Endothelial Cell Migration on RGD Peptide-containing PEG Hydrogels in the Presence of Sphingosine 1-Phosphate

¹ Washington University in St. Louis

^* To whom correspondence should be addressed. E-mail: elbert{at}biomed.wustl.edu.

Submitted on March 19, 2007
Revised on April 3, 2007
Accepted on 6 August 2007

	Abstract

Sphingosine 1-phosphate (S1P) is a potent chemokinetic agent for endothelial cells that is released by activated platelets. We previously developed RGD-containing polyethylene glycol (PEG) biomaterials for the controlled delivery of S1P to promote endothelialization. Here, we studied the effects of cell adhesion strength on S1P-stimulated endothelial cell migration in the presence of arterial levels of fluid shear stress, since an upward shift in optimal cell adhesion strengths may be beneficial for promoting long-term cell adhesion to materials. Two RGD peptides with different integrin-binding specificities were added to the PEG hydrogels. A linear RGD bound primarily to 3 integrins, while a cyclic RGD bound through both 1 and 3 integrins. We observed increased focal adhesion formation and better long-term adhesion in flow with endothelial cells on linear RGD peptide, versus cyclic RGD, even though initial adhesion strengths were higher for cells on cyclic RGD. Addition of 100 nM S1P increased cell speed and random motility coefficients on both RGD peptides, with the largest increases found on cyclic RGD. For both peptides, much of the increase in cell migration speed was found for smaller cells (<1522 µm² projected area), although the large increases on cyclic RGD were also due to medium-sized cells (2288-3519 µm²). Overall, a compromise between high cell migration rates and long-term adhesion will be important in the design of materials that endothelialize following implantation.

Key Words: RGD peptide, cell adhesion, cell migration, endothelial, fluid shear stress, hydrogel