Preparation of Bone Marrow Mesenchymal Stem Cells Combined with Hydroxyapatite/Poly(d,l‑lactide) Porous Microspheres for Bone Regeneration in Calvarial Defects

A novel three-dimensional biomimetic porous microsphere was successfully designed in this study, which was composed of PDLLA, bone marrow mesenchymal stem cells (MSCs), and nanohydroxyapatite (nHAp). nHAp/PDLLA/MSC porous microspheres that are supposed to be a significant constituent of bone in vertebrate were prepared to act as biodegradable support materials. In addition, bone MSCs act as seeding cells in bone defect repair. The microstructure of the obtained nHAp/PDLLA/MSC porous microspheres was characterized. Scanning electronic microscopy showed that the composite materials exhibited a cross-linked porous structure. In vivo biocompatibility was studied by the way of implanting the nHAp/PDLLA porous microspheres subcutaneously in rats for 4 and 8 weeks. In addition, the osteogenic capacity of the nHAp/PDLLA/MSC porous microspheres was assessed by implanting the 10 mm × 10 mm × 3 mm cranial defect of New Zealand white rabbits. In vivo studies confirmed that nHAp/PDLLA/MSC porous microspheres had a good biocompatibility and were better in inducing bone regeneration than nHAp/PDLLA porous microspheres and the self-healing process. All of the results suggested that the nHAp/PDLLA/MSC porous microspheres present a remarkable potential in calvarial defect repair and bone tissue engineering.