Martin Storck

Immunopathological observations after xenogeneic liver perfusions using donor pigs transgenic for human decay-accelerating factor

BACKGROUNDnDonor pigs transgenic for human decay-accelerating factor (hDAF) were used in a xenogeneic ex vivo liver perfusion model to study the effect of this modification on the development of hyperacute rejection.nnnMETHODSnThree transgenic pigs were hepatectomized after hypothermic portal and transaortal gravity perfusion. Livers from six nontransgenic pigs served as controls. All livers were perfused for 3 hr with human blood from two donors diluted to a hematocrit of 30%. Particular importance was placed on the use of an optimal perfusion technique incorporating the floating suspension of the organs in a waterbath and intermittent external pressurization. Biochemical, physiological, and immunological parameters were assessed. Tissue specimens taken before and after perfusion were analyzed using routine histology, electron microscopy, and immunohistology.nnnRESULTSnComplement activation was more pronounced in the control group. AP50 and CH50 values fell to about 60% of the initial levels in control experiments, whereas they remained at 80% of the initial levels during perfusion of hDAF livers. After 180 min, pig tumor necrosis factor alpha levels were 7862+/-1645 pg/ml for unmodified livers and 2830+/-734 pg/ml in the hDAF group. Human tumor necrosis factor alpha levels were similar in both groups. Control livers showed marked morphological alterations and distinct deposition of complement factors, whereas livers expressing hDAF showed no signs of hepatocellular necrosis and almost no complement deposition beyond C3 activation.nnnCONCLUSIONSnThese results confirm that the transgenic expression of the human complement regulatory protein hDAF reduces complement activation and prevents hyperacute rejection in a xenogeneic liver perfusion model over the 3-hr evaluation period used in this study.

Development and application of a high-performance liquid chromatography-based assay for determination of the activity of inosine 5'-monophosphate dehydrogenase in whole blood and isolated mononuclear cells.

With the objective of pharmacodynamic monitoring of the immunosuppressive efficacy of mycophenolate mofetil (MMF) (CellCept, Hoffman-LaRoche, Grenzach-Wyhlen, Germany), a method for determination of the inosine monophosphate dehydrogenase (IMPDH) activity in whole blood cell (WBC) lysates and mononuclear cells (MNCs) was developed. The assay is based on the incubation of WBC lysates or lysed MNCs in the presence of supplemented inosine 5-monophosphate (IMP) and nicotimamide adenine dinucleotide (NAD). The formation of xanthosine 5-monophosphate (XMP) was determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The analytical method was validated, and the obtained data demonstrated that the amount of XMP in WBC and MNC lysates can be reliably determined by this method. Under assay conditions the rate of XMP formation remained constant within the incubation period of 60 minutes and a quantification of product formation at 30 and 60 minutes proved to be sufficient to reliably characterize the IMPDH activity. Applications of this assay with whole blood indicated extremely high IMPDH-activities in samples from patients with renal transplant receiving MMF. IMPDH monitoring within 10 hours after administration of the morning dose demonstrated a marked enzyme inhibition between 2 hours and 3 hours postdosing, but the activities returned to predose levels within one dose interval. The analysis of isolated cell fractions indicated that the IMPDH-activity is predominantly located in erythrocytes. The contribution of MNCs to the whole blood activity remained below 10%. In order to simulate the in vivo exposure of MNCs to mycophenolic acid, an erythrocyte- and platelet-free whole blood was reconstituted by resuspension of isolated MNCs with plasma. This strategy allowed for the reliable measurement of IMPDH activity in the target cells of immunosuppression.

Current practice of first-line treatment strategies in patients with critical limb ischemia.

