Urethral Reconstruction By Heterologous Acellular Dermal Matrix With Rabbit Adipose Derived Stem Cells

BackgroundUrethroplasty or urethral reconstruction is the main treatment for congenital hypospadias,urethral stricture and urethral injury in Urology. At present, there are more than300surgical approaches of urethral reconstruction which are improved and innovated by medical scholars all the time, but the postoperative complications of urethral stricture and urinary fistula still occur.In particular, lackling ideal urethral replacement materials in the repair of long urethral defects、stenosis and complex urethral injury has been the most intractable problems to urologists. With the development of tissue engineering techniques, some gratifying results has been achieved on the urethra reconstruction or repair with the natural biological materials (acellular matrix material). In recent years, with the development of the stem cell engineering and regenerative medicine, the construction of biocomposites with stell cell used for tissues or organs reconstruction has become the hot spot of research in related fields.Meanwhile, some researcher pointed out that adipose derived stem cells could be differentiated into bone tissue, cartilage tissue, myocardial tissue and epithelial tissue. The adipose derived stem cells have been research focus on the field of tissue engineering seed cells,due to its rich source, easy accessiblity and strong regenerative ability. There are some studies which have shown that acellular biological scaffolds is feasible for tissue and organ reconstruction,however,there has no been report on urethral reconstruction with the application of heterologous acellular dermal matrix and rabbit adipose derived stem cells.ObjectivesTo evaluate the feasibility of urethral reconstruction by heterologous acellular dermal matrix with rabbit adipose derived stem cells (ADSCs).Methods1. The rabbit ADSCs were isolated,cultured and amplificated in vitro,and were identified by flow cytometry.2. Heterologous (human) dermal acellular matrix was prepared and examinated,on which the rabbit ADSCs were implanted.3. Fiftyfour rabbits were randomly divided into three groups equally. Group A (experimental group):the heterologous dermal acellular matrix with ADSCs were used for repairing urethral defect after rabbit urethra partial resection with the length of2.0cm. GroupB(control group I):the groupB were given the heterologous dermal acellular matrix without ADSCs. GroupC(control group Ⅱ):the urethral defect was sutured and repaired simply without any urethral replacement materail.4. The newborn uretral tissue was cut regularly (at2weeks、4weeks、7weeks、16weeks after suegey) for histological examination to comepare their differences in the three groups.5. The urodynamics and retrograde urethrography were implented to compared the differences at16weeks after suegey. Results1. The surface antigen of the cultured ADSCs in vitro was CD34negative, CD4、CD105positive,which was in line with characteristics of mesenchymal stem cells. The heterogeneous acellular dermal matrix was:white, translucent, soft and with a certain flexibility and toughness,which was composed of mesh of collagen fibers and on which there was no cell left.2. The histological examination of newborn uretra at16weeks after surgery：the urethral surface of the experimental group was smooth and the newborn urethra approximated the normal urethra tissue.The number of regenerational blood vessels and smooth muscle cell of each control group is smaller and the number of fibrous scar of each control group was larger,compared with the experimental group over the same time.3. The maximum urethra pressure of the experimental group before operation and after operation(16weeks)was no significant difference.(p>0.05), while in the control group Ⅰ, there was significant difference.(p<0.05).ConclusionsIt is feasible to reconstruct or repair urethra defect(2cm long) with the application of heterologous acellular dermal matrix and rabbit adipose derived stem cells. The postoperative urethral mucosal regeneration is in its integrity.