Hyaluronan or hyaluronic acid (HA) is an unsulfated glycosaminoglycan that is comprised of repeating N-acetyl glucosamine-gluconic acid disaccharides using b1,4 and b1,3 linkages. HA is extremely hydrophilic and hydrated HA fills a very large volume. Uncrosslinked hyaluronan at 1 % concentration in aqueous media at 4 ºC is characterized as a viscous liquid. When crosslinked, however, the hyaluronan becomes a hydrogel, which can absorb water to a large percentage of its own weight while maintaining its three dimensional structure (Prestwich et.al., 1999).

HA is synthesized by most cells in the body at the plasma membrane. By extruding the growing molecule into the extracellular space, very large molecules of HA (up to 10,000 Kda) can be formed biologically (Luo et.al., 2000). Uncrosslinked HA is deposited in granulation tissue within skin wounds mainly by fibroblasts. The HA may promote cell migration in granulation tissue through a few mechanisms. The first is the facilitation of adhesion-disadhesion between cells and the extracellular matrix (ECM). High levels of HA in the ECM have been shown to weaken the adhesion of cells. The loss of tight adhesion between the cell and the ECM might allow for rapid migration. The second is that hydrated HA forms a large pore matrix that can accommodate more cell proliferation and invasion. The third is there are specific cell receptors for HA that contributes to cellular interactions with the ECM. Two major cell surface receptors for HA are CD44 and receptor for hyaluronan-mediated motility (RHAMM). CD44 mediates cell adhesion and migration on HA, as well as cellular uptake and degradation of HA. RHAMM regulates cell migration in response to soluble HA (Clark, 1996; Lewis et.al., 2001; Oliferenko et al., 2000).

In addition to interacting with fibroblasts, HA interacts with endothelial cells, thereby playing an important role in angiogenesis. It has been reported that high concentration of high molecular weight HA (> 100 µg/ml) inhibits angiogenesis, while HA degadation byproducts enhance endothelial angiogenesis. The angiogenic properties of HA molecules are probably due to interactions with the cellular integrins CD44 and RHAMM as well (Rahmanian et.al., 2002; Savani et al., 2001).

Introduction

Wound Healing

Product Design

Materials

Methods

Recombinant FN Fragment Purification

Cell Culture

Agarose Droplet Migration Assay