Construction of the Gypsum-Coated Scaffolds for In Situ Bone Regeneration.

It is significant to use functional biomaterials to rationally engineer microenvironments for in situ bone regeneration in the field of bone tissue engineering. To this end, we constructed the gypsum-coated β-tricalcium phosphate (G-TCP) scaffolds by combing a three-dimensional printing technique and an epitaxial gypsum growth method. In vitro simulation experiments showed that the as-prepared scaffolds could establish a dynamic and weakly acidic microenvironment in a simulated body liquid, in which the pH and the calcium ion concentration always changed due to the gypsum degradation and growth of bone-like apatite nanoplates on the scaffold surfaces. The cell experiments confirmed that the microenvironment established by the G-TCP surfaces promoted rapid osteogenic differentiation and proliferation of bone marrow mesenchymal stem cells (BM-MSCs). In vivo experiments confirmed that the G-TCP scaffolds had high bioactivity in modulating in situ regeneration of bone, and the bioactivity of the G-TCP scaffolds was endowed by correct pore structures, degradation of gypsum, and growth of a bone-like apatite layer. The microenvironment established by the gypsum degradation could stimulate tissue inflammation and recruit white blood cells and BM-MSCs and thus accelerating native healing cascades of the bone defects via a bone growth/remodeling-absorption cycle process. Furthermore, in vivo experiments demonstrated that after the bone defects had healed completely, the as-prepared scaffolds also degraded completely within 24 weeks.