Periodontal regenerative medicine using mesenchymal stem cells and biomaterials: A systematic review of pre-clinical studies

International audienceThe aim of the systematic review was to analyze the use of mesenchymal stem cells (MSC) and biomaterial for periodontal regeneration from preclinical animal models and human. Electronic databases were searched and additional hand-search in leading journals was performed. The research strategy was achieved according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The including criteria were as follows: MSC, biomaterial, in vivo studies, with histologic and radiologic analysis and written in English. The risk of bias was assessed for individual studies. A total of 50 articles were selected and investigated in the systematic review. These results indicate that MSC and scaffold provide beneficial effects on periodontal regeneration, with no adverse effects of such interventions. Future studies need to identify the suitable association of MSC and biomaterial and to characterize the type of new cementum and the organization of the periodontal ligament fiber regeneration

Effects of In Vitro Low Oxygen Tension Preconditioning of Adipose Stromal Cells on Their In Vivo Chondrogenic Potential: Application in Cartilage Tissue Repair

International audiencePurpose: Multipotent stromal cell (MSC)-based regenerative strategy has shown promise for the repair of cartilage, an avascular tissue in which cells experience hypoxia. Hypoxia is known to promote the early chondrogenic differentiation of MSC. The aim of our study was therefore to determine whether low oxygen tension could be used to enhance the regenerative potential of MSC for cartilage repair.Methods: MSC from rabbit or human adipose stromal cells (ASC) were preconditioned in vitro in control or chondrogenic (ITS and TGF-b) medium and in 21 or 5% O 2. Chondrogenic commitment was monitored by measuring COL2A1 and ACAN expression (real-time PCR). Preconditioned rabbit and human ASC were then incorporated into an Si-HPMC hydrogel and injected (i) into rabbit articular cartilage defects for 18 weeks or (ii) subcutaneously into nude mice for five weeks. The newly formed tissue was qualitatively and quantitatively evaluated by cartilage-specific immunohistological staining and scoring. The phenotype of ASC cultured in a monolayer or within Si-HPMC in control or chondrogenic medium and in 21 or 5% O 2 was finally evaluated using real-time PCR.Results/Conclusions: 5% O 2 increased the in vitro expression of chondrogenic markers in ASC cultured in induction medium. Cells implanted within Si-HPMC hydrogel and preconditioned in chondrogenic medium formed a cartilaginous tissue, regardless of the level of oxygen. In addition, the 3D in vitro culture of ASC within Si-HPMC hydrogel was found to reinforce the pro-chondrogenic effects of the induction medium and 5% O 2. These data together indicate that although 5% O 2 enhances the in vitro chondrogenic differentiation of ASC, it does not enhance their in vivo chondrogenesis. These results also highlight the in vivo chondrogenic potential of ASC and their potential value in cartilage repair

Inverse Regulation of Early and Late Chondrogenic Differentiation by Oxygen Tension Provides Cues for Stem Cell-Based Cartilage Tissue Engineering

Background/Aims: Multipotent stem/stromal cells (MSC) are considered promising for cartilage tissue engineering. However, chondrogenic differentiation of MSC can ultimately lead to the formation of hypertrophic chondrocytes responsible for the calcification of cartilage. To prevent the production of this calcified matrix at the articular site, the late hypertrophic differentiation of MSCs must be carefully controlled. Given that articular cartilage is avascular, we hypothesized that in addition to its stimulatory role in the early differentiation of chondrogenic cells, hypoxia may prevent their late hypertrophic conversion. Methods: Early and late chondrogenic differentiation were evaluated using human adipose MSC and murine ATDC5 cells cultured under either normoxic (21%O2) or hypoxic (5%O2) conditions. To investigate the effect of hypoxia on late chondrogenic differentiation, the transcriptional activity of hypoxia-inducible factor-1alpha (HIF-1α) and HIF-2α were evaluated using the NoShift DNA-binding assay and through modulation of their activity (chemical inhibitor, RNA interference). Results: Our data demonstrate that low oxygen tension not only stimulates the early chondrogenic commitment of two complementary models of chondrogenic cells, but also inhibits their hypertrophic differentiation. Conclusion: These results suggest that hypoxia can be used as an instrumental tool to prevent the formation of a calcified matrix in MSC-based cartilage tissue engineering

Comparing “intra operative” tissue engineering strategies for the repair of craniofacial bone defects

