Periodontal Cells React Individually to Interactive Mesenchymal Stem Cell Coculture

Objectives: In the context of promising oral tissue regeneration strategies, interactions of periodontal host tissue cells with human mesenchymal stem cells (hMSCs) are poorly understood. Therefore, we aimed to assess behavioural features in periodontal cells, including human alveolar osteoblasts (hOAs), periodontal ligament cells (hPDLs), and gingival fibroblasts (hGFs) upon hMSC interaction.
Methods: Bone marrow hMSCs were successfully characterized according to established protocols. For interactive cocultures of 7, 14 and 21 days, hMSC were incorporated in 3D collagen-gels with periodontal cells grown on the surface. For cell behaviour analysis, cryosectioned cell-harbouring gels were stained for matrix deposits (Giemsa, Masson-Goldner trichrome) and immunolabelled for osteocalcin, osteopontin, osteonectin, collagen 1a1, and DNA strand breaks (TUNEL assay) for apoptosis/survival detection. For proliferation and mRNA quantification, periodontal cells and hMSCs were established in transwell systems, and 5-bromo-2'-deoxyuridine DNA incorporation and gene expression were evaluated by colorimetric ELISA and qRT-PCR, respectively (statistics: Repeated Measures Analysis; Tukey’s/Benjamini-Hochberg adjustment of p-values).
Results: Interactive hMSC coculture globally enhanced the transcription of osteogenic genes in all cell types under study, and sustained proliferation in periodontal cells similar to matched controls. Detection of translates of the above-mentioned proteins in hMSC-cocultured periodontal cells was arranged in the following hierarchy: hOA>hGF>hPDL. This hierarchy also applied for the finding of higher amounts of extracellular matrix and calcium deposits in interactive hMSC coculture. In the context of cell survival, interactive hMSC coculture significantly increased the number of vital cells present in 3D cultures.
Conclusion: The results obtained from our study show for the first time that hMSCs appear to be modulators of the analyzed behavioural features of individual periodontal cells, and that the latter may considerably contribute to periodontal tissue regeneration in innovative customized hMSC-based therapies. Hence, hMSCs render promising candidates for the development of a prospective therapy platform in oral tissue regeneration.