Erythrocyte-endothelial cell adherence in sickle cell disorders

Detachment of individual sickle erythrocytes from cultured endothelial cell monolayers has been evaluated by a fluid-shearing technique in an effort to quantitate adherence at shear forces that would be anticipated in the in vivo circulation. Nonirreversibly sickled cells (non-ISC) were more adherent at normal oxygen tensions than control cells. More than 1% non-ISC remained attached to the monolayer at forces greater than physiologic shear stresses in capillary and venous circulations, and many of the most avidly attached cells, once separated, immediately reattached to adjacent endothelial cells. These data suggest that hemoglobin S-containing erythrocytes may have a higher frequency of adherence in vivo in regions of low shear stress where prolonged erythrocyte-endothelial cell contact could occur. Some of these cells detached by shear force would subsequently reattach in in vivo conditions. Plasma-enhanced attachment frequency and plasma from blood in a case of sickle crisis caused further increase. These observations further support the concept that sickle erythrocyte- endothelial cell interaction may be a significant factor in initiation of vascular occlusive events in sickle cell disease.     

Red cell alloimmunization in sickle cell disease

Alloimmunization to red cell antigens contributes to morbidity in transfused patients. It has been recommended that blood for sickle cell patients need not be matched for antigens other than ABO and Rh(D), as there is no greater incidence of antibody production than in other multitransfused patient populations. Post transfusion alloimmunization was studied in a group of 34 sickle cell disease patients attending a U.K. haemoglobinopathy clinic. Red cell antibodies were formed in 17.6% of the transfused patients and Rhesus and Kell antibodies accounted for 66% of this total. In order to reduce alloimmunization, a policy of performing extended red cell phenotyping on the patients, and providing blood matched for Kell, and in certain circumstances the Rhesus antigens other than Rh(D), is recommended.     

Red cell exchange in sickle cell disease

Red cell exchange transfusion is frequently of use in the management of patients with sickle cell disease either electively or therapeutically. Modern cell separators allow this procedure to be performed rapidly, effectively and safely. These machines have a number of advantages over manual exchange procedures. The patient remains isovolaemic, there is little loss of plasma or platelets, the procedure is relatively short and in elective circumstances can be performed on an outpatient basis. In this series 66 exchanges were performed on 21 patients with an overall increase in HbA of 70%. The COBE Spectra gave a mean increase in HbA of 77%, with the majority of patients achieving an HbA of > 90% post exchange. Automated redcell exchange was well tolerated by most patients, and adverse effects were limited to symptoms of hypocalcaemia which were easily treated, and to transfusion reactions. Cell separators can therefore be recommended for exchange transfusion in patients with sickle cell disease, who require an increase in HbA levels either prophylactically or therapeutically. They are safe, effective, easy and quick to use.     

Automated red cell exchange in sickle cell disease

We used multiple optical trapping to study the mechanism of red cell (dis)aggregation. Two sets of optical 'tweezers' were used to bring two red blood cells together to form a two-cell aggregate and then to pull them apart, to study the interaction between the cells.
We found that cross-bridging occurred in normal reversible aggregation as we observed binding and the occurrence of small tethers between opposite cell membranes. Furthermore, the cells could only be parted by sliding them side by side with a maximum velocity in the order of μm/s indicating accumulation of the cross-bridges.     

Hematopoietic stem cell transplantation in sickle cell disease

Since the first report of a young girl affected by sickle cell anemia, treated successfully by bone marrow transplantation (BMT) for acute myeloid leukemia, more than 200 patients have been transplanted worldwide for sickle cell anemia. The disease-free survival (DFS) is good (80-85% in several series), even though many children who received allografts had already significant sickle-related complications. The best results are obtained in young children who have HLA-identical sibling donors and are transplanted early in the course of the disease (DFS: 93%). Future directions in the field of stem cell transplantation of sickle cell anemia include (1) the establishment of new protocols with less toxicity, but still effective, (2) adapted conditioning regimen for adult patients, and (3) new sources of stem cells for broader application: umbilical cord blood and volunteer unrelated donors.     

Sphere-forming cell subpopulations with cancer stem cell properties in human hepatoma cell lines

Background

Cancer stem cells (CSCs) are regarded as the cause of tumor formation and recurrence. The isolation and identification of CSCs could help to develop novel therapeutic strategies specifically targeting CSCs.

Methods

Human hepatoma cell lines were plated in stem cell conditioned culture system allowed for sphere forming. To evaluate the stemness characteristics of spheres, the self-renewal, proliferation, chemoresistance, tumorigenicity of the PLC/PRF/5 sphere-forming cells, and the expression levels of stem cell related proteins in the PLC/PRF/5 sphere-forming cells were assessed, comparing with the parental cells. The stem cell RT-PCR array was performed to further explore the biological properties of liver CSCs.

