Buffy-coat-derived pooled platelet concentrates and apheresis platelet concentrates: which product type should be preferred?

The efficacy of the ultraviolet C pathogen inactivation system in the reduction of Babesia divergens in pooled buffy coat platelets

BACKGROUND

Babesia spp. is an intraerythrocytic parasite that causes human babesiosis and its transmission by transfusion has been extensively demonstrated. The aim of this study was to ascertain the efficacy of an ultraviolet C (UVC)-based pathogen inactivation system in the reduction of Babesia divergens-infected platelet (PLT) concentrates and to determine the parasite's ability to survive in PLT concentrates stored under blood bank conditions.

STUDY DESIGN AND METHODS

This study was conducted using in vitro cultures of B. divergens. The detection limit of the culture assay was established and, subsequently, 15 buffy coat-derived PLT concentrates (BC-PCs) were inoculated with 10(7) B. divergens-infected red blood cells. Infected BC-PCs were irradiated with 0.2 J/cm(2) UVC light using the THERAFLEX UV-Platelets method (Macopharma). Viability and parasite growth were evaluated before and after inactivation. Culture growth kinetics were monitored by DNA incorporation of [(3) H]thymidine. The ability of B. divergens to survive in PLT concentrates was also analyzed.

RESULTS

The limit of detection in cultures was established at 0.1 × 10(-6) % parasites. The THERAFLEX UV-Platelets system inactivated B. divergens to below the limit of detection in 12 of 15 BC-PCs (log reduction, >6.0) and to the limit of detection (log reduction, 5.0) in three of 15. It was also demonstrated that B. divergens remains viable in BC-PCs stored up to 7 days.

CONCLUSION

Since B. divergens can survive in PLT concentrates and given the performance of UVC, this system could be considered as an alternative to prevent B. divergens and other Babesia species from being transmitted through PLT transfusions.

Single-donor platelet apheresis: observational comparison of the new Haemonetics Universal Platelet protocol with the previous Concentrated Single Donor Platelet protocol

BACKGROUND

The Haemonetics MCS(®)+ cell separator is a device dedicated to the collection of leucoreduced single-donor platelets. The new Universal Platelet protocol has been introduced to improve the efficiency of apheresis and increase flexibility in the collection of leucoreduced platelets in combination with red blood cells and plasma. In this study we compared its performance with that of the previous Concentrated Single Donor Platelet protocol.

MATERIALS AND METHODS

This observational study had a within-subject design and involved 135 donors who underwent plateletapheresis with both protocols. The primary end-point was collection efficiency; secondary end-points were other performance indices, such as procedure time and collection rate. A satisfaction questionnaire was also administered to the 135 donors to evaluate opinions on duration, comfort and side-effects of donations with the two protocols. For each parameter of interest, we tested the difference between the two protocols within donors, using a one-sample t-test or exact McNemar's test as appropriate.

RESULTS

The collection efficiency of the Universal Platelet protocol was significantly higher than that of the Concentrated Single Donor Platelet protocol (58% vs 47%; p<0.0001). The Universal Platelet Protocol collected more platelets in less time, leading to a higher collection rate (6.5 vs 5.0×10(9)/min; p<0.0001). In general, donors found apheresis with the Universal Platelet protocol of equal duration or faster, of similar or greater comfort and with an equal number or fewer side effects, compared with the Concentrated Single Donor Platelet protocol.

DISCUSSION

Our study endorses the use of the new Universal Platelet protocol in daily transfusion practice since it substantially improves collection efficiency in leucoreduced platelet procedures compared with the Concentrated Single Donor Platelet protocol. This technical improvement seems to be accompanied by equal or greater comfort for the donor.

Pooled platelet product using the Acrodose plus system: evaluation of feasibility, safety and efficacy

BACKGROUND

Pooling of whole blood-derived platelets is not practiced in India. Currently available data shows that pooled platelets are equivalent in quality and less costly when compared with apheresis platelets.

AIM

To evaluate feasibility, safety and efficacy of pooled platelets using the Acrodose Plus system.

MATERIAL AND METHODS

Standardization of platelet pooling procedure was done. Sterile docking device was used to maintain closed system. Pools of ABO compatible platelets (N=40) as well as ABO incompatible (N=10) pooled platelets were studied. ABO antibody titers were studied before and after pooling in case of ABO incompatible platelet pools. Corrected count increments (CCIs) (at 1h and 24h) were noted after transfusion of pooled platelets and Apheresis platelets in matched patient groups.

