Lech Cierpka

Effectiveness of haemodialysis access with an autologous tissue-engineered vascular graft: a multicentre cohort study

BACKGROUND Application of a tissue-engineered vascular graft for small-diameter vascular reconstruction has been a long awaited and much anticipated advance for vascular surgery. We report results after a minimum of 6 months of follow-up for the first ten patients implanted with a completely biological and autologous tissue-engineered vascular graft. METHODS Ten patients with end-stage renal disease who had been receiving haemodialysis through an access graft that had a high probability of failure, and had had at least one previous access failure, were enrolled from centres in Argentina and Poland between September, 2004, and April, 2007. Completely autologous tissue-engineered vascular grafts were grown in culture supplemented with bovine serum, implanted as arteriovenous shunts, and assessed for both mechanical stability during the safety phase (0-3 months) and effectiveness after haemodialysis was started. FINDINGS Three grafts failed within the safety phase, which is consistent with failure rates expected for this high-risk patient population. One patient was withdrawn from the study because of severe gastrointestinal bleeding shortly before implantation, and another died of unrelated causes during the safety period with a patent graft. The remaining five patients had grafts functioning for haemodialysis 6-20 months after implantation, and a total of 68 patient-months of patency. In these five patients, only one intervention (surgical correction) was needed to maintain secondary patency. Overall, primary patency was maintained in seven (78%) of the remaining nine patients 1 month after implantation and five (60%) of the remaining eight patients 6 months after implantation. INTERPRETATION Our proportion of primary patency in this high-risk cohort approaches Dialysis Outcomes Quality Initiative objectives (76% of patients 3 months after implantation) for arteriovenous fistulas, averaged across all patient populations.

Mechanical properties of completely autologous human tissue engineered blood vessels compared to human saphenous vein and mammary artery.

We have previously reported the initial clinical feasibility with our small diameter tissue engineered blood vessel (TEBV). Here we present in vitro results of the mechanical properties of the TEBVs of the first 25 patients enrolled in an arterio-venous (A-V) shunt safety trial, and compare these properties with those of risk-matched human vein and artery. TEBV average burst pressures (3490+/-892 mmHg, n=230) were higher than native saphenous vein (SV) (1599+/-877 mmHg, n=7), and not significantly different from native internal mammary artery (IMA) (3196+/-1264 mmHg, n=16). Suture retention strength for the TEBVs (152+/-50 gmf) was also not significantly different than IMA (138+/-50 gmf). Compliance for the TEBVs prior to implantation (3.4+/-1.6%/100 mmHg) was lower than IMA (11.5+/-3.9%/100 mmHg). By 6 months post-implant, the TEBV compliance (8.8+/-4.2%/100 mmHg, n=5) had increased to values comparable to IMA, and showed no evidence of dilation or aneurysm formation. With clinical time points beyond 21 months as an A-V shunt without intervention, the mechanical tests and subsequent lot release criteria reported here would seem appropriate minimum standards for clinical use of tissue engineered vessels.

Case study: first implantation of a frozen, devitalized tissue-engineered vascular graft for urgent hemodialysis access

Previously we reported on the mid- to long-term follow-up in the first clinical trial to use a completely autologous tissue-engineered graft in the high pressure circulation. In these early studies, living grafts were built from autologous fibroblasts and endothelial cells obtained from small skin and vein biopsies. The graft was assembled using a technique called tissue-engineering by self-assembly (TESA), where robust conduits were grown without support from exogenous biomaterials or synthetic scaffolding. One limitation with this earlier work was the long lead times required to build the completely autologous vascular graft. Here we report the first implant of a frozen, devitalized, completely autologous Lifeline™ vascular graft. In a departure from previous studies, the entire fibroblast layer, which provides the mechanical backbone of the graft, was air-dried then stored at −80°C until shortly before implant. Five days prior to implant, the devitalized conduit was rehydrated, and its lumen was seeded with living autologous endothelial cells to provide an antithrombogenic lining. The graft was implanted as an arteriovenous shunt between the brachial artery and the axillary vein in a patient who was dependent upon a semipermanent dialysis catheter placed in the femoral vein. Eight weeks postoperatively, the graft functions without complication. This strategy of preemptive skin and vein biopsy and cold-preserving autologous tissue allows the immediate availability of an autologous arteriovenous fistula, and is an important step forward in our strategy to provide allogeneic tissue-engineered grafts available “off-the-shelf”.

