Treatment for the decline of ionized calcium levels during peripheral blood progenitor cell harvesting

Apheresis collection of mononuclear cells for chimeric-antigen receptor therapies

Collections of lymphocytes to be genetically modified to treat hematologic malignancies have seen a dramatic increase over the last few years as commercial products have been approved. Reports of new products in development that can possibly treat solid organ malignancies represent a massive change in the field. Apheresis is at the center of the collection of cells for the manufacture of these chimeric-antigen receptor therapy products. The expansion of these collections represents one of the areas of apheresis procedures growth. This review will summarize concepts important to this type of collection and variables that need to be optimized to obtain desired cell yields while increasing patients' safety.

Risk analysis of fluctuating hypercalcemia after leukapheresis in cellular therapy

Optimized management of citrate-induced hypocalcemia is required to provide safe leukapheresis. We prospectively analyzed subjects who underwent leukapheresis for cytotherapy, and evaluated serum ionized (iCa) concentrations before, at the end of, and 1 h after leukapheresis. During leukapheresis, calcium gluconate solution was continuously supplemented intravenously with hourly measurement of iCa. 76 patients including 49 lymphapheresis for chimeric antigen receptor T-cell therapy and 27 stem cell collections were enrolled. Median processing blood volume was 10 L (range, 6-15 L). Fluctuating hypercalcemia, in which the iCa concentration rose above its upper limit 1 h after leukapheresis, was observed in 58 subjects (76.3%). Multivariate analysis revealed that higher ratios of processing blood volume to body weight, more rapid calcium supplementation, and lower iCa concentration at the end of leukapheresis significantly increased elevation of serum iCa concentration by 1 h after leukapheresis. Based on multivariate analyses, we developed a formula and a diagram that accurately estimates serum iCa concentration 1 h post-leukapheresis. This suggests optimal targets for iCa concentration and calcium supplementation rates. In cases with high ratios of processing blood volume to body weight, slowing the rate of blood processing, rather than increasing calcium supplementation should safely alleviate hypocalcemia during leukapheresis without inducing hypercalcemia thereafter.

Effectiveness of supplemental oral calcium drink in preventing citrate-related adverse effects in peripheral blood progenitor cell collection

Peripheral blood progenitor cells (PBPCs) are a predominant graft source in allogeneic hematopoietic cell transplantation. Citrate-induced hypocalcemia remains the most frequent side effect of PBPC apheresis. Although the method for preventing severe adverse events is established, more efficient prophylaxis is required so that volunteer donors can donate PBPCs without pain and anxiety. We studied 80 healthy donors who underwent PBPC harvest between February 2014 and June 2020. Of these, 23 donors who underwent apheresis between February 2014 and December 2015 received only the standard prophylaxis of intravenous calcium gluconate. Oral calcium drinks were provided to 57 donors who underwent apheresis from January 2016 to June 2020 to supplement intravenous calcium gluconate prophylaxis. The ionized calcium (ICa) levels at multiple time intervals and the hypocalcemic symptoms were evaluated. Oral supplementation with a calcium drink maintained significantly higher ICa levels. Analysis using the inverse probability weighted regression adjustment method suggested that calcium drinks reduced the frequency of citrate-related reactions by 39.2 %. Administering a prophylactic oral calcium drink before apheresis with intravenous administration of calcium gluconate is promising to further reduce citrate-induced hypocalcemia in volunteer donors.

Unstimulated apheresis for chimeric antigen receptor manufacturing in pediatric/adolescent acute lymphoblastic leukemia patients

Autologous unstimulated leukapheresis product serves as starting material for a variety of innovative cell therapy products, including chimeric antigen receptor (CAR)-modified T-cells. Although it may be reasonable to assume feasibility and efficiency of apheresis for CAR-T cell manufacture, several idiosyncrasies of these patients warrant their separate analysis: target cells (mononuclear cells [MNC] and T-cells) are relatively few which may instruct the selection of apheresis technology, low body weight, and, hence, low total blood volume (TBV) can restrict process and product volume, and patients may be in compromised health. We here report outcome data from 46 consecutive leukaphereses in 33 unique pediatric patients performed for the purpose of CD19-CAR-T-cell manufacturing. Apheresis targets of 2×10⁹ MNC/1×10⁹ T-cells were defined by marketing authorization holder specification. Patient weight was 8 to 84 kg; TBV was 0.6 to 5.1 L. Spectra Optia apheresis technology was used. For 23 patients, a single apheresis sufficed to generate enough cells and manufacture CAR-T-cells, the remainder required two aphereses to meet target dose and/or two apheresis series because of production failure. Aphereses were technically feasible and clinically tolerable without serious adverse effects. The median collection efficiencies for MNC and T-cells were 53% and 56%, respectively. In summary, CAR apheresis in pediatric patients, including the very young, is feasible, safe and efficient, but the specified cell dose targets can be challenging in smaller children. Continuous monitoring of apheresis outcomes is advocated in order to maintain quality.

