Department of Urology and Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, NC 27157, USA.
Eur Urol. 2013 Mar;63(3):531-8. doi: 10.1016/j.eururo.2012.07.041. Epub 2012 Jul 31.
The treatment options for patients requiring repair of a long segment of the urethra are limited by the availability of autologous tissues. We previously reported that acellular collagen-based tubularized constructs seeded with cells are able to repair small urethral defects in a rabbit model.
We explored the feasibility of engineering clinically relevant long urethras for surgical reconstruction in a canine preclinical model.
DESIGN, SETTING, AND PARTICIPANTS: Autologous bladder epithelial and smooth muscle cells from 15 male dogs were grown and seeded onto preconfigured collagen-based tubular matrices (6 cm in length). The perineal urethral segment was removed in 21 male dogs. Urethroplasties were performed with tubularized collagen scaffolds seeded with cells in 15 animals. Tubularized constructs without cells were implanted in six animals. Serial urethrography and three-dimensional computed tomography (CT) scans were performed pre- and postoperatively at 1, 3, 6, and 12 mo. The animals were euthanized at their predetermined time points (three animals at 1 mo, and four at 3, 6, and 12 mo) for analyses.
Statistical analysis of CT imaging and histology was not needed.
CT urethrograms showed wide-caliber urethras without strictures in animals implanted with cell-seeded matrices. The urethral segments replaced with acellular scaffolds collapsed. Gross examination of the urethral implants seeded with cells showed normal-appearing tissue without evidence of fibrosis. Histologically, an epithelial cell layer surrounded by muscle fiber bundles was observed on the cell-seeded constructs, and cellular organization increased over time. The epithelial and smooth muscle phenotypes were confirmed using antibodies to pancytokeratins AE1/AE3 and smooth muscle-specific desmin. Formation of an epithelial cell layer occurred in the unseeded constructs, but few muscle fibers formed.
Cell-seeded tubularized collagen scaffolds can be used to repair long urethral defects, whereas scaffolds without cells lead to poor tissue development and strictures. This study demonstrates that long tissue-engineered tubularized urethral segments may be used for urethroplasty in patients.
对于需要修复尿道长段的患者，治疗选择受到自体组织可用性的限制。我们之前报道过，细胞种植的去细胞胶原管状构建体能够在兔模型中修复小的尿道缺损。
我们在犬临床前模型中探索了用于手术重建的临床相关长尿道的工程可行性。
设计、设置和参与者：从 15 只雄性犬中分离出自体膀胱上皮细胞和平滑肌细胞，并种植在预先配置的胶原管状基质（6cm 长）上。21 只雄性犬的会阴部尿道段被切除。15 只动物进行了尿道成形术，将管状胶原支架与细胞一起种植。6 只动物植入了无细胞的管状构建体。在术前和术后 1、3、6 和 12 个月进行了连续尿道造影和三维计算机断层扫描（CT）扫描。动物在预定时间点（3 只动物在 1 个月，4 只动物在 3、6 和 12 个月）被安乐死进行分析。
不需要对 CT 成像和组织学进行统计分析。
CT 尿道造影显示，植入细胞种植基质的动物尿道宽大，无狭窄。无细胞支架替代的尿道段塌陷。细胞种植的尿道植入物的大体检查显示组织正常，无纤维化证据。组织学上，在细胞种植构建体上观察到由肌纤维束环绕的上皮细胞层，并且细胞组织随着时间的推移而增加。使用针对多角蛋白 AE1/AE3 和平滑肌特异性结蛋白的抗体确认了上皮细胞和平滑肌表型。未种植的构建体中也形成了上皮细胞层，但形成的肌纤维很少。
细胞种植的管状胶原支架可用于修复长段尿道缺损，而无细胞支架则导致组织发育不良和狭窄。本研究表明，长组织工程化管状尿道段可用于患者的尿道成形术。
