Efficacy of the BNT162b2 mRNA COVID-19 vaccine in patients with B-cell non-Hodgkin lymphoma.

Patients diagnosed with B-cell non-Hodgkin lymphoma (B-NHL), particularly if recently treated with anti-CD20 antibodies, are at risk of severe COVID-19 disease. Because studies evaluating humoral response to COVID-19 vaccine in these patients are lacking, recommendations regarding vaccination strategy remain unclear. The humoral immune response to BNT162b2 messenger RNA (mRNA) COVID-19 vaccine was evaluated in patients with B-NHL who received 2 vaccine doses 21 days apart and compared with the response in healthy controls. Antibody titer, measured by the Elecsys Anti-SARS-CoV-2S assay, was evaluated 2 to 3 weeks after the second vaccine dose. Patients with B-NHL (n = 149), aggressive B-NHL (a-B-NHL; 47%), or indolent B-NHL (i-B-NHL; 53%) were evaluated. Twenty-eight (19%) were treatment naïve, 37% were actively treated with a rituximab/obinutuzumab (R/Obi)-based induction regimen or R/Obi maintenance, and 44% had last been treated with R/Obi >6 months before vaccination. A seropositive response was achieved in 89%, 7.3%, and 66.7%, respectively, with response rates of 49% in patients with B-NHL vs 98.5% in 65 healthy controls (P < .001). Multivariate analysis revealed that longer time since exposure to R/Obi and absolute lymphocyte count ≥0.9 × 103/µL predicted a positive serological response. Median time to achieve positive serology among anti-CD20 antibody-treated patients was longer in i-B-NHL vs a-B-NHL. The humoral response to BNT162b2 mRNA COVID-19 vaccine is impaired in patients with B-NHL who are undergoing R/Obi treatment. Longer time since exposure to R/Obi is associated with improved response rates to the COVID-19 vaccine. This study is registered at www.clinicaltrials.gov as #NCT04746092.

PO-46 - Influence of extracellular vesicles derived from AML patients on stem cells and their microenvironment.

INTRODUCTION: Acute myeloid leukemia (AML) is characterized by rapid growth of leukemic blast cells. Extracellular vesicles (EVs) are shed from normal and pathologic cells and express membrane proteins and antigens, reflecting their cellular origin. AIM: To explore whether bone marrow EVs of AML patients originate from blast cells and are capable of influencing hematopoietic stem cells (HSC) in a pseudo-natural microenvironment obtained by co-culture of HSC with mesenchymal stem cells (MSC). MATERIALS AND METHODS: Bone marrow (BM) samples were collected from healthy controls and patients with newly diagnosed AML at three time points: diagnosis, nadir and remission. EV concentration, cell origin and expression of coagulation proteins were characterized by FACS. Stem cells were obtained from Ficoll gradient of cord blood (CB) followed by CD34+ isolation. Cord blood stem cells with or without MSC were co-incubated with AML EVs. EV internalization was demonstrated by FACS-AMNIS and confocal microscopy. Mir-125b and -155 expressions in the cells were analyzed by RT-PCR. RESULTS: AML patients were enrolled in the study. The total BM-EVs number was higher in patients at first remission compared to controls, while blast EV counts (labeled with anti-CD34, CD33, CD117) were higher in patients at diagnosis compared to controls and to patients in remission. Internalization of CD117+/CD33+ BM-EVs to cord blood stem cells in the presence or absence of MSC was evaluated by FACS-AMNIS. Confocal microscopy of CD33+ stained EVs strengthens the findings and shows presence of EVs even in the cytoplasm and the nucleus. Quantitative analysis of mir-125b and mir-155 expression in cord blood stem cells incubated with AML EVs revealed a clear tendency of increased expression in case of cell exposure to AML EVs in comparison to healthy control EVs. This tendency was emphasized in the presence of MSC. CONCLUSIONS: EVs of AML patients are generated from blast cells. By internalization into naïve stem cells they can influence their differentiation. Moreover, the presence of mesenchymal stem cells is likely to be essential to the process.

PO-45 - The role of microvesicles in multiple myeloma progression.

