Preliminary Research On The Tissue Engineering Skin Constructed By Bone Marrow Stem Cells And Bacterial Cellulose/Hyaluroriic Acid

As the largest organ of the human body, the main function of skin is to protect thebody from the invasion of pathogens and microorganisms. A variety of reasons canlead to serious damage of the skin and make it lose its barrier function. At present,skin graft is the most effective way for the treatment of serious skin damage, but, thelack source of autologous skin and allograft immune rejection severely restrict theskin graft in the clinical applications. In recent years, the defects of skin grafts areremedied by the development of tissue engineering skin.Bone marrow mesenchymal stem cells (BMSCs) are multi-potency cells with lowimmunity. BMSCs can promote the healing of damage skin by direct and indirect way.As a promising seed cell, BMSCs has been widely concerned; Bacterial cellulose (BC)was first used in clinic as a stable3-dimensional structure scaffold; As the maincomponents of the extracellular, hyaluronic acid (HA) plays a key role in celladhesion, migration, proliferation and signal transduction. Therefore, the tissueengineering skin constructed by BC/HA composite and BMSCs has potential clinicalapplication value.In this project, the cytotoxicity test, anti-coagulation test, anti-hemotalysis test andscanning electron microscope (SEM) are used to detect the biocompatibility ofcomposites. The healing rate and histopathology observation are used to evaluate therepair effect of the tissue engineering skin. As the content of HA increased and theextension of incubation time, the cytotoxicity of composites decrease significantly(P<0.05). The growth status of the fibroblasts on the surface of materials observed bySEM shows that the fibroblasts is gathered into a sphere on the BC surface, andextend on the surface of composites. When the content of HA is1.25%, the fibroblastsadhere on the surface of composites extend pseudopodia to closely connect withcomposites and show the trend of growing into the composites. The hemolysis rates ofall materials are less than5%and accord with the hemolysis standard of the medicalbiological materials. As the content of HA increased, the hemolysis rate of compositeswhich prepared by crosslinking method shows significantly decrease, and the hemolysis rate of composites which prepared by immersion presents obviously rising.But, all hemolysis rates of composites are significantly less than the hemolysis rate ofBC (P<0.05). According to anti-coagulation experiment, the coagulation time curvesof the composites are close to the natural process of coagulation. However, thecoagulation rate of BC is much faster than the natural process.The experimental results of rat skin damage repairing show that the healing rate oftissue engineering skin is obviously higher than blank control and BC control(P<0.05). With the content of HA increased, the healing effect is getting better. Theresult of histopathology shows that the skin which repairs by tissue engineering skinis much similar to natural skin, and generates skin related glands accompanied by theformation of granulation tissue.To sum up, this project preliminary discovers that composites which prepared bytwo methods have better biological compatibility. And the tissue engineering skin thatconstructed by BMSCs and BC/HA can promote the repair of the wound and theformation of skin related glands. All of these experiment results provide a foundationfor the clinical application of tissue engineering skin.