Bioactive Nanocomposite Microsponges for Effective Reconstruction of Critical-Sized Calvarial Defects in Rat Model

Mohan Wang,1,2 Zheyuan Gu,2 Beibei Li,2 Jingyi Zhang,2 Lu Yang,2 Xianyu Zheng,2 Faming Pan,1 Jiacai He1,2 1Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, 230032, People’s Republic of China; 2Stomatologic Hospital & College, Anhui Medical University, Key Laboratory of Oral Diseases Research of Anhui Province, Hefei, 230032, People’s Republic of ChinaCorrespondence: Jiacai He; Faming Pan, Email hejiacai@ahmu.edu.cn; famingpan@ahmu.edu.cnIntroduction: Micro-sized sponge particulates have attracted extensive attention because of their potential to overcome the intrinsic limitations of conventional monolithic scaffolds in tissue engineering. Bioactive nanocomposite microsponges are regarded as potential bone substitute materials for bone regeneration.Methods: Based on a combination of microfluidic emulsion with further freezing and in situ thawing, chitosan (CS)-hydroxyapatite (HAP) microsponges were prepared and characterized in terms of their morphology and elemental distribution using a scanning electron microscope equipped with an X-ray detector. The swelling ratio, porosity, degradability, antibacterial activity, and bioactivity were detected and analyzed. The biological functions of the CS-HAP microsponges were examined to assess the adhesion, proliferation, and differentiation of in vitro co-cultured rat bone marrow mesenchymal stem cells (rBMSCs). Furthermore, the CS-HAP microsponges were used as cell-free scaffolds and implanted into calvarial defects in a rat model to evaluate the in vivo osteogenesis.Results: The CS-HAP microsponges have a porous structure with high porosity (~76%), good swelling capacity (~1900%), and shape-memory properties. The results of in vitro experiments show that the CS-HAP microsponges achieve good bioactivity and promote osteogenic differentiation of rBMSCs. Furthermore, the CS-HAP microsponges significantly promote bone regeneration in rat calvaria