In vitro effects of two silicate-based materials, Biodentine and BioRoot RCS, on dental pulp stem cells in models of reactionary and reparative dentinogenesis.

BACKGROUND: Calcium silicate-based cements are biomaterials with calcium oxide and carbonate filler additives. Their properties are close to those of dentin, making them useful in restorative dentistry and endodontics. The aim of this study was to evaluate the in vitro biological effects of two such calcium silicate cements, Biodentine (BD) and Bioroot (BR), on dental stem cells in both direct and indirect contact models. The two models used aimed to mimic reparative dentin formation (direct contact) and reactionary dentin formation (indirect contact). An original aspect of this study is the use of an interposed thin agarose gel layer to assess the effects of diffusible components from the materials. RESULTS: The two biomaterials were compared and did not modify dental pulp stem cell (DPSC) proliferation. BD and BR showed no significant cytotoxicity, although some cell death occurred in direct contact. No apoptosis or inflammation induction was detected. A striking increase of mineralization induction was observed in the presence of BD and BR, and this effect was greater in direct contact. Surprisingly, biomineralization occurred even in the absence of mineralization medium. This differentiation was accompanied by expression of odontoblast-associated genes. Exposure by indirect contact did not stimulate the induction to such a level. CONCLUSION: These two biomaterials both seem to be bioactive and biocompatible, preserving DPSC proliferation, migration and adhesion. The observed strong mineralization induction through direct contact highlights the potential of these biomaterials for clinical application in dentin-pulp complex regeneration.

Comparative study of abdominal and thoracic aortic aneurysms: their pathogenesis and a gingival fibroblasts-based ex vivo treatment.

Aortic aneurysms (AAs) consist of slow proteolysis and loss of both collagen and elastin matrix in the aorta wall, leading to wall dilation, weakening and rupture in well-advanced lesions. This can occur in both abdominal aorta (Abdominal Aortic Aneurysm: AAA) and thoracic aorta (Thoracic Aortic Aneurysm: TAA). To date, no non-surgical therapy has been proposed to slow or stop AA progression. Previously published preclinical studies from our team using an aneurysm rabbit model showed a promising concept for treatment of AAs with gingival fibroblast (GFs) which are readily available cells. In this study, we investigated the possible tissue repair of human AAAs and TAAs using ex vivo models co-cultured with GFs. Histological analysis showed that TAA and AAA are two distinct pathologies. Both lesions presented destruction of the aorta wall, highly evidenced in AAA samples. The results have confirmed the presence of the bacterial Porphyromonas gingivalis (Pg) protein in all AAA samples, but not in TAA samples, indicating the possible role of an infectious factor in the developing and progression of AAA lesions compared to TAA. The co-culture of GFs with AA lesions shows increased expression of TIMP-1, the inhibitor of the aneurysm severity marker MMP-9. Our study indicates that GFs might ameliorate aorta wall reestablishment in both AA types by their regenerative and immunomodulatory capacities. It also demonstrates the possible infectious cause of AAA compared with TAA that may explain their different behavior.

Formation of cartilage and synovial tissue by human gingival stem cells.

Human gingival stem cells (HGSCs) can be easily isolated and manipulated in culture to investigate their multipotency. Osteogenic differentiation of bone-marrow-derived mesenchymal stem/stromal cells has been well documented. HGSCs derive from neural crests, however, and their differentiation capacity has not been fully established. The aim of the present report was to investigate whether HGSCs can be induced to differentiate to osteoblasts and chondrocytes. HGSCs were cultured either in a classical monolayer culture or in three-dimensional floating micromass pellet cultures in specific differentiation media. HGSC differentiation to osteogenic and chondrogenic lineages was determined by protein and gene expression analyses, and also by specific staining of cells and tissue pellets. HGSCs cultured in osteogenic differentiation medium showed induction of Runx2, alkaline phosphatase (ALPL), and osterix expression, and subsequently formed mineralized nodules consistent with osteogenic differentiation. Interestingly, HGSC micromass cultures maintained in chondrogenic differentiation medium showed SOX9-dependent differentiation to both chondrocyte and synoviocyte lineages. Chondrocytes at different stages of differentiation were identified by gene expression profiles and by histochemical and immunohistochemical staining. In 3-week-old cultures, peripheral cells in the micromass cultures organized in layers of cuboidal cells with villous structures facing the medium. These cells were strongly positive for cadherin-11, a marker of synoviocytes. In summary, the findings indicate that HGSCs have the capacity to differentiate to osteogenic, chondrogenic, and synoviocyte lineages. Therefore, HGSCs could serve as an alternative source for stem cell therapies in regenerative medicine for patients with cartilage and joint destructions, such as observed in rheumatoid arthritis.