Sherry Shariatmadar

Microparticles in stored red blood cells as potential mediators of transfusion complications.

This article reviews evidence for the involvement of cell‐derived microparticles (MPs) in transfusion‐related adverse events. The controversy concerning possible added risk of older versus fresher stored blood is also reviewed and is consistent with the hypothesis that MPs are involved with adverse events. Although all types of circulating MPs are discussed, the emphasis is on red blood cell–derived MPs (RMPs). The evidence is particularly strong for involvement of RMPs in transfusion‐related acute lung injury, but also for postoperative thrombosis. However, this evidence is largely circumstantial. Work in progress to directly test the hypothesis is also briefly reviewed.

Cellular volume and marker expression in human peripheral blood apheresis stem cells

Coulter volume is far more accurate measure of cell volume than forward angle light scatter. In this report, we have used Coulter volume to determine the mean cell volume and diameter of normal human peripheral blood cells and hematopoietic progenitor cells obtained by apheresis (HPC‐A) from patients with hematological malignancies. Fresh peripheral blood samples (treated with Beckman Coulter IMMUNOPrep erythrocyte lysis solution), HPC‐A samples (treated with BD Biosciences FACSLysing solution), or processed by Ficoll Hypaque sedimentation method were stained with CD45‐FITC and PE‐labeled CD34, CD90, CD117, and CD133 antibodies and analyzed for electronic volume and two color fluorescence. The mean electronic volume and diameter of mononuclear cells from fresh peripheral blood samples prepared with IMMUNOPrep were lymphocytes (191 μm3, 7.16 μm), monocytes (370 μm3, 9.91 μm), and granulocytes (328 μm3, 8.56 μm). In mononuclear cells of HPC‐A samples prepared by Histopaque‐1077 sedimentation, the lymphocytes had volume and diameter of 311 μm3, 8.4 μm, monocytes were 486 μm3, 9.76 μm, and granulocytes were 515 μm3, 9.95 μm. In contrast, HPC‐A samples prepared after lysis with FACSLysing solution had mean electronic volume and diameter of lymphocytes (414 μm3, 9.25 μm), monocytes (797 μm3, 11.5 μm), and granulocytes (670 μm3, 10.85 μm). Cell volume of mononuclear cells in the HPC‐A samples prepared by Histopaque‐1077 sedimentation method was correlated with the expression of stem cell markers CD34, CD90, CD117, and CD133. CD90 positive cells had the smallest mean electronic volume of 299.93 μm3 when compared with cells with positive expression of CD133 (322 μm3), CD117 (349 μm3), CD34 (407 μm3), and CD45 (453 μm3). Correlation of cell volume with stem cell marker expression may allow for the identification of small stem cells, which may not express the conventional markers used for the identification of stem cells in HPC‐A samples.

Alloimmunization to red cell antigens in liver and multivisceral transplant patients.

Background. Alloimmunization to red blood cell (RBC) antigens can significantly impact transfusion support of patients undergoing solid-organ transplantation. This study evaluated the incidence of clinically significant RBC alloantibodies (abs) in 2000 consecutive adults receiving liver (OLTX), intestinal (ITX) or multivisceral (MVT) transplants. Methods. From January 1991 to May 2006, 2000 patients underwent OLTX (n=1892), MVT (n=74), or ITX (n=34). Blood sample for serologic investigation was submitted to the transfusion service no later than 4 hr before surgery. The presence of clinically significant RBC abs before transplant with subsequent transfusion requirements, the incidence of delayed transfusion reactions, and de novo abs after transplant were evaluated. Results. One hundred fifteen patients (5.75%) had clinically significant RBC abs before transplant, with 56.7% directed against Rh system antigens. Forty-six (40%) had multiple abs. A mean of 18 packed RBC units (U) were transfused per patient. Patients requiring >20 U (n=34) or those with multiple abs received antigen-negative units for the first 5–10 U when antibody was still present, switched to antigen-unscreened units during massive blood loss and returned to antigen-negative units for the last 5–10 U transfused. Twelve patients (0.6%) developed de novo abs posttransplant. Twenty-two (1.1%) had delayed serologic transfusion reaction. All patients were successfully managed without delay in initiation of surgery or hemolytic complications. Conclusion. RBC alloimmunization can present a special challenge to solid-organ transplantation. Early serologic testing of the recipient pretransplant and prompt communication between the transfusion service and transplant team facilitates successful transfusion management of these patients.