Organ preservation solutions impair deformability of erythrocytes in vitro

Microcirculatory disturbances are observed frequently after restoration of the circulation in transplanted organ. The exact mechanisms responsible for impaired microcirculation during reperfusion are unknown. Erythrocyte deformability is an important factor maintaining the microcirculation. Red blood cells (RBC) (diameter 8 microm) passing through narrow capillaries (diameter 3-5 microm) undergo deformation due to shear stress present in the microcirculation. RBC with impaired deformability may even plug the capillaries. Immediately after completion a vascular anastomosis and restoration of blood circulation in the transplanted organ, RBC may be intimately exposed to the preservation solution. The aim of the present study was to investigate the effect of the preservation solution on deformability of RBC. Blood from five healthy volunteers was withdrawn by venipuncture from an antecubital vein. EDTA was used as an anticoagulant. RBC were isolated by 10-minute centrifugation (2500 rpm) to separate serum and buffy coat. RBC washed in normal saline were resuspended in autologous plasma, Bretschneiders histidine-tryptophan-ketoglutarate (HTK) or University of Wisconsin solution (UW) at an hematocrit of 20% for incubation at room temperature. After 30 minutes RBC deformability was measured using the shear stress diffractometer Rheodyn SSD to calculate the elongation indexes of RBC at various shear stresses. HTK caused a decrease in the deformability indices of erythrocytes at shear stresses from 0.3 to 1.2 Pa. Erythrocytes incubated with UW solution revealed a decrease in deformability index at all investigated shear stresses. HTK causes less deterioration of erythrocyte deformability compared to UW solution.

‐174G/C interleukin‐6 gene polymorphism and the risk of transplanted kidney failure or graft loss during a 5‐year follow‐up period

The influence of cytokine gene polymorphisms on transplanted kidney outcome is not well understood. The aim of this one-centre study was to analyse the association between tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-10, interferon-γ (IFN-γ) and transforming growth factor-β1 (TGF-β1) genotypes and the incidence of delayed graft function (DGF), acute rejection (AR) and 5-year kidney graft loss. Genotyping was performed in 199 subsequent kidney graft recipients from deceased donors without induction therapy based on polymerase chain reaction method using sequence-specific primers for TNF-α (-308A/G), IL-10 (-1082A/G, -819T/C and -592A/C), IL-6 (-174G/C), IFN-γ (+874T/A) and TGF-β1 (in codons 10T/C and 25G/C). Genotypes were grouped according to the strength of cytokine expression. During a 5-year follow-up period, 14 patients died with functioning graft and 33 developed graft failure. The analysed polymorphisms were not associated with the incidence of DGF. The frequency of early episodes of AR was significantly associated only with TGF-β1 genotype. There was an association between -174G/C IL-6 gene polymorphism and the death-censored kidney graft survival. The risk of graft loss during 5-year follow-up period was greater by 57% for GG or GC (higher IL-6 production) than for CC carriers. None of the other analysed polymorphisms significantly influenced both patients and kidney graft survival, also in the analysis of the subgroup with human leucocyte antigen-DR mismatch. -174G/C IL-6 genotype of the kidney graft recipient could modulate the rate of graft excretory function deterioration and the risk of graft loss by influencing their constitutional expression.

New biological solutions for hemodialysis access.

