”The incidence of skin injuries such as severe burns and scalds caused by various accidents and skin ulcers caused by diseases is high in China. Usually, skin is cut from other parts of the patient’s body or cut from other people for treatment. This “tearing down the east wall to make up for the west wall” method of treatment, whether for the patient himself or for the normal person of the skin donor, is predicated on increased pain, especially for patients with poor skin healing ability, the skin graft is not easily survivable and may lead to surgical failure. In fact, the search for human skin substitutes has been going on for centuries. In recent decades, skin grafts have evolved from autologous and allogeneic grafts to synthetic tissue-engineered biological skin replacement grafts. There are 3 main types of artificial skin: epidermal grafts, dermal substitutes, and composite skin grafts. We have been trying to conduct research on composite skin grafts, i.e. artificial skin, since 1992, using the principles and methods of engineering and cell biology to reconstruct biologically active skin analogs in vitro. Simulation studies are difficult In our early studies, we found that composite skin is histologically close to normal dermis and has transplantation advantages such as the ability to reconstruct both dermis and epidermis in a single surgery and ease of manipulation. However, this composite skin also has some non-negligible defects, such as the collagen gel used will shrink about 80%, poor resistance to collagenase degradation; the use of allogeneic cells and bovine collagen, there is a risk of transmitting viruses and immune rejection; brittle, difficult to operate; collagen gel industrial production process is complicated, etc. Therefore, it has been our scientific goal for a long time to research artificial skin with three conditions at the same time: preventing evaporation and loss of water and fluid from the wound, preventing infection of the wound, and promoting the gradual growth of granulation or new skin. New Material Creates Miracle In many trials, we finally found that the double-layer tissue-engineered skin with compound chitosan not only has active anti-infection ability, but also good physical properties and histological characteristics close to those of natural skin. In other words, this artificial skin has the potential to be used clinically as a new type of skin substitute. Chitosan is a linear polymer material containing many amino and hydroxyl groups that bind to collagen and glycosaminoglycans, facilitating epithelial cell adhesion and growth. Through the cross-linking of chitosan, the microporous structure of the extracellular matrix is more uniform and more conducive to the growth of seed cells and the cell growth into the surrounding tissue after transplantation. At the same time, the unique hydrophilicity of collagen is very suitable for the adhesion and growth of seed cells, which allows the organism’s own cellular components to replace the original cellular components in the grafts. On this basis, we used tissue engineering technology to inoculate the seed cells in a composite chitosan dermal matrix for culture. The toughness of the skin substitute was gradually increased with the extension of the culture time. In animal studies, the artificial skin significantly promoted wound healing in mice, rabbits, cats and pigs, and also effectively prevented the appearance of hyperplasia and scars. The compound chitosan tissue-engineered skin has now begun clinical trials in seven hospitals and research institutes, including the Institute of Dermatology of the Chinese Academy of Medical Sciences and the West China Hospital of Sichuan University, with the aim of being released a year later for patients who need skin transplants. This research result won the second prize of the Army Science and Technology Progress Award. Next, we will further carry out research on artificial skin hair follicles and sweat glands. We hope that in the near future, we can make the artificial skin closer to the natural dermis.