Optimizing interpretation of survival studies of fresh and aged transfused biotin-labeled RBCs

Optimization of biotinylation protocol for next generation studies of red blood cell survival after transfusion

BACKGROUND

Red blood cell (RBC) biotinylation has increasingly become the preferred method for quantifying RBC post-transfusion recovery (PTR). This study evaluated the feasibility of transfusing autologous RBCs labeled with biotin (BioRBCs) 48 h prior to transfusion. The rationale was to facilitate the distribution of BioRBC products from manufacturing sites to remote clinical sites.

STUDY DESIGN

Leukocyte-reduced RBC units from 12 healthy individuals were stored at 1-6°C for 42 days and biotinylated with two biotin densities (3 and 15 μg/mL) 48 and 4 h prior to transfusion. Each individual was transfused with 10 mL of each BioRBC preparation, after which BioRBC 20 h PTR and long-term survival (30 and 90 days) were determined by flow cytometric analyses. Additional quality measurements included phosphatidylserine (PS) exposure on BioRBCs and in vitro metrics of hemolysis.

RESULTS

RBC transfusion 48 h after biotinylation was not associated with altered BioRBC 20 h PTR or 30 and 90 day survival as compared with RBC transfusion 4 h after biotinylation (e.g., PTR 20 h: 85.7% ± 8.4% vs. 87.5% ± 7.3%; 48 and 4 h, respectively, p > .05). Similarly, no significant differences between the BioRBC groups were observed in BioRBC PS exposure at all time points. BioRBC long-term survival, but not 20 h PTR, was negatively associated with donor hemoglobin (Pearson r = -0.71, p = .001) and osmotic hemolysis (r = -0.783, p = .003). None of the participants developed antibodies against BioRBCs during the trial.

CONCLUSIONS

RBC biotinylation 48 h prior to transfusion does not compromise the quality and safety of BioRBC products. BioRBC long-term survival can be used to identify donor characteristics that influence RBC lifespan in the circulation.

A novel acridine flow cytometry marker to track post-transfusion amustaline/glutathione pathogen-reduced red blood cell survival in sickle cell disease patients

BACKGROUND

Measurement of transfused red blood cell (RBC) survival is relevant to the effective management of sickle cell disease (SCD). Following amustaline/glutathione pathogen-reduced (PR) RBC transfusion, small quantities of PR-RBC surface-bound acridine are detectable by flow cytometry. Concurrent biotin labeling was used to validate the acridine marker and track transfused PR-RBCs in SCD.

METHODS

SCD patients (n = 6) on chronic transfusion therapy received three aliquots of different (2 μg/mL, 6 μg/mL, and 18 μg/mL) biotin-dose labeled RBCs during one transfusion episode. Aliquots were from one unit labeled before (Pre-PR) and after PR treatment (PR-RBC) and from a conventional RBC unit. The full RBC units (PR and conventional) were transfused, followed by the labeled aliquots from those units. Serial flow cytometry analyses for acridine- and biotin-labeled RBCs were performed on 10 occasions over 16 weeks. Acridine surface density was quantitated using calibrated beads.

RESULTS

Mean acridine surface density was 5062 molecules/PR-RBC at 1-4 h post-transfusion and declined 84.5% within 7 days, remaining detectable (180 molecules/PR-RBC) at 16 weeks. The biotin-labeled PR-RBC aliquots (initial enrichment 0.6%-1.4%) demonstrated near-identical survival kinetics as the entire acridine-labeled PR-RBC units (initial enrichment 7.5%-13.7%). Pre-PR, PR, and Conventional RBCs revealed non-linear RBC survival kinetics, with similar 24-h post-transfusion recoveries (PTR24) and half-lives (T50), but PR-RBC mean predicted lifespan (mean [SD] 104.4 [4.7] days) was decreased by 9.3% (Pre-PR-RBCs 115.1 [7.2] days, p = 0.006).

CONCLUSIONS

Survival of amustaline/glutathione PR-RBCs can be tracked in vivo by flow cytometry for RBC surface acridine with similar sensitivity as biotin, without additional processing or radiolabeling.

Survival of transfused red blood cells from a donor with alpha-thalassemia trait in a recipient with sickle cell disease

BACKGROUND

Post-transfusion survival of donor red blood cells (RBCs) is important for effective chronic transfusion therapy in conditions including sickle cell disease (SCD). Biotin labeling RBCs allows direct in vivo measurement of multiple donor RBC units simultaneously post-transfusion.