Since Scribner described the first prosthetic chronic dialysis shunt in 1961, the surgical techniques and strategies to maintain vascular access have improved dramatically. Today, hundreds of thousands of patients worldwide are treated with some combination of native vein fistula, synthetic vascular graft, or synthetic semipermanent catheter. Despite significantly lower efficacy compared with autologous fistulae, the basic materials used for synthetic shunts and catheters have evolved surprisingly slowly. The disparity between efficacy rates and concomitant maintenance costs has driven a strong campaign to decrease the use of synthetic grafts and catheters in favor of native fistulae. Whether arguing the benefits of Fistula First or “Catheter Last,” the fact that clinicians are in need of an alternative to expanded polytetrafluoroethylene (ePTFE) is irrefutable. The poor performance of synthetic materials has a significant economic impact as well. End-stage renal disease (ESRD) accounts for approximately 6% of Medicares overall budget, despite a prevalence of about 0.17%. Of that, 15%–25% is spent on access maintenance, making hemodialysis access a critical priority for Medicare. This clinical and economic situation has spawned an aggressive effort to improve clinical care strategies to reduce overall cost and complications. While the bulk of this effort has historically focused on developing new synthetic biomaterials, more recently, investigators have developed a variety of cell-based strategies to create tissue-engineered vascular grafts. In this article, we review the evolution of the field of cardiovascular tissue engineering. We also present an update on the Lifeline™ vascular graft, an autologous, biological, and tissue-engineered vascular graft, which was the first tissue-engineered graft to be used clinically in dialysis patients.

Impact of Pancreas Transplantation on the Quality of Life of Diabetic Renal Transplant Recipients

UNLABELLED Simultaneous pancreas and kidney transplantation (SPKT) is considered to be the best method of treatment for patients with chronic renal failure (CRF) resulting from insulin-dependent diabetes mellitus (IDDM). The aim of the study was to compare the quality of life (QOL) of patients with IDDM and CRF subjected to SPK or kidney transplantation alone (KTA). MATERIALS AND METHODS We analyzed 21 patients after SPKT with good function of both grafts. The results were compared with 17 patients with functioning kidney grafts. Minimal observation time was 6 months. QOL was evaluated using Kidney Disease and Quality of Life Short Form (KDQOL-SF), which was sent to recipients by post. Results were presented as medians and interquartile ranges of calculated scored KDQOL-SF points. RESULTS Observation time was 30 months (range, 6-85). Analyzed groups did not differ as regards patient age at transplantation or duration of diabetes and dialysis treatment before transplantation. After SPKT patients reported higher QOL compared with KTA as regards symptom/problem list, 90.91 (86.36-95.46) versus 84.09 (75.00-90.91; P = .04), effects of kidney disease, 90.63 (84.38-93.75) versus 81.25 (68.75-82.14; P = .001); cognitive function, 93.33 (86.67-100.00) versus 80.00 (73.33-93.33; P = .03); overall health, 80.00 (70.00-90.00) versus 50.00 (50.00-70.00; P = .001); physical functioning, 90.00 (75.00-100.00) versus 80.00 (55.00-85.00; P = .03); and pain, 100.00 (90.00-100.00) versus 67.50 (45.00-90.00; P = .005), respectively. CONCLUSION SPKT had a positive impact on selected parameters of QOL among patients with IDDM and CRF compared to KTA.

Comparing the effect of Biolasol® and HTK solutions on maintaining proper homeostasis, indicating the kidney storage efficiency prior to transplantation.

BACKGROUND Maintaining proper homeostasis involving normal physiological level of extra- and intracellular solutions is one of the factors that determine restoring the life functions of a transplanted organ. The aim of this study was to demonstrate the effectiveness of the newly developed Biolasol(®) solution in kidney storage and to compare its protective effect to the standard HTK solution. MATERIAL/METHODS Isolated porcine kidneys were perfused, preserved (24 and 48 h) and reperfused with Biolasol(®) and HTK solutions. The perfusate samples were used to analyze pH; the amount of released indicator enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH); and the concentration of sodium, potassium and magnesium. RESULTS Kidney storage in the HTK liquid may cause metabolic acidosis after 24 and 48 hour preservation (pH drop below 6.8). pH of perfusates sampled after perfusion and reperfusion with Biolasol(®) solution was within the range 6.8-7.7. The content of sodium ions during perfusion and reperfusion was the closest to the reference values while using the Biolasol(®) solution. Only Biolasol(®) ensured normal homeostasis of Mg2+ ions. In the presence of the HTK solution their level was significantly (more than 1000%) higher than the normal physiological value. For both solutions, ALT and AST activities were within the normal range or differed only slightly. CONCLUSIONS Biolasol(®) and HTK solutions protect kidneys against ischemic damage. Still, Biolasol(®) offers better homeostasis maintenance, which may suggest it more effectively preserves kidneys prior to transplantation.

