Effects of dynamic cell culture conditions on 3D spatial reogarnization of MSCS/HUVECS spheroids in the context of bone tissue

We aim to observe the development and reorganization of MSCs and HUVECs in Pullulan/Dextran hydrogels supplied with nHAp under dynamic culture conditions in a perfusion bioreactor.Hydrogel poreux sous perfusion : modélisation et optimisation d'un modèle in vitro de reconstruction de défaut osseu

Biomimicking polysaccharide nanofibers promote vascular phenotypes : a potential application for vascular tissue engineering

The potential of electrospun pullulan/dextran (P/D) nanofibers (average diameter = 323 nm) for vascular tissue engineering applications is explored. The mechanical properties of the nanofibers are of the same order of magnitude as that of human arteries (Young's modulus ≈0.88 MPa; tensile strength ≈0.35 MPa). It is demonstrated that the nanofiber topography enables cell adhesion and that the endothelial phenotype is maintained on the nanofibers. Moreover, P/D nanofibers support a stable confluent monolayer of endothelial cells over 14 d. SMCs seeded on nanofibers display similar levels of alpha smooth muscle actin and a lower proliferation rate than cells on 2D cultures. The observations suggest that nanofibers promote a shift to a quiescent contractile phenotype in SMCs

Channeled polysaccharide-based hydrogel reveals influence of curvature to guide endothelial cell arrangement in vessel-like structures

International audienc

Nanomedicine for the molecular diagnosis of cardiovascular pathologies

International audienc

Planar and tubular patterning of micro and nano-topographies on poly(vinyl alcohol) hydrogel for improved endothelial cell responses

International audiencePoly(vinyl alcohol) hydrogel (PVA) is a widely used material for biomedical devices, yet there is a need to enhance its biological functionality for in vitro and in vivo vascular application. Significance of surface topography in modulating cellular behaviour is increasingly evident. However, hydrogel patterning remains challenging. Using a casting method, planar PVA were patterned with micro-sized features. To achieve higher patterning resolution, nanoimprint lithography with high pressure and temperature was used. In vitro experiment showed enhanced human endothelial cell (EC) density and adhesion on patterned PVA. Additional chemical modification via nitrogen gas plasma on patterned PVA further improved EC density and adhesion. Only EC monolayer grown on plasma modified PVA with 2 mm gratings and 1.8 mm concave lens exhibited expression of vascular endothelial cadherin, indicating EC functionality. Patterning of the luminal surface of tubular hydrogels is not widely explored. The study presents the first method for simultaneous tubular molding and luminal surface patterning of hydrogel. PVA graft with 2 mm gratings showed patency and endothelialization, while unpatterned grafts were occluded after 20 days in rat aorta. The reproducible, high yield and high-fidelity methods enable planar and tubular patterning of PVA and other hydrogels to be used for biomedical applications

Tuning Physicochemical Properties of a Macroporous Polysaccharide-Based Scaffold for 3D Neuronal Culture

International audienceCentral nervous system (CNS) lesions are a leading cause of death and disability worldwide. Three-dimensional neural cultures in biomaterials offer more physiologically relevant models for disease studies, toxicity screenings or in vivo transplantations. Herein, we describe the development and use of pullulan/dextran polysaccharide-based scaffolds for 3D neuronal culture. We first assessed scaffolding properties upon variation of the concentration (1%, 1.5%, 3% w/w) of the cross-linking agent, sodium trimetaphosphate (STMP). The lower STMP concentration (1%) allowed us to generate scaffolds with higher porosity (59.9 ± 4.6%), faster degradation rate (5.11 ± 0.14 mg/min) and lower elastic modulus (384 ± 26 Pa) compared with 3% STMP scaffolds (47 ± 2.1%, 1.39 ± 0.03 mg/min, 916 ± 44 Pa, respectively). Using primary cultures of embryonic neurons from PGKCre, Rosa26tdTomato embryos, we observed that in 3D culture, embryonic neurons remained in aggregates within the scaffolds and did not attach, spread or differentiate. To enhance neuronal adhesion and neurite outgrowth, we then functionalized the 1% STMP scaffolds with laminin. We found that treatment of the scaffold with a 100 μg/mL solution of laminin, combined with a subsequent freeze-drying step, created a laminin mesh network that significantly enhanced embryonic neuron adhesion, neurite outgrowth and survival. Such scaffold therefore constitutes a promising neuron-compatible and biodegradable biomaterial

Fucoidan promotes early step of cardiac differentiation from human embryonic stem cells and long term maintenance of beating areas.

