"Viscoelastic assessment of skin quality for clinical applications." Computer Methods in Biomechanics and Biomedical Engineering, 14(sup1), pp. 235–236 Acknowledgement This work was partly supported by the Inter-Institutional Centre for Translational Biomechanics EPFL-CHUV-DAL.

La reconstruction musculaire tissulaire permet de reconstruire du muscle suite à un traumatisme ou une brûlure. Nous utilisons de cellules musculaires fœtales humaines sur un support de collagène pour une réparation tissulaire. Nos cellules fœtales peuvent intégrer un muscle de souris sans rejet immunitaire. Le but de cette étude est d’analyser sur un modèle de souris les propriétés mécaniques d’un muscle blessé et traité par des cellules fœtales. Les muscles jumeaux de femelles de souris C57BL/6 ont été blessés avec un punch de 4 mm. Des cellules musculaires fœtales humaines (1×105) associées à un support de collagène ou un support de collagène seul ont été transposés dans ces muscles. Les muscles jumeaux controlatéraux ont servi de contrôle. À différents temps, une analyse de force isométrique puis une tétanisation ont été enregistés grâce à un modèle d’analyse dynamique de la contraction musculaire. Nos résultats préliminaires montrent que le taux de recrutement des unités motrices obtenu dans nos muscles blessés est plus faible en comparaison à celui obtenu à partir de muscles non blessés. L’utilisation de cellules fœtales transposées dans ces muscles lésés améliore le recrutement de fibres musculaires.

The aim of this study was to test the association of fetal bone cells with ceramic reinforced PLA scaffolds for tissue engineering. As animal models, the craniotomy and the femoral condyle approaches in rats were chosen to follow cortical and trabecular bone repair processes. Key findings were the observation of complete bone bridging 12 months after implantation in skulls of PLA porous structures seeded with human fetal bone cells, and a strong induction of trabecular bone ingrowth in femoral condyles 2 months after surgery. The osteogenic properties observed in xenogeneic implants might have been reduced due to adverse response of the hosts, as reported with MSCs from rats used in mice, although immunoprivilege of fetal and adult MSCs is described (4). Further studies must be undertaken to evaluate the respective actions of host and donor cells in the healing process observed. A preliminary study showed that human cells were still detectable in cranial implants 4 weeks after surgery. In conclusion, we demonstrate here, the high potential of human fetal bone cells associated with PLA/ceramic composite structures processed by supercritical gas foaming for their use in cortical and trabecular bone repair.

Reference EPFL-CONF-179731View record in Web of Science Record created on 2012-07-04, modified on 2017-05-10

We envision the use of human fetal bone cells for engineered regeneration of adult skeletal tissue. A description of their cellular function is then necessary. To our knowledge, there is no description of human primary fetal bone cells treated with differentiation factors. The characterization of fetal bone cells is particularly important as the pattern of secreted proteins from osteoblasts has been shown to change during aging. In the first part of this work, human primary fetal bone cells were compared to adult bone cells and mesenchymal stem cells for their ability to proliferate and to differentiate into osteoblasts in vitro. Cell proliferation, gene expression of bone markers, alkaline phosphatase (ALP) activity, and mineralization were analyzed during a time-course study. In the second part of this paper, bone fetal cells behavior exposed to osteogenic factors is further detailed. The doubling time of fetal bone cells was comparable to mesenchymal stem cells but significantly shorter than for adult bone cells. Gene expression of cbfa-1, ALP, α1 chain of type I collagen, and osteocalcin were upregulated in fetal bone cells after 12 days of treatment, with higher inductions than for adult and mesenchymal stem cells. The increase of ALP enzymatic activity was stronger for fetal than for adult bone cells reaching a maximum at day 10, but lower than for mesenchymal stem cells. Importantly, the mineralization process of bone fetal cells started earlier than adult bone and mesenchymal stem cells. Proliferation of fetal and adult bone cells was increased by dexamethasone, whereas 1α,25-dihydroxyvitamin D3 did not show any proliferative effect. Mineralization studies clearly demonstrated the presence of calcium deposits in the extracellular matrix of fetal bone cells. Nodule formation and calcification were strongly increased by the differentiation treatment, especially by dexamethasone. This study shows for the first time that human primary fetal bone cells could be of great interest for bone research, due to their fast growth rate and their ability to differentiate into mature osteoblasts. They represent an interesting and promising potential for therapeutic use in bone tissue engineering.

tissue engineering techniques based on the delivery of cells to the defect through the use of 3-D scaffold materials, are currently investigated. As part of the bone tissue engineering project developed in Lausanne, two bioresorbable polymers (PLA, Boerhinger Ingelheim and PLGA 85/15, Pürac Biochem) were used to create a structure that could guide bone formation by facilitating cell migration, proliferation and differentiation. The 3-D foam morphology could be modified varying the processing conditions. In addition, the possibility of integrating ceramic materials into the polymer matrix might improve its mechanical properties. Hydroxyapatite (HA) and β-tricalciumphosphate (β-TCP) were chosen for this purpose due to their capacity to stimulate natural bone repair and for their stability2. For this project, we choose to use fetal bone cells that, in comparison to adult cells, show a higher proliferation capacity, are less differentiated into mature osteoblasts and present less immunological compatibility issues if used as tissue gafts3. The