Department of Pediatric Dentistry, Uconn Health, Farmington, CT, USA.
Department of Reconstructive Sciences, Uconn Health, Farmington, CT, USA.
J Periodontal Res. 2017 Dec;52(6):1058-1067. doi: 10.1111/jre.12478. Epub 2017 Jul 10.
Mineral trioxide aggregate (MTA) is a biomaterial used in endodontic procedures as it exerts beneficial effects on regenerative processes. In this study, we evaluate the effect of MTA on healing of periodontal ligament (PDL) and surrounding tissue, following injury, in a transgenic mouse model and on the differentiation of murine mesenchymal progenitor cells in vitro.
We used an inducible Cre-loxP in vivo fate mapping approach to examine the effects of MTA on the contributions of descendants of cells expressing the αSMA-CreERT2 transgene (SMA9 ) to the PDL and alveolar bone after experimental injury to the root furcation on the maxillary first molars. Col2.3GFP was used as a marker to identify mature osteoblasts, cementoblasts and PDL fibroblasts. The effects of MTA were examined 2, 17 and 30 days after injury and compared histologically with sealing using an adhesive system. The effects of two dilutions of medium conditioned with MTA on proliferation and differentiation of mesenchymal progenitor cells derived from bone marrow (BMSC) and periodontal ligament (PDLC) in vitro were examined using the PrestoBlue viability assay, alkaline phosphatase and Von Kossa staining. The expression of markers of differentiation was assessed using real-time PCR.
Histological analyses showed better repair in teeth restored with MTA, as shown by greater expansion of SMA9 progenitor cells and Col2.3GFP osteoblasts compared with control teeth. We also observed a positive effect on differentiation of SMA9 progenitors into osteoblasts and cementoblasts in the apical region distant from the site of injury. The in vitro data showed that MTA-conditioned medium reduced cell viability and osteogenic differentiation in both PDLC and BMSC, indicated by reduced von Kossa staining and lower expression of osteocalcin and bone sialoprotein. In addition, cultures grown in the presence of MTA had marked decreases in SMA9 and Col2.3GFP areas as compared with osteogenic medium, confirming reduced osteogenesis.
MTA promotes regeneration of injured PDL and alveolar bone, reflected as contribution of progenitors (SMA9 cells) into osteoblasts (Col2.3GFP cells). In vitro, MTA-conditioned medium fails to promote osteogenic differentiation of both PDLC and BMSC.
矿化三氧化物凝聚体（MTA）是一种在牙髓治疗中使用的生物材料，因为它对再生过程有有益的影响。在这项研究中，我们评估了 MTA 对转基因小鼠模型中牙周韧带（PDL）和周围组织损伤后愈合的影响，以及在体外对鼠间充质祖细胞分化的影响。
我们使用诱导型 Cre-loxP 体内命运映射方法来研究 MTA 对表达αSMA-CreERT2 转基因（SMA9）的细胞后代对上颌第一磨牙根分叉区实验性损伤后 PDL 和牙槽骨的贡献的影响。Col2.3GFP 被用作鉴定成熟成骨细胞、成牙骨质细胞和 PDL 成纤维细胞的标志物。在损伤后 2、17 和 30 天，通过组织学检查与使用粘接剂系统进行的密封效果进行比较。使用 PrestoBlue 活力测定法、碱性磷酸酶和 Von Kossa 染色，检查 MTA 条件培养基的两种稀释液对来源于骨髓（BMSC）和牙周膜（PDLC）的间充质祖细胞增殖和分化的影响。通过实时 PCR 评估分化标志物的表达。
组织学分析表明，用 MTA 修复的牙齿修复效果更好，与对照牙齿相比，SMA9 祖细胞和 Col2.3GFP 成骨细胞的扩张更大。我们还观察到在远离损伤部位的根尖区域，SMA9 祖细胞向成骨细胞和成牙骨质细胞分化的积极影响。体外数据显示，MTA 条件培养基降低了 PDLC 和 BMSC 的细胞活力和成骨分化，表现为 Von Kossa 染色减少，骨钙素和骨涎蛋白的表达降低。此外，与成骨培养基相比，在 MTA 存在的情况下培养的细胞 SMA9 和 Col2.3GFP 区域明显减少，证实了成骨减少。
MTA 促进受损 PDL 和牙槽骨的再生，表现为祖细胞（SMA9 细胞）向成骨细胞（Col2.3GFP 细胞）的贡献。在体外，MTA 条件培养基不能促进 PDLC 和 BMSC 的成骨分化。
