(437f) Dynamic Adhesion of Endothelial Progenitor Cells On Peptide-Coupled Hydrogels Under Flow

Endothelial progenitor cells (EPCs) have the potential to
become a reliable source of autologous cells for endothelialization of
intravascular devices and vascularization of tissue engineered constructs. We
have characterized the rolling velocity and transient adhesion of EPCs on
different peptide-coupled hydrogels using a parallel plate flow chamber. These
results will be applied in the design of future biomaterial surfaces to enhance
endothelialization and improve EPC strength of adhesion under shear. EPCs
are blood-derived cells and little is currently known about their response to
shear stress.  For these studies, umbilical cord blood outgrowth
endothelial colony forming cells (ECFCs), one type of EPCs, were used. To
assess the specific interactions required for EFCFs to interact with material
coatings under shear, copolymers poly(ethylene glycol)
diacrylate (PEG-DA) and acryl-PEG-peptides were formed.  Peptides included Arg-Gly-Asp-Ser (RGDS), Arg-Glu-Asp-Val (REDV), Tyr-Ile-Gly-Ser-Arg (YIGSR), and Arg-Gly-Glu-Ser (RGES). Shear
experiments were performed to examine EFCF rolling and adhesion on the hydrogel
surfaces. First, ECFCs were dissociated and suspended in flow media. Using a
Glycotech parallel plate flow chamber, the ECFC cell suspension was then sheared
over hydrogels containing peptides at shear rates of
20s^-1, 40s^-1, 80s^-1, and 120s^-1.
Rolling velocity of ECFCs was shown to relate to shear rates and adhesion
material surface. Future studies will investigate the role of specific integrin
binding sites in ECFC rolling and capture under shear stress.  Capture of
rolling ECFCs could be maximized by engineering biomaterials to incorporate the
appropriate binding ligands. Our results provide a better understanding of
ECFCs-material interactions under physiological shear stress and will aid in
the design of materials for stent coating and vascular grafts as well as for
other intravascular applications.