Original article: cardiovascular
Multi-photon microscopic evaluation of saphenous vein endothelium and its preservation with a new solution, GALA

https://doi.org/10.1016/S0003-4975(02)04705-7Get rights and content

Abstract

Background

Injury to endothelium can compromise the patency of bypass grafts harvested during coronary artery bypass graft (CABG) surgery. Maintaining structural and functional viability of endothelium in grafts may lead to improved long-term patency. The information gained from the application of multi-photon microscopy in transmission and epifluorescence mode was used to assess the structural and functional integrity of human saphenous vein segments stored in multiple preservation solutions, and to design a superior storage solution.

Methods

Multi-photon microscopy was used to image deep within saphenous vein tissue harvested from patients undergoing CABG for analysis of endothelial structure and function. Endothelial cell structural viability, calcium mobilization, and nitric oxide generation were determined using specific fluorescence markers.

Results

Within 60 minutes of harvest and storage in standard preservation solutions, calcium mobilization and nitric oxide generation were markedly diminished with more than 90% of endothelial cells no longer viable in the vein. In contrast, veins could be stored for 24 hours without substantial loss in cell viability in a newly formulated heparinized physiologic buffered salt solution containing glutathione, ascorbic acid, and L-arginine (GALA).

Conclusions

Standard solutions in clinical use today led to a profound decline in saphenous vein endothelial cell viability, whereas the newly designed physiologic salt solution (GALA) maintained endothelial function and structural viability for up to 24 hours. The improvements seen from using GALA as a vessel storage medium may lead to greater long-term vein graft patency following CABG surgery.

Section snippets

Saphenous veins

Saphenous vein segments (inner diameter 0.05 to 0.2 mm, outer diameter 0.2 to 1.0 mm) were obtained before distension or any other manipulation from male patients of age 67.13 ± 9.78 (mean ± SD) years undergoing CABG surgery at the VA Boston Healthcare System, according to an approved Human Studies Subcommittee protocol. The vein segments were placed in the preservation solutions described below at 21°C and processed within 30 minutes. Excess adipose and adventitia were gently excised. Five

Effects of preservation solutions on endothelial cell viability in explanted saphenous vein

Vein segments stored in heparinized lidocaine saline (HLS), autologous heparinized blood (AHB) or tissue culture medium (TCM) exhibited a red fluorescence pattern in the lumenal region within 1 hour of storage indicative of extensive cell membrane damage and compromised viability of endothelial cells (Fig 1, Table 1). In contrast, the endothelial cells were structurally intact (green fluorescence) after 1 hour of storage in Hank’s balanced salt solution (HBSS; Fig 1), but lost cellular

Comment

The preservation of saphenous vein endothelial cells during the course of CABG surgery is essential for the long-term patency of the grafts. Endothelial cells are important mediators in regulating platelet function and in determining the coagulant and fibrinolytic pathways in the vessel wall. Endothelial injury can lead to acute alterations in these essential pathways, leading to thrombosis and stenosis 1, 2, 3, 4, 5. Histochemical analyses have suggested that structural derangements in the

Acknowledgements

We gratefully acknowledge the expert technical assistance of Jin-Hwa Rhee, Thomas McGarry and Sofija Zagarins. We would like to thank Nancy Healey for editorial assistance and Aditi Thatte for her encouragement. This work was supported by National Institutes of Health grants (TM), a Veteran’s Affairs Merit Review Grant (SFK), and the Richard Warren Surgical Research and Educational Fund (HST, SFK).

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