Quatsomes for the topical delivery of the recombinant human epidermal growth factor (rh-EGF) to treat complex wounds

IntroductionComplex wounds, such as diabetic foot ulcers and chronic venous ulcers, defy cure using conventional and simple "dressings" therapy and, in most cases, surgical treatments are unavoidable. Therefore, new... [ view full abstract ]

Introduction

Complex wounds, such as diabetic foot ulcers and chronic venous ulcers, defy cure using conventional and simple "dressings" therapy and, in most cases, surgical treatments are unavoidable. Therefore, new technologies that improve the conventional treatments should be introduced. EGF is a small polypeptide which exerts a potent mitogenic activity through binding to a specific cell membrane receptor promoting the epidermal regeneration and the corneal epithelialization. Some institutions of the Havana Western Scientific Pole in Cuba have been developing and marketing novel therapeutic products using the rhEGF, known as Heberprot-P® and Cimavax EGF®. Nevertheless, the proteolytic environment present in the complex wounds affects the bioavailability and effectiveness of this rhEGF-based treatment. Consequently, the encapsulation of this drug within nanocarriers, such as vesicles, can provide protection together with an effective delivery of the active molecules in the site of action. Here, we present a new highly stable nanovesicular system named Quatsomes, which confers several advantages over conventional liposomes, for the topical delivery of EGF.

Methods

rhEGF-quatsomes, composed of cholesterol and CTAB, were prepared by the DELOS-SUSP methodology (Figure 1) and deeply characterized to determine their physico-clemical properties (size and zeta potential by dynamic light scattering, morphology by cryo-TEM, entrapment efficiency and protein loadings by an enzyme-linked immunosorbent assay) and their biological properties (bioactivity, resistance to proteases, and in vivo efficacy).

Results and Discussion

rhEGF-quatsomes with nanometric sizes (100-150 nm), with a great degree of unilamellarity, and with high entrapment efficiencies (~99 %), were successfully prepared. These conjugates resulted very stable along time, keeping the same protein/lipid loadings for more than one year. The specific enzymatic activity of the rhEGF entrapped in the quatsomes was at least two times higher than that for the free protein (Figure 2). rhEGF-quatsomes also showed antimicrobial activity and 8 times more resistance to degradation by proteases compared to free rhEGF. The pharmacological efficacy of the developed rhEGF-quatsomes was successfully demonstrated in a rat model of chronic ulcer as well as when used for the compassionate treatment of 12 patients, showing outstanding results in the cicatrization of the treated complex wounds.