Viability of red cells prepared with S-303 pathogen inactivation treatment

BACKGROUND: A nucleic acid-targeted pathogen inactivation process with S-303 was developed to treat red blood cells (RBCs). STUDY DESIGN AND METHODS: Three studies in healthy subjects investigated posttransfusion recovery, life span, and immunogenic potential of autologous RBCs treated with S-303 and stored for 35 days. A two-arm trial in 42 subjects (1A) examined recovery of 35-day-old S-303 RBCs after a single transfusion. A one-arm study (1B) measured recovery and immune response in 28 subjects after multiple transfusions of S-303 RBCs. A randomized, crossover study (1C) in 29 subjects compared recovery and life span of 35-day-old S-303 RBCs and conventional RBCs. RESULTS: In Studies 1A and 1B, mean recovery of S-303 RBCs ranged from 78.7 to 84.4 percent. In Phase 1C, the mean 24-hour posttransfusion recoveries of S-303 and untreated RBCs were 81.7 +/- 6.3 and 84.5 +/- 6.2 percent (p = 0.05). The median life spans (t(1/2)) of S-303 and control RBCs were identical (37.4 days, p = 0.98). No antibodies to S-303 RBCs were detected. CONCLUSION: The mean 24-hour recovery of 35-day-old S-303 RBCs was less than untreated RBCs, but greater than 75 percent. RBCs treated with S-303 and stored for 35 days exhibited median life span not different from that of conventional RBCs.     

Infusion of P-Capt prion-filtered red blood cell products demonstrate acceptable in vivo viability and no evidence of neoantigen formation

BACKGROUND: Transmission of variant Creutzfeldt‐Jacob disease (vCJD) is a major concern in blood transfusion. The P‐Capt filter has been shown to remove around 4 log ID₅₀ prion infectivity from prion‐spiked human red blood cells (RBCs). STUDY DESIGN AND METHODS: Two independent, single‐center, randomized, open‐label studies were designed to analyze the safety of P‐Capt–filtered RBCs. RBCs prepared from leukoreduced whole blood from 43 eligible subjects were randomly assigned to P‐Capt filtration and/or storage in plasma or SAGM and stored for 28 or 42 days. Stored RBCs were analyzed for in vivo 24‐hour recovery, hemolysis, metabolic variables, blood group antigen expression, neoantigen formation, and safety after autologous infusion. RESULTS: Mean P‐Capt filtration times for leukoreduced RBCs were 41 (SAGM) to 51 (plasma) minutes. Thirteen of 14 subjects receiving P‐Capt–filtered RBCs had 24‐hour RBC recoveries of 75% or more after 42‐day storage, with a mean hemolysis of less than 0.6%. No loss of RBC antigen expression or formation of neoantigens was observed. In both studies, RBCs had white blood cell counts of less than 1 × 10⁶/unit after leukofiltration. P‐Capt prion filtration provided an additional greater than 0.8 log leukoreduction. No serious or unexpected adverse events were observed after infusion of P‐Capt–filtered full‐volume RBC units. CONCLUSIONS: P‐Capt–filtered, stored RBCs demonstrated acceptable viability and no detectable neoantigen expression, immunogenic responses. or safety issues after infusion of a complete unit. The additional filtration time and modest reduction in RBC content are within acceptable levels for implementation in countries with transfusion transmission of vCJD.     

A Study of the Pharmacokinetic Properties and the In Vivo Kinetics of Erythrocytes Loaded With Dexamethasone Sodium Phosphate in Healthy Volunteers