OBJECTIVEnCritical limb ischemia (CLI) is growing in global prevalence and is associated with high rates of limb loss and mortality. However, a relevant gap of evidence about the most optimal treatment strategy still exists. The aim of this study of the prospective, multicenter First-Line Treatments in Patients With Critical Limb Ischemia (CRITISCH) registry was to assess the current practice of all first-line treatments strategies in CLI patients in German vascular centers.nnnMETHODSnBetween January 2013 and September 2014, five first-line treatment strategies-endovascular revascularization (ER), bypass surgery (BS), femoral/profundal artery patchplasty (FAP), conservative treatment, and primary amputation-were determined among CLI patients in 27 vascular tertiary centers. The main composite end point was major amputation or death, or both, during the hospital stay. Secondary outcomes were hemodynamic failure, major adverse cardiovascular and cerebral events, and reintervention. Univariate logistic models were additionally built to preselect possible risk factors for either event, which were then used as candidates for a multivariate logistic model.nnnRESULTSnThe study included 1200 consecutive patients. First-line treatment of choice was ER in 642 patients (53.4%), BS in 284 (23.7%), FAP in 126 (10.5%), conservative treatment in 118 (9.8%), and primary amputation in 30 (2.5%). The composite end point was met in 24 patients (4%) after ER, in 17 (6%) after BS, in 8 (6%) after FAP, and in 9 (8%) after conservative treatment (P = .172). The highest rate of in-hospital death was observed after primary amputation (10%) and of hemodynamic failure after conservative treatment (91%). Major adverse cardiovascular and cerebral events developed in 4% of patients after ER, in 5% after BS, in 6% after FAP, in 5% after conservative treatment, and in 13% after primary amputation. The reintervention rate was 8%, 14%, 6%, 5%, and 3% in each group, respectively. In the multivariate regression model, coronary artery disease (odds ratio [OR], 2.96; 95% confidence interval [CI], 1.42-6.17) and previous myocardial infarction (PMI) <6 months (OR, 3.67, 95% CI, 1.51-8.88) were identified as risk factors for the composite end point. Risk factors for amputation were dialysis (OR, 3.31, 95% CI, 1.44-7.58) and PMI (OR, 3.26, 95% CI, 1.23-8.36) and for death, BS compared with ER (OR, 3.32; 95% CI, 1.10-10.0), renal insufficiency without dialysis (OR, 6.34; 95% CI, 1.71-23.5), and PMI (OR, 7.41; 95% CI, 2.11-26.0).nnnCONCLUSIONSnThe CRITISCH registry revealed ER as the most common first-line approach in CLI patients. Coronary artery disease and PMI <6 months were independent risk factors for the composite end point. Special attention should be also paid to CLI patients with renal insufficiency, with or without dialysis, and those undergoing BS.

Morphology of hDAF (CD55) transgenic pig kidneys following ex-vivo hemoperfusion with human blood

Discordant xenotransplantation of pig kidneys into man may be possible in the future using transgenic organs which regulate complement activity. It was the aim of this experimental study to characterize morphologic alterations of organs transgenic for human decay accelerating factor (hDAF/CD55) perfused with human blood since no data on function of these organs after exposure to human blood are available. An ex-vivo system was developed that allows computer driven pressure-controlled perfusion of kidneys including a separate cartridge oxygenator circuit. Following cold ischemia time of 1-4 hr, 8 kidneys from heterozygote transgenic animals (TG) and 9 control kidneys (C) were perfused with 500 ml freshly drawn heparinized human blood at physiological conditions. A histologic grading system from 0 to +4 was used to describe the histologic findings. Using a mouse antihuman DAF moAB, hDAF was stained on all TG kidneys both on glomerular capillary (4+) and vascular endothelium (2+), but there was no detectable hDAF-expression on controls. No difference in xenoantibody deposition on vascular endothelium was seen between both groups. There was comparable staining for complement fraction C4 in both groups, but significant reduction of C3 and C9 staining on glomerular and vascular endothelium in TG. P-selectin was expressed on a higher level in C (+4) compared with TG (+2). Neutrophil extravasation [NP-57 elastase] was higher in C (80.2 vs. 32.2 C vs. TG [values as n/high power field]). Tubular epithelial cell swelling and mild necrosis was paralleled by glomerular hemorrhage and platelet microthrombus formation in both groups as seen in transmission electron microscopy. The observed results allow the conclusion that hDAF expression on transgenic pig kidneys was sufficient to inhibit complement activation beyond C3 during xenoperfusion with human blood despite xenoantibody deposition.

