Biomimetic non-collagenous proteins-calcium phosphate complex with superior osteogenesis via regulating macrophage IL-27 secretion

Abstract

<p>Traumatic defects or non-union fractures presents a substantial challenge in the fields of tissue engineering and regenerative medicine. Although synthetic calcium phosphate-based biomaterials (CaPs) such as dibasic calcium phosphate anhydrate (DCPA) are commonly employed for bone repair, their inadequate cellular immune responses significantly impede sustained degradation and optimal osteogenesis. In this study, drawing inspiration from the key structure of an acidic non-collagenous protein-CaP complex (ANCPs-CaP) essential for natural bone formation, we prepared biomimetic mineralized dibasic calcium phosphate (MDCPA). This preparation utilized plant-derived non-collagenous protein Zein as the organic template and acidic artificial saliva as the mineralization medium. Physicochemical property analysis revealed that MDCPA is a complex of Zein and DCPA, which mimics the composite of the natural ANCP-CaP. Moreover, MDCPA exhibited enhanced biodegradability and osteogenic potential. Mechanistic insight revealed that MDCPA can be phagocytized and degraded by macrophages <em>via</em> the FCγRIII receptor, leading to the release of interleukin 27 (IL-27), which promotes osteogenic differentiation by osteoimmunomodulation. The critical role of IL-27 in osteogenesis is further confirmed using IL-27 gene knockout mice. Additionally, MDCPA demonstrates effective healing of critical-sized defects in rat cranial bones within only 4 w, providing a promising basis and valuable insights for critical-sized bone defects regeneration.<br></p>