The objectives of this 2-phase study were to elucidate pharmacokinetics (PK), in vivo 24-hour recovery, and red blood cell (RBC) survival properties of RBC-encapsulated dexamethasone sodium phosphate (DSP) prepared using the EryDex System (EDS). The 24-hour RBC recovery and T50 survival phase studied subjects were randomized to receive autologous RBCs loaded with either 15-20 mg DSP (Group 1A) or sham saline (Group 2A). Loaded RBCs were radiolabeled with 51-Cr, and the labeled RBCs were followed over time in vivo. The PK phase evaluated dose levels of 2.5-5 mg (Group 1B) and 15-20 mg (Group 2B) DSP encapsulated in RBCs infused into healthy randomized subjects. The mean ± SD 24-hour RBC recovery was 77.9% ± 3.3% and 72.7% ± 10.5% for Groups 1A and 2A, respectively. The mean ± SD RBC life span was 84.3 ± 8.3 days in Group 1A and 88.9 ± 6.2 days in Group 2A. The PK phase actual DSP loading doses (mean ± SEM) were 4.2 ± 0.27 mg and 16.9 ± 0.90 mg in Groups 1B and 2B, respectively. Release of dexamethasone from RBCs in vivo peaked at 1 hour, and a sustained release of dexamethasone could be detected until 35 days after the single intravenous infusion in Group 2B. The mean RBC in vivo recovery for DSP-loaded processed cells compares similarly to the 24-hour recovery of regulated RBC products intended for transfusion. There was a minimal but acceptable adverse impact on the survival of EDS-processed RBCs. DSP-loaded autologous RBCs, prepared using the EDS, delivered a sustained dose of dexamethasone in vivo.     

IMMUNOHEMATOLOGY: Storage of murine red blood cells enhances alloantibody responses to an erythroid‐specific model antigen

BACKGROUND: Red blood cell (RBC) alloimmunization can be a serious complication of blood transfusion, but factors influencing the development of alloantibodies are only partially understood. Within FDA‐approved time limits, RBCs are generally transfused without regard to length of storage. However, recent studies have raised concerns that RBCs stored for more than 14 days have altered biologic properties that may affect medical outcomes. To test the hypothesis that storage time alters RBC immunogenicity, we utilized a murine model of RBC storage and alloimmunization. STUDY DESIGN AND METHODS: Blood from transgenic HOD donor mice, which express a model antigen (hen egg lysozyme [HEL]) specifically on RBCs, was filter leukoreduced and stored for 14 days under conditions similar to those used for human RBCs. Fresh or 14‐day‐stored RBCs were transfused into wild‐type recipients. The stability of the HOD antigen and posttransfusion RBC survival were analyzed by flow cytometry. RBC alloimmunization was monitored by measuring circulating anti‐HEL immunoglobulin levels. RESULTS: Transfusion of 14‐day‐stored, leukoreduced HOD RBCs resulted in 10‐ to 100‐fold higher levels of anti‐HEL alloantibodies as detected by enzyme‐linked immunosorbent assay than transfusion of freshly collected, leukoreduced RBCs. RBC expression of the HOD antigen was stable during storage. CONCLUSIONS: These findings demonstrate that HOD murine RBCs become more immunogenic with storage and generate the rationale for clinical trials to test if the same phenomenon is observed in humans. Length of storage of RBCs may represent a previously unappreciated variable in whether or not a transfusion recipient becomes alloimmunized.     

Anaerobic storage of red blood cells in a novel additive solution improves in vivo recovery

BACKGROUND: In preliminary studies, anaerobic red blood cell (RBC) storage reduced oxidative damage and phosphatidylserine exposure while maintaining adenosine triphosphate levels. The purpose of this study was to compare the 24-hour recovery and life span of autologous RBCs stored 6 and 9 weeks using OFAS3 additive solution in an anaerobic environment, compared to control RBCs aerobically stored in AS-3 for 6 weeks.
STUDY DESIGN AND METHODS: Eight subjects were entered into a randomized, crossover study. Whole blood was collected from each subject twice separated by 12 weeks or more into CP2D and leukoreduced. Controls were stored in AS-3. Test units in OFAS3 were oxygen depleted with argon then stored 9 weeks in an anaerobic chamber at 1 to 6°C. At the end of each storage period, RBCs were labeled with ⁵¹Cr and ^99mTc and reinfused to the subject following standard methods to determine double-label recovery and life span. Hypotheses tests were conducted using paired, repeated-measures analysis of variance.
RESULTS: Recovery for the anaerobically stored test RBC was significantly better than control at 6 weeks (p = 0.023). Test units at 9 weeks were not different than the 6-week control units (p = 0.73). Other in vitro measures of RBC characteristics followed the same trend. Two test units at 9 weeks had hemolysis of greater than 1 percent.
CONCLUSION: Anaerobically stored RBCs in OFAS3 have superior recovery at 6 weeks compared to the controls and equivalent recovery at 9 weeks with no change in life span. Anaerobic storage of RBCs may provide improved RBCs for transfusion at 6 weeks of storage and may enable extending storage beyond the current 42-day limit.     

