Objective To investigate the feasibil ity of prefabricating urethra in the expander capsule with gelatin sponge and micro-mucosa compound transplantation. Methods Eight 8-week-old Guizhou miniature pigs (male and/or female) weighing 20-25 kg were used. Six expanders (15 mL) were placed subcutaneously on the dorsal thorax of each miniaturepig. Autologous oral mucosa of every pig was harvested 2 weeks later to prepare micro-mucosa with a diameter less than 1 mm. Gelatin sponge 3 cm × 2 cm in size was transplanted to the expander capsule after being coated by the autologous micromucosa at the area expansion ratio of 4 ∶ 1 (group A), 8 ∶ 1 (group B), and 16 ∶ 1 (group C), respectively (n=2 per group). The implantation of gelatin sponge served as the blank control (group D, n=2). Physiological sal ine was injected into the expander immediately after operation, and the pressure in the expander was 40 mm Hg (1 mm Hg=0.133 kPa). The postoperative general condition of the animals was observed. At 1, 2, and 3 weeks after operation, the animals were killed to receive general, HE staining, and immunohistochemistry staining observations. Results All animals survived till the end of the experiment. The wounds healed well. General observation: in groups A, B, and C at 1 week after operation, there was no obvious degeneration of gelatin, the mucous was survived partially, and there were significant differences among three groups in terms of mucosa healing rate (P lt; 0.05), groups A and B were better than group C, and group A was better than group B; at 2 weeks, the gelatin sponge was partly absorbed, most of the mucosa survived, and the mucosa healing rate of groups A and B was better than that of group C (P lt; 0.05); at 3 weeks, the gelatin sponge was still not absorbed completely, the wound reached epithel ial ization approximately,and there were no significant differences among three groups in terms of mucosa heal ing rate (P gt; 0.05). No neo-mucosa was evident in group D at each time point. Histology and immunohistochemistry staining observation: at each time point, the mucosa epithel ium survival, inflammatory cell infiltration, and pan-cytokeratin were evident in groups A, B, and C; at 3 weeks after operation, the stratified squamous epithel ium presented obvious polarity and the submucous neovascularization was abundant in groups A, B, and C. There was no mucosa epithelium and positive stained pan-cytokeratin in group D. For the percentage of positive pan-cytokeratin stained area, there were significant differences among groups A, B, and C 1 week after operation (P lt; 0.05); at 2 and 3 weeks after operation, there was significant difference between group A and group C, and between group B and group C (P lt; 0.05); but no significant difference was evident between group A and group B (P gt; 0.05). Conclusion Micro-mucosa and gelatin spongy compound transplantation on the expander capsule can form mucosal l ining, achieve complete epithel ial ization in 2 weeks, and contribute to maintain the normal function of prefabricatied urethra.
Objective To investigate the histological and keratinous variation of prefabricated urethra in the capsule with micro-mucosa and gelatin sponge compound graft. Methods Five 8-week-old Guizhou miniature pigs (2 females and3 males) weighing 20-25 kg were used. Eight tissue expanders were bilaterally inserted into subcutaneous position on the dorsal thorax of each pig. Forty inserted expanders were randomized into two groups (n=20 per group). For the experimental group, the free buccal mucosa was cut into particles less than 1 mm in diameter, spread onto the gelatin sponge (3 cm × 2 cm) and then transplanted to the capsule; the area expansion ratio of autogenous micro-mucosa was 8 ∶ 1. For the control group, soft tissue expander without mucosa graft was implanted. The pressure in inserted expander was about 40 mm Hg (1 mm Hg=0.133 kPa). Inflation should be stopped when the injected sal ine volume reached 15 mL. The animals were killed 1 and 2 weeks and 1, 2, and 4 months after the implant to receive examination. Macroscope, histology, and immunohistochemistry changes were observed. Results All the animals survived to the end of the experiment and the wounds healed by first intention. There was no obvious degeneration of gelatin sponge, and some of the mucosa survived 1 week after implant. The gelatin sponge was partly absorbed, most of the mucosa survived 2 weeks after implant. Visual examination showed complete epithel ial ization of the entire cavity 1 month after implant. The experimental group at 2 and 4 months were similar to that of at 1 month in gross observations.The neo-mucosa was not found in the control group at different time points after implant. Histology examination revealed that compound implant was mainly infiltrated by inflammatory cells and the micro-mucosa survived well 1 week after implant in the experimental group. The stratified squamous epithel ium presented obvious polarity and the submucous neovascularization was abundant 2 weeks after implant. The compound implant achieved complete epithel ial ization 1 month after implant. The epithel ium degeneration occurred 2 months after implant. The stratified squamous epithel ium presented no abovious polarity 4 months after implant. No neo-mucosa was evident in control group at different time points. The experimental group was positive for the pan-cytokeratin staining at 1, 2 weeks, and 1, 2 months after implant, but negative at 4 months after implant The pan-cytokeratin staining was negative in the control group at different time points. Conclusion The buccal micromucosa and gelatin sponge compound graft can grow well on the expanded capsule 1 month after implant and the epithel ium degeneration is evident 2 months after implant. Environment of implanted mucosa has great influence on epithel ium mucosa.