Solving the calcium gluconate shortage in real-time: Mistakes made and lessons learned

PURPOSE

During a national shortage of calcium gluconate, we switched to calcium chloride for routine supplementation for peripheral blood stem cell (PBSC) collections. Subsequently, we analyzed the postprocedure ionized calcium level, as we aimed for an equivalent result compared to before the shortage.

METHODS

Pharmacy representatives helped us to find an "equivalent" substitute for calcium gluconate at 46.5 mEq in 500 mL normal saline, infused at 100 mL/hour. After instituting a presumably comparable protocol using calcium chloride (40.8 mEq in 250 mL normal saline at a rate of 100 mL/hour), we reviewed ionized calcium results post-PBSC procedures to compare with those obtained with calcium gluconate. Having noticed a difference in the mean values, we adjusted the rate of calcium chloride to reach our desired outcome.

RESULTS

Twenty-seven procedures were analyzed on 15 unique patients. We used the Spectra OPTIA with a whole blood: anticoagulant ratio of 13:1. Ionized calcium levels post-PBSC collection with the first calcium chloride protocol were significantly higher (P = 0.003) in nine patients treated. Subsequently, we decreased the calcium chloride infusion rate to 75 mL/hour and achieved similar mean levels to calcium gluconate (P = 0.382).

CONCLUSION

Changes in replacement fluids for apheresis procedures can be complex, particularly when dealing with electrolytes that could be clinically significant at critically high or low levels. Once we recognized the need to take into account the amount of elemental calcium infused, we achieved the desired postprocedure ionized calcium results. This study can serve as a lesson for future shortages of infusions used during apheresis procedures.

Apheresis on aged patients/donors with complicated backgrounds like ischemic heart disease, arrhythmia, and others

Peripheral blood stem cells (PBSCs) are currently one of the most important stem cell sources for hematopoietic stem cell transplantation as well as cell therapy for ischemic heart disease or critical limb ischemia. Thus, it is sometimes necessary to collect autologous PBSCs from donors who have comorbidities. In terms yield, a sufficient number of PBSCs can be collected from donors with comorbidities for performing cell therapy if their age is < 60 years or up to a maximum of 70 years, although the number of PBSCs collected from older donors would probably be lower than that obtained from younger donors. On the other hand, granulocyte colony-stimulating factor (G-CSF) administration sometimes results in severe adverse events (AEs), such as ischemic heart disease and vascular thrombosis. Therefore, it is very important to perform strict medical check-ups according to the standards for donor operations in each country before apheresis. The apheresis procedure and G-CSF administration should be performed after administering the appropriate treatment. There is very less information available regarding AEs related to citrate administration during apheresis in aged donors with complicated medical histories. Medical staff should have knowledge of the electrocardiogram (ECG) QTc prolongation that occurs during apheresis owing to hypocalcemia caused by citrate administration, necessitating electrocardiographic monitoring of patients. Calcium should be administered during apheresis to prevent citrate related symptoms.

Comprehensive technical and patient-care optimization in the management of pediatric apheresis for peripheral blood stem cell harvesting

BACKGROUND

Pediatric apheresis for peripheral blood stem cell transplantation should be carried out with due concern for low corporeal blood volume and vulnerability to hypocalcemia-related complications, hypovolemic shock, and hypervolemic cardiac overload.

STUDY DESIGN AND METHODS

We retrospectively investigated a total of 267 apheresis procedures from 1990 to 2013 on 93 children between 0 and 10 years old, including 89 patients and 4 healthy donors, with body weights of 6.3 to 44.0 kg.

RESULTS

The median CD34+ cell yield per apheresis procedure was 2.3 × 10⁶ CD34+ cells/kg (0.2-77.9 × 10⁶ CD34+ cells/kg). Adverse events occurred in 11.6% of procedures (n = 31), including mild perivascular pain (n = 12), emesis (n = 9), hypotension (n = 3), urticaria (n = 2), numbness (n = 2), chest pain (n = 1), facial flush (n = 1), and abdominal pain (n = 1). Among hypotensive events, shock in a 9.6 kg one-year-old boy required emergency treatment in 1996. Thereafter, we adopted continuous injection of calcium gluconate, ionized calcium monitoring, central venous catheter access and circuit priming with albumin in addition to concentrated red cells. Since then we have had fewer complications: 16.4% per apheresis during 1990-1997 versus 5.8% during 1998-2013. No healthy pediatric donors suffered from any late-onset complications related to apheresis or G-CSF administration.

CONCLUSION

By employing appropriate measures, peripheral blood stem cell apheresis for small children can have an improved safety profile, even for children weighing <10 kg.

Citrate anticoagulation: Are blood donors donating bone?

