Figure 4.
Heterogeneous NP protects growth factors from protease-mediated degradation. (A) Formation of heterogeneous NP using chimeric fusion proteins comprising different functional domains (gray or black). (B–E) Growth factor alone or heterogeneous NPs containing growth factor and protease inhibitor were incubated with HNE (250 μU/μL) at the indicated times. Growth factor degradation was visualized using western blots using antibodies specific to the respective growth factor under study. We tested (B) PDGF, (C) EGF, (D) KGF, and (E) VEGF. (F) PDGF-ELP or heterogeneous NPs comprising PDGF-ELP and PMPD2-ELP were incubated with chronic wound fluid at the indicated times and protein degradation was quantified using western blots. This experiment was carried out using the wound fluid from 11 patients and an example western blot is shown. (G) The overall percent increase in residual PDGF at 24 h was quantified for all patients (n = 11) by taking a ratio of remaining PDGF detected at 24 h with PMPD2-ELP and without PMPD2-ELP. EGF, epidermal growth factor; KGF, keratinocyte growth factor; NP, nanoparticle; VEGF, vascular endothelial growth factor.