International audienceSomatic stem cells require specific niches and 3D scaffolds may provide a way to mimic this microenvironment. Here, we tested a scaffold based on fucoidan, a sulfated polysaccharide known to influence morphogen gradients during embryonic development, to support human Embryonic Stem Cells (hESCs) differentiation towards the cardiac lineage. A macroporous (pore 200 µm) Fucoidan scaffold was selected to support hESCs attachment and proliferation. Using a protocol based on the cardiogenic morphogen BMP2 and TGFb followed by TNFa, an effector of cardiopoietic priming. we examined the cardiac differentiation in the scaffold compared to culture dishes and embryoid bodies (EBs). At day 8, Fucoidan scaffolds supported a significantly higher expression of all 3 genes encoding for transcription factors marking the early step of embryonic cardiac differentiation NKX2.5 (p<0.05), MEF2C (p<0.01) and GATA4 (p<0.01), confirmed by flow cytometry analysis for MEF2C and NKX2.5. Fucoidan scaffolds ability to locally concentrate and slowly release TGF and TNF was confirmed by Luminex technology. We also found that Fucoidan scaffolds supported the late stage of embryonic cardiac differentiation marked by a significantly higher ANF expression (p<0.001), although only rare beating areas were observed. We postulated that absence of mechanical stress in the soft hydrogel impaired sarcomere formation, as confirmed by molecular analysis of the cardiac muscle myosin MYH6 and immunohistological staining of sarcomeric -actinin. Nevertheless, Fucoidan scaffolds contributed to the development of thin filaments connecting beating areas through promotion of smooth muscle cells, thus enabling maintenance of beating areas for up to 6 months. In conclusion, Fucoidan scaffolds appear as a very promising biomaterial to control cardiac differentiation from hESCs that could be combined with mechanical stress to promote sarcomere formation at terminal stages of differentiation

Fucoidan: a marine polysaccharide for SPECT diagnosis of thrombosis

peer reviewe

Interplay between crosslinking and ice nucleation controls the porous structure of freeze-dried hydrogel scaffolds

International audienc

Bone Regeneration in Small and Large Segmental Bone Defect Models after Radiotherapy Using Injectable Polymer-Based Biodegradable Materials Containing Strontium-Doped Hydroxyapatite Particles

International audienceThe reconstruction of bones following tumor excision and radiotherapy remains a challenge. Our previous study, performed using polysaccharide-based microbeads that contain hydroxyapatite, found that these have osteoconductivity and osteoinductive properties. New formulations of composite microbeads containing HA particles doped with strontium (Sr) at 8 or 50% were developed to improve their biological performance and were evaluated in ectopic sites. In the current research, we characterized the materials by phase-contrast microscopy, laser dynamic scattering particle size-measurements and phosphorus content, before their implantation into two different preclinical bone defect models in rats: the femoral condyle and the segmental bone. Eight weeks after the implantation in the femoral condyle, the histology and immunohistochemistry analyses showed that Sr-doped matrices at both 8% and 50% stimulate bone formation and vascularization. A more complex preclinical model of the irradiation procedure was then developed in rats within a critical-size bone segmental defect. In the non-irradiated sites, no significant differences between the non-doped and Sr-doped microbeads were observed in the bone regeneration. Interestingly, the Sr-doped microbeads at the 8% level of substitution outperformed the vascularization process by increasing new vessel formation in the irradiated sites. These results showed that the inclusion of strontium in the matrix-stimulated vascularization in a critical-size model of bone tissue regeneration after irradiation