An estimated 2.4 million volunteer apheresis blood donation procedures were performed in the United States in 2010, and increases in the proportion of transfused blood products derived from apheresis blood collections have been consistently reported. Anticoagulation is required during apheresis and is achieved with citrate. Donor exposure to citrate causes an acute physiological response to maintain serum mineral homeostasis. Some data are available on the sequelae of this acute response in the days and weeks following exposure, raising questions about bone mineral density in regular apheresis donors. New research is emerging that addresses the potential long-term health outcomes of repeated citrate exposure. This article reviews the acute physiological response to citrate anticoagulation in volunteer blood donors, presents contrasting perspectives on the potential effects of citrate exposure on bone density, and identifies key knowledge gaps in our understanding of long-term health outcomes in apheresis donors. J. Clin. Apheresis 31:459-463, 2016. © 2015 Wiley Periodicals, Inc.

Peripheral blood progenitor cell collection by two programs for autologous and allogeneic transplantation

BACKGROUND

In the Spectra apheresis instrument (Terumo BCT), both manual (Spectra-MNC) and automated (Spectra-Auto) programs have been widely used to collect peripheral blood progenitor cells (PBPCs). However, direct comparison of these programs remains extremely limited.

STUDY DESIGN AND METHODS

We investigated 188 collections and products from autologous (patient) and allogeneic (donor) subjects and analyzed a subset of 89 allogeneic collections and products. Twenty-nine subjects who received apheresis for 2 consecutive days using both programs were also evaluated with a paired crossover comparison.

RESULTS

The two programs processed similar volumes, but run time was longer with Spectra-Auto. Yield and efficiency of CD34+ cell collection were similar between these programs in the whole cohort, although white blood cell (WBC) and mononuclear cell (MNC) yields were higher with Spectra-MNC. In the allogeneic cohort, yield and efficiency of WBC collection were greater in Spectra-MNC. However, collected WBCs, MNCs, and CD34+ cells were similar between these programs in paired comparison. Regardless of program, preapheresis peripheral WBC, MNC, and CD34+ cell counts correlated with the number of cells collected. In contrast, preapheresis WBC counts in the whole cohort were negatively correlated with collection efficiencies of CD34+ cells in Spectra-MNC but not Spectra-Auto. The products collected using Spectra-MNC contained more contaminating platelets (PLTs) than Spectra-Auto, with a corresponding reduction in postdonation circulating PLTs.

CONCLUSION

Spectra-MNC and Spectra-Auto showed distinct features that should be considered on a case-by-case basis. Similar investigations should be undertaken as new collection platforms are introduced.

Anticoagulation techniques in apheresis: from heparin to citrate and beyond

Anticoagulation is essential for maintaining the fluidity of extravascular blood on the apheresis circuit. Although both citrate and heparin are used as an anticoagulant during apheresis, citrate is preferred for the majority of exchange procedures because of its safety and effectiveness. Complications of citrate are primarily due to physiologic effects of hypocalcemia. Symptoms of hypocalcemia and other citrate-induced metabolic abnormalities affect neuromuscular and cardiac function and range in severity from mild dysesthesias (most common) to tetany, seizures, and cardiac arrhythmias. Oral or intravenous calcium supplementation is advised for decreased ionized calcium levels and/or symptomatic management of hypocalcemia. Heparin-based anticoagulation is limited to certain apheresis procedures (membrane-based plasma exchange, LDL apheresis, or photopheresis) or is used in combination with citrate to reduce citrate load. While effective, heparin anticoagulation is associated with an increased frequency of bleeding complications and heparin-induced thrombocytopenia. J. Clin. Apheresis 2012. © 2012 Wiley Periodicals, Inc.

Anticoagulation in large-volume leukapheresis: comparison between citrate- versus heparin-based anticoagulation on safety and CD34 (+) cell collection efficiency

BACKGROUND AIMS

Little is known of the effect of anticoagulation on peripheral blood progenitor cell (PBPC) harvest during large-volume leukapheresis (LVL). Because of the interaction of heparin with stromal cell-derived factor (SDF)-1α, it has been proposed that a heparin-based anticoagulation may result in an increased PBPC collection efficiency compared with standard citrate-based anticoagulation.

METHODS

We conducted a prospective randomized trial to address the effect of both anticoagulation regimes on safety, subjective comfort and CD34 (+) collection efficiency in 90 adult patients undergoing standardized LVL. Anticoagulation consisted of either citrate (group C) or a combination of heparin and low-dose citrate (group H).

RESULTS

The overall incidence of adverse reactions (AR) during LVL was 17%. AR consisted only of citrate-related AR; no bleeding complications were observed. Determination of parameters of the acid-base balance revealed a higher frequency of metabolic alkalosis in group C. Analysis of serum SDF-1α revealed no differences in SDF-1α plasma levels. There were no differences in the CD34 (+) cell collection efficiency, resulting in the harvest of equal CD34 (+) cell yields independent of the anticoagulation used.

CONCLUSIONS

Our data show no clinical relevant effect of a heparin containing anticoagulation in terms of an increased overall CD34 (+) cell collection during LVL, although this regime shows some benefits in terms of the incidence and subjective tolerance towards AR. Based on our results the decision between a citrate- and heparin-substituted anticoagulation for LVL should be driven by patient-related factors, and should concern potential contraindications of both methods.

