No abstract

Chitosan is a naturally occurring polysaccharide obtained from chitin, present in abundance in the exoskeletons of crustaceans and insects. It has aroused great interest as a biomaterial for tissue engineering on account of its biocompatibility and biodegradation and its affinity for biomolecules. A significant number of research groups have investigated the application of chitosan as scaffolds for tissue regeneration. However, there is a wide variability in terms of physicochemical characteristics of chitosan used in some studies and its combinations with other biomaterials, making it difficult to compare results and standardize its properties. The current systematic review of literature on the use of chitosan for tissue regeneration consisted of a study of 478 articles in the PubMed database, which resulted, after applying inclusion criteria, in the selection of 61 catalogued, critically analysed works. The results demonstrated the effectiveness of chitosan-based biomaterials in 93.4% of the studies reviewed, whether or not combined with cells and growth factors, in the regeneration of various types of tissues in animals. However, the absence of clinical studies in humans, the inadequate experimental designs, and the lack of information concerning chitosan's characteristics limit the reproducibility and relevance of studies and the clinical applicability of chitosan.

No abstract

The molecular weight of chitosan (CS) may affect its physical properties and its ability to induce an appropriate host response. The biocompatibilities of CS membranes of low (LMWCS) and high (HMWCS) molecular weight were investigated by inserting these materials into the subcutaneous tissue of rats for 1-28 days and evaluating leukocyte infiltration, granulation tissue, fibrosis, arginase-1 immunostaining, as well as nuclear factor-κB (NF-κΒ) and fibroblast growth factor (FGF)-2 expressions. Both CS membranes induced a peak of leukocyte infiltration on the first day of insertion and stimulated granulation and fibrous tissue generation when compared to control.LMWCS induced more collagen deposition a week earlier, when compared to the control and HMWCS membrane. The membranes also increased arginase-1 immunostaining, a M2 macrophage marker. M2 macrophage is recognized as anti-inflammatory and pro-regenerative. NF-κB is an essential biomarker of the inflammatory process and induces the expression of several pro-inflammatory cytokines. The LMWCS membrane reduced inflammation, as indicated by a reduced nucleus/cytoplasm NF-κB ratio in surrounding tissue from days 7 to 14 when compared to control. On the first day, the expression of FGF-2, a biomarker of inflammatory resolution, was increased in the tissue of the LWMCS group, when compared with HMWCS, which was consistent with the type I collagen deposition. Thus, LWMCS was associated with a prior reduction of the inflammatory response and improved wound healing.

ABSTRACT