Abstract:
Excessive proteolysis of fibronectin (FN) impairs tissue repair in chronic wounds. Since FN is
essential in wound healing, our goal is to improve its proteolytic stability and at the same time preserve
its biological activity. We have previously shown that reduced FN conjugated with polyeth-
ylene glycol (PEG) at cysteine residues is more proteolytically stable than native FN. Cysteine-
PEGylated FN supported cell adhesion and migration to the same extent as native FN. However,
unlike native FN, cysteine-PEGylated FN was not assembled into an extracellular matrix (ECM)
when immobilized. Here, we present an alternative approach in which FN is preferentially
PEGylated at lysine residues using different molecular weight PEGs. We show that lysine
PEGylation does not perturb FN secondary structure. PEG molecular weight, from 2 to 10 kDa,
positively correlates with FN–PEG proteolytic stability. Cell adhesion, cell spreading, and gelatin
binding decrease with increasing molecular weight of PEG. The 2-kDa FN–PEG conjugate shows
comparable cell adhesion to native FN and binds gelatin. Moreover, immobilized FN–PEG is
assembled into ECM fibrils. In summary, lysine PEGylation of FN can be used to stabilize FN
against proteolytic degradation with minimal perturbation to FN structure and retained biological
activity.