Adverse events and safety issues in blood donation--a comprehensive review

Although blood donation is generally safe, a variety of risks and complications exist, the most common being iron deficiency, vasovagal reactions and citrate-related events. In the last decades, extensive efforts have significantly improved recipient and product safety, but there is still great potential to optimise donor care. Many therapies in modern medicine depend on the prompt availability of blood products, therefore it is crucial to maintain a motivated and healthy donor pool in view of a limited number of healthy volunteers willing and able to give blood or blood components. We present a comprehensive review on adverse events addressing all types of blood donation including whole blood, plasma, platelet, peripheral blood stem cell, leucocyte and bone marrow donation. In addition, we outline strategies for the prevention and treatment of these events and give a blueprint for future research in this field.

Collection of peripheral blood progenitor cells for autologous use: performance enhancements of COBE spectra, auto-PBSC

Collection of peripheral blood stem cells (PBSC) must be performed in a safe and effective manner. Issues like automation, collection efficiency (CE), and adverse events must be considered. Auto-PBSC (COBE Spectra) is a fully automated program for PBSC collection. Changes in the protocol were made to achieve high CE, low product volume, and resulted in three groups of patients. Standard operating procedures (SOPs) were developed to reduce citrate toxicity and patients with central venous catheter. Twenty patients and 27 collections (Group 1), 88 patients and 112 collections (Group 2), and 158 patients and 194 collections (Group 3) were recorded. The protocol changes increased CE significantly from 31% (Group 1) to 57 and 59% (Group 2 and 3). Adjusting endpoint according to the preapheresis number of CD34+ cells reduced the collection time and the volume of the product significantly (median 227 min and 56 mL) without affecting CE. Mean level of ionized calcium before collection was 1.22 mmol/L, measured in 31 patients. This declined to a mean of 1.07 mmol/L after 1 h of collection and remained unchanged despite continuous calcium infusion. The number of patients with mild symptoms of citrate toxicity was reduced from 20 to 6%. A central venous catheter was used in 15%. Compared to peripheral access no differences in blood flow rate or time to perform the collection were found. Changes in the Auto-PBSC protocol resulted in an improved CE and a small product. SOPs reduced the number of patients with citrate toxicity and with central venous catheter.

Regional citrate anticoagulation is safe in intermittent high-flux haemodialysis treatment of children and adolescents with an increased risk of bleeding

BACKGROUND

Regional citrate anticoagulation (RCA) is strongly recommended for adults with an increased risk of bleeding complications. The objective of this retrospective analysis was to evaluate an RCA protocol concerning feasibility and safety in intermittent high-flux haemodialysis (iHD) treatment in children and adolescents.

METHODS

Eighteen children and adolescents aged 5-17 years (median 15 years) underwent 74 iHD treatment sessions with RCA. Twelve of 18 patients presented with overt local or diffuse haemorrhage before beginning the HD sessions, and six had an increased risk of haemorrhagic complications. Forty children on acute haemodialysis with general heparin anticoagulation, matched for bleeding risk, age and body surface area, served as a control group. Citrate 3% solution was begun with 3.3% blood flow rate, and calcium gluconate 10% substitution was started with 0.4% of blood flow rate. Citrate flow was adapted to achieve a post-filter ionized calcium of ≤0.30 mmol/L; calcium substitution was adapted to maintain the patients' serum calcium levels within the physiological range. Calcium-free dialysis fluid was used. The blood flow rate ranged from 3 to 5 mL per minute and kilogram body weight.

RESULTS

Regional anticoagulation was successfully achieved within the extracorporeal blood circuit, while the coagulation of all 18 patients remained within physiological parameters. No adverse effects of RCA were observed. In all 18 children, neither new haemorrhage nor worsening of the bleeding situation occurred, and in 10/12 patients, bleeding stopped during dialysis with RCA. In contrast, one-third of the control group developed new haemorrhagic complications or presented with worsening of pre-existing bleeding during haemodialysis (P = 0.006).

CONCLUSION

RCA is feasible, safe and effective in paediatric intermittent haemodialysis treatment.

Hypocalcemic symptoms during plateletpheresis using the COBE Spectra: a comparison of oral combination of 600mg calcium+300mg magnesium+100IU vitamin D3 vs. a 1000mg calcium in symptomatic donors

BACKGROUND

The aim of this study was to find an effective treatment for hypocalcemic symptoms during plateletpheresis and to evaluate if a combination of calcium, magnesium and vitamin D3 is more effective in comparison to routine calcium supplementation.

MATERIAL AND METHODS

A study group consisting of 10 donors, having a history of previous hypocalcemic symptoms during plateletpheresis, donated platelets twice in a one-month period. During the first donation combination tablets (600mg Ca+300mg Mg+100IU vitamin D3) were used to treat hypocalcemic symptoms while routine treatment calcium carbonate tablets (1000mg Ca) were used during the second donation. If symptoms persisted after 10min the same dose was repeated. A control group, with no supplementation, consisting of five donors, with no history of hypocalcemic symptoms, were included. Donor subjective symptoms were graded and recorded on four occasions: at the start of plateletpheresis, when symptoms appeared, 10min after the first tablet and at the end of donation. Samples for analysis of ionized calcium (iCa), magnesium and potassium were also taken at the same occasions.

