Eligibility of extracorporeal cardiopulmonary resuscitation on in-hospital cardiac arrests in Sweden: a national registry study.

AIMS: Extracorporeal cardiopulmonary resuscitation (ECPR) for refractory cardiac arrest (CA) is used in selected cases. The incidence of ECPR-eligible patients is not known. The aim of this study was to identify the ECPR-eligible patients among in-hospital CAs (IHCA) in Sweden and to estimate the potential gain in survival and neurological outcome, if ECPR was to be used. METHODS AND RESULTS: Data between 1 January 2015 and 30 August 2019 were extracted from the Swedish Cardiac Arrest Register (SCAR). Two arbitrary groups were defined, based on restrictive or liberal inclusion criteria. In both groups, logistic regression was used to determine survival and cerebral performance category (CPC) for conventional cardiopulmonary resuscitation (cCPR). When ECPR was assumed to be possible, it was considered equivalent to return of spontaneous circulation, and the previous logistic regression model was applied to define outcome for comparison of conventional CPR and ECPR. The assumption in the model was a minimum of 15 min of refractory CA and 5 min of cannulation. A total of 9209 witnessed IHCA was extracted from SCAR. Depending on strictness of inclusion, an average of 32-64 patients/year remains in refractory after 20 min of cCPR, theoretically eligible for ECPR. If optimal conditions for ECPR are assumed and potential negative side effects disregarded of, the estimated potential benefit of survival of ECPR in Sweden would be 10-19 (0.09-0.19/100 000) patients/year, when a 30% success rate is expected. The benefit of ECPR on survival and CPC scoring was found to be detrimental over time and minimal at 60 min of cCPR. CONCLUSION: The number of ECPR-eligible patients among IHCA in Sweden is dependent on selection criteria and predicted to be low. There is an estimated potential benefit of ECPR, on survival and neurological outcome if initiated within 60 min of the IHCA.

Extracorporeal Cardiopulmonary Resuscitation Guided by End-Tidal Carbon Dioxide-a Porcine Model.

Extracorporeal membrane cardiopulmonary resuscitation (ECPR) during cardiopulmonary resuscitation (CPR) for selected cases and end-tidal carbon dioxide (ETCO2) could be used to guide initiation of ECPR. Ventricular fibrillation was induced in 12 pigs and CPR was performed until ETCO2 fell below 10 mmHg; then, ECPR was performed. Animals were divided into group short (GShort) and group long (GLong), according to time of CPR. Carotid blood flow was higher (p = 0.02) and mean arterial blood pressure lower in GLong during CPR (p < 0.05). B-Lactate was lower and pH higher in GShort (p < 0.01). In microdialysis lactate-pyruvate ratio, glycerol and glutamate increased in both groups during CPR, but considerably in GLong (p < 0.01). No difference could be seen in histopathology of the brain or kidney post-ECPR. No apparent histological differences of tissue damage in brains or levels of S100B in plasma were detected between groups. This might suggest that ETCO2 could be used as a marker for brain injury following ECPR.

Severe chronic aortic regurgitation after percutaneous coronary intervention: a case report and literature review.

BACKGROUND: Severe aortic regurgitation (AR) is an extremely rare complication after coronary catheterization and percutaneous coronary intervention (PCI), where most reported cases have required relatively urgent surgical intervention due to acute-onset AR and cardiac decompensation. CASE SUMMARY: We report a case of a 60-year-old woman that previously presented with a non-ST-elevation myocardial infarction (NSTEMI) due to an ostial right coronary artery stenosis. During the course of 2 years, she developed five recurrent NSTEMI due to in-stent thrombosis, necessitating either a new coronary stent or balloon. She developed a chronic severe AR due to a drug-eluting coronary stent protruding from the right coronary artery and underwent successful aortic valve replacement and coronary artery by-pass grafting. DISCUSSION: We performed a literature review and identified 16 reported cases of iatrogenic severe aortic regurgitation related to coronary catheterization or percutaneous coronary intervention. All patients developed an acute aortic regurgitation and, thus, we report the first case of a delayed complication caused by a protruding coronary stent. The surgical strategy is related to the extent of the damage, where smaller perforations or lacerations seems to be feasible for aortic valve repair and larger defects more often lead to aortic valve replacement. Our patient developed a fibrotic right coronary cusp which could not be used to perform a successful aortic valve repair.

