Biochemistry, histology and clinical uses of chitins and chitosans in wound healing

Biodegradability, biocompatibility and capacity to promote the synthesis of hyaluronan are main characteristics of chitin-derived wound healing materials, whose biological significance in the human body depends largely on the actions that certain hydrolases exert on them. The resulting chitooligomers stimulate various cells, while the released monomers are phosphorylated and incorporated into hyaluronan, keratan sulphate and chondroitin sulphate, components of the intracellular matrix and connective tissue. The healing process favoured by these materials is examined in terms of macrophage activation, cytokine production by macrophages and fibroblasts, antiinflammatory action, angiogenesis stimulation, granulation and scar formation. Current biomedical applications are illustrated by the treatment of leg ulcers, the use of skin substitutes, and the regeneration of bone, nerve and meniscus tissues.