RESULTS

All donors from the study group experienced minor or medium hypocalcemic symptoms and needed a second dose of supplementation. Calcium carbonate tablets completely relieved the hypocalcemic symptoms in six donors, it had no effect on three donors and one donor experienced aggravated symptoms. The combination tablets completely relieved the symptoms in three donors, one donor experienced a partial relief and six donors had no relief of symptoms. There were no significant differences in iCa, potassium and magnesium levels were noted in the study group irrespective of which tablets were used for treatment of hypocalcemic symptoms. After plateletpheresis the median iCa levels declined by 30% and potassium levels declined by 3-11% in all donors while the magnesium levels were not significantly affected. There was no correlation between the presence of symptoms and the changed levels of iCa or magnesium.

CONCLUSION

Addition of magnesium and vitamin D3 to calcium seems to have no beneficial effect in the treatment of hypocalcemic symptoms in plateletpheresis donors.

Automated programs for collection of mononuclear cells and progenitor cells by two separators for peripheral blood progenitor cell transplantation: comparison by a randomized crossover study

BACKGROUND

Although automated programs have been increasingly used to collect peripheral blood (PB) progenitor cells (PBPCs), differences among them remain unclear. The automated programs of Amicus (Baxter Healthcare) and Spectra (software Version 6.1, Gambro BCT) apheresis machines were compared in a crossover study.

STUDY DESIGN AND METHODS

The patients for autologous and donors for allogeneic PBPC transplantation mobilized with granulocyte-colony-stimulating factor were randomly assigned into two groups. PBPCs were collected by the Amicus on the first day and the Spectra on the second of 2 consecutive days in Group I, and the reverse order was used in Group II. Of 39 patients or donors enrolled, 17 reached their collection goal with only one procedure and did not participate in the paired study. Thus, 44 paired procedures of the remaining 22 subjects were evaluated.

RESULTS

The product yields of white blood cells (WBCs; p < 0.005), mononuclear cells (MNCs; p < 0.02), and CD34+ PBPCs (p < 0.0002) from patients or donors were higher in the Amicus collections than those in the Spectra collections. The collection efficiencies of WBCs (p < 0.03), MNCs (p < 0.02), and CD34+ PBPCs (p < 0.03) were higher in the Amicus collections. The numbers of contaminating platelets (PLTs) in the Amicus collections were lower than those in the Spectra collections (p < 0.05) with a greater decrease in PB PLT counts after apheresis with the Spectra (p < 0.01). The Amicus had a longer running time than the Spectra for processing similar volumes (p < 0.005).

CONCLUSION

The automated program of the Amicus may be better than that of the Spectra for collecting MNCs and CD34+ PBPCs and avoiding apheresis-induced thrombocytopenia.

Tolerable infusion rate of citrate based on clinical signs and the electrocardiogram in conscious dogs

BACKGROUND & AIMS

The possible clinical significance of the toxic effects of citrate has not yet been fully clarified. This study was therefore conducted to confirm the toxicity and determine the tolerable infusion rate of citrate administered by rapid intravenous infusion to conscious dogs.

METHODS

Citrate solutions were infused via the cephalic vein of 4 conscious dogs at 0.33, 0.67, or 1.33mmol/kg/h up to 1.33mmol/kg. Clinical signs and the electrocardiogram were observed during and after infusion. Serum citrate and ionized calcium levels were also measured.

RESULTS

Although the mean citrate level increased in accordance with the infusion rate, the calcium level decreased. No significant changes in clinical signs or the electrocardiogram were observed during infusion at 0.33mmol/kg/h despite an increase in the serum citrate level to 1.22+/-0.11mmol/l (pre-infusion value: 0.38+/-0.01mmol/l) and a decrease in the serum calcium level to 1.28+/-0.03mmol/l (pre-infusion value: 1.50+/-0.05mmol/l). Vomiting and QTc prolongation were observed at 0.67mmol/kg/h or higher. Salivation and tachycardia were observed at 1.33mmol/kg/h.

CONCLUSIONS

Based on clinical signs and the electrocardiogram, the tolerable infusion rate of citrate in conscious dogs is concluded to be 0.33mmol/kg/h.

Complications of donor apheresis

A decreasing blood donor pool in the presence of increasing blood transfusion demands has resulted in the need to maximally utilize each blood donor. This has led to a trend in the increasing use of automated blood collections. While apheresis donation shares many reactions and injuries with whole blood donation, because of the differences, unique complications also exist. Overall, evidence in the literature suggests that the frequency of reactions to apheresis donation is less than that seen in whole blood donation, though the risk of reactions requiring hospitalization is substantially greater. The most common apheresis-specific reaction is hypocalcemia due to citrate anticoagulation, which, while usually mild, has the potential for severely injuring the donor. Other reactions to apheresis donation are uncommon (e.g., hypotension) or rare (e.g., air embolism). More worrisome, and in need of additional study, are the long-term effects of apheresis donation. Recent evidence suggests that repeated apheresis platelet donations may adversely effect thrombopoiesis as well as bone mineralization. Granulocyte donation has also been implicated in unexpected long-term consequences.

