What tissue bankers should know about the use of allograft blood vessels

Vascular allografts for clinical application in Europe: assessment of 30 years of experience with vascular tissue banking in Brussels

Vascular tissue banking has been carried out in Brussels for over 30 years in compliance with EU and Swiss tissue banking regulations. A total of 2.765 vascular tissue donations were performed in Belgian, French, Netherlands and Suisse transplant centres: 547(20%), 1.013(37%) and 1.205(43%) during the first, second and third periods, respectively. 85% and 18% increase in donations during the second and third decades compared to previous one, were remarkable. Of the 7.066 evaluated vascular tissues, 2.407(227, 921 and 1.259) were discarded (34.1%), whereas 4.659(523, 1.861 and 2.275) accepted (65.9%) during the respective period. Of the 92 donated veins, 44(47.8%) were discarded and 48(52.2%) accepted. Allografts available for clinical application were stored in vapours of liquid nitrogen. A total of 4.636 allografts were delivered and transplanted for cases of infection (58%), critical limb ischaemia (16%) and congenital cardiac surgery (15%). Thirty veins were implanted. The progressive increases in donations of 20%, 37% and 43% and in transplantations of 20.8%, 34.6% and 45% during the first, second and third periods, respectively, were remarkable. Complications were reported after transplantation and these included acute rejection of two femoral arteries one month after transplantation. We conclude that the donation and transplantation of cryopreserved vascular allografts was stable with a progressive increase over time. Allografts were used predominantly for the treatment of infection, limb salvage for critical ischaemia and for neonates and infants with congenital cardiac malformation. Immune related rejection was observed. This should be a subject of future investigation.

Limb salvage after aneurysmal degeneration of a cryopreserved vein allograft: Searching the autologous veins of the arm is worth the effort

CLINICAL DATA

We hereby report a case of limb salvage involving a 64-year-old man who was hospitalized with ischemic foot ulcers for two months. Endarterectomy with patching and stenting of the left iliofemoral artery failed. A composite bypass of two segments of the endarterectomized superficial femoral artery and a cryopreserved saphenous vein graft was implanted one week later. On day 4 postoperatively, an infection (Staphylococcus epidermidis and Pseudomonas aeruginosa) was treated empirically with antibiotics. Four months later, the femoro-tibial bypass thrombosed and the patency was restored by thrombolysis. The aneurysmal cryopreserved vein was excised. Iterative complications followed and final success was attained after implantation of autologous cephalic and basilic veins. Four years later, this femoro-tibial is still patent.

PATHOLOGICAL ANALYSES

After a gross observation, the explant was dissected and the most significant sections were processed for histology, followed by analyses in scanning electron microscopy, light microscopy and transmission electron microscopy.

RESULTS

The explanted specimen showed a smooth flow surface proximally but a severe distortion distally, with an accumulation of poorly organized mural thrombi. The wall of the arterialized vein was accompanied with an important inflammatory reaction. The degradation of the collagen structure was evidenced in TEM. The fibrils of collagen were still individualized but were fragmented and did not display parallelly. The regular banding was preserved. The presence of Pseudomonas aeruginosa was shown inside the wall of the homologous vein.

COMMENTS

In case of sepsis, the most aggressive antibiotic treatments cannot fully eliminate the bacteremic colonizations within the wall of an alternative conduit. The cephalic and basilic autologous veins are proved to be preferable in absence of the autologous saphenous vein. The amputation was prevented and four years later the bypass is still patent. This is an outstanding result based upon the comorbidities of the patient. The most aggressive harvesting shall be recommended. This patient represented a considerable challenge and the clinical result is highly gratifying: the search for the autologous cephalic and basilic veins proved to be worth the effort.

Acellular vascular matrix grafts from human placenta chorion: Impact of ECM preservation on graft characteristics, protein composition and in vivo performance