End-Tidal Carbon Dioxide Impacts Brain and Kidney Injury in Experimental Extracorporeal Cardiopulmonary Resuscitation (ECPR).

PURPOSE: Extracorporeal membrane oxygenation-assisted cardiopulmonary resuscitation (ECPR) is proposed for cardiac resuscitation in selected cases. End-tidal carbon dioxide (ETCO2) is easily obtained during conventional cardiopulmonary resuscitation (CPR). We hypothesized that the level of ETCO2 during CPR would reflect the degree of brain and kidney damage following ECPR in experimental refractory cardiac arrest. METHODS: Ventricular fibrillation was induced in 10 pigs, followed by mechanical CPR for 45 min and thereafter ECPR for 180 min. Blood- and urine-samples, physiologic parameters, and histopathology of brain and kidney were analyzed. Animals were divided into Group High (GHigh) and Group Low (GLow) according to value of ETCO2 (10 mm Hg) at the end of CPR. RESULTS: Carotid blood pressure and blood flow declined over time in both groups during CPR but was higher in GHigh. Coefficient of determination for ETCO2 and carotid blood flow was substantial (r2 = 0.62). The oxygen delivery index was higher for GHigh 444 (396-485) L/min/m2 as compared with GLow at 343 (327-384) L/min/m2 (P = 0.02) at the end of ECPR. Also, P-S100B were lower in GHigh, (P < 0.05) and GLow demonstrated worse histopathological injury in central parts of the brain (P < 0.01). During ECPR, urinary output was higher in GHigh (P < 0.05). Kidney injury marker Plasma Neutrophil Gelatinae-associated Lipocalin increased in both groups during ECPR but was more pronounced in GLow (P = 0.03). Renal histopathology revealed no difference between groups. CONCLUSIONS: ETCO2 at the end of mechanical CPR is inversely associated with extent of brainstem and renal injury following ECPR.

Commando procedure in a patient with double-valve endocarditis after transcatheter aortic valve implantation.

The indication for transcatheter aortic valve implantation (TAVI) is continuously expanding with a simultaneous increase in number of TAVI associated prosthetic valve endocarditis (TAVI-PVE). Evidence for management of TAVI-PVE is lacking but the need for surgical management of complex TAVI-PVE is expected to increase. The Commando procedure, a technically challenging surgery for treatment of complex endocarditis, has never been described in a patient with TAVI-PVE. An 80-year-old female with TAVI-PVE, native mitral valve endocarditis and an abscess in the intervalvular fibrous body was admitted to our clinic. She successfully underwent the Commando procedure with implantation of biological mitral and aortic valve prostheses and reconstruction of the intervalvular fibrous body. We demonstrate that the Commando procedure is a feasible surgical alternative in patients with TAVI-PVE and that it can be considered in patients with high surgical risk.

Survival after refractory cardiogenic shock is comparable in patients with Impella and veno-arterial extracorporeal membrane oxygenation when adjusted for SAVE score.

OBJECTIVES: Survival after different short-term mechanical circulatory support is difficult to compare because various systems are used and patient disease severity is most often not adjusted for. This study compares the outcome after the use of Impella and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) in refractory cardiogenic shock, adjusted for disease severity through the survival after the VA-ECMO (SAVE) score. METHODS: Patients with refractory shock treated with either VA-ECMO or Impella between January 2003 and August 2015 were included. Data were analysed to assess short and long-term survival and complications. The SAVE score was calculated for the two groups and outcome was compared adjusted for the SAVE score. RESULTS: There was no difference between VA-ECMO patients (n=46) and Impella patients (n=48) in mean age or renal failure. ECMO patients were more often intubated and had lower diastolic blood pressure at device implantation. ECMO patients had a lower SAVE score (-0.4 (6.5)) compared to Impella patients (4.1 (5.4)). There was no difference in intensive care unit survival between ECMO patients 65% (52-80) or Impella patients 63% (55-79), or long-term survival between groups. When stratified into worse (III-IV) or better SAVE class (I-II) there was no difference in survival between the groups. CONCLUSIONS: Short and long-term survival is not measurably different among patients treated with Impella or VA-ECMO due to refractory cardiogenic shock, after adjustment for disease severity through the SAVE score.