EFFECT OF WHOLE BLOOD CLOTTING TIME IN RATS WITH IONIZED HYPOCALCEMIA INDUCED BY RAPID INTRAVENOUS CITRATE INFUSION

Although the toxic effects of citrate including hemodynamic and cardiovascular changes result from a decrease in ionized calcium levels in serum due to chelating action, these effects of citrate on blood coagulation have not yet been fully clarified. The present study examines whether serum citrate and ionized calcium levels affect whole blood clotting time in rats using the test tube method in which citrate is administered by rapid intravenous infusion. Citrate was infused via the tail vein into 10 rats at 3, 4 or 5 mmol/kg/hr for 1 hr, and then whole blood clotting time, serum citrate and ionized calcium levels were determined. Whole blood clotting time did not significantly change at citrate infusion rates of 3 and 4 mmol/kg/hr. However, at 5 mmol/kg/hr, whole blood clotting time was significantly prolonged by a factor of 2.1 relative to the untreated group, when the serum citrate level was 10.03 +/- 1.39 mmol/l (59.0-fold higher than that in the untreated group) and the serum-ionized calcium level was 0.29 +/- 0.02 mmol/l (0.2-fold lower than that in the untreated group). These results suggest that whole blood clotting time is significantly prolonged in rats with severe ionized hypocalcemia.

Prospective randomised comparison of the COBE Spectra version 6 and Haemonetics MCS+ cell separators for hematopoietic progenitor cells leucapheresis in patients with multiple myeloma

A randomised crossover trial of two separators was undertaken to compare the mononuclear cell, CD34(+) cell and CFU-GM yield, in patients (<61 years) with previously untreated symptomatic multiple myeloma. After first-line therapy, all patients received mobilising chemotherapy (cyclophosphamide 4 g/m(2)) and daily G-CSF. The first leucapheresis was performed on the first day the peripheral blood absolute CD34(+) cell count was > 20 cells/microl. All patients underwent 2 leucaphereses on consecutive days. The patients were randomised to undergo either the first or second leucapheresis using the COBE Spectra. The target duration of the procedure on the COBE Spectra was 2 total blood volumes, and for the Haemonetics MCS(+) it was 20 cycles with four recirculations. Between September 2003 and March 2005, 60 patients were entered in the study. COBE Spectra version 6 processed significantly larger volumes of blood than the Haemonetics MCS(+) (8,845 and 5,680 ml, respectively, P < 0.01). The absolute yield of mononuclear cells (2.1 vs. 1.5 x 10(8)/kg, P = 0.04), CFU-GM (11 vs. 3 x 10(4)/kg, P = 0.01) and CD34(+) cells (3 vs. 1.7 x 10(6)/kg, P = 0.02) were all significantly higher with the COBE Spectra version 6, as were the yields per unit volume of blood processed. In conclusion, our study shows that COBE Spectra Version 6 is faster and has a better yield than the Haemonetics MCS(+), in patients with multiple myeloma.

Safety and efficacy of allogeneic PBSC collection in normal pediatric donors: The Pediatric Blood and Marrow Transplant Consortium Experience (PBMTC) 1996–2003

The use of peripheral blood stem cells (PBSC) for allogeneic transplants in adults has greatly increased. This trend is reflected in pediatrics, where healthy children increasingly are donating PBSC or donor lymphocyte infusion (DLI) via apheresis for use by ill siblings. There is a potential concern that the risks of PBSC collection may differ for pediatric donors. However, no large studies have assessed safety issues in this population. To address this need, we reviewed 218 (213 PBSC, five DLI) collections in 201 normal pediatric donors (8 months to 17 years, median 11.8 years) at 22 institutions in the Pediatric Blood and Marrow Transplant Consortium. Donors received a median of 4 days of growth factor, and mean collection yield was 9.1 x 10(6) CD34+ cells/kg recipient weight. Younger age, days of apheresis, and male gender predicted increased yield of CD34+ cells/kg donor weight. Growth factor-induced pain was mild and reported in less than 15% of patients. Most donors <20 kg (23/25, 92%) required PRBC priming of the apheresis machine. This experience with over 200 collections demonstrates that PBSC collection is safe in normal pediatric donors and desired CD34 cell yields are easily achieved. Younger children utilize more medical resources and children <20 kg usually require a single blood product exposure.

Pediatric large-volume leukapheresis: a single institution experience with heparin versus citrate-based anticoagulant regimens

BACKGROUND

Anticoagulant-associated toxicity may exert significant effects on the safety and efficacy of large-volume leukapheresis (LVL) in children, however, few studies specifically address management of this issue.