INTRODUCTION: Multiple myeloma (MM) is an incurable, genetically heterogeneous malignancy of plasma cells that secrete non-functioning immunoglobulins and present high proteasome activity. MM is characterized by bone marrow infiltration leading to multiple lytic bone lesions, cytopenia and increased rate of thrombotic events. Microvesicles (MVs) include exosomes (30-100 nm) and microparticles (0.1-1 micron) shed from various cells and expressing antigens reflecting their cellular origin. MVs are involved in thrombosis, inflammation and cancer.However, the effect of MM-MVs on disease progression and their mechanism of action are unclear. We assume that MVs play a role in the interaction between malignant plasma cells and mesenchymal and endothelial cells (EC). AIM: To characterize MM-MVs and investigate their effects on microenvironment cells. MATERIALS AND METHODS: MVs were isolated from MM cell line RPMI 8226 untreated or treated with bortezomib and from peripheral blood (PB) and bone marrow (BM) of MM patients (n=13) and healthy controls (n=14). MM-MV size, concentration and cell origin were measured by Nanosite and FACS. Protein content was evaluated by protein arrays and ELISA. Coagulation and proteasome activity were assessed using chromogenic assays. Migratory capacity (migration assay), proliferative rate (XTT assay) and cell-signaling effects (Western blot analysis) of MVs on BM-mesenchymal and ECs were analyzed. RESULTS: MM cells exhibited high MV shedding rate, which further increased with the exposure to bortezomib. Significant elevation in MV production was found in MM patients compared to controls. MM-MVs expressed membrane MM markers (syndecan-1/ CD138, CD38), coagulation factor (TF, TFPI, EPCR, TM) and angiogenic factors (VEGFR1, VEGFR2, and CD31). MM-MVs contained high levels of growth factors (Angiogenin, PDGF-BB and VEGF) and displayed procoagulant and proteasome activity. MM-MVs penetrated cells and affected their function. MVs of untreated cells and patient MVs increased EC and mesenchymal cell migration and EC proliferation, while MVs obtained from bortezomib-treated cells decreased these effects. MVs of untreated cells increased ERK1/2 and c-Jun phosphorylation in ECs (by 6.15 and 1.84 fold) but did not affect MAPKAPK-2. MVs of bortezomib-treated cells reduced c-Jun phosphorylation in ECs. CONCLUSIONS: MM cells are characterized by high shedding rate of MVs. They are pro-coagulants and increase EC thrombogenicity, suggesting their involvement in MM-related thrombosis. MVs contain high levels of angiogenic factors that affect mesenchymal and EC, induce cell migration and proliferation via specific signal transductions. MVs exposed to bortezomib display lower levels of angiogenic factors, which limits proliferation and migration of MVs, reflecting the efficacy of therapy and MM dynamics.

Modified Norwood operation for hypoplastic left heart syndrome.

BACKGROUND: We examined early results in infants with hypoplastic left heart syndrome undergoing the Norwood operation with perioperative use of inhaled nitric oxide and application of extracorporeal membrane oxygenation. METHODS: Medical records were reviewed retrospectively. RESULTS: Between April 1997 and March 2001, 50 infants underwent a modified Norwood operation for hypoplastic left heart syndrome. Mean age at operation was 7.5 +/- 5.7 days, and mean weight was 3.1 +/- 0.5 kg. Five infants had a delayed operation because of sepsis. The mean diameter of the ascending aorta by echocardiography was 3.6 +/- 1.8 mm. Ductal cannulation was used to establish cardiopulmonary bypass in all patients. Mean circulatory arrest time was 39.4 +/- 4.8 minutes. The size of the pulmonary-systemic shunt was 3.0 mm in 6 infants, 3.5 mm in 37, and 4.0 mm in 7. Infants with persistent hypoxia (partial pressure of oxygen < 30 mm Hg) received nitric oxide after they were weaned from cardiopulmonary bypass. Extracorporeal membrane oxygenation was initiated in 8 infants in the pediatric intensive care unit primarily for low cardiac output and in 8 in the operating room because of the inability to separate them from cardiopulmonary bypass. The 30-day mortality rate was 22% (11 of 50 patients), and the hospital mortality rate was 32% (16 of 50 patients). Mean follow-up was 17 months. Ten patients (20%) underwent stage-two repair, with one operative death. One survivor had a Fontan procedure, and 2 underwent heart transplantation, with one death. CONCLUSIONS: Early application of extracorporeal membrane oxygenation for hemodynamic instability and selective use of nitric oxide for persistent hypoxia in the immediate postoperative period may improve survival of patients with hypoplastic left heart syndrome. Renal failure requiring hemofiltration during extracorporeal membrane oxygenation (p < 0.05) and cardiopulmonary arrest in the pediatric intensive care unit (p < 0.05) were predictors of hospital mortality.