Small diameter vascular grafts from human placenta, decellularized with either Triton X-100 (Triton) or SDS and crosslinked with heparin were constructed and characterized. Graft biochemical properties, residual DNA, and protein composition were evaluated to compare the effect of the two detergents on graft matrix composition and structural alterations. Biocompatibility was tested in vitro by culturing the grafts with primary human macrophages and in vivo by subcutaneous implantation of graft conduits (n = 7 per group) into the flanks of nude rats. Subsequently, graft performance was evaluated using an aortic implantation model in Sprague Dawley rats (one month, n = 14). In situ graft imaging was performed using MRI angiography. Retrieved specimens were analyzed by electromyography, scanning electron microscopy, histology and immunohistochemistry to evaluate cell migration and the degree of functional tissue remodeling. Both decellularization methods resulted in grafts of excellent biocompatibility in vitro and in vivo, with low immunogenic potential. Proteomic data revealed removal of cytoplasmic proteins with relative enrichment of ECM proteins in decelluarized specimens of both groups. Noteworthy, LC-Mass Spectrometry analysis revealed that 16 proteins were exclusively preserved in Triton decellularized specimens in comparison to SDS-treated specimens. Aortic grafts showed high patency rates, no signs of thrombus formation, aneurysms or rupture. Conduits of both groups revealed tissue-specific cell migration indicative of functional remodeling. This study strongly suggests that decellularized allogenic grafts from the human placenta have the potential to be used as vascular replacement materials. Both detergents produced grafts with low residual immunogenicity and appropriate mechanical properties. Observed differences in graft characteristics due to preservation method had no impact on successful in vivo performance in the rodent model.

Right renal vein extension with cryopreserved external iliac artery allografts in living-donor kidney transplantations

INTRODUCTION

A short right renal vein remains a challenge for renal transplant surgery, especially in the living donor. Our objective was to report on a new technique to solve this problem.

TECHNICAL CONSIDERATIONS

We describe our experience with the use of cryopreserved iliac artery grafts for right renal vein extension. Two renal grafts from living donors with a short right renal vein were subjected to an extension with a cryopreserved external iliac artery allograft. There were no perioperative or postoperative complications. There were also no changes in ischemia times. The renal implantation was performed easily and conveniently using our standard technique. For the first and second procedures, at 3 and 3.5 years after surgery, respectively, both vascular grafts maintain good patency, and the renal function of both recipients is optimal.

CONCLUSION

Tissue-banked cryopreserved cadaveric vessels can be a useful tool in renal transplant surgery. The use of a cryopreserved iliac artery for renal vein extension is a simple and effective new technique that can be added to the pool of surgical solutions for a short renal vein in living-donor kidney transplantation. To our knowledge, this is the first time that the use of such grafts for this purpose has been described.

Preclinical evaluation of ice-free cryopreserved arteries: structural integrity and hemocompatibility

OBJECTIVE

Arterial allografts are routinely employed for reconstruction of infected prosthetic grafts. Usually, banked cryopreserved arteries are used; however, existing conventional freezing cryopreservation techniques applied to arteries are expensive. In contrast, a new ice-free cryopreservation technique results in processing, storage and shipping methods that are technically simpler and potentially less costly. The objective of this study was to determine whether or not ice-free cryopreservation causes tissue changes that might preclude clinical use.

METHODS

Conventionally frozen cryopreserved porcine arteries were compared with ice-free cryopreserved arteries and untreated fresh controls using morphological (light, scanning electron and laser scanning microscopy), viability (alamarBlue assay) and hemocompatibility methods (blood cell adhesion, thrombin/antithrombin-III-complex, polymorphonuclear neutrophil-elastase, β-thromboglobulin and terminal complement complex SC5b-9).

RESULTS

No statistically significant structural or hemocompatibility differences between ice-free cryopreserved and frozen tissues were detectable. There were no quantitative differences observed for either autofluorescence (elastin) or second harmonic generation (collagen) measured by laser scanning microscopy. Cell viability in ice-free cryopreserved arteries was significantly reduced compared to fresh and frozen tissues (p < 0.05).

CONCLUSIONS

The formation of ice in aortic artery preservation did not make a difference in histology, structure or thrombogenicity, but significantly increased viability compared with a preservation method that precludes ice formation. Reduced cell viability should not reduce in vivo performance. Therefore, ice-free cryopreservation is a potentially safe and cost-effective technique for the cryopreservation of blood vessel allografts.

Novel surgical reconstruction of a mycotic abdominal aortic aneurysm using cryopreserved femoral arterial allograft from the NHS tissue bank: a new resource for UK vascular surgeons

The treatment of mycotic abdominal aortic aneurysms remains a significant surgical challenge associated with significant morbidity and mortality. In the following case report, we describe our successful management of a patient with a mycotic abdominal aortic aneurysm using two cryopreserved superficial femoral artery allografts (available from the UK NHS tissue bank) to create a Y-shaped allograft to permit immediate aortic reconstruction after surgical debridement. To our knowledge, this is the first time such a reconstruction has been reported in the literature.