STUDY DESIGN AND METHODS

Seventy-four consecutive LVL procedures (mean, 4 blood volumes processed) in children weighing less than or equal to 30 kg (minimum, 10.9 kg) were analyzed. The first 21 procedures were evaluated retrospectively; 11 used heparin alone (Group I) and 10 used heparin plus reduced-dose ACD-A (whole blood to anticoagulant ratio > or =20:1) (Group II). The next 53 procedures were evaluated prospectively and used full-dose ACD-A (whole blood to anticoagulant ratio < or =13:1), intravenous divalent cation prophylaxis and no heparin; 11 used calcium alone (Group III) followed by 42 with calcium plus magnesium (Group IV).

RESULTS

Seventy-four LVL (56 PBPC and 18 MNC) collections were performed in 38 subjects. One donor in Group I experienced a significant groin hematoma at the site of line placement. One donor each in Groups III and IV had mild paresthesias. Despite a mean citrate infusion rate of 2.6 mg per kg per minute, mean postapheresis serum potassium and ionized magnesium and calcium concentrations in Group IV declined by only 9, 8, and 4 percent, respectively, and stable levels of these variables were maintained 24 hours later. Postapheresis PLT counts declined significantly from baseline preapheresis levels in all groups (mean, 52% decrease).

CONCLUSIONS

Use of full-dose citrate anticoagulant with prophylactic intravenous divalent cation infusion offers an effective and safe approach to management of anticoagulant-related toxicity in children undergoing LVL.

Reduction of adverse citrate reactions during autologous large-volume PBPC apheresis by continuous infusion of calcium-gluconate

BACKGROUND

Citrate-related side effects are common adverse reactions during PBPC apheresis. To reduce the incidence of citrate-related reactions, the effect of a continuous calcium-gluconate infusion on the appearance of hypocalcemic symptoms and on the subjective tolerance toward large-volume leukapheresis (LVL) was tested.

STUDY DESIGN AND METHODS

A double-blinded, placebo-controlled trial was carried out in 50 patients undergoing standardized LVL at a median ACD-A ratio of 1.99 mg per kg and minute. Patients were randomly assigned to receive a continuous IV infusion of either saline or calcium-gluconate at a dose of 1.8 mmol calcium per hour. Subjective tolerance toward LVL was determined by standardized rating systems. Further, hormonal and electrolyte changes were monitored to assess the effect of continuous calcium infusion on calcium homeostasis.

RESULTS

Continuous IV administration of calcium-gluconate throughout LVL reduced the incidence of citrate-related effects by 65 percent. In patients who developed signs of hypocalcemia, the symptoms were weaker, and less medical intervention was needed to resolve clinical symptoms. The subjective tolerance toward LVL was superior in patients receiving calcium support compared to control patients. Continuous calcium infusion attenuated changes in serum phosphorus compared to patients receiving saline. No differences were observed in the variation of serum potassium and serum magnesium between the control group and the treatment group. The administration of calcium was not associated with technical problems related to the apheresis procedure, neither was any effect of calcium support on the total number of CD34+ cells collected observed.

CONCLUSION

These results indicate that continuous support of calcium-gluconate during LVL is an effective means of reducing the incidence of citrate-related symptoms and improving subjective tolerance toward LVL, without affecting the technical performance or the number of CD34+ cells collected.

Randomized placebo-controlled study of oral calcium carbonate administration in plateletpheresis: I. Associations with donor symptoms

BACKGROUND

The effect of oral calcium (Ca) supplements in preventing citrate-induced symptoms during plateletpheresis was evaluated in a randomized, blinded, placebo-controlled trial.

STUDY DESIGN AND METHODS

Twenty-three donors (12 men, 11 women) underwent four plateletpheresis procedures each, ingesting either 1 or 2 g of oral Ca carbonate or an equivalent placebo 30 minutes before donation. Ten of these subjects subsequently ingested 4 g of open-label Ca before a fifth procedure. All procedures were conducted at the same citrate infusion rate (1.5 mg/kg/min) for 90 minutes.

RESULTS

Ingestion of 2 g of oral Ca resulted in a significant reduction in the severity of paresthesias and a significant, though modest, increase in serum ionized calcium (iCa), but no significant improvement in total symptom scores, compared to placebo. Minimal effects were seen with the 1-g dose. The two factors most highly correlated with development of severe symptoms were decreased levels of iCa and ionized magnesium (iMg) at 30 minutes into apheresis. Lower preapheresis serum albumin, creatinine, vitamin D, iMg, and total Mg concentrations were also significantly associated with symptoms. Women experienced more frequent and severe symptoms than men, however, gender was not associated with symptoms after adjustment for lower serum albumin, creatinine, and Mg levels. Ingestion of 4 g of Ca offered no improvement in symptoms or iCa levels compared with the 2-g dose.

CONCLUSION

Prophylactic oral Ca was associated with modest improvements in citrate-induced symptoms and laboratory parameters. Baseline albumin and Mg levels were strongly predictive of the development of symptoms. In donors with a prior history of uncomfortable citrate-related effects, a 2-g oral Ca dose before apheresis is recommended.