Therapeutic efficacy and safety of red blood cells treated with a chemical process (S-303) for pathogen inactivation: a Phase III clinical trial in cardiac surgery patients

BACKGROUND: A randomized, double-blind trial is reported of the clinical efficacy of red blood cells (RBCs) treated for pathogen inactivation with S-303, a synthetic labile alkylating agent. STUDY DESIGN AND METHODS: Patients undergoing complex cardiac surgeries were randomly assigned to receive either S-303-treated (test) or conventional (control) RBC transfusion during surgery and for 6 days thereafter. Efficacy was evaluated by comparing the occurrence of a composite primary endpoint of treatment-related morbidity (myocardial infarction and renal failure) and mortality. RESULTS: Two-hundred twenty-three patients were randomly assigned and 148 patients who received transfusions (74 with S-303-treated RBCs and 74 with control RBCs) were evaluable. The incidence of the primary endpoint was equivalent between the two groups (22 and 21% in the S-303-treated and control RBC groups, respectively). Secondary endpoints, including hemoglobin increment (mean, 1.4 vs. 1.5 g/dL), number of RBC transfusions (mean, 4.4 vs. 3.8 units), and other blood product support, were also comparable. The adverse event profile was similar between groups; however, patients who received S-303 RBCs were significantly more likely to develop constipation and less likely to suffer supraventricular extrasystoles. Four patients (2 test and 2 control) demonstrated positive indirect antiglobulin tests with reactivity for S-303 RBCs at one or more time points before or after transfusion, without evidence of hemolysis. CONCLUSION: S-303-treated and conventional RBCs were equivalent with respect to clinical efficacy and safety in supporting the transfusion needs of cardiac surgery patients. Investigations are under way to ascertain the significance of S-303 RBC antibodies and to prevent their occurrence.     

Preclinical pharmacokinetic and toxicology assessment of red blood cells prepared with S-303 pathogen inactivation treatment

BACKGROUND: A system has been developed to inactivate a wide spectrum of blood‐borne pathogens in red blood cells (RBCs) before transfusion. The system utilizes S‐303 to target nucleic acids of pathogens and white blood cells. The safety of pathogen inactivated RBC was assessed using S‐303–treated RBCs (S‐303 RBCs) and S‐300, the primary degradation product of S‐303. STUDY DESIGN AND METHODS: As part of a preclinical safety evaluation program, intravenous toxicity, safety pharmacology, toxicokinetic, and pharmacokinetic studies were conducted in rats and dogs with S‐303 RBCs and S‐300. RESULTS: Single and repeated transfusions of S‐303 RBCs were well tolerated in rats and dogs at S‐303 concentrations up to five times higher than that used to prepare RBCs for clinical use. For S‐300, the doses ranged from the lowest level representative of a clinical exposure from transfusion of 1 unit (0.052 mg/kg/day) to up to the amount of S‐300 that would result from exposure to more than 1900 units of RBCs (100 mg/kg/day). There were no related effects of S‐303 RBCs or S‐300 on mortality, clinical status, body weight, or clinical laboratory assessments and no evidence of organ toxicity. S‐300 did not accumulate in the plasma of rats and dogs after repeated transfusions. For all the studies, plasma S‐303 was consistently below the limit of quantitation. CONCLUSION: The level of residual S‐303 and S‐300 in the treated blood component is well below that at which no adverse effects were observed. These results support further clinical development of S‐303 RBCs for prevention of transfusion‐transmitted infections.     