Extracorporeal membrane oxygenation in children after repair of congenital cardiac lesions.

BACKGROUND: The purpose of this study was to review our experience in the early application of extracorporeal membrane oxygenation (ECMO) in patients requiring mechanical assistance after cardiac surgical procedures. METHODS: The hospital records of all children requiring ECMO after cardiac operation were retrospectively reviewed, and an analysis of variables affecting survival was performed. RESULTS: Fifty pediatric patients between May 1997 and October 2000 required ECMO for cardiopulmonary support after cardiac operation. Patients ranged in age from 1 day to 11 years (median age, 40 days). Forty-eight patients underwent repair of congenital cardiac lesions and 2 were included after receiving a heart transplant. Twenty-two children could not be weaned from cardiopulmonary bypass and were placed on ECMO in the operating room for circulatory support. Of the 28 children who required ECMO in the intensive care unit, 10 had ECMO instituted after cardiopulmonary arrest (mean cardiopulmonary resuscitation time 42 minutes; range, 5 to 110 minutes). In infants with single-ventricle physiology, survival to discharge was 61% (11 of 18 patients) as compared with 43% (14 of 32 patients) in those with biventricular physiology. Thirty of the 50 patients (60%) were successfully weaned from ECMO, of which 25 (83%) were discharged home. Overall survival to discharge in the entire cohort was 50%. Extracorporeal membrane oxygenation support greater than 72 hours was a grave prognostic indicator. Overall survival in this group was 36% (9 of 25 patients) compared with 56% (14 of 25 patients) in those with ECMO support less than 72 hours (p < 0.05). Univariate analysis revealed the presence of renal failure, extended periods of circulatory support, and a prolonged period of cardiopulmonary resuscitation as risk factors for mortality. The presence of shunt-dependent flow, operative procedure, and institution of ECMO in the intensive care unit did not alter survival. CONCLUSIONS: Extracorporeal membrane oxygenation provides effective support for postoperative cardiac and pulmonary failure refractory to medical management. Early institution of ECMO may decrease the incidence of cardiac arrest and end-organ damage, thus increasing survival in these critically ill patients.

The paracetamol absorption test: a useful addition to the enteral nutrition algorithm?

BACKGROUND: Enteral nutrition in critically ill patients given via the nasogastric route is often decreased or stopped because of large gastric residual volumes. AIM: To assess the effect of continuing enteral nutrition in patients with an elevated gastric residual volume but normal gastric emptying by the paracetamol absorption test. METHODS: The paracetamol absorption test was performed on all patients receiving enteral nutrition via a nasogastric tube who had a residual volume (assessed every 8 hours) of >150 ml or more than twice the hourly infusion rate. Patients were then divided into 2 groups according to the result of the test: Group 1 (n=8), normal gastric emptying; and Group II (n=24), abnormal gastric emptying. Group I continued to receive enteral nutrition. In Group II feeding was interrupted in 18 patients and prokinetic agents administered, while a subgroup of six patients continued to receive enteral nutrition without prokinetic agents. All patients were followed for evidence of delayed gastric emptying and aspiration. RESULTS: Residual volumes were similarly elevated in both groups (p=0.25). Enteral nutrition was continued in Group I with no adverse effects. Prokinetic agents allowed enteral nutrition to be resumed in 88% of the 18 Group II patients. Enteral nutrition in the subgroup had to be stopped because of persistently elevated residual volumes. CONCLUSION: The paracetamol absorption test may be normal in patients with relatively high gastric residual volumes. These patients may continue to receive enteral nutrition.

Successful treatment of early secondary myelofibrosis in SLE with IVIG.

