Biobanking: Objectives, Requirements, and Future Challenges-Experiences from the Munich Vascular Biobank.

Collecting biological tissue samples in a biobank grants a unique opportunity to validate diagnostic and therapeutic strategies for translational and clinical research. In the present work, we provide our long-standing experience in establishing and maintaining a biobank of vascular tissue samples, including the evaluation of tissue quality, especially in formalin-fixed paraffin-embedded specimens (FFPE). Our Munich Vascular Biobank includes, thus far, vascular biomaterial from patients with high-grade carotid artery stenosis (n = 1567), peripheral arterial disease (n = 703), and abdominal aortic aneurysm (n = 481) from our Department of Vascular and Endovascular Surgery (January 2004⁻December 2018). Vascular tissue samples are continuously processed and characterized to assess tissue morphology, histological quality, cellular composition, inflammation, calcification, neovascularization, and the content of elastin and collagen fibers. Atherosclerotic plaques are further classified in accordance with the American Heart Association (AHA), and plaque stability is determined. In order to assess the quality of RNA from FFPE tissue samples over time (2009⁻2018), RNA integrity number (RIN) and the extent of RNA fragmentation were evaluated. Expression analysis was performed with two housekeeping genes-glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and beta-actin (ACTB)-using TaqMan-based quantitative reverse-transcription polymerase chain reaction (qRT)-PCR. FFPE biospecimens demonstrated unaltered RNA stability over time for up to 10 years. Furthermore, we provide a protocol for processing tissue samples in our Munich Vascular Biobank. In this work, we demonstrate that biobanking is an important tool not only for scientific research but also for clinical usage and personalized medicine.

The initial tangent of the aortic pressure increase is an estimate of left ventricular contractility in pigs.

The aim was, to identify an estimate of left ventricular contractility derived from the aortic pressure wave without load changing manoeuvres. For this purpose, left ventricular contractility was assessed with several aortic pressure wave form derived parameters and was compared to standard parameters of left ventricular contractility (conductance technique) in an experimental study. Measurements were taken during baseline, after beta-stimulation and after injection of a beta-antagonist. The initial and the secondary tangent, the area under the aortic pressure, and the stroke volume were correlated with the endsystolic elastance, a mainly load independent measure of left ventricular contractility: The initial tangent of the aortic pressure increase correlated significantly with the endsystolic elastance (r = 0.54, P < 0.05). The initial tangent of the aortic pressure increase was significantly increased from baseline at beta-stimulation (from 20.2 +/- 4.7 to 36.4 +/- 6.8 mmHg s(-1), P < 0.05) and decreased after injection of a beta-antagonist (from 20.2 +/- 4.7 to 12.3 +/- 2.0, P < 0.05). Thus, we conclude that the initial tangent of the aortic pressure increase is a valid estimate of left ventricular contractility in piglets.

Causes of metabolic acidosis in canine hemorrhagic shock: role of unmeasured ions.

INTRODUCTION: Metabolic acidosis during hemorrhagic shock is common and conventionally considered to be due to hyperlactatemia. There is increasing awareness, however, that other nonlactate, unmeasured anions contribute to this type of acidosis. METHODS: Eleven anesthetized dogs were hemorrhaged to a mean arterial pressure of 45 mm Hg and were kept at this level until a metabolic oxygen debt of 120 mLO2/kg body weight had evolved. Blood pH, partial pressure of carbon dioxide, and concentrations of sodium, potassium, magnesium, calcium, chloride, lactate, albumin, and phosphate were measured at baseline, in shock, and during 3 hours post-therapy. Strong ion difference and the amount of weak plasma acid were calculated. To detect the presence of unmeasured anions, anion gap and strong ion gap were determined. Capillary electrophoresis was used to identify potential contributors to unmeasured anions. RESULTS: During induction of shock, pH decreased significantly from 7.41 to 7.19. The transient increase in lactate concentration from 1.5 to 5.5 mEq/L during shock was not sufficient to explain the transient increases in anion gap (+11.0 mEq/L) and strong ion gap (+7.1 mEq/L), suggesting that substantial amounts of unmeasured anions must have been generated. Capillary electrophoresis revealed increases in serum concentration of acetate (2.2 mEq/L), citrate (2.2 mEq/L), alpha-ketoglutarate (35.3 microEq/L), fumarate (6.2 microEq/L), sulfate (0.1 mEq/L), and urate (55.9 microEq/L) after shock induction. CONCLUSION: Large amounts of unmeasured anions were generated after hemorrhage in this highly standardized model of hemorrhagic shock. Capillary electrophoresis suggested that the hitherto unmeasured anions citrate and acetate, but not sulfate, contributed significantly to the changes in strong ion gap associated with induction of shock.

