Cell-Penetrating Peptides Enhance the Activity of Human Fibroblast Growth Factor 2 by Prolonging the Retention Time: A New Vision for Drug-Delivery Systems.

Jaehoon Lee,Sangkyu Park,Jaehyun Park,Sangho Roh,Jeongmin Seo,Mijin Kwon,Naeun Oh

doi:10.3390/ijms21020442

Abstract

Cell-penetrating peptides (CPPs) are defined by their ability to deliver cargo into cells and have been studied and developed as a promising drug-delivery system (DDS). However, the issue of whether the CPPs that have already entered the cells can be re-released or reused has not been studied. The purpose of this research was to construct CPP-conjugated human fibroblast growth factor 2 (hFGF2) and investigate whether they can be re-released from the cell membrane for reuse. This study combined hFGF2 with Tat or Ara27, a newly developed CPP derived from the zinc knuckle (CCHC-type) family protein of Arabidopsis. Human dermal fibroblast (HDF) was treated with Tat-conjugated hFGF2 (tFGF2) and Ara27-conjugated hFGF2 (NR-FGF2) for both long and short durations, and the effects on cell growth were compared. Furthermore, tFGF2 and NR-FGF2 re-released from the cells were quantified and the effects were evaluated by culturing HDF in a conditioned medium. Interestingly, the proliferation of HDF increased only when NR-FGF2 was treated for 1 h in endocytosis-independent manner. After 1 h, NR-FGF2 was significantly re-released, reaching a maximum concentration at 5 h. Furthermore, increased proliferation of HDF cultured in the conditioned medium containing re-released NR-FGF2 was discovered. While previous studies have focused on the delivery of cargo and its associated applications, this study has revealed that combinations of superior CPPs and therapeutics can be expected to prolong both the retention time and the cell-penetrating capacity, even in the presence of external factors. Therefore, CPPs can be applied in the context of topical drugs and cosmetics as a new DDS approach.

Highlights

Advances in drug screening research have enabled the identification of candidates with desired therapeutic effects, delivering a drug to a specific target to maximize its effect has proven to be challenging
When low-molecular-weight protamine (LMWP) was combined with human fibroblast growth factor 2 or human vascular endothelial growth factor, cell permeability was significantly increased, suggesting that it could be used as an effective percutaneous delivery system [15]
The results showed that only NR-FGF2 significantly increased the cell viability of Human dermal fibroblast (HDF), and the interaction between cell-penetrating peptides (CPPs) and the cell membranes did not contribute to the results by using heparin which was known to block the effects of CPPs

Summary

Introduction

Advances in drug screening research have enabled the identification of candidates with desired therapeutic effects, delivering a drug to a specific target to maximize its effect has proven to be challenging. In order to maximize the efficiency of the drug, various DDS vehicles (e.g., liposomes, hydrogels, nanoparticles, and micelles) have been developed One such channel is cell-penetrating peptides (CPPs), defined by their ability to cross cell membranes without specific receptors and to carry cargo into cells. CPPs have been studied and developed as a promising DDS strategy since the first discovery of the HIV-1 transactivating protein known as Tat [8,9]. These CPPs have been used to transfer nucleic acids [10], proteins [11], small-molecule therapeutics [12], fusion complexes [13], and quantum dots [14]. Preclinical evaluations by CPP-applied therapeutics in a variety of disease models have indicated promising results, providing basic evidence for clinical trials [18,19,20]

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