RESULTS

Loss of platelet product due to pooling and leucodepletion was not statistically significant (p=0.23). Leucodepletion >3 log was achieved in all pooled platelets. The total platelet content, time taken for procedure and pH were within acceptable limits. There were no issues related to platelet availability and turn around time during the study period. There was a reduction in the ABO antibody titers after pooling in case of the ABO incompatible pools. None of the pooled platelets showed evidence of bacterial contamination on testing with eBDS system at 18 h and 24h intervals after pooling. CCI with pooled platelets was equivalent to that with apheresis platelets at 1h (p=0.36) and 24h (p=0.15).

CONCLUSION

Whole blood derived platelets can be pooled safely using closed system without altering the platelet quality in vitro as well as in vivo survival post transfusion. Pooled platelets can be a cost effective and safe alternative to thrombocytopenic patients whose transfusion requirements cannot be fulfilled with apheresis platelets alone.

Clinical indications for thrombopoietin and thrombopoietin-receptor agonists

Thrombocytopenia is a common hematologic disorder. Stimulation of thrombopoiesis may reduce the risk for thrombocytopenia-induced bleeding, prevent severe thrombocytopenia, and reduce the need for platelet transfusion. The key cytokine is thrombopoietin (TPO). It regulates proliferation and maturation of megakaryocytes as well as platelet production. TPO is synthesized in the liver. Development of TPO from the laboratory into a therapeutic tool has turned out to be an unexpected challenge. Clinical trials on first-generation thrombopoietic growth factors were stopped in 2001. At present, second-generation thrombopoiesis-stimulating agents have only been approved as orphan drugs for third-line therapy of patients with chronic immune thrombocytopenia. Larger groups in need are patients with myelodysplastic syndrome, chemotherapy-induced thrombocytopenia, other forms of hereditary and acquired bone marrow failure, hepatitis C infections, or liver cirrhosis.

Platelet lysate as replacement for fetal bovine serum in mesenchymal stromal cell cultures

Mesenchymal stromal cells (MSC) emerged as highly attractive in cell-based regenerative medicine. Initially thought to provide cells capable of differentiation towards mesenchymal cell types (osteoblasts, chondrocytes, adipocytes etc.), by and by potent immunoregulatory and pro-regenerative activities have been discovered, broadening the field of potential applications from bone and cartilage regeneration to wound healing and treatment of autoimmune diseases. Due to the limited frequency in most tissue sources, ex vivo expansion of MSC is required compliant with good manufacturing practice (GMP) guidelines to yield clinically relevant cell doses. Though, still most manufacturing protocols use fetal bovine serum (FBS) as cell culture supplement to isolate and to expand MSC. However, the high lot-to-lot variability as well as risk of contamination and immunization call for xenogenic-free culture conditions. In terms of standardization, chemically defined media appear as the ultimate achievement. Since these media need to maintain all key cellular and therapy-relevant features of MSC, the development of chemically defined media is still - albeit highly investigated - only in its beginning. The current alternatives to FBS rely on human blood-derived components: plasma, serum, umbilical cord blood serum, and platelet derivatives like platelet lysate. Focusing on quality aspects, the latter will be addressed within this review.

Transportation conditions for prompt use of ex vivo expanded and freshly harvested clinical-grade bone marrow mesenchymal stromal/stem cells for bone regeneration

Successful preliminary studies have encouraged a more translational phase for stem cell research. Nevertheless, advances in the culture of human bone marrow-derived mesenchymal stromal/stem cells (hBM-MSC) and osteoconductive qualities of combined biomaterials can be undermined if necessary cell transportation procedures prove unviable. We aimed at evaluating the effect of transportation conditions on cell function, including the ability to form bone in vivo, using procedures suited to clinical application. hBM-MSC expanded in current Good Manufacturing Practice (cGMP) facilities (cGMP-hBM-MSC) to numbers suitable for therapy were transported overnight within syringes and subsequently tested for viability. Scaled-down experiments mimicking shipment for 18 h at 4°C tested the influence of three different clinical-grade transportation buffers (0.9% saline alone or with 4% human serum albumin [HSA] from two independent sources) compared with cell maintenance medium. Cell viability after shipment was >80% in all cases, enabling evaluation of (1) adhesion to plastic flasks and hydroxyapatite tricalcium phosphate osteoconductive biomaterial (HA/β-TCP 3D scaffold); (2) proliferation rate; (3) ex vivo osteogenic differentiation in contexts of 2D monolayers on plastic and 3D HA/β-TCP scaffolds; and (4) in vivo ectopic bone formation after subcutaneous implantation of cells with HA/β-TCP scaffold into NOD/SCID mice. Von Kossa staining was used to assess ex vivo osteogenic differentiation in 3D cultures, providing a quantifiable test of 3D biomineralization ex vivo as a rapid, cost-effective potency assay. Near-equivalent capacities for cell survival, proliferation, and osteogenic differentiation were found for all transportation buffers. Moreover, cGMP-hBM-MSC transported from a production facility under clinical-grade conditions of 4% HSA in 0.9% saline to a destination 18 h away showed prompt adhesion to HA/β-TCP 3D scaffold and subsequent in vivo bone formation. A successfully validated transportation protocol extends the applicability of fresh stem cells involving multicentric trials for regenerative medicine.