Effect of rosiglitazone treatment on plaque inflammation and collagen content in nondiabetic patients: data from a randomized placebo-controlled trial.

BACKGROUND: Therapeutic strategies to stabilize advanced arteriosclerotic lesions may prevent plaque rupture and reduce the incidence of acute coronary syndromes. Thiazolidinediones (TZDs), like rosiglitazone, are oral antidiabetic drugs with additional antiinflammatory and potential antiatherogenic properties. In a randomized, placebo-controlled, single-blind trial, we examined the effect of 4 weeks of rosiglitazone therapy on histomorphological characteristics of plaque stability in artery specimen of nondiabetic patients scheduled for elective carotid endarterectomy. METHODS AND RESULTS: A total of 24 nondiabetic patients with symptomatic carotid artery stenosis were randomly assigned to rosiglitazone (4 mg BID) or placebo in addition to standard therapy. In this population of nondiabetic patients, rosiglitazone treatment did not significantly change fasting blood glucose, fasting insulin, or lipid parameters. In contrast, rosiglitazone significantly reduced CD4-lymphocyte content as well as macrophage HLA-DR expression in the shoulder region, reflecting less inflammatory activation of these cells by lymphocyte interferon-gamma. Moreover, rosiglitazone significantly increased plaque collagen content (7.7+/-1.6% versus 3.7+/-0.7% of plaque area; P=0.036) compared with placebo, suggesting that TZD treatment may stabilize arteriosclerotic lesions. In addition, rosiglitazone reduced serum levels of 2 inflammatory arteriosclerosis markers: C-reactive protein and serum amyloid A. CONCLUSIONS: Four weeks of treatment with rosiglitazone significantly reduces vascular inflammation in nondiabetic patients, leading to a more stable type of arteriosclerotic lesion.

Oxygent as a top load to colloid and hyperoxia is more effective in resuscitation from hemorrhagic shock than colloid and hyperoxia alone.

Perfluorocarbon (PFC) emulsions are intravascular oxygen therapeutics that temporarily enhance tissue oxygenation in dilutional anemia. However, PFC emulsions are not resuscitation fluids because PFCs only work optimally in the presence of high O2 partial pressure (hyperoxia); moreover, because they have no oncotic potential, dosing limitations prevent their use to permanently replace large hemorrhage volumes. Our objective was to clarify whether in the presence of hyperoxia a conventional colloid therapy supplemented by PFC is more efficacious than colloid alone. To answer this question, 22 anesthetized, ventilated dogs were hemorrhaged to a mean arterial pressure of 45 mmHg and were kept at this level until a metabolic O2 debt of 120 mL kg(-1) body weight had evolved. Hyperoxia was established and dogs were randomly allocated to receive colloid (6% HES, Hydroxy Ethyl Starch shed blood volume) or colloid together with Oxygent (perflubron emulsion, 60%, w/v; Alliance Pharmaceutical Corp., San Diego, CA; single dose, 4.5 mL kg(-1); i.e., 2.7 g PFC kg body weight) in a blinded fashion. Hemodynamic and O2 transport parameters, intestinal mucosal blood flow (microspheres), and O2 partial pressure (MDO-Electrode; Eschweiler, Kiel, Germany) were measured at baseline, in shock, and during 3 h post-therapy. In the presence of hyperoxia, Oxygent improved the amount of physically dissolved O2 in plasma and increased the contribution of physically dissolved O2 to global O2 delivery (P < 0.05) and thus whole body O2 consumption when compared with colloid alone (P < 0.05). As a result, Oxygent reduced intestinal mucosal hypoxia and global O2 debt within the first hour post-therapy (P < 0.05). We conclude that under hyperoxic conditions, fluid resuscitation supplemented by Oxygent was more efficacious than colloid and hyperoxia alone. PFC temporarily enhanced intestinal mucosal tissue oxygenation during resuscitation.

Effect of prostaglandin I2 analogues on left ventricular diastolic function in vivo.

