The effect of fresh versus standard blood transfusion on microvascular endothelial function

Choroidal Thickness Evaluation in a Transfusion-Dependent Beta-Thalassemia Greek Population

Purpose

To evaluate choroidal thickness in a group of beta-thalassemia patients as assessed by enhanced depth imaging optical coherence tomography.

Patients and Methods

This single-center, observational study involved transfusion-dependent beta-thalassemia (TD-β-thal) patients and healthy controls. One eye of each participant was included in the study. Submacular and peripapillary choroidal thickness, as well as central macular thickness and retinal nerve fiber layer thickness, were evaluated.

Results

Thirty-eight TD-β-thal patients (mean age 42 ± 10.7 years) and 22 healthy controls (mean age 40.3 ± 10.2 years) were included in the study. Subfoveal choroidal thickness was 297.4 ± 74.5 μm in the patient group and 358.4 ± 71.4 μm in the control group (p=0.003). Overall, in the submacular area, the choroid was found to be significantly thinner in the beta-thalassemia population compared to controls in all evaluated points, except for the spot located 1500 μm nasally to the fovea (p=0.093). In the peripapillary area, choroidal thickness was also significantly lower in the thalassemic population compared to the controls (nasal p=0.033, temporal p=0.01, superior p=0.01), except for the inferior quadrant (p= 0.191). We did not observe statistically significant differences in the retinal nerve fiber layer thickness and the central macular thickness between the two groups (p=0.658 and p=0.276, respectively). No correlations with hemoglobin, serum ferritin or iron levels emerged. Patients with the intermediate subtype appeared to have significantly thinner choroids than the ones with thalassemia major.

Conclusion

Our findings suggest that choroidal thickness in the submacular and peripapillary area is significantly reduced in thalassemic patients, compared to healthy individuals. Choroidal thinning in beta-thalassemia possibly reflects the effect of chronic anemia and underlying hemodynamic changes on choroidal tissue.

Endothelial Dysfunction Is Not Associated With Spontaneous Coronary Artery Dissection

BACKGROUND

Spontaneous coronary artery dissection (SCAD) is an important cause of acute coronary syndrome, yet its pathophysiology is only partially understood. We sought to assess the association between endothelial dysfunction (ED) and SCAD.

METHODS

We prospectively assessed patients presenting with acute coronary syndrome who were diagnosed with SCAD. The control arm had established coronary artery atherosclerotic disease (AD) according to previous coronary angiography. ED was assessed using the EndoPAT 2000 while patients returned to their steady state condition. A total of 16 patients with SCAD and 66 patients with AD were included.

RESULTS

Microvascular reactivity as assessed with the EndoPAT was significantly worse in the AD group compared to the SCAD group. The median RHI in the AD group was 1.76 (IQR 1.52, 2.2) vs. a median RHI of 2.08 (IQR 1.73, 2.79) in the SCAD group (p < 0.05). While the RHI values in half of the AD group (33 patients; 50%) were below the cut-off of 1.67 only one patient had an RHI below this cut-off in the SCAD group.

CONCLUSIONS

Patients with SCAD were not found to have ED and it is therefore unlikely that ED takes part in SCAD formation.

Development of a flow standard to enable highly reproducible measurements of deformability of stored red blood cells in a microfluidic device

BACKGROUND

Great deformability allows red blood cells (RBCs) to flow through narrow capillaries in tissues. A number of microfluidic devices with capillary-like microchannels have been developed to monitor storage-related impairment of RBC deformability during blood banking operations. This proof-of-concept study describes a new method to standardize and improve reproducibility of the RBC deformability measurements using one of these devices.

STUDY DESIGN AND METHODS

The rate of RBC flow through the microfluidic capillary network of the microvascular analyzer (MVA) device made of polydimethylsiloxane was measured to assess RBC deformability. A suspension of microbeads in a solution of glycerol in phosphate-buffered saline was developed to be used as an internal flow rate reference alongside RBC samples in the same device. RBC deformability and other in vitro quality markers were assessed weekly in six leukoreduced RBC concentrates (RCCs) dispersed in saline-adenine-glucose-mannitol additive solution and stored over 42 days at 4°C.

RESULTS

The use of flow reference reduced device-to-device measurement variability from 10% to 2%. Repeated-measure analysis using the generalized estimating equation (GEE) method showed a significant monotonic decrease in relative RBC flow rate with storage from Week 0. By the end of storage, relative RBC flow rate decreased by 22 ± 6% on average.

CONCLUSIONS

The suspension of microbeads was successfully used as a flow reference to increase reproducibility of RBC deformability measurements using the MVA. Deformability results suggest an early and late aging phase for stored RCCs, with significant decreases between successive weeks suggesting a highly sensitive measurement method.

Spectral domain optical coherence tomography findings in Turkish sickle-cell disease and beta thalassemia major patients

Purpose

To assess probable structural changes using spectral domain optical coherence tomography (SD-OCT) on sickle-cell disease (SCD) and beta thalassemia major (B-TM) patients, without any retinal abnormalities.

Methods

This cross-sectional study included 32 B-TM, 34 SCD patients, and 44 healthy controls. One of the eyes of all participants was evaluated for SD-OCT and choroidal thickness, retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), ganglion cell complex (GCC).