Absorbable suture in vascular surgery

The choice of suture material in surgery is often individual and a result of personal experience. Cardiovascular surgeons have always been reluctant to use absorbable suture material for direct arterial or venous anastomoses for differ ent reasons, mainly because of suspected anastomotic dilatation or even rupture during or after the absorption phase. More than ten years ago, a new class of synthetic, monofilament, flexible, biodegradable suture material was intro duced for clinical use. Since then, much experimental and clinical work has been carried out to evaluate physical and biological characteristics of this class of suture material (polydioxanone/polydimethylsiloxane = [PDS] and polytri methylene-carbonate = [PTMC]) in many different tissues, including vascular tissue. There is increasing evidence that slow-absorbable sutures will gain clini cal importance for cardiovascular and peripheral vascular surgery in the fu ture, since many experimental and clinical studies during the last forty years have proven histologic superiority over nonabsorbable materials. Descriptions of healing processes in blood vessels after surgical anastomoses lead to the con clusion that persisting foreign suture material results in persistent cellular reac tions and chronic inflammatory responses and may consequently disturb physi ologic functions such as compliance at the anastomotic site. It is the purpose of this article to give a review of the literature. Implications are discussed for surgery of growing vessels, transplantation surgery, microsurgery, and surgery in infected anastomoses. Nonabsorbable suture material should no longer be used for direct vascular anastomoses.

Short Time Interval Between Neurologic Event and Carotid Surgery Is Not Associated With an Increased Procedural Risk

Background and Purpose— Guidelines recommend that carotid endarterectomy should be performed within 2 weeks in patients with a symptomatic carotid stenosis. Because a Swedish register study indicated that patients treated within the first days after a stroke or transient ischemic attack might have an increased perioperative stroke and mortality risk, this study aimed to find out whether these findings are also true under everyday conditions in Germany. Methods— Secondary data analysis including 56u2009336 elective carotid endarterectomy procedures performed for symptomatic carotid stenosis under everyday conditions between 2009 and 2014. The patient cohort was divided into 4 groups according to time interval between index event and surgery (I: 0–2, II: 3–7, III: 8–14, and IV: 14–180 days). Primary outcome was any in-hospital stroke or death. For risk-adjusted analyses, a multilevel multivariable regression model was used. Results— Mean patients’ age was 71.1±9.6 years; 67.5% were men. Overall rate of any stroke or death was 2.5% (n=1434). Risk of any in-hospital stroke or death was 3.0% in group I, 2.5% in group II, 2.6% in group III, and 2.3% in group IV. Multivariable regression analysis revealed that the time interval was not significantly associated with the primary outcome. Conclusions— The time interval between the index event and carotid endarterectomy was not associated with the risk of any in-hospital stroke or death in patients with symptomatic carotid stenosis in Germany. In clinically stable patients, carotid endarterectomy might, therefore, be performed safely as soon as possible after the neurological index event.

Endovascular Therapy Versus Bypass Surgery as First-Line Treatment Strategies for Critical Limb Ischemia: Results of the Interim Analysis of the CRITISCH Registry

OBJECTIVESnThe most effective first-line treatment between endovascular therapy and bypass surgery for patients with critical limb ischemia (CLI) is still not well defined. The primary aim of the interim analysis of CRITISCH (Registry of First-Line Treatments in Patients With Critical Limb Ischemia) was to compare both treatment options in a prospective confirmatory manner.nnnBACKGROUNDnOnly 1 randomized controlled trial between endovascular therapy and bypass surgery has been published yet. Several retrospective studies showed comparable outcomes between the 2 treatment strategies, but in the majority of them, current endovascular technologies have not been included.nnnMETHODSnBetween January 2013 and September 2014, 1,200 CLI patients (Rutherford 4 to 6) from 27 vascular centers were enrolled. The selection of the first-line treatment was left completely to the discretion of the responsible physician. The primary composite endpoint was amputation-free survival (AFS), that is, time to major amputation and/or death from any cause. A pre-specified interim analysis aimed at showing noninferiority of the endovascular therapy versus bypass surgery as to the hazard ratio (HR) of AFS (noninferiority boundxa0= 1.33; interim αxa0=xa00.0058). Time-to-event analyses of major amputation, death, and the composite endpoint of reintervention and/or above-ankle amputation were also conducted.nnnRESULTSnEndovascular therapy was applied to 642 (54%) and bypass surgery to 284 (24%) patients. Median follow-up time was 12 months in both groups. One-year AFS was 75% and 72%, respectively. The noninferiority of endovascular therapy versus bypass surgery for AFS was confirmed (HR: 0.91; upper bound of 1-sided (1xa0- 0.0058) confidence interval [CI]: 1.29; pxa0= 0.003). An impact of the treatment strategy on time until death (HR: 1.14; 95% CI: 0.80 to 1.63; pxa0=xa00.453), major amputation (HR: 0.86; 95% CI:0.56 to 1.30; pxa0= 0.463), and reintervention and/or above-ankle amputation (HR: 0.89; 95% CI: 0.70 to 1.14; pxa0= 0.348) was not observed.nnnCONCLUSIONSnThe interim analysis confirmed that when physicians are free to individualize therapy to CLI patients, the endovascular-first approach achieved a noninferior AFS rate compared with bypass surgery. (Registry of First-Line Treatments in Patients With Critical Limb Ischemia [CRITISCH]; NCT01877252).