The prostaglandin I2 analogues epoprostenol and iloprost increase left ventricular contractility. Therefore, we hypothesize that the prostaglandin I2 analogues epoprostenol and iloprost improve also left ventricular diastolic function. To test this hypothesis, the effects of epoprostenol and iloprost on left ventricular diastolic function were assessed in vivo and compared to two vasodilators sodium nitroprusside and adenosine, not formerly associated with changes of left ventricular contractility. Eleven pigs (25.9+/-2.8 kg, balanced anaesthesia) were exposed to the short-acting intravenous vasodilators sodium nitroprusside, adenosine and epoprostenol in a randomized cross over design. The long-acting iloprost was administered at the end of the protocol. The drugs are titrated to achieve a 25% reduction of diastolic aortic pressure. Active isovolumic relaxation properties of the left ventricle were assessed by the maximum velocity of left ventricular pressure drop. Passive phase of relaxation and filling was assessed by the determination of end diastolic compliance during a preload reduction manoeuvre. The maximum velocity of left ventricular pressure drop worsened during the infusion of sodium nitroprusside (baseline: -1950; sodium nitroprusside: -1293 mm Hg/s, p<0.05, Wilcoxon signed rank test versus vs. baseline) and adenosine (baseline: -2015; adenosine: -1345 mm Hg/s, p<0.05), but remained stable during the infusion of the prostaglandins (baseline: -1943; epoprostenol: -1785 mm Hg/s; baseline: -2042; iloprost: -1923 mm Hg/s). End diastolic compliance was not altered significantly by any vasodilator. Interstitial myocardial cAMP increased during the infusion of epoprostenol (7.60 to 13.87 fmol/ml, p<0.05) and tended to increase during the infusion of iloprost (7.56 to 11.66 fmol/ml, p=0.21). The prostaglandin I(2) analogues epoprostenol and iloprost preserved the early phase of active isovolumic relaxation, presumably mediated by myocardial cAMP, whereas sodium nitroprusside and adenosine impaired early active isovolumic relaxation. Passive relaxation and filling properties remained stable during the infusion of each applied vasodilator in the intact left ventricle in vivo.

The prostaglandins epoprostenol and iloprost increase left ventricular contractility in vivo.

OBJECTIVE: The principal effects of prostaglandin I(2) are vasodilation and inhibition of platelet aggregation induced by a rise in the intracellular second messenger cAMP. In the heart a rise in intracellular myocardial cAMP increases contractility. We examined whether prostaglandin I(2) increases left ventricular contractility in vivo. The effects of epoprostenol and iloprost on left ventricular contractility were assessed in vivo and compared to the effects of adenosine and sodium nitroprusside, which exerts vasodilatory properties independently of cAMP. DESIGN AND SETTING: Prospective, randomized, cross-over in a university laboratory. SUBJECTS: Eleven pigs (25.9+/-2.8 kg, balanced anesthesia). INTERVENTIONS: Each animal was exposed to intravenous sodium nitroprusside, adenosine, and epoprostenol in randomized order. Iloprost was administered at the end due to its longer half-life. The dose was titrated to achieve a 25% reduction in diastolic aortic pressure. MEASUREMENTS AND RESULTS: Left ventricular contractility was assessed before, during, and after each intervention by determination of the endsystolic elastance with the conductance method. While there was no change in endsystolic elastance upon the infusion of adenosine and sodium nitroprusside; endsystolic elastance increased in the case of epoprostenol (57%) and iloprost (71%). CONCLUSIONS: Left ventricular contractility is increased in vivo by epoprostenol and iloprost but not by adenosine or sodium nitroprusside at equipotent hypotensive dose. A contribution of sympathetic reflex activation of cardiac nerves on the increase in left ventricular contractility cannot be completely ruled out.

Stent-based approach for ventricle-to-coronary artery bypass.

BACKGROUND: Ventricle-to-coronary artery bypass (VCAB) is an experimental revascularization procedure that provides predominantly systolic instead of diastolic blood flow to a coronary artery. METHODS AND RESULTS: In a pig model, a stent-based procedure (VSTENT) was developed to create a VCAB. After thoracotomy, a covered VSTENT was implanted between the left ventricle and the left anterior descending coronary artery (LAD). Distal LAD flow, regional myocardial function, and intracoronary pressures were determined at different degrees of LAD stenosis and during complete LAD occlusion. During 3 hours of LAD occlusion, VSTENT preserved net forward flow at 70+/-6% and regional myocardial function at 71+/-8% of baseline. Preservation of net flow was influenced by the positioning of the VSTENT, with higher preservation also under conditions of increased oxygen demand if a "valve-like mechanism" was present during diastole. At a hemodynamically relevant level of LAD stenosis (>70%), systolic inflow was predominant after VSTENT implantation. Changes in mean diastolic intracoronary pressure that resulted from different degrees of LAD stenosis were linearly correlated to net flow after VSTENT implantation (r=0.88; P<0.001). CONCLUSIONS: VSTENT for ventricle-to-coronary artery bypass was feasible and preserved 70+/-6% of baseline flow during complete LAD occlusion. The degree of preservation was dependent on the position of the VSTENT creating a valve-like mechanism during diastole. Residual diastolic blood flow through a high-grade LAD stenosis influenced net flow favorably, because diastolic backflow decreased with increasing mean diastolic intracoronary pressure.