Results

Age, gender, and intraocular pressure (IOP) were not statistically different between the three groups. Hemoglobin (Hgb), hematocrite (Htc), and ferritin levels were not statistically different between the SCD and B-TM groups. Choroidal thickness at the subfoveal region was statistically higher in the control group (353.79 ± 71.93) than in the B-TM (317.41 ± 53.44) and SCD (283.21 ± 63.27) groups. In addition, it was statistically higher in the B-TM group than the SCD group (P = 0.05). CMT did not differ among the three groups, average RNFL was only significantly thinner in SCD than in controls, and GCC thickness was significantly thinner in SCD than in controls and B-TM.

Conclusion

In both diseases, we can show early structural changes even if proliferative or non-proliferative retinopathy or other ocular manifestations were not developed yet.

Real Age: Red Blood Cell Aging During Storage

BACKGROUND

During cold storage, some red blood cell (RBC) units age more rapidly than others. Yet, the Food and Drug Administration has set a uniform storage limit of 42 days. Objectives of this review are to present evidence for an RBC storage lesion and suggest that functional measures of stored RBC quality-which we call real age-may be more appropriate than calendar age.

METHODS

During RBC storage, biochemical substances and byproducts accumulate and RBC shape alters. Factors that influence the rate of degradation include donor characteristics, bio-preservation conditions, and vesiculation. Better understanding of markers of RBC quality may lead to standardized, quantifiable, and operationally practical measures to improve donor selection, assess quality of an RBC unit, improve storage conditions, and test efficacy of the transfused product.

RESULTS

The conundrum is that clinical trials of younger versus older RBC units have not aligned with in vitro aging data; that is, the units transfused were not old enough. In vitro changes are considerable beyond 28 to 35 days, and average storage age for older transfused units was 14 to 21 days.

CONCLUSIONS

RBC product real age varies by donor characteristics, storage conditions, and biological changes during storage. Metrics to measure temporal changes in quality of the stored RBC product may be more appropriate than the 42-day expiration date. Randomized trials and observational studies are focused on average effect, but, in the evolving age of precision medicine, we must acknowledge that vulnerable populations and individuals may be harmed by aging blood.

Hemodynamic Functionality of Transfused Red Blood Cells in the Microcirculation of Blood Recipients

The primary goal of red blood cell (RBC) transfusion is to supply oxygen to tissues and organs. However, due to a growing number of studies that have reported negative transfusion outcomes, including reduced blood perfusion, there is rising concern about the risks in blood transfusion. RBC are characterized by unique flow-affecting properties, specifically adherence to blood vessel wall endothelium, cell deformability, and self-aggregability, which define their hemodynamic functionality (HF), namely their potential to affect blood circulation. The role of the HF of RBC in blood circulation, particularly the microcirculation, has been documented in numerous studies with animal models. These studies indicate that the HF of transfused RBC (TRBC) plays an important role in the transfusion outcome. However, studies with animal models must be interpreted with reservations, as animal physiology may not reflect human physiology. To test this concept in humans, we have directly examined the effect of the HF of TRBC, as expressed by their deformability and adherence to vascular endothelium, on the transfusion-induced effect on the skin blood flow and hemoglobin increment in β-thalassemia major patients. The results demonstrated, for the first time in humans, that the TRBC HF is a potent effector of the transfusion outcome, expressed by the transfusion-induced increase in the recipients' hemoglobin level, and the change in the skin blood flow, indicating a link between the microcirculation and the survival of TRBC in the recipients' vascular system. The implication of these findings for blood transfusion practice and to vascular function in blood recipients is discussed.

Leukoreduction of packed red blood cells attenuates proinflammatory properties of storage-derived microvesicles

BACKGROUND

Leukoreduction prior to packed red blood cell (pRBC) storage is not a universally accepted practice. Our laboratory has previously shown that microvesicles (MVs) accumulate in pRBC units during storage and play an important role in lung injury after resuscitation. Currently, the effect of leukoreduction on MV formation in stored pRBC units is unknown. In the present study, we investigated the hypothesis that leukoreduction of pRBC units prior to storage would attenuate the production of MVs and decrease pulmonary inflammation after hemorrhage and resuscitation.

METHODS

Leukoreduced and nonleukoreduced pRBC units were prepared from human donors and C57/Bl6 mice and stored for up to 42 d and 14 d, respectively. At intervals during storage, MVs were isolated from pRBC units, quantified and characterized based on size, morphology, and levels of proinflammatory cytokines. In additional experiments, mice underwent controlled hemorrhage followed by resuscitation with normal saline (NS) with or without equal numbers of MVs isolated from leukoreduced or nonleukoreduced stored mouse pRBC. Histologic lung sections were evaluated for the presence of tissue edema and inflammatory cells.

RESULTS

For both human and mouse pRBCs, the number of MVs significantly increased throughout the storage period. There were significantly fewer MVs present in leukoreduced units. The average MV size significantly increased over time and was similar between groups. Levels of interleukin 1α (IL-1α), regulated on activation, normal T cell expressed and secreted (RANTES), and macrophage-derived chemokine (MDC) were lower in MVs from leukoreduced pRBC units as compared with MVs from nonleukoreduced units. Hemorrhaged mice resuscitated with NS with the addition of MV from leukoreduced pRBC demonstrated significantly less pulmonary edema and inflammatory cell recruitment as compared to those resuscitated with NS with the addition of MV from nonleukoreduced pRBC.

CONCLUSIONS

Prestorage leukoreduction of pRBC units reduces the formation and proinflammatory properties of MV, which in turn decreases lung injury secondary to MV from stored pRBC units after hemorrhage and resuscitation.