Results

The PLC/PRF/5, MHCC97H and HepG2 cells could form clonal nonadherent 3-D spheres and be serially passaged. The PLC/PRF/5 sphere-forming cells possessed a key criteria that define CSCs: persistent self-renewal, extensive proliferation, drug resistance, overexpression of liver CSCs related proteins (Oct3/4, OV6, EpCAM, CD133 and CD44). Even 500 sphere-forming cells were able to form tumors in NOD/SCID mice, and the tumor initiating capability was not decreased when spheres were passaged. Besides, downstream proteins DTX1 and Ep300 of the CSL (CBF1 in humans, Suppressor of hairless in Drosophila and LAG1 in C. elegans) -independent Notch signaling pathway were highly expressed in the spheres, and a gamma-secretase inhibitor MRK003 could significantly inhibit the sphere formation ability.

Conclusions

Nonadherent tumor spheres from hepatoma cell lines cultured in stem cell conditioned medium possess liver CSC properties, and the CSL-independent Notch signaling pathway may play a role in liver CSCs.     

Indications for red cell transfusion in sickle cell disease

Transfusion of red blood cells is an important therapeutic method employed in the care of people with sickle cell disease (SCD). There are several clinical situations in which patients with SCD clearly need red cell transfusion (RCT). In other situations, the indication for RCT is doubtful, controversial, or ill-advised. RCT is used on either an episodic or chronic basis in the management of SCD. Episodic transfusions are usually applied in a patient who has already developed a serious complication of SCD or are used to reduce the chances for the development of a complication. Chronic transfusion therapy is often used to prevent the recurrence of a major complication such as a stroke. Recently, chronic transfusion has been applied to patients with evidence of cerebrovascular disease to prevent the first occurrence of stroke.     

Red cell transfusion and alloimmunization in sickle cell disease

Red cell transfusion remains a critical component of care for acute and chronic complications of sickle cell disease. Randomized clinical trials demonstrated the benefits of transfusion therapy for prevention of primary and secondary strokes and postoperative acute chest syndrome. Transfusion for splenic sequestration, acute chest syndrome, and acute stroke are guided by expert consensus recommendations. Despite overall improvements in blood inventory safety, adverse effects of transfusion are prevalent among patients with sickle cell disease and include alloimmunization, acute and delayed hemolytic transfusion reactions, and iron overload. Judicious use of red cell transfusions, optimization of red cell antigen matching, and the use of erythrocytapheresis and iron chelation can minimize adverse effects. Early recognition and management of hemolytic transfusion reactions can avert poor clinical outcomes. In this review, we discuss transfusion methods, indications, and complications in sickle cell disease with an emphasis on alloimmunization.     

Red cell rheology in stomatocyte-echinocyte transformation: roles of cell geometry and cell shape

The influence of the shape of the red blood cell during stomatocyte- echinocyte transformation on its deformability was studied by microsieving through pores with diameters of 2.6, 4.5, and 6.9 micron. A stomatocytic transformation was produced by chlorpromazine (0.02, 0.1, and 0.5 mmol/L) and an echinocytic transformation by sodium salicylate (7.5, 30, and 120 mmol/L). For spherostomatocytes, an increase in filtration resistance through 2.6 and 4.5 micron pores was observed, whereas for spheroechinocytes, a decrease in filtration resistance through 2.6 micron pores was found. Larger pores (6.9 micron) were not sensitive to those shape changes. The changes in deformability can be explained by the fact that the surface area of (sphero)-stomatocytes decreased, whereas that of (sphero)-echinocytes increased; the cell volume remained essentially constant. Echinocytes produced by 24-hour adenosine triphosphate depletion differed from drug- induced echinocytes: they had an increased cell volume at constant surface area and consequently an increased filtration resistance through 2.6- and 4.5-micron filter pores. Shape changes with spicule formation are therefore not a homogeneous entity, and cell geometric factors (eg, surface area and volume) must be assessed with care. The viscosity of red cell suspensions at a hematocrit level of 45% was higher for drug-induced echinocytes than discocytes or stomatocytes at all shear rates tested. We conclude that the normal discocyte represents an optimum shape for the flow in vivo since a stomatocytic transformation could impair the passage through the microcirculation (decrease in cell filterability) and an echinocytic transformation could impair the flow in larger vessels (increase in blood viscosity).     