Myelofibrosis has been reported as a rare cause of pancytopenia in patients with autoimmune diseases. We describe a 54y old female patient who was admitted with severe anemia subsequently found to be due to marrow fibrosis. During the course of her hospitalization, relying both on her clinical symptoms as well as the results of a wide range of laboratory tests and diagnostic procedures, the diagnosis of systemic lupus erythematosus was established. The patient was treated with high dose steroids, but improvement of her clinical symptoms as well as normalization of her peripheral blood count were achieved only after high dose intravenous therapy with gamma globulin (IVIG) was instituted. Along with the improvement in the peripheral blood parameters normalization of the bone marrow architecture was recorded on a repeated bone marrow biopsy. IVIG therapy should be considered in extreme cases of bone marrow suppression in SLE.

Evidence of improved microvascular perfusion when using antegrade and retrograde cardioplegia.

BACKGROUND: The maximum degree of microvascular distribution of cardioplegic solution is considered important to achieve optimum myocardial protection. This study attempts to demonstrate that the addition of retrograde cardioplegia to antegrade cardioplegia improves overall microvascular perfusion. METHODS: Explanted human hearts (n = 6) were treated with cold cardioplegic arrest and bicaval cardiectomy. Blood cardioplegia (37 degrees C) containing colored microspheres (color A for antegrade, color B for retrograde) was simultaneously infused antegrade at a pressure of 80 mm Hg and retrograde at a pressure of 40 mm Hg for 2 minutes. The ventricular myocardium was then sampled at three sites to determine absolute and relative cardioplegic microvascular flow. RESULTS: Of the total microvascular capillary flow, 27% to 32% was found to be the contribution of retrogradely delivered cardioplegia. CONCLUSIONS: Despite being delivered simultaneously and at a lower pressure, retrograde cardioplegia contributed substantially to overall microvascular perfusion. This suggests that antegrade cardioplegia alone does not perfuse all available myocardial capillaries and that the addition of retrograde cardioplegia enhances overall microvascular distribution and perfusion.

A comparison of distribution between simultaneously or sequentially delivered antegrade/retrograde blood cardioplegia.

UNLABELLED: Commercially available cardioplegia delivery systems now allow for antegrade (aortic root, coronary ostia, saphenous vein graft) perfusion to occur either sequentially or simultaneous with retrograde (coronary sinus) perfusion. This study was designed to compare the total flow and local distribution of sequential versus simultaneous antegrade/retrograde cardioplegia delivery. METHODS: Explanted human hearts diagnosed with idiopathic cardiomyopathy underwent a cold cardioplegic arrest and bicaval cardiectomy. Thirty-seven degree centigrade blood cardioplegia containing colored microspheres was then delivered antegrade (red color) at a pressure of 80 mmHg or retrograde (blue color) at a pressure of 40 mmHg. In the sequential group (n = 6), cardioplegia was delivered antegrade and then retrograde for 2 minutes, respectively. For the simultaneous group (n = 6), cardioplegia was delivered both antegrade and retrograde for 2 minutes. The ventricular myocardium was then sampled at 12 representative sites to determine regional cardioplegic flow. RESULTS: Mean total cardioplegia delivery/minute was 0.69 +/- 0.62 mL/g per minute for sequential cardioplegia, and 0.46 +/- 0.19 mL/g per minute for simultaneous cardioplegia (p > 0.05, NS). At the 12 ventricular sites sampled, mean regional cardioplegic flow (mL/g per min) was in general slightly greater for sequential delivery. However, this was not statistically significant (p > 0.05, NS). CONCLUSION: The data suggest that there may be a slight advantage in total cardioplegia delivery and regional cardioplegia delivery when using sequential rather than simultaneous cardioplegia delivery. However, this difference was not statistically significant and is likely not of clinical significance. Therefore, we would recommend using either sequential or simultaneous antegrade/retrograde cardioplegia based upon whichever technique facilitates the conduct of the individual operation.

Can improved microvascular perfusion be achieved by using both antegrade and retrograde cardioplegia?

