Vascular growth factor binding kinetics to the endothelial cell basement membrane, with a kinetics-based correction for substrate binding.

Vascular growth factors, including vascular endothelial growth factor and fibroblast growth factor-2, bind to heparan sulfate proteoglycans in the basement membrane. While this binding, storage, and release system provides a critical model for controlled drug release devices, basement membrane-growth factor binding kinetics have not been fully established. We modified endothelial cell-growth factor binding kinetics protocols for the basement membrane. The basement membrane showed low affinity for fibroblast growth factor-2 (K d = 185.8 nM), with a slow off rate (k off = 0.00338 min(-1)). However, results were confounded by growth factor binding to tissue culture polystyrene in a manner strikingly similar to basement membrane. Since substrate binding could not be blocked, a binding kinetics based correction technique was developed to account for polystyrene growth factor binding. This method was validated by conducting binding kinetics experiments on bacteriologic plates that exhibit little growth factor binding. This novel method will improve our understanding of cell and protein interaction with the basement membrane in health and disease. They can also further be applied to develop biomimetic drug delivery systems.