International audienceBACKGROUND:In craniofacial reconstruction, the gold standard procedure for bone regeneration is the autologous bone graft (BG). However, this procedure requiring bone harvesting is a source of morbidity. Bone substitutes, such as biphasic calcium phosphate (BCP), represent an interesting alternative but are not sufficient for bone healing in hypoplastic conditions. In such conditions, osteoprogenitors are essential to provide osteoinduction. Previous studies have shown that BCP associated with total bone marrow (TBM) provides same bone reconstruction as bone graft in a rat model of calvaria defect. Furthermore, adipose tissue stromal vascular fraction (SVF) seems to be another promising source of osteoprogenitor cells that can be used intra-operatively. This study aimed to combine, intra-operative BCP-based bone tissue engineering strategies with TBM or SVF from human sources.METHODS:5 mm critical-size calvaria defects were performed in 18 nude rat. The defects were filled with intra-operative bone tissue engineering procedures: human BG, human TBM + BCP, human SVF + BCP and, rat TBM + BCP. Animals were sacrificed 8 weeks after implantation and calvaria were processed for histological and radiological examinations. Implanted cells were labelled with a fluorochrome.RESULTS:Micro-CT analysis revealed partial repair of bone defect. Only hBG significantly succeeded in healing the defect (43.1%). However, low rate of newly formed bone tissue was observed in all tissue engineering conditions (hTBM, hSVF, ratTBM).DISCUSSION:The lack of bone formation observed in this study could possibly be attributed to the model.CONCLUSION:This study combined with a literature analysis show the stringency of the nude rat calvaria model in term of bone regeneration

The In Vitro and In Vivo Effects of a Low-Molecular-Weight Fucoidan on the Osteogenic Capacity of Human Adipose-Derived Stromal Cells

International audienceHuman adipose-derived stromal cells (hASCs) may hold potential for bone tissue engineering. Osteogenic differentiation of these cells is crucial to bone formation. Low-molecular-weight fucoidan (LMWF) is a sulfated polysaccharide that potentiates several growth factors, including pro-angiogenic growth factors. To investigate whether hASC preconditioning with LMWF promoted bone repair, we compared the effects of LMWF and low-molecular-weight heparin on hASC phenotype and osteogenic differentiation. LMWF did not modify the stem-cell phenotype of hASCs but enhanced their osteogenic differentiation (formation of calcium deposits, increased activity and expression of alkaline phosphatase, and increased expression of osteopontin and runt-related transcription factor 2). However, when hASCs were exposed to LMWF before their adhesion to biphasic calcium phosphate particles and implantation in a bone-growth mouse model, no bone formation was apparent after 5 or 8 weeks, probably due to cell death. In conclusion, LMWF may hold promise for enhancing the osteogenic differentiation of hASCs before their implantation. However, concomitant vascularization would be required to enhance bone formation

Chondrogenic potential of differentially preconditioned rabbit ASC (rASC).

<p><b>A)</b> rASC were cultured under normoxic conditions (21% O₂) in control medium (NCT) and chondrogenic medium (NCH) or under hypoxic conditions (5% O₂) in chondrogenic medium (HCH). The expression of transcripts encoding type II collagen (<i>col2a1</i>) and aggrecan (<i>acan</i>) was measured by real-time PCR. The results are expressed as relative expression levels. ND: not detected. # <i>p</i><0.05 compared with NCT; * <i>p</i><0.05 compared with NCH. <b>B)</b> rASC were cultured in NCT (a, b, c, d), NCH (e, f, g, h), or HCH (i, j, k, l) and implanted with the Si-HPMC hydrogel in rabbit osteochondral defects. Rabbit nasal chondrocytes (RNCs) incorporated into the Si-HPMC hydrogel were used as a control (m, n, o, p). After 18 weeks of implantation, the defects were macroscopically observed [gross appearance (a, e, i, m)], histologically stained using Movat's pentachrome (b, f, j, n) and alcian blue (c, g, k, o) and immunostained for type II collagen (d, h, l, p). a, e, i, m: bar indicates 1 mm. b–d; f–h, j–l, n–p: bar indicates 100 µm. <b>C)</b> A semi-quantitative analysis of the regenerated tissue was performed using O′Driscoll's repair score as described in the “Materials and Methods” section. The results are expressed as a mean O′Driscoll score.</p

Schematic overview of <i>in vivo</i> experimental design.

<p>A) Schematic overview of the chondrogenic potential of differentially preconditioned rabbit adipose stromal cells (rASC). rASC were isolated and cultured under normoxic conditions (21% O₂) in control medium or chondrogenic medium or under hypoxic conditions (5% O₂) in chondrogenic medium. As a positive control, rabbit nasal chondrocytes (RNC) were used. Preconditioned rASC and RNC were finally associated with Si-HPMC hydrogel and implanted in rabbit articular cartilage defects for 18 weeks. B) Schematic overview of the chondrogenic potential of differentially preconditioned human adipose stromal cells (hASC). hASC were isolated and cultured under normoxic conditions (21% O₂) in control medium or chondrogenic medium or under hypoxic conditions (5% O₂) in chondrogenic medium. As a positive control, horse nasal chondrocytes (HoNC) were used. Preconditioned hASC and HoNC were finally associated with Si-HPMC hydrogel and implanted in nude mice subcutis for 5 weeks.</p