Quality control of leucocyte-depleted platelet concentrates obtained by buffy-coat method

OBJECTIVES

Quality control results on leukoreduced buffy-coat platelet pools during the 7-year period (2005-2011) are presented with the aim to assess their overall quality and trends recorded during the study period.

METHODS

Data of the Quality Assurance Department, Croatian Institute of Transfusion Medicine were used in the study. Measurement results of all study parameters are presented for the entire study period, while the rate of controlled platelet pools consistent with the specified quality requirements is additionally presented for each study year.

RESULTS

The mean component volume was 50 ± 9 mL per 6 × 10(10) platelets (91.5% of conformable results), mean platelet count 7.81 ± 1.26 × 10(10) per single unit equivalent (97.5% of conformable results), mean leucocyte count 0.01 ± 0.08 × 10(6) per single unit equivalent (99.6% of conformable results), and mean pH 7.45 ± 0.16 (99.4% of conformable results). Bacteriologic testing showed negative result in 99.8% of tested components.

CONCLUSION

Study results indicated the results of platelet pool quality control to be highly conformable with the specified quality requirements. It is illustrated how simple interventions in the preparation process can have significant impact on product quality improvement and thus on redefining quality requirements.

Tissue Factor Expression on Platelet Surface during Preparation and Storage of Platelet Concentrates

BACKGROUND

Tissue factor (TF), the main activator of blood coagulation, is expressed on platelet surface and, together with procoagulant phospholipids, contributes to the global coagulation potential of these blood components. The present study evaluated, for the first time, the expression of TF on platelet surface during preparation and storage of platelet concentrates (PC) for transfusional use.

METHODS

Platelet TF was measured by flow cytometry in healthy donor whole blood (WB) and in pooled buffy-coat-derived PC on the day of preparation and up to 4 days of storage in parallel with classical markers of platelet activation, i.e., fibrinogen, P-selectin, and glycoprotein GPIIb. Data were analyzed according to donor age and blood ABO group.

RESULTS

TF was detected on whole blood platelets and was found highest in O donors. Compared to whole blood, platelet surface TF was higher upon PC preparation and further increased during storage. The rise in TF levels positively correlated with the elevations of the other platelet markers.

CONCLUSIONS

Our findings show that platelet surface TF is maintained in PC obtained by the pooled buffy coat method. Further studies are warranted to investigate a possible correlation between TF levels and the hemostatic response of the platelet transfusion recipient.

Effects of blood products on inflammatory response in endothelial cells in vitro

BACKGROUND

Transfusing blood products may induce inflammatory reactions within the vascular compartment potentially leading to a systemic inflammatory response. Experiments were designed to assess the inflammatory potential of different blood products in an endothelial cell-based in vitro model and to compare baseline levels of potentially activating substances in transfusion products.

METHODS

The inflammatory response from pre-activated (endotoxin-stimulated) and non-activated endothelial cells as well as neutrophil endothelial transmigration in response to packed red blood cells (PRBC), platelet concentrates (PC) and fresh frozen plasma (FFP) was determined. Baseline inflammatory mediator and lipid concentrations in blood products were evaluated.

RESULTS

Following incubation with all blood products, an increased inflammatory mediator release from endothelial cells was observed. Platelet concentrates, and to a lesser extent also FFP, caused the most pronounced response, which was accentuated in already pre-stimulated endothelial cells. Inflammatory response of endothelial cells as well as blood product-induced migration of neutrophils through the endothelium was in good agreement with the lipid content of the according blood product.

