Functional periodontal regeneration using biomineralized extracellular matrix/stem cell microspheroids

Engineering complete periodontal tissue regeneration remains a considerable clinical challenge because the native periodontium is composed of hard mineralized and soft unmineralized tissues. Stem cell therapies that use endogenous extracellular matrix (ECM) have the potential for structural and functional periodontal regeneration. Here, mineralized ECM/dental pulp stem cell microspheroids (MMCMs) mimicking native mesenchymal microspheroid precursors were developed, and showed an enhanced Young's modulus ranging from 0.4 GPa to 1.9 GPa. Furthermore, biomineralization promoted cell viability, inhibited cell apoptosis, and enhanced ECM secretion and osteogenic differentiation potential in dental pulp stem cells. After implantation in the full periodontal defect, MMCMs regenerated complete periodontium with native-like hierarchically organized periodontal ligament collagen fibers inserted into the newly formed alveolar bone and cementum; they also recruited CD90+CD73+ host mesenchymal stem cells. Mechanistically, MMCMs promoted functional periodontal regeneration through activation of the transforming growth factor beta 1 (TGF-β1)/Smad3 signaling pathway. Inhibition of TGF-β1 signaling pathway significantly impaired osteogenic potential and matrix secretion of MMCMs, while exogenous TGF-β1 treatment enhanced the osteogenesis and periodontal regeneration outcomes of MMCMs. These results indicate the promising application of MMCMs in complex tissue regeneration.