Institute of Stomatology, First Medical Center of Chinese PLA General Hospital, Beijing, China.
Stem Cells Dev. 2021 Apr;30(8):441-457. doi: 10.1089/scd.2020.0170. Epub 2021 Apr 7.
Dental stem/progenitor cells are a promising cell sources for alveolar bone (AB) regeneration because of their same embryonic origin and superior osteogenic potential. However, their molecular processes during osteogenic differentiation remain unclear. The objective of this study was to identify the responsiveness of dental follicle cells (DFCs) and AB marrow-derived mesenchymal stem cells (ABM-MSCs) to recombinant human bone morphogenetic protein-2 (rhBMP-2). These cells expressed vimentin and MSC markers and did not express cytokeratin and hematopoietic stem cell markers and showed multilineage differentiation potential under specific culture conditions. DFCs exhibited higher proliferation and colony-forming unit-fibroblast efficiency than ABM-MSCs; rhBMP-2 induced DFCs to differentiate toward a cementoblast/osteoblast phenotype and ABM-MSCs to differentiate only toward a osteoblast phenotype; and rhBMP-2-induced DFCs exhibited higher osteogenic differentiation potential than ABM-MSCs. These cells adhered, grew, and produced extracellular matrix on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA). During a 14-day culture on nHAC/PLA, the extracellular alkaline phosphatase (ALP) activity of DFCs decreased gradually and that of ABM-MSCs increased gradually; rhBMP-2 enhanced their extracellular ALP activity, intracellular osteocalcin (OCN), and osteopontin (OPN) protein expression; and DFCs exhibited higher extracellular ALP activity and intracellular OCN protein expression than ABM-MSCs. When implanted subcutaneously in severe combined immunodeficient mice for 3 months, DFCs+nHAC/PLA+rhBMP-2 obtained higher percentage of bone formation area, OCN, and cementum attachment protein expression and lower OPN expression than ABM-MSCs+nHAC/PLA+rhBMP-2. These results showed that DFCs possessed superior proliferation and osteogenic differentiation potential in vitro, and formed higher quantity and quality bones in vivo. It suggested that DFCs might exhibit a more sensitive responsiveness to rhBMP-2, so that DFCs enter a relatively mature stage of osteogenic differentiation earlier than ABM-MSCs after rhBMP-2 induction. The findings imply that these dental stem/progenitor cells are alternative sources for AB engineering in regenerative medicine, and developing dental tissue may provide better source for stem/progenitor cells.
牙源性干/祖细胞因其相同的胚胎起源和优越的成骨潜能,成为牙槽骨(AB)再生的有前途的细胞来源。然而,它们在成骨分化过程中的分子过程尚不清楚。本研究的目的是确定牙囊细胞(DFC)和 AB 骨髓间充质干细胞(ABM-MSC)对重组人骨形态发生蛋白-2(rhBMP-2)的反应性。这些细胞表达波形蛋白和 MSC 标志物,不表达细胞角蛋白和造血干细胞标志物,并在特定培养条件下显示多谱系分化潜能。DFC 的增殖和集落形成单位-成纤维细胞效率高于 ABM-MSC;rhBMP-2 诱导 DFC 分化为成牙骨质/成骨细胞表型,而 ABM-MSC 仅分化为成骨细胞表型;rhBMP-2 诱导的 DFC 具有比 ABM-MSC 更高的成骨分化潜能。这些细胞在纳米羟基磷灰石/胶原/聚(L-乳酸)(nHAC/PLA)上附着、生长并产生细胞外基质。在 nHAC/PLA 上培养 14 天时,DFC 的细胞外碱性磷酸酶(ALP)活性逐渐降低,ABM-MSC 的 ALP 活性逐渐升高;rhBMP-2 增强了它们的细胞外 ALP 活性、细胞内骨钙素(OCN)和骨桥蛋白(OPN)蛋白表达;DFC 的细胞外 ALP 活性和细胞内 OCN 蛋白表达均高于 ABM-MSC。当皮下植入严重联合免疫缺陷小鼠 3 个月时,DFC+nHAC/PLA+rhBMP-2 获得了更高的骨形成面积百分比、OCN 和牙骨质附着蛋白表达以及较低的 OPN 表达,而 ABM-MSCs+nHAC/PLA+rhBMP-2 则获得了更高的骨形成面积百分比、OCN 和牙骨质附着蛋白表达以及较低的 OPN 表达。这些结果表明,DFC 在体外具有更高的增殖和成骨分化潜能,并在体内形成更高数量和质量的骨。这表明 DFC 对 rhBMP-2 的反应更敏感,因此在 rhBMP-2 诱导后,DFC 比 ABM-MSC 更早地进入成骨分化的相对成熟阶段。这些发现意味着这些牙源性干/祖细胞可能是再生医学中 AB 工程的替代来源,并且开发牙组织可能为干细胞/祖细胞提供更好的来源。
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