In-hospital outcomes in patients with critical limb ischemia and end-stage renal disease after revascularization

OBJECTIVEnAnalysis of in-hospital outcomes in patients treated for critical limb ischemia (CLI) and end-stage renal disease (ESRD) compared to CLI patients with normal renal function.nnnMETHODSnA subgroup analysis of the German CRITISCH registry, a prospective multicenter registry, assessing the first-line treatment strategies in CLI patients in 27 vascular centers in Germany was performed. The study cohort wasxa0divided into ESRD patients (nxa0= 102) and patients with normal renal function (nxa0= 674; glomerular filtration ratexa0>60/mL/min/1.73xa0m(2)). The following first-line treatment strategies were assessed: endovascular therapy (EVT), bypass surgery, patch plasty, and no vascular intervention (conservative treatment, primary amputation). Uni- and multivariate analyses were performed to identify differences between groups as to six end points: amputation or death (composite end point), amputation, death, hemodynamic failure, major adverse cardiac and cerebrovascular events, and reintervention.nnnRESULTSnDifferences between the ESRD and non-ESRD group were found regarding the applied first-line therapy (Pxa0=xa0.016): The first-line treatment strategies in ESRD patients were EVT in 64% (nxa0= 65), bypass surgery in 13% (nxa0=xa013), patch plasty in 11% (nxa0= 11), and no vascular intervention in 13% (nxa0= 13). In non-ESRD patients, EVT was applied in 48% (nxa0= 326), bypass surgery in 27% (nxa0= 185), patch plasty in 13% (nxa0= 86), and no vascular intervention in 11% (nxa0= 77). For ESRD patients, a noticeably increased risk of the composite end point (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.19-5.79; Pxa0= .017), amputation (OR, 3.14; 95% CI, 1.35-7.31; Pxa0= .008), and hemodynamic failure (OR, 2.19; 95% CI, 1.19-4.04; Pxa0= .012) was observed.nnnCONCLUSIONSnCLI patients on dialysis represent a challenging cohort prone to in-hospital death, amputation, and hemodynamic failure. Two-thirds of these high-risk patients are treated with EVT. Present data suggest that this modality is generally considered as the most favorable treatment option in this patient subgroup.

Results from the First in Man German Pilot Study of the Silver Graft, a Vascular Graft Impregnated with Metallic Silver