BACKGROUND: The complete and uniform distribution of cardioplegia to the microvasculature of the heart is considered critical for myocardial protection. This study explores the hypothesis that enhanced microvascular perfusion can be achieved by using both antegrade and retrograde cardioplegia. METHODS: Infant piglet hearts (n = 15) were arrested with antegrade blood cardioplegia, excised, and fixed with 2.5% glutaraldehyde by retrograde perfusion. Hearts were then perfused retrograde with an inert intracapillary marker (NTB-2). Six of these hearts served as controls (group 1) to anatomically demonstrate the degree of capillary perfusion achieved by the retrograde delivery route. Nine experimental hearts (group 2) underwent a subsequent infusion of antegrade blood cardioplegia to wash out NTB-2 capillaries coperfused by both the antegrade and retrograde delivery techniques. Sections of the left ventricular free wall and anterior-mid interventricular septum were taken and examined by light microscopy at four separate sites (average, 126 capillaries per section). RESULTS: In control hearts, 91.9% +/- 0.9% of ventricular capillaries and 91.4% +/- 5.8% of septal capillaries were perfused by retrograde cardioplegia. After antegrade blood cardioplegia washed out group 2 hearts, 14.0% +/- 4.1% of capillaries in the ventricle still contained NTB-2, as did 12.5% +/- 5.4% of capillaries in the septum. CONCLUSIONS: In this experimental model, antegrade blood cardioplegia did not coperfuse (and therefore washout) 12.5% to 14% (p < 0.05) of capillaries perfused by retrograde cardioplegia. This suggests that an additional 12.5% to 14% of capillaries within the myocardium may receive cardioplegia if retrograde cardioplegia is used in addition to antegrade cardioplegia. We conclude that by combining both antegrade and retrograde cardioplegia, there is a potential for enhanced overall microvascular perfusion.

University of Wisconsin solution versus Stanford cardioplegic solution and the development of cardiac allograft vasculopathy.

BACKGROUND: University of Wisconsin (intracellular) solution has been shown to offer some distinct benefits of myocardial preservation over Stanford (extracellular) solution, including a more rapid functional recovery, improved adenosine triphosphate preservation, and a tendency for less postoperative inotropic agents. However intracellular solutions with high potassium content have been reported to cause a functional if not structural endothelial injury in laboratory experiments. METHODS: Because of this information we retrospectively viewed our follow-up angiographic data for the development of the cardiac allograft vasculopathy in a consecutive series of 195 heart transplant recipients. These patients were treated in identical fashion, with the same immunosuppression regimen, except for the type of cardioplegia used--Stanford solution (group I n = 95) and University of Wisconsin solution (group II n = 100). RESULTS: With a mean follow-up of 24 months after transplantation, a significant difference was seen in the development of cardiac allograft vasculopathy in group II (22%) versus group I (14%, p < 0.03). Although significant differences were observed with univariate analysis with respect to donor age and ischemic time favoring group I and with multivariate statistical analysis with respect to overall rejections favoring group II, the only significant variable for the difference in the development of allograft vasculopathy was University of Wisconsin cardioplegic solution (p < 0.003). A subgroup of 30 patients previously randomized for a functional study comparing the two cardioplegic agents showed a tendency for statistical significance with a freedom from allograft vasculopathy of 93% in group I, as compared with 83% in group II, after 13 months follow-up (p = 0.09). The overall probability of being free of vasculopathy at 24 months was 86% for group I and 70% for group II. CONCLUSIONS: The data support the conclusion that University of Wisconsin intracellular solution is associated with an increased incidence of vasculopathy versus Stanford solution and warrants investigation for modification of this preservation agent in heart transplantation.

Modification of the Fontan procedure. Superior vena cava to left pulmonary artery connection and inferior vena cava to right pulmonary artery connection with adjustable atrial septal defect.