CONCLUSION

Within the group of different blood transfusion products both PC and FFP have a high inflammatory potential with regard to activation of endothelial cells. Inflammation upon blood product exposure is strongly accentuated when endothelial cells are pre-injured. High lipid contents in the respective blood products goes along with an accentuated inflammatory reaction from endothelial cells.

Platelet lysate from whole blood-derived pooled platelet concentrates and apheresis-derived platelet concentrates for the isolation and expansion of human bone marrow mesenchymal stromal cells: production process, content and identification of active components

Background aims

The clinical use of human mesenchymal stromal cells (MSC) requires ex vivo expansion in media containing supplements such as fetal bovine serum or, alternatively, human platelet lysate (PL).

Methods

Platelet concentrates were frozen, quarantine stored, thawed and sterile filtered to obtain PL. PL content and its effect on fibroblast-colony-forming unit (CFU-F) formation, MSC proliferation and large-scale expansion were studied.

Results

PL contained high levels of basic fibroblast growth factor (bFGF), soluble CD40L (sCD40L), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-derived growth factor AA (PDGF-AA), platelet-derived growth factor AB/BB (PDGF-AB/BB), chemokine (C-C) ligand 5 (CCL5; RANTES) transforming growth factor-β1 (TGF-β1) and chemokine (C-X-C) ligand 1/2/3 (GRO), with low batch-to-batch variability, and most were stable for up to 14 days. Inhibition of PDGF-BB and bFGF decreased MSC proliferation by about 20% and 50%, respectively. The strongest inhibition (about 75%) was observed with a combination of anti-bFGF + anti-PDGF-BB and anti-bFGF + anti-TGF-β1 + anti-PDGF-BB. Interestingly, various combinations of recombinant PDGF-BB, bFGF and TGF-β1 were not sufficient to promote cell proliferation. PL from whole blood-derived pooled platelet concentrates and apheresis platelet concentrates did not differ significantly in their growth-promoting activity on MSC.

Conclusions

PL enhances MSC proliferation and can be regarded as a safe tool for MSC expansion for clinical purposes. \in particular, PDGF-BB and bFGF are essential components for the growth-promoting effect of PL, but are not sufficient for MSC proliferation.

Manufacture of pooled platelets in additive solution and storage in an ELX container after an overnight warm temperature hold of platelet-rich plasma

The processing of whole blood-derived platelet-rich plasma (PRP) to a platelet concentrate and platelet-poor plasma is currently performed within 8 hours to comply with the requirements to manufacture fresh frozen plasma. Maintaining PRP at room temperature for a longer period can have the advantage of shifting the completion of component manufacture onto day shifts. Pairs of ABO-identical prepooled platelets were manufactured by the PRP method, using the current approach with platelet storage in a CLX HP container (Pall Medical, Covina, CA) and plasma, or a novel approach with an 18- to a 24-hour room temperature hold of the PRP and the manufacture of pooled platelets in a glucose-containing additive solution (AS) and storage in a new ELX container (Pall Medical). Standard in vitro assays were performed on days 2, 5, and 7. The results showed that the AS platelets in ELX have in vitro characteristics that are equivalent or superior to those of the standard product.