Changes in cell surface antigens during stem cell ontogeny

A panel of monoclonal antibodies that bind to the murine pluripotential stem cell CFU-s was used to examine the antigenic profile of the stem cell during ontogeny. The results show that the stem cell surface changes dramatically during development. One group of three independently derived monoclonal antibodies binds to subpopulations (50%-70%) of stem cells at plateau values, and these populations increase marginally during development. A second group of four monoclonal antibodies, including anti-H-2Kk (11-4.1), define stem cell antigens that increase from low levels in the fetal liver to high levels in adult bone marrow. The presence of these two classes of antigens on adult splenic stem cells was in general similar to that observed on adult bone marrow. Antigens defined by the first group of monoclonal antibodies were present in similar amounts on CBA, C57B1/6, and Balb/c bone marrow stem cells, whereas antigens of the second group showed mouse strain variations. Quantitative absorption analysis was used to distinguish H-2Kk (11-4.1) from 9F6, which showed a similar developmental profile. Monoclonal antibodies recognizing subpopulations of stem cells were shown to be distinct by complementation studies and recognized antigens not present on brain tissue.     

T cell regeneration in pediatric allogeneic stem cell transplantation

Delayed and/or insufficient T cell recovery post hematopoietic stem cell transplantation (HSCT) leads to an increased risk of morbidity and mortality. We evaluated thymic function and its association with T cell regeneration post HSCT and identified factors involved in the process among pediatric stem cell transplant recipients. T cell regeneration in 66 pediatric patients was prospectively followed by naive T cell phenotyping, measuring of T cell receptor excision circles (TRECs) and expression of Foxp3 by regulatory T cells for the first 18 months post HSCT. TRECs were lower pre-HSCT in children with a malignant than non-malignant primary disease or immunosuppressed controls (P=0.001). Naive T lymphocyte reconstitution and thymic recovery were slow in the recipients of allogeneic stem cell grafts post HSCT. Infections caused by herpesviruses had a prognostic impact on mortality. Children with low TRECs had a high mortality (P=0.05) and low TRECs were also associated with extensive chronic graft-versus-host disease from 6 months onwards. Low amount of Foxp3 pre-HSCT was associated with an increased mortality post HSCT (P=0.03). Our study indicates an association between impaired T cell regeneration and thymic dysfunction and the clinical post transplant complications in pediatric allogeneic stem cell transplantation.     

Bryostatin analogue-induced apoptosis in mantle cell lymphoma cell lines

The anti-cancer effects of bryostatin-1, a potent diacylglycerol analogue, have traditionally been attributed to its action on protein kinase C. However, we previously documented apoptosis in a B non-Hodgkin lymphoma cell line involving diacylglycerol analogue stimulation of Ras guanyl-releasing protein, a Ras activator, and Bim, a proapoptotic Bcl-2 family protein. To further explore the role of Bim, we examined several Bim-deficient B non-Hodgkin lymphoma cells for their responses to pico, a synthetic bryostatin-1-like compound. The Bim(-) mantle cell lymphoma cell lines Jeko-1, Mino, Sp53, UPN1, and Z138 and the Bim(+) cell line Rec-1, as well as the Burkitt lymphoma cells lines BL2 (Bim(-)) and Daudi (Bim(+)), were examined for their response to pico using assays for proliferation and apoptosis as well as biochemical methods for Ras guanyl-releasing proteins and Bcl-2 family members. With the exception of UPN1, mantle cell lymphoma cell lines underwent pico-induced apoptosis, as did BL2. In some cases, hallmarks of apoptosis were substantially diminished in the presence of mitogen-activated protein kinase kinase inhibitors. Pico treatment generally led to increased expression of proapoptotic Bik, although the absolute levels of Bik varied considerably between cell lines. A pico-resistant variant of Z138 exhibited decreased Bik induction compared to parental Z138 cells. Pico also generally decreased expression of anti-apoptotic Bcl-XL and Mcl1. Although, these changes in Bcl-2 family members seem unlikely to fully account for the differential behavior of the cell lines, our demonstration of a potent apoptotic process in most cell lines derived from mantle cell lymphoma encourages a re-examination of diacylglycerol analogues in the treatment of this subset of B non-Hodgkin lymphoma cases.     