BACKGROUND: A modification of the Fontan procedure with unidirectional cavopulmonary connection is described in which the superior vena cava (SVC) is connected to the left pulmonary artery (PA) and the inferior vena cava (IVC) is connected to the right PA via a lateral tunnel with a snare-controlled, adjustable atrial septal defect (ASD). This allows matching of the SVC and IVC flows with the lung of appropriate size. The obligatory left Glenn shunt provides an adequate arterial oxygen saturation, and the elevation in SVC pressure is well tolerated. The adjustable ASD allows selective decompression of the IVC that maintains cardiac output and reduces fluid accumulation in the serous cavities. METHODS AND RESULTS: Since March 1992, we have performed this procedure in 18 patients. There were 17 children and 1 adult. Median age was 3 years and 9 months (range, 13 months to 36 years). Six patients had been staged with a previous bidirectional Glenn shunt. Preoperative cardiac catheterization revealed a PA pressure of 13 +/- 2 mm Hg and a transpulmonary gradient of 5 +/- 3 mm Hg. Ventricular function was satisfactory in all patients. At the completion of bypass, the pressures in the SVC and IVC were 16 +/- 4 mm Hg and 10 +/- 3 mm Hg, respectively (P < .01). The left atrial pressure was 6.0 +/- 3.0 mm Hg and the arterial O2 saturation on 100% oxygen was 93 +/- 3%. There was one death as a result of intractable atrial arrhythmias. The remaining 17 patients had a mean hospital stay of 9.7 days (6 to 18 days). The length of pleural drainage was 7 +/- 3 days. The ASD was adjusted in 11 patients before discharge. Oxygen saturation at discharge was 85.4 +/- 4%. Nine patients had repeat catheterization. The ASD was completely closed in 6 patients, an average of 2.5 months after surgery (range, 3 weeks to 5 months). After ASD closure, the arterial oxygen saturation was 96 +/- 3%, and the SVC and IVC pressures were both 13 +/- 3 mm Hg. CONCLUSIONS: The Fontan procedure with unidirectional cavopulmonary connection and adjustable ASD has several advantages that may reduce mortality and morbidity for the high-risk Fontan candidate.

The regional capillary distribution of retrograde blood cardioplegia in explanted human hearts.

Warm retrograde blood cardioplegia is frequently used for myocardial protection, despite experimental studies questioning the adequacy of capillary flow to the right ventricle and septum. The capillary distribution of retrograde blood cardioplegia in the human heart is unknown. Hearts from eight transplant recipients with the diagnosis of idiopathic or dilated cardiomyopathy were arrested in situ with cold blood cardioplegia and excised with the coronary sinus intact. Within 20 minutes of explanation, colored microspheres mixed in 37 degrees C blood cardioplegia were administered through the coronary sinus at a pressure of 30 to 40 mm Hg for 2 minutes. Twelve transmural myocardial samples were taken horizontally at the level of midventricle and apex to determine regional capillary flow rates. When retrograde warm blood cardioplegia was administered at a rate of 0.42 +/- 0.06 ml/gm/min, the left ventricle, the septum, the posterior wall of the right ventricle, and the apex consistently received capillary flow rates in excess of their metabolic requirements. The capillary perfusion of anterior and lateral walls of the right ventricle was marginally adequate to sustain aerobic metabolism. In explanted human hearts, retrograde blood cardioplegia provides adequate capillary flow to the left ventricle, the septum, the posterior wall of the right ventricle, and the apex; however, capillary flow to the anterior and lateral walls of the right ventricle is marginal. This study delineates the tenuous balance between supply and demand for right ventricular protection with warm continuous retrograde blood cardioplegia.

Coronary sinus ostial occlusion during retrograde delivery of cardioplegic solution significantly improves cardioplegic distribution and efficacy.

UNLABELLED: This study documents the gross flow characteristics and capillary distribution of cardioplegic solution delivered retrogradely with the coronary sinus open versus closed. METHODS: Five explanted human hearts from transplant recipients were used as experimental models. Hearts served as their own controls and received two doses of warm blood cardioplegic solution, each containing colored microspheres. The first dose was delivered through a retroperfusion catheter with the coronary sinus open and the second dose was delivered with the sinus occluded. Capillary flow was measured at twelve ventricular sites and gross flow was measured by examining coronary sinus regurgitation, thebesian vein drainage, and aortic effluent (nutrient flow). RESULTS: Coronary sinus ostial occlusion allowed for a significant decrease in total cardioplegic flow (1.74 +/- 0.40 ml/gm versus 1.06 +/- 0.32 ml/gm; p < 0.05) to occur while maintaining an identical intracoronary sinus pressure. Ostial occlusion also resulted in an increase in the ratio of nutrient flow/total cardioplegic flow from 32.3% +/- 15.1% to 61.3% +/- 7.9% (p < 0.05). A statistically significant improvement in capillary flow was found at the midventricular level in the posterior intraventricular septum and posterolateral right ventricular free wall. This improvement was also documented for the intraventricular septum and right ventricle at the level of the apex. CONCLUSION: Coronary sinus occlusion during retrograde cardioplegia significantly improves cardioplegic delivery to the right ventricle and posterior intraventricular septum. Furthermore, the technique affords a significant improvement in nutrient cardioplegic flow while reducing the overall volume of cardioplegic solution administered.