Stabilization of epidermal growth factor on thermal and proteolytic degradation by conjugating with low molecular weight chitosan

Abstract

Epidermal growth factor (EGF, 5900 Da) has been reported to have the high efficiency of wound repair. However, the half-life of EGF in the body is too short to exert the biological activity effectively when applied in free forms. Conjugation of the low molecular weight chitosan (LMC) to EGF was carried out to enhance its stability. EGF was conjugated with LMC activated by water-soluble carbodiimide. The formation of EGF-LMC was quantitatively measured by indirect enzyme-linked immunosorbent assay (ELISA). In a study of the thermal and the proteolytic stability of free EGF and EGF-LMC, EGF covalently attached to LMC was found to be more stable than free EGF in thermal and proteolytic stabilities. In animal experiments of which free EGF (control), EGF-LMC (test) and LMC (carrier) diluted in viscous carboxymethyl cellulose (CMC) solution (vesicle) were applied to the incisional wounds in rats, the EGF-LMC conjugates are considered to be potent wound healing agent with mitogenicity and wound-healing property.

Preparation of hydrogel embedded polymer-growth factor conjugated nanoparticles as a diabetic wound dressing

“…The results of an experiment for the determination of the appropriate pH for conjugation reaction showed that rhEGF was unstable in pH of less than 6. This finding was in controversy with some literature which have claimed that pH above 4 is appropriate for rhEGF conjugation reaction 23 . After realizing the importance of the pH in this conjugation reaction, using one of the CMCh salts (NaCMCh) was preferred instead of low M W chitosan and CMCh.…”

“…Accordingly, Hardwicke et al developed a dextrin-growth factor conjugate as a bioactive medicine to extend and sustain the rhEGF release 29,42,43 . Low M W chitosan-conjugated rhEGF was more stable than free rhEGF both thermally and proteolytically, and exerted a stronger biological effect than rhEGF on proliferation of fibroblasts 23,27 . In the current study, turbidity formation was observed after adding rhEGF to low M W chitosan and CMCh.…”

“…To prolong the tissue exposure time and to preserve growth factor stability, controlled delivery systems have been developed that incorporate the growth factors into polymeric biomaterials 21 . Among the growth factors, it has been demonstrated that EGF can particularly stimulate in vitro cell proliferation and in vivo wound healing 23 . Localized and sustained delivery of EGF significantly decreases the size of wound area 21,24,25 .…”

Growth factor conjugation: Strategies and applications

“…To enhance EGF stability, Son et al suggested EGF conjugation to low molecular weight chitosan via carbodiimide mediated reaction. EGF conjugated chitosan was more stable than free EGF both thermally and proteolytically and exerted a stronger biological effect than EGF on proliferation of fibroblasts …”

“…EGF conjugated chitosan was more stable than free EGF both thermally and proteolytically and exerted a stronger biological effect than EGF on proliferation of fibroblasts. 50,51 Another reason behind EGF reformulation through conjugation reactions is for targeting purposes (Fig. 7).…”