胆红素对肝星状细胞-T6增殖及细胞周期的影响

[目的]观察胆红素对肝星状细胞(HSC)-T6增殖及细胞周期影响.[方法]将培养细胞分成正常组和胆红素不同浓度(10 μmol/L、30 umol/L、50 /μmol/L、70 μmol/L、100 μmol/L)干预组,采用MTT法观察胆红素对HSC-T6增殖的影响,流式细胞仪观察各组细胞周期的变化.[结果]①不同浓度胆红素对HSC-T6均有促进增殖作用,且呈一定的量效关系,与正常组比较差异有统计学意义(P＜0.05);②10 μmol/L、50 μmol/L、100 μmol/L浓度胆红素作用HSC-T6后,G0/G1期减少,S期增加,G2/M期增加,与正常组比较均P＜0.05.[结论]胆红素对HSC-T6均有促进增殖作用.     

Microfluidic devices for modeling cell–cell and particle–cell interactions in the microvasculature

Cell–fluid and cell–cell interactions are critical components of many physiological and pathological conditions in the microvasculature. Similarly, particle–cell interactions play an important role in targeted delivery of therapeutics to tissue. Development of in vitro fluidic devices to mimic these microcirculatory processes has been a critical step forward in our understanding of the inflammatory process, developing of nano-particulate drug carriers, and developing realistic in vitro models of the microvasculature and its surrounding tissue. However, widely used parallel plate flow based devices and assays have a number of important limitations for studying the physiological conditions in vivo. In addition, these devices are resource hungry and time consuming for performing various assays. Recently developed, more realistic, microfluidic based devices have been able to overcome many of these limitations. In this review, an overview of the fluidic devices and their use in studying the effects of shear forces on cell–cell and cell–particle interactions is presented. In addition, use of mathematical models and Computational Fluid Dynamics (CFD) based models for interpreting the complex flow patterns in the microvasculature is highlighted. Finally, the potential of 3D microfluidic devices and imaging for better representing in vivo conditions under which cell–cell and cell–particle interactions take place is discussed.     

Kinetics of dendritic cell chimerism and T cell chimerism in allogeneic hematopoietic stem cell recipients

Dendritic cells (DC) as potent antigen-presenting cells (APC) and T cells as effector cells play an essential role in the pathophysiology of both graft-versus-host (GvH) and graft-versus-leukemia (GvL) reactions after transplantation. Therefore, we determined the kinetics of DC and T-cell chimerism establishment after allogeneic hematopoietic cell transplantation (AHCT) in a group of 144 patients, using fluorescence-activated cell sorting (FACS) or magnetic cell sorting (MACS) followed by FISH or STR-PCR analysis for chimerism evaluation. In all, three cell lines investigated (CD3(+) T cells, CD11c(+) DC1 and CD123(+) DC2), we found a rapid and consistent establishment of complete donor chimerism (CDC) in over 70% of all patients during the first 6 weeks after AHCT. The rate of patients with CDC increased significantly over time within the first year after transplantation. A related donor (P=0.004) as well as an underlying lymphatic leukemia (P=0.03) were found to be significantly associated with development of MC in T cells. No significant correlation between DC or T cell chimerism and GvHD or relapse was detected. Our results thus demonstrate a fast and stable CDC in DC1, DC2 and T cells after AHCT that continuously increases over time in nearly all patients.     

Rituximab: enhancing stem cell transplantation in mantle cell lymphoma

Mantle cell lymphoma (MCL) responds poorly to standard chemotherapy regimens used in non-Hodgkin's lymphoma. As a result, a combination of high-dose chemotherapy (HDT) with autologous stem cell transplantation (ASCT) is being investigated in patients with MCL. So far, however, there is no evidence for long-term remission -- believed, in part, to be due to contamination of the transfusion product with residual cancer cells. Many ex-vivo purging methods have been developed to remove tumour cells, but these are complicated, time-consuming and expensive. This study describes an in vivo purging method using rituximab to produce a tumour-free stem cell product for re-infusion following HDT. The regimen is split into a purging phase and a myeloablative phase, which together consist of four-step high-dose sequential chemotherapy (sHDT) and six infusions of rituximab immunotherapy. The sHDT comprises cyclophosphamide, cytosine arabinoside, melphalan and mitoxantrone plus melphalan. There are two separate stem cell harvests and three reinfusions. In a pilot study 28 patients with untreated MCL received standard chemotherapy followed by sHDT with rituximab in vivo purging. Preliminary results indicate that in PCR analyses of leukaphereses from 20 assessable patients, 100% lymphoma-negative harvests were achieved following in vivo purging. PCR analyses of the bone marrow following the four-step high-dose regimen with purging and transplantation showed that all patients achieved molecular remission. After a median follow-up of 22 months (range 10-42 months), two patients had died while 26 were alive and disease free. This method allows efficient in vivo purging in the context of an effective chemotherapy regimen and may have a role as first-line therapy in MCL patients who respond poorly to standard treatment.