The survival, function, and hemolysis of human RBCs stored at 4 degrees C in additive solution (AS-1, AS-3, or AS-5) for 42 days and then biochemically modified, frozen, thawed, washed, and stored at 4 degrees C in sodium chloride and glucose solution for 24 hours

BACKGROUND: A study was done to assess the quality of RBCs stored at 4 degrees C in AS-1, AS-3, or AS-5 for 42 days before biochemical modification and freezing. STUDY DESIGN AND METHODS: RBCs were stored at 4 degrees C for 42 days in AS-1, AS-3, or AS-5 and then biochemically modified with pyruvate, inosine, phosphate, and adenine solution (Rejuvesol), frozen with 40-percent (wt/vol) glycerol, and stored at -80 degrees C for at least 2 months. The RBCs were deglycerolized by the use of a cell washer (Haemonetics 115), and stored for 24 hours at 4 degrees C in a 0.9-percent sodium chloride and 0.2-percent glucose solution before the autologous transfusion. RESULTS: The mean freeze-thaw-wash recovery process produced RBC recovery values of 85 percent, with the mean 24-hour posttransfusion survival at 75 percent, and the mean index of therapeutic effectiveness at 64 percent for the RBCs stored at 4 degrees C in AS-1, AS-3, or AS-5 for 42 days before biochemical modification and freezing. All the units exhibited normal or slightly higher than normal 2,3 DPG levels after deglycerolization and postwash storage at 4 degrees C for 24 hours. CONCLUSION: RBCs stored in AS-1, AS-3, or AS-5 at 4 degrees C for 42 days and then biochemically modified with pyruvate, inosine, phosphate, and adenine and glycerolized, frozen, washed, and stored at 4 degrees C for 24 hours before autologous transfusion had acceptable in vitro and in vivo measurements.     

Survival of red blood cells after transfusion: a comparison between red cells concentrates of different storage periods

BACKGROUND: The use of fresh red blood cells (RBCs) is recommended for critically ill patients and patients undergoing surgery, although there is no conclusive evidence that this is beneficial. In this follow-up study, the short-term and the long-term recovery of irradiated, leukoreduced RBCs transfused after either a short storage (SS) or a long storage (LS) period were compared. By consecutive transfusion of RBCs with a SS and LS period, a direct comparison of their survival within the same patient was possible. STUDY DESIGN AND METHODS: Ten transfusion-requiring patients each received a SS RCCs (stored 0-10 days) and a LS RCCs (stored 25-35 days) consecutively. Short-term and long-term survival of the transfused RBCs was followed by flow cytometry using natural differences in RBC antigens between donors and patients. Posttransfusion recovery (PTR) was measured at several time points after transfusion. RESULTS: The mean 24-hour PTR of SS RBCs is 86.4 +/- 17.8 percent and that of LS RBCs 73.5 +/- 13.7 percent. After the first 24 hours, the mean times to reach a PTR of 50 percent of the 24-hour PTR (T50) and mean potential life spans (mPLs) of the surviving SS and LS RBCs (41 and 116 days and 41 and 114 days, respectively) do not differ. CONCLUSIONS: The mean 24-hour PTR of both SS and LS RBCs complies with the guidelines, even in a compromised patient population. The 24-hour PTR of SS RBCs, however, is significantly higher than that of LS RBCs. The remaining population of SS and LS RBCs has a nearly identical long-term survival. Therefore, depletion of the removal-prone RBCs before transfusion may be an efficient approach for product improvement.     

Evaluation of red blood cells stored at -80 degrees C in excess of 10 years

BACKGROUND: RBCs frozen in 40 percent (wt/vol) glycerol are currently approved by the FDA and the AABB for storage at -80 degrees C for up to 10 years. STUDY DESIGN AND METHODS: This study examined 20 RBC units that had been cryopreserved in 40 percent (wt/vol) glycerol and stored at -80 degrees C for up to 22 years. Measures of the freeze-thaw-wash (FTW) recovery, ATP, 2,3-DPG, methemoglobin, RBC indices, morphology, and osmotic fragility were made immediately after deglycerolization and after 24 hours of storage at 4 degrees C. RESULTS: RBCs frozen for longer than 10 years had acceptable mean FTW recovery, normal oxygen transport function, RBC morphology, RBC indices, methemoglobin, and osmotic fragility. Statistical analysis indicated that the in-vitro viability and function of cryopreserved RBCs was not dependent on the length of frozen storage or postthaw storage at 4 degrees C but did correlate with the storage length at 4 degrees C before cryopreservation. CONCLUSION: The data reported in this study demonstrate that RBCs can be stored at -80 degrees C beyond 10 years with acceptable in-vitro quality and suggest that more defined criteria for the cryopreservation process be adopted.     

