מורן אביב

תלמידת המחלקה לתואר שלישי תרצה בנושא:

Polysaccharide-based hydrogels employed under tissue engineering technologies, which foster steps in biological development stages of differentiation of tissues and cells

Abstract

Hydrogels are of special interest as class of materials for tissue engineering (TE) and regenerative medicine, since they offer 3D scaffolds that can support the growth of cultured cells. Natural-semi-solid-fluid viscous based hydrogels, especially polysaccharides such as hyaluronic acid (HA), can mimic the natural extra cellular matrix, which is considered as biocompatible. Mesenchymal stem cells (MSCs) taken from limb-buds of 4.5 day old chick embryo, were collected, isolated and seeded on covalently coated plates with either HA or chitosan (CS), and compared to regular plastic plates (polystyrene). Our goals were aimed to study factors that manipulate the interplay between proliferation versus differentiation of MSCs. It was observed that the chondrogenic fate is induced by a high initial cell density, and by HA and CS coated plates. On the other hand, the osteogenic fate is mainly introduced by growth factors, and the intermediate initial cell density, while the biomaterials coated plates did not show a significant effect. The project was extended and aimed to develop a homogenously composite hybrid hydrogel with improved mechanical properties, without using cross-linking agents. This goal was achieved by mixing HA solution with the self-assembled peptide, FmocFF. Self-assembled peptide hydrogels such as FmocFF (N-fluorenylmethoxycarbonyl-di-phenylalanine), have recently attracted attention as nanoscale objects with potential applications in the field of nanomaterials. A set of different hybrid hydrogels was formed by using diverse FmocFF/HA weight ratios, and their physiochemical, mechanical and biological properties were examined. These innovative composite hydrogels are injectable and malleable for the use in TE, exerting good mechanical properties combined with good biocompatibility both in vitro and in ovo (examined on the chick chorioallantoic membrane of a fertilized egg). HA improves the hybrid recovery after shear stress (elasticity) and contributes to cell adhesion and biocompatibility. Whereas FmocFF improves the biomechanical features (shear stress), and slows down HA degradation as well. Employing the above products in an optic nerve axotomy model in rats, an accelerated rate of axons’ regeneration was observed in the presence of the FmocFF/HA hybrids (evidenced by employing immunostaining procedure of GAP43). In summary, the development of these natural-synthetic composite hydrogels opens up great scientific and technological interests and opportunities for their wide-range applications in regenerative medicine, biotechnology and TE.

העבודה נעשתה בהנחייתם של פרופ' שמואל עינב, המחלקה להנדסה ביו-רפואית, פרופ' אהוד גזית, המחלקה לביולוגיה מוליקולרית וביוטכנולוגיה ופרופ' צבי נבו, המחלקה לגנטיקה מוליקולרית של האדם וביוכימיה, אוניברסיטת תל-אביב

ההרצאה תתקיים ביום ראשון 6.5.2012, בשעה 14:45,

בחדר 315, הבניין הרב תחומי, אוניברסיטת תל אביב