muramidase and gluconic-acid

We previously developed chitosan cryogels from chitosan-gluconic acid conjugate without using toxic additives for wound care. In this study, we improved physiological characteristics of the previous cryogels by incorporating poly(vinyl alcohol) that also form cryogels. Mechanical strength of the cryogels was more than two times higher than that of the previous cryogels. Furthermore, the incorporation of poly(vinyl alcohol) enhanced water retention and resistance to degradation of the gels by lysozyme. The cryogels retained the favorable biological properties of the previous cryogels that they accelerate infiltration of inflammatory cells into wound sites. Time period for repairing 50 % of initial area of partial-thickness skin wound treated with the cryogels (4.0 ± 1.1 days) was shorter than those with gauze (6.5 ± 0.3 days) or a commercial hydrogel dressing (5.7 ± 0.3 days). Finally, we confirmed that incorporation of basic fibroblast growth factor into the cryogels was effective to further accelerate wound healing (2.7 ± 1.0 days). These results demonstrate that the cryogels in this study are promising for wound care.

Topics: Animals; Bandages, Hydrocolloid; Chitosan; Cryogels; Diabetes Mellitus, Experimental; Fibroblast Growth Factor 2; Gluconates; Male; Materials Testing; Microscopy, Electron, Scanning; Muramidase; Polyvinyl Alcohol; Rats; Rats, Wistar; Stress, Mechanical; Water; Wound Healing

Conventional chitosan hydrogels exhibit an acidic nature and contain unfavorable additives because (i) chitosan is soluble only in acidic solutions and (ii) toxic chemicals or proteins of non-human origin that serve as antigens are necessary for preparing chitosan hydrogels. These characteristics of the chitosan hydrogels limit their possibilities as wound dressings. In this study, a chitosan-gluconic acid conjugate is developed, soluble in an aqueous solution at neutral pH and gellable by freeze-thawing (cryogelation) without using additives. The viability of L929 fibroblasts cultured in the presence of the chitosan derivative for 24 h was >96%. The degradation rate of the corresponding chitosan cryogels by lysozyme was tunable via the derivative concentration in the gels. The gels had low cellular adhesiveness. The gels promoted the accumulation of inflammatory cells such as polymorphonuclear leukocytes, which have the potential to release chemical mediators effective for wound healing, in full-thickness skin wounds in rats and accelerated the healing of the wounds. These results demonstrate that cryogels are promising for wound care.

Topics: Animals; Cell Adhesion; Cell Survival; Cells, Cultured; Chickens; Chitosan; Cryogels; Fibroblasts; Freezing; Gluconates; Humans; Hydrogen-Ion Concentration; Male; Mice; Muramidase; Nephelometry and Turbidimetry; Rats; Solubility; Solutions; Spectroscopy, Fourier Transform Infrared; Wound Healing