In vivo viability of stored red blood cells derived from riboflavin plus ultraviolet light-treated whole blood

BACKGROUND: A novel system using ultraviolet (UV) light and riboflavin (Mirasol System, CaridianBCT Biotechnologies) to fragment nucleic acids has been developed to treat whole blood (WB), aiming at the reduction of potential pathogen load and white blood cell inactivation. We evaluated stored red blood cell (RBC) metabolic status and viability, in vitro and in vivo, of riboflavin/UV light–treated WB (IMPROVE study). STUDY DESIGN AND METHODS: The study compared recovery and survival of RBCs obtained from nonleukoreduced WB treated using three different UV light energies (22, 33, or 44 J/mL_RBC). After treatment, WB from 12 subjects was separated into components and tested at the beginning and end of component storage. After 42 days of storage, an aliquot of RBCs was radiolabeled and autologously reinfused into subjects for analysis of 24‐hour recovery and survival of RBCs. RESULTS: Eleven subjects completed the in vivo study. No device‐related adverse events were observed. By Day 42 of storage, a significant change in the concentrations of sodium and potassium was observed. Five subjects had a 24‐hour RBC recovery of 75% or more with no significant differences among the energy groups. RBC t_1/2 was 24 ± 9 days for the combined three groups. Significant correlations between 24‐hour RBC recovery and survival, hemolysis, adenosine triphosphate (ATP), and CO₂ levels were observed. CONCLUSIONS: This study shows that key RBC quality variables, hemolysis, and ATP concentration may be predictive of their 24‐hour recovery and t_1/2 survival. These variables will now be used to assess modifications to the system including storage duration, storage temperature, and appropriate energy dose for treatment.     

In vitro and in vivo measurements of human RBCs frozen with glycerol and subjected to various storage temperatures before deglycerolization and storage at 4 degrees C for 3 days

BACKGROUND: This study was designed to assess the effects of changes in storage temperature of frozen RBCs such as might occur during a malfunction of the -80 degrees C mechanical freezer or during shipment. STUDY DESIGN AND METHODS: Fifteen participants donated blood for autologous transfusion of RBCs; all RBCs were frozen with 40-percent (wt/vol) glycerol. Five subjects received RBCs that were stored at -80 degrees C alone before transfusion. Five subjects received RBCs that were stored initially at -80 degrees C, then at -40 degrees C for 4 weeks, and finally at -80 degrees C before transfusion. Five subjects received RBCs that were stored at -80 degrees C, then at -20 degrees C for 2 weeks, and finally at -80 degrees C before transfusion. After deglycerolization, the RBCs were stored at 4 degrees C in a sodium chloride-glucose solution for 3 days before transfusion. RESULTS: No significant differences were observed in freeze-thaw recovery, freeze-thaw-wash recovery, 24-hour posttransfusion survival, index of therapeutic effectiveness, or RBC ATP levels. Greater hemolysis and reduced RBC K+ levels were observed in the units stored at -80 degrees C/-40 degrees C/-80 degrees C and in those stored at -80 degrees C/ -20 degrees C/-80 degrees C compared with the units stored at -80 degrees C alone, but these differences did not affect the 24-hour posttransfusion survival. CONCLUSIONS: The results of this study indicated that RBCs frozen with 40-percent (wt/vol) glycerol can be stored at -40 degrees C for 4 weeks or at -20 degrees C for 2 weeks between periods of frozen storage at -80 degrees C with satisfactory results.     

