From the initial brainstorming, we came up with the idea of working with cell lines for burn treatment. We decided to address second-degree skin burns, as they pose a severe issue in our country, due to the lack of prevention measures and deficient health care services.

The main goal of our project is to enhance the proliferation of epithelial cells in a burned area. One of the most severe problems coming with a burn injury is the destruction of the extracellular matrix, which dramatically slows down the proliferation of the epithelium, making it a long-term healing wound. The fast reconstruction of the extracellular matrix is necessary so that skin tissue can recover quicker due to the presence of an improved and well structured adhesive environment. Therefore, we aimed at proposing a scaffold design that could replace the natural extracellular matrix, providing enhanced characteristics for accelerated cell attachment and proliferation.

We decided which components would constitute our scaffold. It was necessary that its components were non-cytotoxic and biodegradable. Collagen is the most abundant type of extracellular matrix and is frequently used in experimental procedures, so we decided to use it as the base of the scaffold. Although collagen exhibits a strict primary structure, it has been proven that it can still be engineered to yield an efficient matrix. Besides, collagen molecules are shown to interact with other components of extracellular matrices, like heparin and heparan sulfate, hence, the latter is included in the proposed system.

Previous works on extracellular matrices assert that tenascin is involved in tissue regeneration processes, as it has multiple growth factor binding sites, and that it partakes in stem cell signaling. In addition, it has a heparin binding site, so we chose it as another component of our scaffold.

Heparin is a small glycosaminoglycan that can bind both collagen and tenascin; thus, we hypothesize it will link collagen and tenascin.

To better enhance epithelial proliferation a growth factor was added to our project: leptin. Leptin works by increasing the rate of conversion of T4 to T3 which is known to increase basal glucose intake and speeding up metabolism, thus, accelerating cell proliferation. Nevertheless, previous works have shown that an uncontrolled amount of leptin can cause a swelling reaction. Accordingly, it was necessary to design a vehicle that could carry leptin into the cells and that could liberate it gradually.

Chitosan is a biocompatible, biodegradable and antimicrobial natural polymer that can be protonated at pH < 6.5. When protonated it can interact with negative molecules and form nanoparticle complexes with a crosslinking agent like sodium tripolyphosphate (TPP). We used this chitosan nanoparticles as the vehicle for our leptin in order that it could reach the epithelial cells and be liberated gradually.