Yonsei Med J.  2011 Mar;52(2):227-233. 10.3349/ymj.2011.52.2.227.

The Decellularized Vascular Allograft as an Experimental Platform for Developing a Biocompatible Small-Diameter Graft Conduit in a Rat Surgical Model

• Hwang SJ
• Kim SW
• Choo SJ
• Lee BW
• Im IR
• Yun HJ
• Lee SK
• Song H
• Cho WC
• Lee JW

• KMID: 1779656
• DOI: http://doi.org/10.3349/ymj.2011.52.2.227

Abstract

PURPOSE
The present study was aimed to assess the feasibility of using decellularized aortic allograft in a rat small animal surgical model for conducting small diameter vascular tissue engineering research.
MATERIALS AND METHODS
Decellularized aortic allografts were infra-renally implanted in 12 Sprague-Dawley (SD) adult rats. The conduits were harvested at 2 (n = 6) and 8 weeks (n = 6), and assessed by hematoxylin and eosin (H&E), van Gieson, Masson Trichrome staining, and immunohistochemistry for von Willebrand factor, CD 31+, and actin.
RESULTS
Consistent, predictable, and reproducible results were produced by means of a standardized surgical procedure. All animals survived without major complications. Inflammatory immune reaction was minimal, and there was no evidence of aneurysmal degeneration or rupture of the decellularized vascular implants. However, the aortic wall appeared thinner and the elastic fibers in the medial layer showed decreased undulation compared to the normal aorta. There was also minimal cellular repopulation of the vascular media. The remodeling appeared progressive from 2 to 8 weeks with increased intimal thickening and accumulation of both collagen and cells staining for actin. Although the endothelial like cells appeared largely confluent at 8 weeks, they were not as concentrated in appearance as in the normal aorta.
CONCLUSION
The results showed the present rat animal model using decellularized vascular allograft implants to be a potentially durable and effective experimental platform for conducting further research on small diameter vascular tissue engineering.

Keyword

Tissue engineering; vessel; rat; animal model

MeSH Terms

Animals
Aorta, Abdominal/anatomy & histology/cytology/*surgery
Biocompatible Materials/*therapeutic use
*Disease Models, Animal
Female
Graft Survival/immunology
Rats
Rats, Sprague-Dawley
Tissue Engineering/*methods
Transplantation, Homologous/*methods

Figure

• 

  Fig. 1 Interposition of decellularized aortic conduit in the infrarenal abdominal aorta. Anastomosis was achieved with multiple interrupted Nylon #9-0 sutures. The proximal part of the graft was marked by P and distal part by D in reference to the direction of blood flow.

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  Fig. 2 Histologic assessment of the decellularized scaffold. (A) Normal aortic wall with a confluent endothelial cell lining and abundant cellularity in the native vascular wall matrix. (B) Decellularized vascular scaffold with absence of endothelial cell lining and cellularity or nuclear staining within vascular matrix. (C) DAPI staining against DNA content in the aorta with dense cellularity. (D) Post decellularized aorta showing only the supporting matrix scaffold with complete absence of DNA content.

• 

  Fig. 3 Von Gieson's stain (black, far left column) shows absence of elastin fibers within the intimal proliferative layer. Collagen accumulation (middle column) and actin-positive smooth muscle cells (far right column) are present at 2 weeks. Both the thickness of collagenous matrix layer and cells staining positively for actin are increased at 8 weeks. Insert image shows staining without primary antibody.

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  Fig. 4 Luminal surfaces of normal and decellularized aortic implant at 2 and 8 weeks. Greater numbers of endothelial cells are seen at 8 weeks, compared to 2 weeks, but in fewer concentrations than the normal aorta (upper row). Factor VIII staining shows a similar pattern correlating with the degree of endothelialization (lower row). Insert shows image of staining without primary antibody.

• 

  Fig. 5 DAPI study at 8 weeks showed evenly distributed cellular nuclei in the media of the normal aorta (A and E). In the De-cell specimen it was evident mostly in the neo intima layer with sparse cellularity in the media layer. Both the normal and De-cell specimen shows positive staining for von WIllebrandt factor (B and F) and CD 31+ (C and G). These signals were clearly co-localized on the innermost confluent cell layer in both groups albeit more strongly present in the normal aorta compared with the decellularized graft. Merging of the von Willebrand factor and CD 31 stains enhanced visualization of the endothelial cell markers (D and H).

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