Transfusion of stored red blood cells adhere in the rat microvasculature

BACKGROUND: Ex vivo storage of red blood cells (RBCS) for transfusions is associated with a “storage lesion,” which decreases RBC deformability and increases RBC adhesiveness to vascular endothelium. This may impair microcirculatory flow with deleterious effects on oxygen delivery after transfusion. Previous studies have shown that human RBCs adhere to endothelial monolayers in vitro with prolonged storage and is reduced by prestorage leukoreduction (LR). The objective of this study was to determine whether duration of RBC storage and LR influence RBC adhesion in vivo in capillaries. STUDY DESIGN AND METHODS: Rat RBCs were collected and stored in CPDA‐1 under standard blood bank conditions. Three RBC products were compared: 1) fresh RBCs, less than 24 hours of storage (n = 6); 2) nonleukoreduced (NLR) RBCs stored for 7 days (n = 6); and 3) prestorage LR RBCs stored for 7 days (n = 6). RBCs were labeled with fluorescein isothiocyanate (FITC) 24 hours before transfusion and reinjected in an isovolemic manner into healthy rats. The FITC‐labeled RBCs were visualized in the extensor digitorum longus muscle using intravital video microscopy (20× magnification). The number of RBCs adherent in capillaries was counted 1 hour after transfusion in 10 random fields and the median values were compared with one‐way analysis of variance. RESULTS: Stored RBCs showed increased levels of adherence in capillaries compared to their fresh counterparts (p < 0.05). Prestorage LR decreased RBC adherence to levels equivalent to those of fresh RBCs (p < 0.05 for stored LR vs. stored NLR). CONCLUSION: Rat RBCs stored under conditions that closely mimicked clinical transfusion adhere in capillaries. The decreased RBC adherence with LR suggest a direct effect of white blood cells or their byproducts on RBC deformability and/or adhesiveness to microvascular endothelium. Further study will examine the mechanism of adherence and the impact it has on microcirculatory flow and oxygen delivery in the critically ill host.     

Transfusion of fresh murine red blood cells reverses adverse effects of older stored red blood cells

BACKGROUND: Although a subset of recent studies have suggested that red blood cell (RBC) storage length is associated with adverse patient outcomes, others have shown no such relationship. Adults may be transfused with RBC units of different storage lengths, and existing studies do not take into consideration that fresh RBCs may alter responses to concurrently transfused stored RBCs. To test this possibility, we utilized a murine model and investigated transfusion outcomes of fresh, stored, or fresh‐plus‐stored RBCs. STUDY DESIGN AND METHODS: Fresh, 14‐day‐stored or fresh plus 14‐day‐stored leukoreduced RBCs from HOD‐transgenic donors (with RBC‐specific expression of hen egg lysozyme, ovalbumin, and human Duffy^b) were transfused into naïve C57BL/6 recipients. Serum cytokines and anti‐HOD alloimmunization were evaluated after transfusion. RESULTS: In six of six experiments (n = 90 mice total), a proinflammatory serum cytokine storm of interleukin‐6, keratinocyte‐derived chemokine/CXCL1, and monocyte chemoattractant protein‐1 was observed in transfusion recipients of stored but not fresh RBCs, along with high degrees of anti‐HOD alloimmunization. However, concurrent transfusion of fresh HOD RBCs along with stored HOD RBCs significantly decreased these adverse outcomes (p < 0.05). CONCLUSIONS: These results are consistent with fresh murine HOD RBCs losing protective properties during storage, and introduce a previously unrecognized variable in RBC storage studies. If translatable to humans, uniform “old blood” groups may be needed in future clinical studies to more accurately investigate the biologic effects of older RBC units.     

Addition of L-carnitine to additive solution-suspended red cells stored at 4 degrees C reduces in vitro hemolysis and improves in vivo viability

BACKGROUND: The role of L-carnitine (LC) as the requisite carrier of long-chain fatty acids into mitochondria is well established. Human red cells (RBCs), which lack mitochondria, possess a substantial amount of LC and its esters. In addition, carnitine palmitoyl transferase, an enzyme that catalyzes the reversible transfer of the acyl moiety from acyl-coenzyme A to LC is found in RBCs. It has recently been shown that LC and carnitine palmitoyl transferase play a major role in modulating the pathway for the turnover of membrane phospholipid fatty acids in intact human RBCs, and that LC improved the membrane stability of RBCs subjected to high shear stress. RBC membrane lesions occur during storage at 4 degrees C; this study investigated whether the addition of LC (5 mM) to a standard RBC preservative solution (AS-3) affected cellular integrity with 42 days' storage. STUDY DESIGN AND METHODS: A paired (n = 10) crossover design was used for RBCs stored in AS-3 with and without LC. Both in vitro RBC properties reflective of metabolic and membrane integrity and in vivo measures of cell viability (24-hour percentage of recovery and circulating lifespan) were measured at the end of the storage. In addition, the turnover of membrane phospholipid and long-chain acylcarnitine fatty acids and the carnitine content of control and LC-stored RBCs were measured. RESULTS: It was shown that LC was irreversibly taken up by RBCs during storage, with a fourfold increase at 42 days. Furthermore, as found by the use of radiolabeled palmitate, the stored RBCs were capable of generating long-chain acylcarnitine. The uptake of LC during storage was associated with less hemolysis and higher RBC ATP levels and by a significantly greater in vivo viability for LC-stored RBCs than for control-stored RBCs: a mean 24-hour percentage of recovery of 83.9 +/? 5.0 vs. 80.1 +/? 6.0 percent and a mean lifespan of 96 +/? 11 vs. 86 +/? 14 days, respectively (p < 0.05). CONCLUSION: A beneficial effect of the addition of LC to RBCs stored at 4 degrees C was evident. This effect may be related to both biophysical and metabolic actions on the cell membrane.     

