Endothelial cell growth factor (ECGF) enmeshed with fibrin matrix enhances proliferation of EC in vitro

The vascular biomaterials that are currently used for clinical implants have been considered as poor substrates for human endothelial cell adhesion and spreading. Therefore, thrombotic occlusion is the predominant cause for the failure of small diameter vascular grafts made out of Dacron or Teflon. To reduce surface thrombogenicity of material surfaces used for vascular implants, in vitro seeding of endothelial cells using adhesive protein matrix is under evaluation in various laboratories. Evidences suggest that fibrin matrix is a suitable matrix for endothelial cell (EC) adhesion to the currently available vascular graft materials; however, poor proliferation of attached cells seems to be a major limitation. During this study we have also found that fibrin is a better matrix compared to gelatin to support cell attachment and spreading. However, the poor proliferation of initially attached human umbilical cord vein endothelial cell (HUVEC) necessitated modification of the matrix composition to get a monolayer within a limited period. Since fibrin can form a network of protein bundles, an effort is made to incorporate growth factors within the matrix. Endothelial cell growth factor (ECGF) isolated from bovine hypothalamus is immobilized on the surface with fibrin glue (FG) to promote proliferation of HUVEC. The results demonstrate that proteins with similar molecular weights as growth factors (GF) are retained within the matrix and released into the culture medium for 96 h, in quantities that would be sufficient to promote cell proliferation. When cells were seeded on the matrix composed with components of FG and ECGF, the HUVEC proliferated at a significantly higher rate compared to the cells on surfaces coated with gelatin or fibrin. The EC thus grown on the composite (FG + ECGF) resisted the shear stress as compared to the cells grown on gelatin. The HUVEC monolayer grown on the composite seems thromboresistant as adhesion and activation of platelets are negligible after platelet rich plasma is incubated with the monolayer for about 1 h with agitation. Therefore, the composite of fibrin and ECGF can be a suitable matrix for further evaluation of patients' autologous endothelial cell attachment and proliferation for clinical application.