Experimental Venoarterial Extracorporeal Membrane Oxygenation Induces Left Ventricular Dysfunction.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) has experienced an increased use in acute cardiac failure. There are some reports on negative effects of VA-ECMO on cardiac function, such as left ventricular (LV) dilatation and cardiac stun, but the support in the literature is scarce. This study investigates the effects of experimental VA-ECMO on LV function in both peripheral and central cannulation. Ten pigs were randomized to VA-ECMO by either peripheral cannulation through the femoral vessels or central cannulation in the right atrium and ascending aorta. Left ventricular performance was measured with pressure-volume catheters during 5 hours of VA-ECMO. The LV end-diastolic and end-systolic volumes increased comparably in both groups during ECMO. Left ventricular ejection fraction, stroke work, and maximum rate of pressure change decreased comparably in both groups as a function of time on ECMO. The site of cannulation had no impact on the LV response to ECMO. In conclusion, VA-ECMO increased LV volumes and reduced LV function, irrespective of cannulation site in this experimental model. Reduced LV ejection fraction and stroke work indicated LV dysfunction during ECMO.

The Impella® Recover mechanical assist device in acute cardiogenic shock: a single-centre experience of 66 patients.

OBJECTIVES: Short-term ventricular assist devices are more frequently used in patients with acute cardiogenic shock. The aim of this study was to evaluate its effect on haemodynamic parameters, as well as the short- and long-term outcome and complication rate associated with the device. METHODS: All patients treated with the Impella® Recover device at our centre from 2003 to 2014 (n = 66) were included in this study, and follow-up time was 2.9 (±0.4) years. Data were obtained through patient records and the population register. Patient-related factors, preimplantation and early postimplantation haemodynamic and biochemical parameters were analysed. Characteristics of survivors and non-survivors were compared. RESULTS: The device was implanted in 66 patients and 58% (38/66) were alive at 30 days post-implantation. The mean duration of support was 7.4 (±0.8) days. Mean time in the intensive care unit was 24 (±4) days. Following device implantation, patients' cardiac index improved from 2.1 l/min/m(2) (±0.20) to 3.8 l/min/m(2) (±0.20) at Day 7, mixed venous saturation increased from 56% (±2.0) to 68% (±1.2) and diuresis increased from 69 ml/h (±9) at device insertion to 105 ml/h (±19) at Day 7 on support. Central venous pressure, lactate levels and inotropic support decreased on support. No difference between survivors and non-survivors was established. No correlation was established between preimplant parameters and 30-day mortality. CONCLUSIONS: The Impella® Recover device improved haemodynamics in patients with acute cardiogenic shock. Still, 30-day mortality remains high and future studies must focus on the optimal timing of placement of the device.

A modified Glenn shunt reduces right ventricular stroke work during left ventricular assist device therapy.

