Abstract：
The arteriovenous loop (AVL) model allows the in vivo engineering of axially vascularized flaps, the so-called AVL flaps. Although AVL flaps can be transplanted microsurgically to cover tissue defects, they lack an epithelial layer on the surface. Therefore, the objective of this study was to engineer axially vascularized AVL flaps with an accompanying epithelial layer for local defect reconstruction. In this study, AVLs were established in 20 male Lewis rats. Minimally invasive injection of keratinocytes onto the surface of the AVL flaps was performed on postoperative day (POD) 21. AVL flaps were explanted from 12 rats on POD 24 or POD 30, then the epithelium formed by the keratinocytes on the surface of the flaps was evaluated using immunofluorescence staining. In six other rats, the AVL flap was locally transposed to cover a critical defect in the rats\' leg on POD 30 and explanted for analysis on POD 40. In two control rats, sodium chloride was applied instead of keratinocytes. These control flaps were also transplanted on POD 30 and explanted on POD 40. Our results revealed that 3 days after keratinocyte application, a loose single-layered epithelium was observed histologically on the AVL flaps surface, whereas after 9 days, a multilayered and structured epithelium had grown. The epithelium on the transplanted AVL flaps showed its physiological differentiation when being exposed to an air-liquid interface. Histologically, a layered epithelium identical to the rats\' regular skin was formed. In the sodium chloride control group, no epithelium had been grown. This study clearly demonstrates that axially vascularized AVL flaps can be processed in the subcutaneous chamber by minimally invasive injection of keratinocytes. Thus, AVL flaps with an intact epithelial layer were engineered and could be successfully transplanted for local defect coverage in a small animal model.
摘要：
动静脉环（AVL）模型允许轴向血管化皮瓣的体内工程，所谓的AVL襟翼。虽然AVL皮瓣可以通过显微外科移植来覆盖组织缺损，表面缺乏上皮层。因此,这项研究的目的是设计带有上皮层的轴向血管化AVL皮瓣，用于局部缺损重建。在本研究中,在20只雄性Lewis大鼠中建立了AVL。在术后第21天（POD）将角质形成细胞微创注射到AVL皮瓣的表面上。从12只大鼠的POD24或POD30上移植AVL皮瓣，然后使用免疫荧光染色评估皮瓣表面角质形成细胞形成的上皮。在其他六只老鼠中，将AVL皮瓣局部移位以覆盖POD30上大鼠\'腿部的严重缺损，并移植用于POD40上的分析。在两只对照大鼠中，使用氯化钠代替角质形成细胞。这些对照皮瓣也被移植到POD30上并移植到POD40上。我们的结果显示，应用角质形成细胞后三天，在组织学上观察到AVL皮瓣表面有一个松散的单层上皮，而九天后，多层和结构化的上皮已经生长。移植的AVL皮瓣上的上皮显示其生理分化，当暴露于空气-液体界面时。组织学上形成了与大鼠常规皮肤相同的层状上皮。在氯化钠对照组中，没有上皮生长。这项研究清楚地表明，可以通过微创注射角质形成细胞在皮下腔室中处理轴向血管化的AVL皮瓣。因此，具有完整上皮层的AVL皮瓣经过工程改造，可以在小动物模型中成功移植以覆盖局部缺损。
