SCC-P as per a comparative in vitro evaluation against a typical PMMA-BC; (2) repeating the study on SCC-P systems using mixtures of a phosphate and a silicate to produce three additional candidates comprising phosphate and silicate components (SCC-PS), selecting the most promising SCC-PS, and conducting a comparative in vitro evaluation against a typical PMMA-BC; (3) using the two selected SCC-P and SCC-PS candidates to determine their in vivo efficacies, relative to a PMMA-BC control, in repairing a typical bone defect in rabbits; (4) reinforcing the selected SCC-P and SCC-PS candidates with warp-knitted absorbable mesh and determining the in vitro physical properties of the reinforced composites before and after aging; and (5) analyzing the in vitro and in vivo performance data and selecting a candidate for Phase II study. Plans for Phase II study will include (1) optimization of the selected SCC-P or SCC-SP system into an absorbable, bioactive, self-setting bone cement (ABS-BC) with and without knitted mesh reinforcement, relying on in vitro physical and mechanical properties as cementing/defect filling materials, with or without absorbable, mesh reinforcements; (2) completion of development, scale-up, sterilization, and packaging studies; (3) completion of the validation studies of all processes; (4) development of a suitable animal model for at least three clinical indications and demonstrating the ABS-BC in vivo efficacy using selected animal models; and (5) securing a marketing partner to develop plans for the manufacturing and marketing of the ABS-BC. PUBLIC HEALTH RELEVANCE: Developing absorbable, self-setting, bioactive cyanoacrylate-based composites comprising inorganic silicate and/or phosphate microparticles with or without reinforcement with an absorbable knitted mesh will provide the clinical community with novel biomaterials for use as preferred alternatives to the non-absorbable polymethyl methacrylate bone cement and in repairing or substituting cranial and maxillofacial bone defects through guided bone regeneration.