OBJECTIVES: Right ventricular (RV) failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) placement and remains hard to predict. We hypothesized that partial surgical exclusion of the RV with a modified Glenn shunt during LVAD treatment would reduce RV stroke work. METHODS: An LVAD was implanted in eight pigs and a modified Glenn shunt was constructed. A conductance pressure-volume catheter was placed in the right ventricle through the apex. Haemodynamic data and pressure-volume loops were obtained at the following time periods: (i) baseline, (ii) open shunt, (iii) LVAD with closed shunt and (iii) LVAD and open shunt. RESULTS: During LVAD therapy, the right atrial (RA) pressure increased from 9 mmHg (9-9) to 15 mmHg (12-15), P = 0.01. RV stroke volume increased from 30 ml (29-40) to 51 ml (42-53), P < 0.01. Also, RV stroke work increased to 708 mmHg ml (654-1193) from 535 mmHg ml (424-717), P = 0.04, compared with baseline. During LVAD therapy in combination with a Glenn shunt, the RA pressure decreased from 15 mmHg (12-15) to 10 mmHg (7-11) when compared with LVAD therapy only, P = 0.01. A decrease in RV stroke work from 708 mmHg ml (654-1193) to 465 mmHg ml (366-711), P = 0.04, was seen when the LVAD was combined with a shunt, not significantly different from the baseline value (535 mmHg ml). The developed pressure in the right ventricle decreased from 29 mmHg (26-32) to 21 mmHg (20-24), P < 0.01. The pressure-volume loops of the RV show a significant reduction of RV stroke work during the use of the shunt with LVAD treatment. CONCLUSIONS: A modified Glenn shunt reduced RV volumes, RV stroke work and RA pressure during LVAD therapy in an experimental model of heart failure in pigs.

In Vivo Effects of Mesenchymal Stromal Cells in Two Patients With Severe Acute Respiratory Distress Syndrome.

UNLABELLED: Mesenchymal stromal cells (MSCs) have been investigated as a treatment for various inflammatory diseases because of their immunomodulatory and reparative properties. However, many basic questions concerning their mechanisms of action after systemic infusion remain unanswered. We performed a detailed analysis of the immunomodulatory properties and proteomic profile of MSCs systemically administered to two patients with severe refractory acute respiratory distress syndrome (ARDS) on a compassionate use basis and attempted to correlate these with in vivo anti-inflammatory actions. Both patients received 2×10(6) cells per kilogram, and each subsequently improved with resolution of respiratory, hemodynamic, and multiorgan failure. In parallel, a decrease was seen in multiple pulmonary and systemic markers of inflammation, including epithelial apoptosis, alveolar-capillary fluid leakage, and proinflammatory cytokines, microRNAs, and chemokines. In vitro studies of the MSCs demonstrated a broad anti-inflammatory capacity, including suppression of T-cell responses and induction of regulatory phenotypes in T cells, monocytes, and neutrophils. Some of these in vitro potency assessments correlated with, and were relevant to, the observed in vivo actions. These experiences highlight both the mechanistic information that can be gained from clinical experience and the value of correlating in vitro potency assessments with clinical effects. The findings also suggest, but do not prove, a beneficial effect of lung protective strategies using adoptively transferred MSCs in ARDS. Appropriate randomized clinical trials are required to further assess any potential clinical efficacy and investigate the effects on in vivo inflammation. SIGNIFICANCE: This article describes the cases of two patients with severe refractory adult respiratory syndrome (ARDS) who failed to improve after both standard life support measures, including mechanical ventilation, and additional measures, including extracorporeal ventilation (i.e., in a heart-lung machine). Unlike acute forms of ARDS (such in the current NIH-sponsored study of mesenchymal stromal cells in ARDS), recovery does not generally occur in such patients.

Percutaneous Fluoroscopic-Guided Endomyocardial Delivery in an Experimental Model of Left Ventricular Assist Device Support.

Endomyocardial delivery in the setting of active left ventricular assist device (LVAD) support has rarely been studied. The objective was to establish a protocol for endomyocardial injections during LVAD support without compromising mechanical circulation. LVAD implantation was performed in four pigs. A curved needle catheter was percutaneously inserted into the right carotid artery and positioned into the left ventricle under fluoroscopic guidance. In the setting of increasing LVAD flows (2.3-3.1 l/min), percutaneous methylene blue dye administration into the myocardium proceeded without complications in all pigs. Transection of excised hearts revealed an anterior, lateral, inferior, and septal wall distribution of methylene blue documenting injections in all four regions of the left ventricle. Ex vivo, the catheter could be maneuvered close to the LVAD inflow cannula despite augmentation of LVAD flow up to 5 l/min. Endomyocardial injections during LVAD support was found to be feasible and safe with the curved needle catheter.

