体外诱导间皮细胞向尿路细胞及血管内皮细胞定向分化并构建预血管化组织工程尿道修复长段尿道缺损的实验研究

Proper substituted materials are necessary to repair long segmental urethral defect. The scarring repairing mode of traditional materials leads to high rates of re-stricture. Through inducing tissue regeneration to accomplish tissue repair, tissue engineering is hopeful to improve repairing effect. However, multiple disadvantages exists when using urothelial cells and bladder smooth muscle cells for engineering urethra, such as difficulties to culture urothelial cells in vitro and to keep both seed cells proliferating synchronously. Finding seed cells with stem cell characteristics has became the main direction for urethra tissue engineering. It has been demonstrated that mesothelial cells have the potential to differentiate to urothelial cells, smooth muscle cells and vascular endothelial cells. For successful long segmental urethral repair, it is essential to use grafts with sufficient epithelial barrier and vascularization. In the present study, we plan to induce mesothelial cells to differentiate to urothelial cells, smooth muscle cells and vascular endothelial cells in vitro for construction of pre-vascularized tissue engineered urethra to investigate it’s feasibility to repair long segmental urethral defect, which may provide an ideal tissue engineered material for urethral reconstruction and a new multi-potent seed cell source for urethral tissue engineering.

长段尿道缺损的修复需要应用合适替代材料进行尿道重建。传统材料瘢痕化的修复方式导致术后再狭窄发生率较高。组织工程技术通过诱导组织再生完成组织修复，有望提高尿道修复效果。但尿路上皮细胞和膀胱平滑肌细胞作为种子细胞构建组织工程尿道存在诸多不足，如上皮细胞培养困难、周期长以及难以保持两种细胞扩增同步性等。寻找干细胞性种子细胞来源已逐渐成为尿道组织工程研究的主要方向。研究显示，间皮细胞具备向尿路上皮细胞、平滑肌细胞及血管内皮细胞分化的潜能。对于长段尿道缺损修复，移植物上皮粘膜屏障及充分的血管化是成功的关键。本研究拟体外诱导间皮细胞向尿路上皮细胞、平滑肌细胞及血管内皮细胞定向分化，并复合膀胱脱细胞基质构建预血管化组织工程尿道，修复长段尿道缺损，以期为尿道修复提供一种理想的组织工程材料并为尿道组织工程研究提供一种新型多能干细胞性种子细胞来源。

先天性畸形、外伤及炎症等导致的尿道损伤或狭窄是泌尿男科常见的疾病，其治疗较为棘手。行尿道重建术时需要将异常尿道组织彻底切除，若病变范围大，切除后难以行无张力的尿道端端再吻合，通常需要应用合适的替代材料进行全周管状尿道重建。目前临床常用的尿道替代材料包括自体阴茎及阴囊皮肤、膀胱粘膜、口腔颊粘膜、睾丸鞘膜、肠粘膜等，但远期修复效果并不理想，诸如尿道再狭窄、毛发生长、尿漏、黏液分泌、结石生成等并发症屡见不鲜。且应用上述材料进行尿道全周修复时，移植前需将片状移植物围绕尿管缝制成管状，不但增加了手术时间而且会增加术后尿漏及感染等并发症的发生率。早期研究显示将管状异物置入动物皮下后可诱导生成自体管状肉芽组织，其口径可通过改变置入异物的直径进行调节，该组织被成功用于修复动脉缺损，显示出良好的抗拉伸性能及生物相容性。本研究尝试应用此种自体管状肉芽组织修复兔全周尿道缺损。研究结果显示，自体管状肉芽组织可成功修复1cm以内的尿道缺损，尿道腔保持通畅，新尿道组织再生满意，但修复1.5cm尿道缺损时，出现尿道狭窄及瘢痕化。为此，本研究又尝试将间皮细胞接种到自体管状组织上，结果显示间皮细胞可在管状组织表面生长形成一层上皮粘膜屏障，本研究发现应用复合间皮细胞的自体管状组织可成功修复1.5cm尿道缺损，组织再生类似正常尿道。本研究结果有望为全周尿道修复提供一种天然管状自体移植物，可有效避免免疫排斥、降低修复难度，同时避免组织取材所致并发症。