A feasibility evaluation of an automated bloodcomponent collection system platelets and red cells

BACKGROUND: The purpose of these studies was to evaluate the functional properties of blood components collected with an automated collection system. STUDY DESIGN AND METHODS: Single-donor platelets (n = 44) and packed red cell (RBC) units (n = 10) were collected. In vitro and in vivo assays were used to assess the function of single-donor platelet components stored for 5 days and of packed RBC units after storage for 42 days at 4 degrees C. RESULTS: Adverse events observed in the 44 study subjects were minor. The mean 24-hour recovery value for the packed RBC units stored for 42 days was 83.6 +/- 5.4 percent, with a mean percentage of hemolysis on Day 42 at 0.46 +/- 0.19 percent. The 25 patients receiving platelet components achieved a mean corrected count increment of 15.1 +/- 10.4 x 10(3). All platelet concentrates had less than 1 x 10(6) total white cells. CONCLUSION: Both in vitro and in vivo testing for the packed RBCs collected and stored for 42 days met the standards for both hemolysis and percentage of 51Cr 24-hour RBC recovery. The in vitro results and transfusion data on white cell-reduced platelet components transfused to thrombocytopenic patients were comparable to those on available platelet components.     

Rapid clearance of transfused murine red blood cells is associated with recipient cytokine storm and enhanced alloimmunogenicity

BACKGROUND: Fourteen‐day stored red blood cells (RBCs) containing an RBC‐specific transgenic antigen (HOD) induce a recipient proinflammatory cytokine storm and are significantly more immunogenic compared to fresh RBCs. Given that recipient mice clear transfused stored RBCs more rapidly than fresh RBCs, we hypothesized that rapid RBC clearance was associated with adverse transfusion outcomes. STUDY DESIGN AND METHODS: HOD RBCs were treated by two distinct methods known to lead to rapid posttransfusion RBC clearance: phenylhydrazine or heat. HOD antigen expression was analyzed on the treated cells before transfusion, and RBC recovery, recipient cytokine response, and recipient anti‐HOD alloimmunization response were measured after transfusion. RESULTS: Phenylhydrazine and heat treatment each led to near complete RBC clearance in recipients by 24 hours posttransfusion, without significantly altering HOD antigen expression on the transfused RBCs. Recipients of phenylhydrazine‐ or heat‐treated RBCs had elevated circulating levels of keratinocyte‐derived chemokine/CXCL‐1, monocyte chemoattractant protein‐1, and interleukin‐6 after transfusion. Furthermore, phenylhydrazine‐ or heat‐treated RBCs were significantly more immunogenic than control RBCs, with a mean 25.1‐ and 10.3‐fold enhancement, respectively, of anti‐HOD alloimmunization magnitude by flow cytometric crossmatch. CONCLUSIONS: Three separate insults to RBCs (storage, phenylhydrazine, or heat treatment) result in rapid posttransfusion clearance, with a recipient proinflammatory cytokine storm and enhanced alloimmunogenicity. These data are consistent with the hypothesis that rapid clearance of RBCs is causally involved in these outcomes and suggest that human donor RBCs with favorable posttransfusion clearance profiles may be less immunogenic.     

