Bacterial cellulose/phytotherapic hydrogels as dressings for wound healing

Skin, the largest organ of the human body, is formed mainly by epidermis and dermis and its main functions are assurance of mechanical protection and prevention against contamination.1,2 Wound healing begins from a skin-barrier disruption and is divided into inflammatory, proliferative, and maturation phases. The former consists in the recruitment of leukocytes to the site of the lesion. In the proliferative phase, the migration and proliferation of keratinocytes, fibroblasts, and endothelial cells results in reepithelization and formation of granulation tissue with a large quantity of type III collagen. Finally, in the maturation phase, most type III collagen fibers are substituted by type I fibers and the excess collagen is degraded by proteolytic enzymes that promote tissue remodeling. Despite some recent advances in the understanding of such basic processes, wound healing disorders continue to cause diseases and even death.3 Dressings play a substantial role in the conglutination of certain types of open wounds (e.g. traumatic, thermal or chronic wounds), since the moist, warm and nutritious environment of wound beds provides an ideal condition for microbial growth. The wound healing process can interfere with bacterial colonization and subsequent infection, which may cause an excessive and prolonged inflammatory response from the host tissues. The nature of lesions, patient’s physiologic state, wound degree of infection and contamination and other disease processes can interfere with the cutaneous wound healing.4 The basic requirement for a material to be used for tissue engineering purposes is biocompatibility. Over the past two decades, significant advances have been made regarding the development of biodegradable polymers and biodegradability is one of the most important properties, since the scaffold should degrade with time and be replaced with newly regenerated tissues.5