Preparation of Venous Allografts

Abstract

In order to evaluate alternate techniques of preparing veins for use as homografts, 102 femoral veins were harvested from adult mongrel dogs. The veins were treated in four different ways, then transplanted into recipient animals bypassing their ligated femoral arteries. Group I--24 veins (6 cm each) were harvested and immediately transplanted. Group II--24 veins were stored in 15% dimethyl sulfoxide (DMSO) solution at -120 C for 21 days prior to transplantation. Group III--26 veins were stored for 21 days in plasminate solution at -60 C prior to use as allografts. Group IV--28 veins were stored in 0.5% gluteraldehyde solution for 21 days prior to implantation. Animals were randomly sacrificed at 1-month, 2-month, 6-month, and 12-month intervals. Patency of the transplant was determined weekly by ultrasound. Specimens were sent for light and scanning electron microscopy at the time of harvest, prior to implantation, and at sacrifice. Endothelial damage was graded on a scale of 0-16. Veins in Group II had a significantly higher patency rate (68% at 1 year) than Group III (35%) and Group IV (11%) (p less than 0.05). The intimal layer of all patent vessels was replaced by an organized mural thrombus. Partial endothelialization of the luminal surface was most prevalent in Group II. Intimal damage related to storage technique was significant in Group III (p less than 0.01). At sacrifice, severe endothelial damage was present in all groups (p less than 0.01). In conclusion, veins stored in 15% dimethylsulphoxide (DMSO) solution at -120 C have immunologic and physical characteristics that yield patency rates acceptable for clinical use when autogenous tissue is not available.

A multicenter, phase I evaluation of cryopreserved venous valve allografts for the treatment of chronic deep venous insufficiency

“…Also, the allograft being studied was processed, frozen, and thawed by only one protocol. The rate of freezing/thawing, culture media used, use of specific cryopreservatives, and other factors may affect results observed with the use of cryopreserved tissue, 35,36 and the data presented cannot be extrapolated to all cryopreserved allografts.…”

“…34 Certainly, endothelial cells are often lost in the first 10 days after allograft transplantation into the vascular system of experimental animals, with reendothelialization occurring within the next 6 months. 35,36 However, not all allografts are so challenged by significant rejection, leading one to conclude that local injury, hypercoagulability, or stasis may still be the causative factor or factors in some cases. 34 Duplex evaluation of valves in the absence of or before failure demonstrated cusps that were thin and rapidly responsive to hemodynamic change.…”

Cryopreserved Vein Transplantation

“…Cryopreserved allograft veins, using cryoprotective agents, have historically met with mixed results in experimental animals. [12][13][14][15][16] We believe these mixed results using experimental cryopreserved allograft veins were due to lack of attention to vein removal technique, misuse of controlled rate freezing, inappropriate storage conditions, and lack of posttransplanta-C RYO P R ES E RVE D V E I N TRAIJ S P LA NTAT 1 0 N tion antiplatelet therapy. Our investigations on the importance of these detaits resulted in a series of animal studies and a clinical cryopreserved saphenous vein transplantation program.…”

Functional analysis of cryopreserved veins

“…Since the first allograft vessel transplants performed in 1912 by Carrel, ~ there have been several preclinical and clinical studies of cryopreserved allograft veins. [2][3][4][5][6][7] The graft patency rates obtained in these studies have been variable, ranging from good s to very poor. 7 These investigations did not report the level of vascular tissue functions remaining after thawing of cryopreserved tissue or assess the vessels as autologous grafts.…”