Randomized placebo-controlled study of oral calcium carbonate supplementation in plateletpheresis: II. Metabolic effects

BACKGROUND

The metabolic effects of oral calcium (Ca) supplementation during plateletpheresis were evaluated in a randomized, placebo-controlled trial.

STUDY DESIGN AND METHODS

Twenty-three donors underwent four plateletpheresis procedures each, receiving in random order, elemental Ca (Ca) 1 or 2 g orally, or a corresponding placebo, 30 minutes before donation. Ten of these donors underwent a fifth procedure using a 4-g Ca dose. All procedures were performed at a fixed citrate infusion rate of 1.5 mg per kg per minute.

RESULTS

Oral Ca induced dose-sensitive changes in parathyroid hormone (iPTH), total (tCa), and ionized (iCa) calcium levels. Compared to placebo, the greatest improvement in tCa and iCa levels occurred after the 2-g Ca dose (tCa of 73, 89, and 25% above placebo levels at 60 min, using 1, 2, and 4 g of oral Ca, respectively). Twenty-four hours after apheresis, serum tCa and iCa levels were higher, and iPTH levels lower, in donors who received oral Ca rather than placebo. Marked increases in urinary Ca and magnesium (Mg) excretion occurred at the completion of apheresis, were unaffected by Ca dose, and returned to baseline within 24 hours. Plateletpheresis also induced significant changes in serum alkaline phosphatase, 1,25-dihydroxyvitamin D, and osteocalcin levels immediately and at 24 hours after apheresis.

CONCLUSION

Plateletpheresis induces marked acute metabolic effects, with sustained changes evident up to 24 hours after the completion of apheresis. Oral Ca supplementation exerts a significant but clinically modest impact on selected laboratory variables associated with these effects. Further studies are indicated to examine the long-term impact of plateletpheresis, with or without Ca supplementation, on donor Ca balance and bone density.

Collection of MNCs and progenitor cells by two separators for PBPC transplantation: a randomized crossover trial

BACKGROUND

Efficient collection of progenitor cells is essential for PBPC transplantation. Two apheresis machines (Amicus, Baxter Healthcare; and Spectra, Gambro BCT, software version 4.7) were compared prospectively by a crossover trial.

STUDY DESIGN AND METHODS

Apheresis collections were performed for two consecutive days on patients for autologous and donors for allogeneic PBPC transplantation. The patients and donors, receiving a G-CSF, were randomized into two groups. In Group I, PBPCs were collected by the Amicus on the 1st day and the Spectra on the 2nd day, and the reverse order was used with Group II. A total of 60 apheresis procedures of 30 (16 in Group I and 14 in Group II) among 40 patients and donors enrolled were performed and evaluated.

RESULTS

The nucleated cell counts, MNC counts, CD34+ PBPC counts, and amounts of CFU-GM collected per procedure were similar with the Amicus and the Spectra. On the other hand, the decrease of peripheral blood platelet counts of patients and donors was more prominent from using Spectra than Amicus (p < 0.0001). Components collected by the Amicus had fewer platelets than those collected by the Spectra (p < 0.0001). The efficiencies of collecting nucleated cells, MNCs, and CD34+ PBPCs were not different between the machines (p > 0.05). However, the efficiency of collecting platelets was significantly higher with Spectra than with Amicus (p < 0.0001). The Amicus took longer than the Spectra to process the same volume (p < 0.05).

CONCLUSION

Amicus is superior to Spectra in avoiding apheresis-induced thrombocytopenia caused by platelets contaminating the collected samples. Therefore, the Amicus is useful for patients with thrombocytopenia or with a less-than-normal platelet count.

Circulatory arrest during PBPC apheresis in an unrelated donor

BACKGROUND

Nowadays, the collection of PBPCs by apheresis from healthy donors is a routine method. The mobilization with rHu G-CSF and the apheresis procedures are usually well tolerated without severe side effects.

STUDY DESIGN AND METHODS

We report a severe complication in a 41-year-old unrelated female donor who was allowed to donate PBPCs and was mobilized with 10 microg of G-CSF per kg per day. During PBPC apheresis, she experienced a circulatory arrest after 132 minutes and processing of 7078 mL of blood (twice the donor's blood volume).

RESULTS

Immediate cardiopulmonary resuscitation restored sinus rhythm and regulatory respiration without sequelae. Subsequent cardiologic examinations (heart catheterization, electrophysiologic testing, tilting table test) resulted in the diagnosis of a neurocardiogenic syncope. Other cardiac or circulatory disorders could be excluded. The implantation of a cardiac pacemaker was recommended to the donor. The 4-year-old recipient was successfully transplanted with the partial product collected until the arrest occurred. The patient received a total of 2.54 x 106 CD34+ cells per kg of body weight.

CONCLUSION

After exclusion of other cardiac diseases, the diagnosed neurocardiogenic syncope probably induced the circulatory arrest during apheresis rather than the administration of G-CSF.