Risk Factors for Early Hemorrhagic and Thrombotic Complications After Kidney Transplantation

INTRODUCTION Clotting disturbances resulting from chronic renal failure do not remit immediately after successful kidney transplantation (KTx). Hemorrhagic and thrombotic complications after KTx increase the risk of transplanted kidney loss. The aim of the study was to analyze the influence of clotting system disturbances and applied antithrombotic prophylaxis on the development of hemorrhagic and thrombotic complications among KTx patients in the early postoperative period. MATERIALS AND METHODS Sixty seven KTx patients underwent measurement of plasma activated partial thromboplastin time (APTT); international normalized ratio; fibrinogen and D-dimer concentration; activity of antitrombin III; protein C and S, VIII, IX; and von Willebrand factors, as well as platelet counts. RESULTS A perigraft hematoma developed in 25.4% patients, of whom 4.5% required reoperation. Lower antithrombin III activity (96.2±27.6 vs 112.3±17.4, P=.02) on postoperative day (POD) 7 and higher fibrinogen concentration (4.41±2.03 vs 3.35±0.87, P=.01) and platelet count (269.8±117.5 vs 215.8±64.8, P=.03) on POD 14 were noted in recipients with a hematoma compared to those free of this complication. A perigraft hematoma developed in 57.9% patients undergoing antithrombotic prophylaxis and in 12.5% without this treatment (P=.0002). Among patients receiving unfractionated heparin, we observed extension of APTT on POD 1 (45.9±53.2 vs 30.9±7.5 seconds, P=.04), higher von Willebrand factor activity on POD 7 (348.8±122.2 vs 218.5±125.5, P=.02), and higher D-dimer concentrations POD 7 and 14 (1662±894 vs 757±708, P=.002 and 1614±1372 vs 672±532, P=.003, respectively). No significant differences were observed as regards to analyzed parameters between patients receiving low-molecular-weight heparin versus those not receiving antithrombotic prophylaxis. CONCLUSIONS Disturbances in analyzed parameters of hemostasis did not increase the risk of hemorrhagic and thrombotic complications in the early period after KTx. Antithrombotic prophylaxis increases the risk of hemorrhagic complications and should be introduced only for selected renal transplant recipients.

Donor-Dependent Risk Factors for Early Surgical Complications After Simultaneous Pancreas-Kidney Transplantation

INTRODUCTION The success of simultaneous pancreas-kidney transplantation (SPK) depends in a large degree on avoidance of surgical complications in the early postoperative period. The aim of the study was to analyze the Pre-procurement Pancreas Allocation Suitability Score (P-PASS) and the deceased donor parameters included within it as risk factors for early surgical complications after SPK. MATERIAL AND METHODS Forty-six consecutive donors whose kidney and pancreas were simultaneously transplanted were included in the study. RESULTS Donor age was older among recipients who lost their pancreatic grafts: 30.4±6.9 versus 24.1±6.9 years. Donor age was also older among recipients who lost their pancreatic grafts or died compared with those discharged with a functioning graft: 29.3±5.7 versus 24.0±6.9 years. Donor body mass index (BMI) was higher among patients who died compared with those who were discharged: 25.3±1.1 versus 23.2±2.5 kg/m2. P-PASS was higher in patients who lost their pancreatic grafts (17.6±2.1 vs 15.2±1.8) or died (15.3±1.9 vs 17.2±1.9), or lost pancreatic graft or died (15.2±1.8 vs 17.0±2.2) or with intra-abdominal infections (IAI; 17.1±1.7 vs 15.0±1.8). The incidence of donors≥30 years old was higher among recipients with IAI (45.4% vs 14.3%; P=.04). An higher rate of donors with P-PASS>16 was revealed among patients who lost their pancreatic grafts (26.7% vs 3.2%), died (26.7% vs 3.2%), lost the pancreatic graft or died (33.3% vs 6.4%), or experienced IAI (46.7% vs 9.7%). Multivariate logistic regression analysis revealed P-PASS (odds ratio 2.57; P=.014) and serum sodium (odds ration, 0.91; P=.048) to be important predictors of IAI development. CONCLUSION Older age and higher BMI among deceased donors increased the risk of IAI, pancreatic graft loss, or recipient death after SPK. Transplantation of a pancreas from a donor with a low P-PASS score was associated with a lower risk of surgical complications after SPK.