Early microrecanalization of vas deferens following biodegradable graft implantation in bilaterally vasectomized rats

Abstract

We evaluated a biodegradable graft for reconstruction of rat vasa deferentia with long obstructed or missing segments. A total of 47 Sprague-Dawley rats underwent bilateral vasectomy and were divided into groups according to length of the vas deferens affected (0.5, 1, 1.5 cm). After 8 weeks, poly-(D,L-lactide) (PDLA) grafts were used to reconnect the vas deferens. Grafts and adjoining vasa deferentia were excised 8 and 12 weeks later and evaluated microscopically. At 8 weeks, microscopic changes included a robust inflammatory response around the grafts. All grafts were still intact but in the early stages of degradation. No microtubules, indicative of vas deferens recanalization, were identified. One specimen showed evidence of healing and neovascularization at the interface zone between the vas deferens and the graft. At 12 weeks, grafts were further degraded but still present. Microscopic evaluation showed decreased inflammation. Seven specimens showed neovascularization at the interface zone; two of these showed distinct epithelialized vas deferens microcanals at the graft edges. One specimen showed a microcanal spanning the entire 0.5-cm graft. A time period of 8 weeks is not ample enough for vas deferens regeneration in the setting of a biodegradable PDLA graft; however, early evidence of re-growth was seen at 12 weeks. A longer healing time should permit further biodegradation of the graft, as well as re-growth and possible eventual reconnection of the vas deferens, allowing passage of sperm. These findings suggest a potential role for biodegradable grafts in the reconstruction of vas deferens with long obstructed segments.

Figure 1

Study timeline.

Figure 2

Scanning electron microscope image of a polymer conduit. Bar = 200 μm.

Figure 3

Gross appearance of 0.5-cm poly-(D,L-lactide) (PDLA) graft after harvest at 8 weeks. Note the vas deferens attached to both ends of the graft in an end-to-end anastamosis.

Figure 4

A 1.5-cm poly-(D,L-lactide) (PDLA) graft at 8 weeks, with evidence of neovascularization (arrows) (magnification × 200). Bar = 0.5 mm.

Figure 5

(A): Evidence of microrecanalization at the midpoint of a 0.5-cm poly-(D,L-lactide) (PDLA) graft (magnification × 40). Bar = 1 mm. (B): Microcanal at the midpoint of a 0.5-cm PDLA graft (magnification × 200). Bar = 0.5 mm. (C): Microcanal at the interface zone of a 0.5-cm PDLA graft (magnification × 40). Bar = 1 mm. All panels: white arrows, microcanal; black arrows, graft.

Figure 6

Murine vas deferens (magnification × 20). Bar = 1 mm.