Distribution and localization of cells and collagens in the proliferated intima of arterially implanted autovein grafts

Large animal model of vein grafts intimal hyperplasia: A systematic review

Coronary artery bypass grafting remains the treatment of choice for a large cohort of patients with significant coronary disease. Despite the increased use of arterial grafts, the long saphenous vein remains the most commonly used conduit. Long-term graft patency continues to be the Achilles heel of saphenous vein grafts. This is due to the development of intimal hyperplasia, a chronic inflammatory disease that results in the narrowing and occlusion of a significant number of vein grafts. Research models for intimal hyperplasia are essential for a better understanding of pathophysiological processes of this condition. Large animal models resemble human anatomical structures and have been used as a surrogate to study disease development and prevention over the years. In this paper, we systematically review all published studies that utilized large animal models of vein graft disease with a focus on the type of model and any therapeutic intervention, specifically the use of external stents/mesh.

Immunohistochemical study of NF-E2-related factor 2 (Nrf2) in an end-to-end anastomosis of the rat carotid artery

INTRODUCTION

The detailed process and underlying mechanism of stenosis following microvascular anastomoses remains unclear. NF-E2-related factor 2 (Nrf2), is a pleiotropic regulator of cell survival and plays a crucial role in modulating acute inflammatory response. An animal experiment was employed to obtain new information on the histomorphological changes and distribution of Nrf2 in anastomoses.

METHODS

An end-to-end anastomotic model in rat carotid arteries was carried out. The stoma was examined by H&E staining and immunostaining to evaluate histomorphological change as well as the intensity of anti-Nrf2 and а-SMA staining.

RESULTS

Compression, dehiscence and inflammatory cells infiltration were often seen following vessel anastomoses. Inflammatory cells infiltrate was reduced and the granulation tissue fibrosis and endothelium reforming become apparent with times. Marked tunica media hyperplasia consisting of a packed layer of neogenetic smooth muscle cell was present around the anastomosis. Nrf2 expression was upregulated after the operation and was mainly distributed in the neogenetic smooth muscle cells.

CONCLUSION

Stenosis following the micro-artery anastomoses may be mainly due to the progressive myointimal hyperplasia in the media of the arteries. Nrf2 was involved in the pro-inflammatory stress during the vascular morphogenesis/angiogenesis and can be a valuable tool for studying the process of wound healing.

Immunohistochemical long-term evaluation of laminin expression in microvascular anastomoses of the carotid artery in the Wistar rat

INTRODUCTION

The main risk of complications of free-flap tissue transfer is from the microvascular anastomoses. The anastomoses are threatened by thrombosis, aneurysm and vascular insufficiency. Laminin is associated with the basement membrane complex and plays an essential role in vascular tissue organization, wound healing and supports mechanical properties of vessels. A long-term animal experiment was used to obtain new information on the distribution of laminin in anastomoses.

METHODS

Seventy Wistar rats, seven groups of 10 animals each, were operated upon. A 4mm long segment of common carotid artery was removed and reinserted. After various periods (from directly postoperative to 6 months later), the common carotid arteries, including the bifurcation, were isolated after cardiovascular perfusion. Carotid arteries were embedded and cross-sections stained using an immunohistochemical anti-laminin-antibody. Two anastomoses with four sutures each were examined by using this technique to evaluate histomorphology and intensity of anti-laminin staining.

RESULTS

Compression, shift and dehiscence were often seen following vessel apposition. A loss of laminin expression was observed in the media in cases of compression and shift after 6 months. The grade of expression of laminin in anastomoses was dependent on the extent of injury.

CONCLUSIONS

The application of antibodies to identify the laminin distribution was valuable for studying vascular healing. A well-performed microvascular anastomosis is clinically important not only for the acute phase following the operation, but also long term. Further antibody studies could be used in follow-up studies of vascular prostheses.