Preoperative brain natriuretic peptide predicts late mortality and functional class but not hospital readmission after cardiac surgery.

OBJECTIVES: N-terminal brain natriuretic peptide (NT-proBNP) is an established biomarker of heart failure and has been found to predict mortality and morbidity after cardiac surgery. The aim of this study was to investigate whether preoperative NT-proBNP can predict postoperative New York Heart Association (NYHA) functional class and hospital readmission in addition to morbidity and mortality. DESIGN: Retrospective. SETTING: University hospital. PARTICIPANTS: All patients undergoing aortic valve replacement for aortic stenosis and coronary artery bypass grafting from January to December 2008 (n = 390). MEASUREMENTS AND MAIN RESULTS: Preoperative NT-proBNP was recorded prospectively. Five-year mortality was obtained through national registries. Postoperative functional class, morbidity, and hospital readmission were obtained through telephone interviews. Patients were divided into quartiles based on preoperative NT-proBNP; the medians of each quartile were 103 ng/L, 291 ng/L, 825 ng/L and 2,375 ng/L. Increased preoperative NT-proBNP was associated with reduced postoperative functional class. In the first quartile, 7% (7/97) were in NYHA functional class III-IV compared to 26% (25/97) in the fourth quartile (p<0.01). Increased preoperative NT-proBNP was also associated with reduced long-term survival (p<0.01). The covariate adjusted hazard ratio for mortality in the fourth quartile was 2.9 (1.61-5.08; p<0.01) compared to the other quartiles. No association was found between preoperative NT-proBNP and postoperative hospital readmission. CONCLUSIONS: Increased preoperative NT-proBNP is associated with reduced long-term survival and functional class but not hospital readmission post-cardiac surgery. Thus, NT-proBNP might have additive value to established risk factors in the preoperative assessment of patients undergoing cardiac surgery.

A modified Glenn shunt reduces venous congestion during acute right ventricular failure due to pulmonary banding: a randomized experimental study.

OBJECTIVES: Right ventricular failure after left ventricular assist device implantation is a serious complication with high rates of mortality and morbidity. It has been demonstrated in experimental settings that volume exclusion of the right ventricle with a modified Glenn shunt can improve haemodynamics during ischaemic right ventricular failure. However, the concept of a modified Glenn shunt is dependent on a normal pulmonary vascular resistance, which can limit its use in some patients. The aim of this study was to explore the effects of volume exclusion with a modified Glenn shunt during right ventricular failure due to pulmonary banding, and to study the alterations in genetic expression in the right ventricle due to pressure and volume overload. METHODS: Experimental right ventricular failure was induced in pigs (n = 11) through 2 h of pulmonary banding. The pigs were randomized to either treatment with a modified Glenn shunt and pulmonary banding (n = 6) or solely pulmonary banding (n = 5) as a control group. Haemodynamic measurements, blood samples and right ventricular biopsies for genetic analysis were sampled at baseline, at right ventricular failure (i.e. 2 h of pulmonary banding) and 1 h post-right ventricular failure in both groups. RESULTS: Right atrial pressure increased from 10 mmHg (9.0-12) to 18 mmHg (16-22) (P < 0.01) and the right ventricular pressure from 31 mmHg (26-35) to 57 mmHg (49-61) (P < 0.01) after pulmonary banding. Subsequent treatment with the modified Glenn shunt resulted in a decrease in right atrial pressure to 13 mmHg (11-14) (P = 0.03). In the control group, right atrial pressure was unchanged at 19 mmHg (16-20) (P = 0.18). At right heart failure, there was an up-regulation of genes associated with heart failure, inflammation, angiogenesis, negative regulation of cell death and proliferation. CONCLUSIONS: Volume exclusion with a modified Glenn shunt during right ventricular failure reduced venous congestion compared with the control group. The state of right heart failure was verified through genetic expressional changes.

