Construction and Characterization of Cell-Penetrating Peptide-Fused Fibroblast Growth Factor and Vascular Endothelial Growth Factor for an Enhanced Percutaneous Delivery System

The exogenous administration of growth factors has been examined for treating wounds and such factors serve as cosmetic agents for skin regeneration. However, the topical application of growth factors is hampered by their limited percutaneous absorption. In this study, we genetically modified basic fibroblast growth factor (bFGF) and vascular endothelial growth factor-A (VEGF-A) using a cell-penetrating peptide to facilitate their permeation into skin and to avoid multiple steps in the chemical or physical modification of biomaterials. Low-molecular-weight protamine (LMWP)-fused bFGF and VEGF-A (LMWP-bFGF and LMWP-VEGF-A) were designed by serial polymerase chain reaction (PCR)-mediated addition of the LMWP codons onto the bFGF and VEGF-A genes and then produced in Escherichia coli. The purified LMWP-bFGF and LMWP-VEGF-A represented >90% of the total proteins, as determined by SDS-PAGE and densitometric quantification, and their actual molecular weights, determined by mass spectroscopy, were 19,026 and 15,715 Da, respectively, corresponding to the theoretical values. N-terminal amino acid sequencing analyses confirmed the N-terminal conjugation of LMWP to bFGF and VEGF-A. Immunoblotting analyses using antibodies against bFGF and VEGF-A, together with the proliferative effects of LMWP-bFGF and LMWP- VEGF-A on human keratinocytes and fibroblasts, demonstrated that the original biological activity of each growth factor was not altered by LMWP conjugation. In addition, the LMWP conjugation did not induce further cytotoxic effects on the skin cells, while the cell membrane-penetrating activities of LMWP-bFGF and LMWP-VEGF-A were significantly enhanced compared with the respective unconjugated growth factors. These results suggest that LMWP-bFGF and LMWP-VEGF-A can be used as effective topical therapeutic or cosmetic agents for skin regeneration and anti-aging treatments.