Immune Response to Synthesized Pnipam-Based Graft Hydrogels Containing Chitosan and Hyaluronic Acid

Abstract

<p>p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Helvetica}</p> <p>Biomaterials are thought to be the magical solution to improving the quality of life and lengthening lifespans of human beings. To date, there is no biomaterial that can completely escape immune responses. However, successes have recently been made in reducing immune responses to biomaterials.P(N-isopropylacrylamide) (PNIPAM), chitosan , and hyaluronan are examples of polymers that are gaining great interest in the field of biomaterials. The most attractive property of PNIPAM is thermo-responsiveness. Adequate literature has been published on improving the mechanical strength of PNIPAM, but not much has been published on host response to PNIPAM based graftpolymers. Chitosan and hyaluronan are generally considered non-toxic and nonimmunogenic.</p> <p>The first part of this project focuses on the synthesis and characterization of hyaluronan-grafted-chitosan-grafted-P(NIPAM-co-acrylic acid), while the second part examines the effect of grafting on the extent of immune reaction compared to P(NIPAM-co-acrylic acid) alone. The incorporation of chitosan into P(NIPAM-co-acrylic acid), and hyaluronan into chitosan-grafted-P(NIPAM-coacrylic acid) was confirmed by Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance , 2,4,6-trinitrobenzenesulfonic acid (TNBS), and Lower Critical Solution Temperature (LCST) experiments. The optimum molecular p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px Helvetica}</p> <p>weight for P(NIPAM-co-acrylic acid) that could provide sufficient amount of reactive sites while maintaining LCST below 37°C was found to be in the range of 2-2.5kDa. Western blotting results demonstrated that incorporating chitosan into P(NIPAM-co-acrylic acid) reduces the amount of fibrinogen, fibronectin, and vitronectin adsorbed, and eliminates complement component 3 (C3) adsorption.</p> <p>Furthermore, incorporating hyaluronan eliminates more inflammatory proteins including fibrinogen and reduces Immunoglobulin G (lgG) adsorption. Chitosan-grafted-P(NIPAM-co-acrylic acid) elicited lower levels of inflammatory cytokine release compared to P(NIPAM-co-acrylic acid), but higher than hyaluronan-grafted-chitsan-grafted-P(NIPAM-co-acrylic). In vitro and in vivo results revealed lowest density of leukocytes adhesion to hyaluronan containing surface compared to the other surfaces. The extent and duration of inflammation was reduced on chitosan-grafted-P(NIPAM-co-acrylic acid) and hyaluronangrafted-chitosan-grafted-P(NIPAM-co-acrylic acid) hydrogels.</p>