Cavoaortic shunt improves hemodynamics with preserved oxygen delivery in experimental right ventricular failure during left ventricular assist device therapy.

OBJECTIVE: Right heart failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) implantation. This study evaluated the approach of a cavoaortic shunt included in the LVAD circuit, which would aim to relieve venous congestion and improve hemodynamics with preserved oxygen delivery during induced right ventricular failure. METHODS: Right ventricular failure was induced by coronary ligation in 10 pigs. An LVAD was implanted and a cavoaortic shunt was created from the right atrium and included in the assist circuit. Hemodynamic measures and blood gas analyses were analyzed. Oxygen delivery and oxygen consumption were estimated. RESULTS: Right atrial pressure decreased from more than 20 mm Hg to 17.2 mm Hg (14.8-18.4) with the LVAD and to 14.1 mm Hg (11.2-15.5) (P < .01) with the LVAD and cavoaortic shunt. Mean arterial pressure increased from 70.9 mm Hg (67.6-79.8) to 81.5 mm Hg (70.8-92.6) (P = .02) with addition of the shunt into the assist circuit. Cardiac output increased from 3.5 L/min (2.6-4.2) to 4.9 L/min (3.5-5.6) (P < .01) with cavoaortic shunting. Oxygen delivery with the cavoaortic shunt was 337 mL/min (± 70) as compared with left ventricular assist alone at 258 mL/min (± 52) (P < .01). Oxygen consumption was restored during use of the cavoaortic shunt. CONCLUSIONS: A cavoaortic shunt combined with an LVAD during right ventricular failure reduces central venous pressures, increases systemic arterial pressure, and enables increased cardiac output compared with device therapy alone. This was feasible with preserved oxygen delivery.

A modified Glenn shunt improves haemodynamics in acute right ventricular failure in an experimental model.

OBJECTIVES: Right heart failure is a major cause of morbidity and mortality after left ventricular assist device implantation and is still hard to predict. This study investigated the haemodynamic effect of a modified Glenn shunt on induced right ventricular (RV) failure. METHODS: Isolated RV failure was induced by coronary ligation in 11 pigs. A modified Glenn shunt was established by a superior vena cava to pulmonary artery connection. Haemodynamic data were obtained at baseline, RV failure, and RV failure and open shunt. Myocardial biopsies were taken to ascertain established heart failure. RESULTS: RV failure defined as right atrial pressure ≥20 mmHg was achieved in all 11 animals. A reduction in cardiac output (CO) from 3.7 (3.5-4.2) to 2.3 l/min (2.0-2.6) and mean arterial pressure (MAP) from median 72.7 (70.1-82.2) to 55.9 mmHg (52.6-59.8) was seen during heart failure. The median flow in the shunt was 681 ml. Right atrial pressures decreased from 20.3 (19.6-21.1) to 13.4 mmHg (12.7-14.0), and RV pressures decreased from 18.1 (16.4-20.1) to 13.6 mmHg (13.5-14.2) with open shunt (P = 0.001 for both). CO increased to 2.9 l/min (2.4-3.3) when the shunt was in use. Mixed venous oxygen saturation increased with the shunt from 32 (27-38) to 49% (45-56), P = 0.001. Genes associated with heart failure were upregulated during heart failure. CONCLUSIONS: A modified Glenn shunt improved haemodynamics by reduced right atrial pressure, increased CO, MAP and mixed venous oxygen saturation in an experimental model of induced RV failure.

αB-Crystallin regulates expansion of CD11b⁺Gr-1⁺ immature myeloid cells during tumor progression.