Initial hematocrit predicts the use of blood transfusion in the pediatric trauma patient

PURPOSE Initial hematocrit (Hct) is generally not considered a marker of acute blood loss because it is assumed that physiologic response of fluid conservation to hemorrhage is delayed. We challenged this idea by theorizing that admission Hct correlates with conventional signs of shock and predicts the use of blood transfusion during resuscitation of pediatric trauma patients. METHODS Data from 1928 pediatric admissions (<18 years) at a Level I trauma center (2000-2012) were compared using standard statistical analyses and logistic regression modeling to identify factors associated with blood transfusion during initial trauma resuscitation. RESULTS Overall mortality rate was 3.5%, with a transfusion rate of 10.7%. Factors significantly associated with transfusion were initial Hct, Glasgow Coma Score, base deficit, and injury severity score (all p<0.001). Initial Hct is a stronger predictor for transfusion (area under receiver operator curve (AUC: 0.728) compared to age-specific tachycardia (AUC: 0.689), age-specific hypotension (AUC: 0.673), and altered mental status (AUC: 0.654)). On multivariate analysis, initial Hct was an independent predictor (OR [95% CI]: 2.94 [1.56, 5.52]) along with hypotension (6.37 [2.95, 13.8]), base deficit (4.14 [1.38, 12.4]), and tachycardia (3.07 [1.62, 5.81]). CONCLUSIONS Initial Hct correlates significantly with conventional signs of shock and is a strong independent predictor for blood transfusion with better predictability than other clinical factors.

Electronic volume of CD34 positive cells from peripheral blood apheresis samples

The authors have used a flow analyzer to measure electronic cellular volume of peripheral blood hematopoietic stem/progenitor cells obtained by granulocyte‐colony stimulating factor (G‐CSF) mobilization and apheresis (HPC‐A) of patients with hematological malignancies.

Electronic volume, aldehyde dehydrogenase, and stem cell marker expression in cells from human peripheral blood apheresis samples†

Over‐expression of aldehyde dehydrogenase and other stem cell markers is characteristic of cells with tumorigenic potential in NOD/SCID mice. Most of these studies have focused on metastatic cells in bone marrow and on solid tumors. There are no studies on correlation of marker expression with ALDH1 expression in cells from human peripheral blood apheresis (HPC‐A) samples.

Microparticles in Stored RBC as Potential Mediators of Transfusion Complications

This article reviews evidence for the involvement of cell‐derived microparticles (MPs) in transfusion‐related adverse events. The controversy concerning possible added risk of older versus fresher stored blood is also reviewed and is consistent with the hypothesis that MPs are involved with adverse events. Although all types of circulating MPs are discussed, the emphasis is on red blood cell–derived MPs (RMPs). The evidence is particularly strong for involvement of RMPs in transfusion‐related acute lung injury, but also for postoperative thrombosis. However, this evidence is largely circumstantial. Work in progress to directly test the hypothesis is also briefly reviewed.

Microparticles in stored red blood cells as potential mediators of transfusion complications: MICROPARTICLES IN STORED RBCs

This article reviews evidence for the involvement of cell‐derived microparticles (MPs) in transfusion‐related adverse events. The controversy concerning possible added risk of older versus fresher stored blood is also reviewed and is consistent with the hypothesis that MPs are involved with adverse events. Although all types of circulating MPs are discussed, the emphasis is on red blood cell–derived MPs (RMPs). The evidence is particularly strong for involvement of RMPs in transfusion‐related acute lung injury, but also for postoperative thrombosis. However, this evidence is largely circumstantial. Work in progress to directly test the hypothesis is also briefly reviewed.