The Study Of Gene-enhanced Tissue Engineering On Urethral Reconstruct

Reconstructive procedures in the genitourinary tract system are usually performed in conditions, such as congenital abnormalities, trauma, inflammation, infection and cancer. The goal of urologic tissue reconstruction is to replace, restore or improve existing tissue function. Surgical reconstruction is best achieved by using existing native urologic tissues, however, this is not possible in numerous instances due to the limited autologous tissue available. Whenever there is a lack of native urologic tissue, reconstruction is usually performed with native non-urologic tissue,such as bowel, skin, muscle or mucosa from various body sites. Other alternate sources, such as allogeneic, xenogeneic or synthetic biomaterials have also been used. However, the use of these tissue substitutes often creates problems, such as metabolic abnormalities, infection, perforation, urolithiasis and malignancy. In addition, these complications often necessitate additional procedures, including ablation, repair or reconstruction.Tissue engineering is one of the most intriguing and exciting areas in biotechnology, due to its requirement for state-of-the-art techniques from both the biologic and engineering disciplines. Tissue engineering follows the principles of cell transplantation, materials science and engineering towards the development of biological substitutes, which would restore and maintain normal function.Hypospadias and urethra stricture are common disease. Due to the lack of native tissue, reconstruction is usually performed with other sources, such as genital and extra genital skin flaps. Biodegradable stents are alternative conduits for urethralsubstitution. But significant complications such as fistulas, infection, hair growth, stone formation, graft contracture and donor site morbidity were reported with long-term follow up. Tissue engineered urethra was required when pathological conditions need extensive urethral reconstruction, and in case of no local epithelial tissue available. But, a piece of tissue with a volume exceeding a few cubic millimeters cannot survive by diffusion of nutrients and requires the growth of blood capillaries for the supply of essential nutrients and oxygen. Under this circumstances, some complications, such as urethrocutaneous fistula and strictures, may appear.We hypothesized that vascularization would enhance the growth and regeneration of urethra. For this purpose, we used VEGF gene, which involves in angiogenesis, to induce vascularization in vivo. Retrovirus has been applied in many research, and has become a hot spot these years. In our study, A pMSCV-VEGFi65-GFP vector was cloned by insertion of VEGF sequence into retrovirus vector pMSCV-GFP. Retrovirus was generated using package cell line 293T. Rabbit urothelial cells, modified with pMSCV-VEGFi65-GFP, were implanted onto decellularized rabbit artery matrix. We expect VEGF gene therapy might be a suitable approach to increase the blood supply in tissue engineering of urethra for treatment of urethral damage or loss.pMSCV-VEGF-GFP has been constructed, and the in vivo and in vitro study shows that pMSCV-VEGF-GFP has vascularization effect, significantly enhanced neovascularization and urethral tissue formation. Gene therapy with pMSCV-VEGF-GFP might be a suitable approach to increase the blood supply in tissue engineering of urethra for treatment of urethral damage or loss.