The molecular chaperone αB-crystallin has emerged as a target for cancer therapy due to its expression in human tumors and its role in regulating tumor angiogenesis. αB-crystallin also reduces neuroinflammation, but its role in other inflammatory conditions has not been investigated. Here, we examined whether αB-crystallin regulates inflammation associated with tumors and ischemia. We found that CD45(+) leukocyte infiltration is 3-fold increased in tumors and ischemic myocardium in αB-crystallin-deficient mice. Notably, αB-crystallin is prominently expressed in CD11b(+) Gr-1(+) immature myeloid cells (IMCs), known as regulators of angiogenesis and immune responses, while lymphocytes and mature granulocytes show low αB-crystallin expression. αB-Crystallin deficiency results in a 3-fold higher accumulation of CD11b(+) Gr-1(+) IMCs in tumors and a significant rise in CD11b(+) Gr-1(+) IMCs in spleen and bone marrow. Similarly, we noted a 2-fold increase in CD11b(+) Gr-1(+) IMCs in chronically inflamed livers in αB-crystallin-deficient mice. The effect of αB-crystallin on IMC accumulation is limited to pathological conditions, as CD11b(+) Gr-1(+) IMCs are not elevated in naive mice. Through ex vivo differentiation of CD11b(+) Gr-1(+) cells, we provide evidence that αB-crystallin regulates systemic expansion of IMCs through a cell-intrinsic mechanism. Our study suggests a key role of αB-crystallin in limiting expansion of CD11b(+) Gr-1(+) IMCs in diverse pathological conditions.

Ninein is expressed in the cytoplasm of angiogenic tip-cells and regulates tubular morphogenesis of endothelial cells.

OBJECTIVE: Angiogenesis is an integral part of many physiological processes but may also aggravate pathological conditions such as cancer. Development of effective angiogenesis inhibitors requires a thorough understanding of the molecular mechanisms regulating vessel formation. The aim of this project was to identify proteins that regulate tubular morphogenesis of endothelial cells. METHODS AND RESULTS: Phosphotyrosine-dependent affinity-purification and mass spectrometry showed tyrosine phosphorylation of ninein during tubular morphogenesis of endothelial cells. Ninein was recently identified as a centrosomal microtubule-anchoring protein. Our results show that ninein is localized in the cytoplasm in endothelial cells, and that it is highly expressed in the vasculature in normal and pathological human tissues. Using embryoid bodies as a model of vascular development, we found that ninein is abundantly expressed in the cytoplasm of endothelial cells during sprouting angiogenesis, in particular in the sprouting tip-cell. In accordance, siRNA-dependent silencing of ninein in endothelial cells inhibited tubular morphogenesis. CONCLUSIONS: In this study, we show that ninein is expressed in developing vessels and in endothelial tip cells, and that ninein is critical for formation of the vascular tube. These data strongly implicate ninein as an important new regulator of angiogenesis.

alphaB-crystallin promotes tumor angiogenesis by increasing vascular survival during tube morphogenesis.

Selective targeting of endothelial cells in tumor vessels requires delineation of key molecular events in formation and survival of blood vessels within the tumor microenvironment. To this end, proteins transiently up-regulated during vessel morphogenesis were screened for their potential as targets in antiangiogenic tumor therapy. The molecular chaperone alphaB-crystallin was identified as specifically induced with regard to expression level, modification by serine phosphorylation, and subcellular localization during tubular morphogenesis of endothelial cells. Small interfering RNA-mediated knockdown of alphaB-crystallin expression did not affect endothelial proliferation but led to attenuated tubular morphogenesis, early activation of proapoptotic caspase-3, and increased apoptosis. alphaB-crystallin was expressed in a subset of human tumor vessels but not in normal capillaries. Tumors grown in alphaB-crystallin(-/-) mice were significantly less vascularized than wild-type tumors and displayed increased areas of apoptosis/necrosis. Importantly, tumor vessels in alphaB-crystallin(-/-) mice were leaky and showed signs of caspase-3 activation and extensive apoptosis. Ultrastructural analyses showed defective vessels partially devoid of endothelial lining. These data strongly implicate alphaB-crystallin as an important regulator of tubular morphogenesis and survival of endothelial cell during tumor angiogenesis. Hereby we identify the small heat shock protein family as a novel class of angiogenic modulators.