STUDY DESIGN AND METHODS

In an observational trial of patients with SCD receiving monthly chronic transfusion therapy, aliquots of RBCs from one transfusion episode were biotin-labeled and infused along with the unlabeled RBC units. Serial blood samples were obtained to measure RBC survival. Donor units were tested for RBC indices, hemoglobin fractionation, and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity. For microcytic donor RBCs (MCV < 70 fL), HBA1 and HBA2 genetic testing was performed on whole blood.

RESULTS

We present one recipient, a pediatric patient with SCD and splenectomy who received two RBC units with aliquots from each unit labeled at distinct biotin densities (2 and 18 μg/mL biotin). One donor unit was identified to have microcytosis (MCV 68.5 fL after biotinylation); whole blood sample obtained at a subsequent donation showed 2-gene deletion alpha-thalassemia trait (ɑ-3.7kb/ɑ-3.7kb) and normal serum ferritin. G6PD activity was >60% of normal mean for both. The RBCs with alpha-thalassemia RBC had accelerated clearance and increased surface phosphatidylserine post-transfusion, as compared with the normocytic RBC (half life 65 vs. 86 days, respectively).

DISCUSSION

Post-transfusion RBC survival may be lower for units from donors with alpha-thalassemia trait, although the impact of thalassemia trait donors on transfusion efficacy requires further study.

Advancing in vivo assessment of red blood cell transfusions: A call for radiation-free methods in transfusion medicine

RBC transfusions are a vital clinical therapy to treat anemic patients. The in vivo assessment of red blood cell (RBC) quality post-transfusion is critical to ensuring that the introduction of new RBC products meet established regulatory and clinical quality requirements. Although in vitro quality control testing is routinely performed by blood manufacturers, it is crucial that in vivo tests are performed during the evaluation and regulatory process of new RBC products. This article reviews existing in vivo techniques, like chromium-51 labelling and biotinylation, for determining the circulation and survival of RBCs, and advocates for a move to radiation-free methods. The timely need for radiation-free methods to assess emerging non-DEHP container systems is just one example of why efforts to improve the methods available for in vivo quality assessment is important in transfusion medicine. This review aims to advance our understanding of RBC transfusion in vivo quality assessment and enhance transfusion practices.

Novel approaches to measure transfusion effectiveness

PURPOSE OF REVIEW

This review encompasses different considerations of transfusion effectiveness based upon clinical scenario and transfusion indication. Tissue oxygenation, cerebral metabolic oxygen use, and red blood cell (RBC) survival are important elements of transfusion effectiveness in individuals with acute and chronic transfusion requirements.

RECENT FINDINGS

Noninvasive measures of tissue and cerebral oxygen extraction include near-infrared spectroscopy (NIRS) and specialized MRI sequences. RBC survival timepoints including 24 h posttransfusion recovery, 50% recovery timepoint, and mean potential lifespan may be accurately measured with biotin-labeling of RBC prior to transfusion. Labeling at different cell surface densities allows survival of multiple RBC populations to be determined.

SUMMARY

Although past trials of optimal transfusion thresholds have focused on Hb as a singular marker for transfusion needs, measures of oxygenation (via NIRS or specialized MRI) and RBC survival (via biotin labeling) provide the opportunity to personalize transfusion decisions to individual patient's acute health needs or chronic transfusion goals.

Red Blood Cell Storage: From Genome to Exposome Towards Personalized Transfusion Medicine

Over the last decade, the introduction of omics technologies-especially high-throughput genomics and metabolomics-has contributed significantly to our understanding of the role of donor genetics and nongenetic determinants of red blood cell storage biology. Here we briefly review the main advances in these areas, to the extent these contributed to the appreciation of the impact of donor sex, age, ethnicity, but also processing strategies and donor environmental, dietary or other exposures - the so-called exposome-to the onset and severity of the storage lesion. We review recent advances on the role of genetically encoded polymorphisms on red cell storage biology, and relate these findings with parameters of storage quality and post-transfusion efficacy, such as hemolysis, post-transfusion intra- and extravascular hemolysis and hemoglobin increments. Finally, we suggest that the combination of these novel technologies have the potential to drive further developments towards personalized (or precision) transfusion medicine approaches.