Posttransfusion recovery of stored red blood cells in very low birth weight infants using a hemoglobin balance model

BACKGROUND: A Hb balance model was used in very low birth weight (VLBW) infants to predict posttransfusion Hb levels from which we inferred allogeneic RBC recovery after transfusion of RBCs stored for varying periods of time. STUDY DESIGN AND METHODS: Premature VLBW infants receiving RBC transfusions during the 1st month of life were evaluated retrospectively for RBC survival of stored donor blood. Actual Hb levels measured in infant blood 1 and 2 days after RBC transfusions were compared to those predicted using a Hb balance model based on factors affecting blood Hb loss and gain. Transfusions were subgrouped according to whether or not infants were clinically stable at the time of RBC transfusion. Model-predicted RBC recovery was also evaluated relative to duration of RBC storage. RESULTS: Model-predicted mean (+/- SD) Hb levels 2 days after transfusion among the 30 VLBW infants receiving a total of 57 RBC transfusions were only 4 percent higher than actual values observed (15.2 +/- 1.2 g/dL vs. 14.7 +/- 1.4, respectively; p < 0.05). The infant's clinical status at the time of transfusion did not affect predicted 1- and 2-day posttransfusion RBC recovery. Model-predicted recovery of transfused RBCs was modestly, but significantly, decreased with increasing duration of donor RBC storage (i.e., 10% lower by 42 days-the maximal allowed storage period for donor blood [p < 0.01]). CONCLUSIONS: Our model-predicted RBC survival results are consistent with-but not direct evidence of-hemolysis of donor blood after RBC transfusion. Although observed post-RBC Hb levels 2 days after transfusion averaged only 4 percent less than predicted, model-predicted survival of donor RBCs at 42 days suggested a modest decrease (i.e., by 10%).     

mPEG修饰红细胞的动物实验

本研究采用异硫氰酸荧光素标记鼠、猕猴、猪和人的修饰与未修饰自体和异体红细胞（RBC）并给小鼠和猕猴实施输注，观察回输体内RBC24小时存活率的变化和差异。结果发现：未修饰小鼠RBC在小鼠体内24小时存活率为74％，2．0mmol／Lm PEG—SPA修饰的小鼠RBC在小鼠体内24小时存活率为45％，两者间有显著差异；未修饰人RBC在小鼠体内24小时存活率为8％，2．0mm01／Lm PEG—SPA修饰人RBC在小鼠体内24小时存活率为5％，两者间无显著差异，修饰的猕猴RBC自体回输后24小时的存活率大于90％，而修饰的人RBC和猪RBC在给称猴回输后2小时其存活率已降至零。结论：RBC标记方法及不同种实验小鼠的选择对小鼠实验结果影响不大，但mPEG种类和浓度对鼠RBC寿命的有一定程度影响。用鼠RBC做自体回输来评价mPEG修饰人RBC的中mPEG是否影响人红细胞的寿命是不可靠的，修饰人RBC回输给小鼠可以作为评价修饰人RBC寿命和安全性的动物模型， 大哺乳动物异种RBC输注很难观察到修饰RBC的存活率和寿命长短。适合评价修饰人RBC寿命和安全性的大动物模型有待于进一步探索。     

Radiolabeled red cell viability. I. Comparison of 51Cr, 99mTc, and 111In for measuring the viability of autologous stored red cells

The simultaneous determination of autologous 99mTc red cell (RBC) and 51Cr RBC viability at 24 hours was measured in 19 normal volunteers whose RBCs had been stored in additive media (Nutracel) for 42 or 49 days. The ratio of the 51Cr:99mTc value was 1.23. In this experiment we also calculated 51Cr RBC viability by both the single-isotope method (extrapolation) and the double-isotope method (using 125I human serum albumin for an independent plasma volume) in the same volunteers. The corresponding viability values were not significantly different. The simultaneous determination of autologous 111In-oxine RBC and 51Cr RBC viability at 24 hours was measured in 19 other normal volunteers whose RBCs had been stored in citrate-phosphate-dextrose-adenine (CPDA-1) for 1 or 15 days. The ratio of the 51Cr:111In value was 1.1. Use of these 24-hour viability ratios as conversion factors permits direct comparison of 99mTc or 111In RBC viability with a 51Cr standard, and therefore expands the application of these newer RBC radiolabels.