Optimized hyaluronic acid-hydrogel design and culture conditions for preservation of mesenchymal stem cell properties.

A novel approach that preserved most mesenchymal stem cell (MSC) characteristics was developed using MSC encapsulation in a hydrogel based on hyaluronic acid (HA). An optimized HA-hydrogel composition, whose characteristics were assessed by scanning electron microscopy and viscoelastic property analyses, as well as the more favorable MSC seeding density, was established. These optimal three-dimensional MSC culture conditions allowed morphological cell remodeling, maintained the expression of stem cell markers over 28 days of culture, and preserved MSC differentiation plasticity. In addition, MSCs in HA-hydrogel submitted for 7 days to mechanical constraint that aimed at mimicking in vivo cardiac beat displayed enhanced cell survival by more than 40% compared to static culture conditions. Thus, the optimized HA-based hydrogel provides a niche for MSCs, which preserves their properties and opens ways for cell therapy, in particular in aortic repair medicine.

Influence of polysaccharide composition on the biocompatibility of pullulan/dextran-based hydrogels.

The implantation of a biomaterial for tissue engineering requires the presence of a suitable scaffold on which the tissue repair and regeneration will take place. Polymers have been frequently used for that purpose because they show similar properties to that of the natural extracellular matrix. Scaffold properties and biocompatibility are modulated by the composition of the polymers used. In this work four polysaccharide-based hydrogels (PSH) made of dextran and pullulan were synthesized. Their in vitro properties were determined and then tested in vivo in a rat model. As pullulan concentration increased in dextran hydrogels, the glass transition temperature and the maximum modulus decreased. In vitro degradation studies for 30 days demonstrated no significant degradation of PSH except for 100% pullulan hydrogel. In vivo tissue response evaluated 30 days after PSH subcutaneous implantation in rats indicated that all PSH were surrounded by a fibrous capsule. Adding pullulan to dextran induced an increased inflammatory reaction compared to PSH-D(100% dextran) or PSH-D(75)P(25)(75% dextran). This in vitro and in vivo data can be used in the design of hydrogels appropriate for tissue engineering applications.

A biocompatible polysaccharide hydrogel-embedded polypropylene mesh for enhanced tissue integration in rats.

Prosthetic materials are largely used in surgery and tissue engineering. However, many postoperative complications are due to poor integration of the materials, which delays the healing process. The objective of our study was to develop a synthetic scaffold that, according to histopathological and biomechanical criteria, would achieve both tolerance and efficiency. In this study, we evaluated the effect of intramuscular and subcutaneous implantation of a new hybrid mesh (HM) in rats. This HM was composed of clinical grade polypropylene mesh embedded in a polysaccharide hydrogel. Histological and biomechanical studies on the polysaccharide gel alone and on HM were performed 15 and 30 days after implantation, and then compared with two clinically used materials, porcine decellularized small intestinal submucosa and a polypropylene mesh. Results showed that the incorporation of a polypropylene mesh within the polysaccharide hydrogel led to the absence of adverse effects and better tissue organization. Thus, this new synthetic biocompatible HM with suitable properties for tissue repair appears to be a promising material for clinical applications.