The purpose of this study was to assess the safety of a novel vascular prosthesis in 50 patients who underwent inguinal and infrainguinal vascular reconstructions. The safety data were based on ultrasound Doppler data at 2 and 18 months to quantify the graft-tissue integration in this patient cohort. Between August 9, 2005, and January 25, 2006, 50 patients underwent inguinal or infrainguinal reconstructions with the Silver Graft (SG; B. Braun Melsungen AG, B. Braun Aesculap AG, Tuttlingen, Germany) in six vascular centers. All participating centers received the metallic silver-coated polyester graft (SG) with a diameter of 8 mm and a total length of 60 cm, which was length adjusted to fit the patients anatomy and the planned vascular reconstruction. The mean patient age was 69.1 ± 9.0 years, the male inclusion rate was 72.0%, and the Fontaine classifications were stage IV (16%), stage III (14%), stage IIb (66%), and stage IIa (4%), whereas aneurysm repairs amounted to 4%. In-hospital results revealed the presence of minimal perigraft fluid in 14.0% of all cases (7 of 50). At the 2-month follow-up, perigraft fluid was detected in one patient (1 of 50). At 18 months, a single case of minimal perigraft fluid was detected in an asymptomatic patient. Wound healing was accomplished at discharge in 96% of all patients, whereas at the 2-month follow-up, no signs of wound infection or irritation could be detected. The accumulated primary patency rates were 94% at 2 months and 88% at 18 months. The available clinical data on perigraft fluid as a marker for graft-tissue incorporation at 2 and 18 months, patency, and wound healing are comparable to those of other relevant clinical results with polyester grafts and support the safety of the metallic SG in the studied patient population with inguinal and infrainguinal reconstructions. However, it cannot be guaranteed that all graft infections can be avoided with the SGs.

Randomized controlled trial comparing the safety and efficacy between the FUSION BIOLINE heparin-coated vascular graft and the standard expanded polytetrafluoroethylene graft for femoropopliteal bypass

OBJECTIVEnDespite improvements in endovascular therapy for lower extremity arterial disease, open surgical revascularization is still required when the disease is extensive. Although autogenous vein is the conduit of choice for open femoropopliteal bypass, prosthetic grafts can be an acceptable alternative when adequate vein is not available. The FUSION BIOLINE heparin-coated vascular graft (Maquet Endovascular, Wayne, NJ) was developed to improve the patency rate associated with standard prosthetic grafts. The current study, the FINEST Trial (Comparison of Safety and Primary Patency Between the FUSION BIOLINE Heparin-Coated Vascular Graft and EXXCEL Soft ePTFE), was designed to assess the clinical outcome of heparin-coated and standard vascular grafts in a prospective, randomized, controlled, multicenter trial.nnnMETHODSnDuring a 25-month period ending in June 2012, 209 eligible patients scheduled to undergo elective prosthetic femoral to above-knee or below-knee popliteal bypass were randomized to receive a standard expanded polytetrafluoroethylene (ePTFE) graft or the heparin-coated FUSION BIOLINE vascular graft. Among 203 patients in the efficacy analysis, claudication was the presenting symptom in 147 (72.4%), and the site of the distal anastomosis was at the above-knee level in 174 (85.7%). Grafts were assessed by duplex ultrasound imaging and ankle-brachial indices performed postoperatively at discharge and at 30 days, 6 months, and 12 months. The primary efficacy end point was primary patency of the study graft. The primary safety end point was the composite of major adverse events and periprocedural death. Secondary end points included the time to hemostasis of bleeding at the anastomotic suture hole and primary assisted and secondary patency.nnnRESULTSnThe primary patency rates at 6 months were 86.4% for the FUSION BIOLINE heparin-coated vascular graft group compared with 70.0% for the standard ePTFE group, a difference of 16.4% (95% confidence interval, 2.7%-29.9%; P = .006), and the respective rates at 12 months were 76.5% and 67.0% (95% confidence interval, -4.8% to 23.0%; P = .05). The mean time to hemostasis of bleeding at the suture hole was 3.5 minutes in the FUSION BIOLINE group and 11.0 minutes in the standard ePTFE group (P < .0001). Major adverse events were significantly lower in the FUSION BIOLINE group, occurring in 17.1%, compared with 30.7% in the standard ePTFE group (P = .033), principally a result of a lower rate of major graft reinterventions through 12 months in the FUSION BIOLINE group (16.2% vs 30.7%).nnnCONCLUSIONSnData from this randomized multicenter study demonstrated improved midterm patency, less bleeding at the suture hole, and lower major adverse events with the FUSION BIOLINE heparin-coated vascular graft compared with standard ePTFE grafts. Although the ultimate long-term benefit of the graft cannot be ascertained with the data currently available, the utility of the FUSION BIOLINE vascular graft appears promising.