1 Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Osaka, Japan.
2 Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Osaka, Japan.
J Dent Res. 2018 Sep;97(10):1137-1143. doi: 10.1177/0022034518772260. Epub 2018 Apr 27.
Dental pulp regeneration therapy for the pulpless tooth has attracted recent attention, and clinical trial studies are underway with the tissue engineering approach. However, there remain many concerns, including the extended period for regenerating the dental pulp. In addition, the use of scaffolds increases the risk of inflammation and infection. To establish a basic technology for novel dental pulp regenerative therapy that allows transplant of pulp-like tissue, we attempted to fabricate scaffold-free 3-dimensional (3D) cell constructs composed of dental pulp stem cells (DPSCs). Furthermore, we assessed viability of these 3D DPSC constructs for dental pulp regeneration through in vitro and in vivo studies. For the in vitro study, we obtained 3D DPSC constructs by shaping sheet-like aggregates of DPSCs with a thermoresponsive hydrogel. DPSCs within constructs remained viable even after prolonged culture; furthermore, 3D DPSC constructs possessed a self-organization ability necessary to serve as a transplant tissue. For the in vivo study, we filled the human tooth root canal with DPSC constructs and implanted it subcutaneously into immunodeficient mice. We found that pulp-like tissues with rich blood vessels were formed within the human root canal 6 wk after implantation. Histologic analyses revealed that transplanted DPSCs differentiated into odontoblast-like mineralizing cells at sites in contact with dentin; furthermore, human CD31-positive endothelial cells were found at the center of regenerated tissue. Thus, the self-organizing ability of 3D DPSC constructs was active within the pulpless root canal in vivo. In addition, blood vessel-rich pulp-like tissues can be formed with DPSCs without requiring scaffolds or growth factors. The technology established in this study allows us to prepare DPSC constructs with variable sizes and shapes; therefore, transplantation of DPSC constructs shows promise for regeneration of pulpal tissue in the pulpless tooth.
牙髓再生疗法吸引了人们对无髓牙的关注，组织工程方法的临床试验正在进行中。然而，仍有许多问题需要关注，包括牙髓再生的延长时间。此外，支架的使用增加了炎症和感染的风险。为了建立一种新的牙髓再生治疗的基本技术，允许牙髓样组织的移植，我们试图制造无支架的三维（3D）细胞构建体，由牙髓干细胞（DPSCs）组成。此外，我们通过体外和体内研究评估了这些 3D DPSC 构建体用于牙髓再生的活力。在体外研究中，我们通过将 DPSCs 形成热响应水凝胶的片状聚集体来获得 3D DPSC 构建体。构建体中的 DPSCs 即使在长时间培养后仍然保持活力；此外，3D DPSC 构建体具有作为移植组织所必需的自组织能力。在体内研究中，我们将 DPSC 构建体填充到人牙根管中，并将其植入免疫缺陷小鼠的皮下。我们发现，植入后 6 周，在人牙根管内形成了富含血管的牙髓样组织。组织学分析显示，移植的 DPSCs 在与牙本质接触的部位分化为成牙本质样矿化细胞；此外，在再生组织的中心发现了人 CD31 阳性的内皮细胞。因此，3D DPSC 构建体的自组织能力在无髓牙根管内具有活性。此外，无需支架或生长因子即可用 DPSCs 形成富含血管的牙髓样组织。本研究建立的技术允许我们制备具有不同大小和形状的 DPSC 构建体；因此，DPSC 构建体的移植有望用于无髓牙的牙髓组织再生。
