**5. Conclusion**

Chitin and its ester derivatives, as well as chitosan obtained as a result of chitin deacetylation, have many valuable chemical, physical and biological properties that determine their use in many areas, also in medicine.

The widest use of chitin and its derivatives is observed in biomedical sciences, in particular: in dressing materials (active dressings), active substance carriers (drugs and growth factors), in tissue engineering (cell scaffolds - scaffolds, mainly orthopedics) and in regenerative medicine (stem cell differentiation). Chitin accelerates the wound healing process by having a beneficial effect on processes such as angiogenesis, granulation, epithelialization and scar formation, which play a key role in the physiological wound healing process. It increases the inflow of phagocytic cells (segmented granulocytes and macrophages) to the site of infection, stimulates the migration and proliferation of endothelial cells and fibroblasts. Chitin derivative dressings are considered to be very effective medical devices in the healing of difficult-to-heal wounds [6–11].

The results of clinical trials with dressings based on butyryl-acetyl chitin co-polyesters have also shown their high effectiveness in healing wounds of various etiologies, mainly those caused by chronic venous insufficiency and diabetes. Their use leads to a reduction in the ulcer area and its depth. These dressings were assessed as having a high safety profile [38].

On the other hand, the results of clinical trials with chitosan dressings showed high effectiveness and durability of the anti-haemorrhagic effect. These studies also confirmed the safety of the dressing [96]. The antibacterial test confirmed that the dressing is bactericidal. Thus, there are currently many different hemostatic dressings based on chitosan on the market.
