Experimental results and clinical impact of using autologous rectus fascia sheath for vascular replacement

Can a Peritoneal Conduit Become an Artery?

Objective

Current vascular grafts all have limitations. This study examined peritoneum as a potential graft material and the in vivo transfer of peritoneum into a functional artery like conduit after end to end anastomosis into the common carotid artery of sheep. The aim was to investigate whether implantation of a peritoneal tube into the arterial tree results in a structure with function, histological findings, and gene expression like an artery, and whether such arterialisation occurs through a conversion of the phenotype of peritoneal cells or from host cell migration into the implant.

Methods

Peritoneum with adherent rectus aponeurosis from sheep was used to form tubular vascular grafts that were implanted into the common carotid artery of six sheep, then removed after five months. Two sheep received allogenic peritoneal grafts and four sheep received autologous peritoneal grafts.

Results

One sheep died shortly after implantation, so five of the six sheep were followed. Five months after implantation, four of the five remaining grafts were patent. Three of four patent grafts were aneurysmal. The four patent grafts had developed an endothelial layer indistinguishable from that of the adjacent normal artery, and a medial layer with smooth muscle cells with a surrounding adventitia. The new conduit displayed vasomotor function not present at the time of implantation. DNA genotyping showed that the media in the new conduit consisted of recipient smooth muscle cells. Little difference in mRNA expression was demonstrated between the post-implantation conduit and normal artery.

Conclusion

During a five month implantation period in the arterial system, peritoneum converted into a tissue that histologically and functionally resembled a normal artery, with a functional genetic expression that resembled that of an artery. Single nucleotide polymorphism analysis indicated that this conversion occurs through host cell migration into the graft.

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Alternative vascular graft material examined in a large mammal.

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Peritoneal graft converts into artery – like conduit after 5 months in arterial system.

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Arterialisation through host cell migration into graft.

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Potential model of aneurysm with low risk of rupture.

Morphological evaluation of experimental autologous rectus fascia sheath vascular grafts used for arterial replacement in a dog model

Although experimental autologous patch or tubular conduit vascular grafts made from the internal rectus fascia sheath (IRFS) have been reported in the literature, thorough morphological evaluation and verification of the histological arterialisation of such grafts are lacking. Four purpose-bred Beagle dogs were utilised to create eight arterial internal rectus fascia sheath (ARFS) grafts implanted between bisected ends of the external iliac arteries. Four out of the eight ARFS grafts were patent after three months. Haematoxylin-eosin and Azan staining verified that the grafts gained a vessel-like layered structure with the presence of large amounts of collagen fibres. Although the inner surface of the intact IRFS was originally covered with claudin-5-negative and pancytokeratin-positive mesothelial cells in control samples, the internal cells of the ARFS grafts became claudin-5 positive and pancytokeratin negative like in intact arteries. Spindle-shaped cells of the wall of ARFS grafts were α-smooth muscle actin (α-SMA) positive just like the smooth muscle cells of intact arteries, but α-SMA immunoreactivity was negative in the intact IRFS. According to these findings, the fibroblast cells of the ARFS graft have changed into myofibroblast cells. The study has proved that ARFS grafts may be used as an alternative in arterial replacement, since the graft becomes morphologically and functionally similar to the host vessel via arterialisation.

Experimental results of using autologous rectus fascia sheath for venous patch grafts in dogs

Autologous vascular patch grafts developed from the internal rectus sheath were implanted onto the bilateral common iliac vein and jugular vein of 4 experimental beagle dogs. During the development and implanting of the grafts no technical difficulties or perioperative complications were encountered. The follow-up lasted 6 months and 3 months in the case of the common iliac vein grafts and the jugular grafts, respectively. In the postoperative period, the morphological and functional characteristics of the implanted venous sections were examined by Doppler ultrasonography and CT angiography. Normal patency was detected, and none of these check-ups showed obturation or stenosis. The histological survey showed no mesothelial cell layer, but the insides of the grafts showed total restructuring and were covered by a normal endothelial layer. No difference could be detected between samples harvested 3 and 6 months after implanting. The immunohistochemical examinations using anti-claudin-5 and anti-CD31 antibodies confirmed the preliminary results of the histological examinations that the luminal surfaces of the implanted grafts developed a differentiated monolayer endothelium which was free of degenerative and inflammatory signs. The control examinations show the suitability of the internal rectus sheath as a venous wall donor.

Results and complications after living related kidney transplantation in Hungary: 30 years' experience

The number of patients suffering from kidney disorders is increasing the need for kidney transplantation. Kidneys originating from living donors (LD) show substantially better results than those originating from cadaveric donors (CD). We performed 3000 kidney transplantations between November 1973 and December 2007, including 154 from LD (5.13%). The early kidney function as measured by the delta creatinine clearance was significantly better among the LD group (P < .001). There was no significant difference in the immunologic data between the LD and the CD groups (P = .047). Four years after transplantation the glomerular filtration rate (GFR) and the serum creatinine level treated to be better among the LD group with tacrolimus versus cyclosporine immunosuppression (P = .089). In the LD group, the acute rejection rate was lower with tacrolimus- versus cyclosporine based immunosuppression (P = .014).