Periodic acid-Schiff (PAS) staining of immature platelets in donors

Glycogen in platelets (PLTs) on smears of peripheral blood of 40 donors was investigated by the periodic acid-Schiff (PAS) method. Three groups were formed. Group 1 was consisted of 21 men undergoing the donor selection procedure. Additionally, 9 first-time donors undergoing plateletpheresis (Group 2) and 10 donors who frequently underwent platelet apheresis (Group 3) were studied as a model of relative thrombocytopenia. Cell sizes were measured with the use of a Image Analyzer "ASPBC" (Russia). The training procedure and classification of PAS-blood PLTs were made on the basis of expert evaluation. In this article, we have established three facts. First, the PAS-positive PLT area was larger than that of the PAS-negative cells (9.5 ± 3.6 sq.mkm vs. 3.9 ± 1.3 sq.mkm, p < 0.001, n = 21). The PAS-positivity of PLTs was 23.1 ± 9.2%. Second, the PAS-positivity correlated (r(S) = 0.63, p < 0.05) with the immature platelets fraction (IPF %), determined using Sysmex XE-2100. The mean IPF was 2.1 ± 1.0% (range 0.3-4.6%). Third, using the IPF% values obtained in Group 1, we found a significantly higher level of IPF in the samples both in Group 2 [mean value 4.2 ± 2.0% (range 1.9-7.0), p < 0.01] and in Group 3 [mean value 5.1 ± 2.5% (range 1.2-8.6), p < 0.004] with relative thrombocytopenia [Group 2: median 198 (95% confidence interval, CI 166-227) vs. median 229 (95% CI 206-267), p < 0.05; Group 3: median 142.5 (95% CI 132-173) vs. median 214.5 (95% CI 196-267), p < 0.01] after plateletpheresis. There was also a significant difference between the pre- and post-plateletpheresis for IPF% in Group 2 and Group 3: median 1.7 (95% CI 1.4-4.0) vs. median 4.0 (95% CI 2.7-5.8), p < 0.05 and median 4.0 (95% CI 2.7-6.0) vs. median 5.1 (95% CI 3.3-6.9), p < 0.01. The increased IPF shows a correlation with the PAS positivity [r(S) = 0.5 (p = 0.14) and r(S) = 0.6 (p = 0.05)] which has a tendency to increase [Group 2: median PAS 24.3% (95% CI 14.8-26.2) vs. median PAS 30% (95% CI 21.6-34.2), p = 0.05 and Group 3: median PAS 31% (95% CI 19-36.4) vs. median PAS 27.4% (95% CI 18.7-34.9), p = 0.35] and correlated negatively with the decrease in the platelet count [Group 2: r(S) = -0.7 (p = 0.21) and Group 3: r(S) = -0.5 (p = 0.14)]. Our findings support the significance of platelet evaluation by light microscopy to understand why morphologic changes of thrombocytopoiesis may be expected in thrombocytopenia due to donation of platelets.

Bacterial contamination in platelets: incremental improvements drive down but do not eliminate risk

BACKGROUND

Bacterial contamination of platelet components (PCs) remains an important cause of transfusion-associated infectious risk. In 2004, Canadian Blood Services (CBS) implemented bacterial testing of PCs using the BacT/ALERT 3D system (bioMérieux). This system has been validated and implemented and continuous monitoring of culture rates allows gathering of data regarding true and false positives as well as false negatives.

STUDY DESIGN AND METHODS

National data gathered between March 2004 and October 2010 from 12 CBS sites were analyzed to compare bacterial contamination rates across three platelet (PLT) preparation methods: apheresis, buffy coat, and PLT-rich plasma. Data were compared before and after implementation of protocol changes that may affect bacterial detection or contamination rates.

RESULTS

Initial positive rates among the three production methods were significantly different, with apheresis PCs being the highest. The rates of confirmed positives among production methods did not differ significantly (p = 0.668). Increasing sample testing volumes from 4 to 6 mL to 8 to 10 mL significantly increased the rate of initial positives, while confirmed positives increased from 0.64 to 1.63 per 10,000, approaching significance (p = 0.055). Changing the skin disinfection method from a two-step to a one-step protocol did not significantly alter the rate of confirmed positives. During the period of data analysis, eight false-negative cases were reported, with five implicated in adverse transfusion reactions.

CONCLUSION

Bacterial testing of PCs and implementation of improved protocols are incrementally effective in reducing the risk of transfusion of bacterially contaminated PLT concentrates; however, the continued occurrence of false-negative results means the risk has not been eliminated.

Meta-analysis of the randomized controlled trials of the hemostatic efficacy and capacity of pathogen-reduced platelets

BACKGROUND

A recent independently funded randomized controlled trial (RCT; Br J Haematol 2010;150:209-17) questioned prevailing opinion concerning the hemostatic capacity of pathogen-reduced platelets (PLTs). Meta-analysis was used to calculate the effect of pathogen reduction (PR) of PLTs on hemostatic efficacy and capacity based on all available data and to investigate possible reasons for the variation in reported findings.

STUDY DESIGN AND METHODS

RCTs allocating patients to receive routine PLT transfusions with pathogen-reduced or untreated PLTs and reporting on at least one of six hemostasis endpoints were eligible for analysis. Five RCTs of hemato-oncology patients met eligibility criteria. Endpoints determined by similar criteria in all RCTs were integrated by fixed-effects methods. Endpoints determined by different criteria were integrated by random-effects methods.

RESULTS

Studies were statistically homogeneous in all analyses. Pathogen-reduced PLTs were associated with a significant (p < 0.05) reduction in 1- and 24-hour posttransfusion corrected count increments (summary mean difference, 3260; 95% confidence interval [CI], 2450-4791; and summary mean difference, 3315; 95% CI, 2027-4603) as well as a significant increase in all and in clinically significant bleeding complications (summary odds ratio [OR], 1.58; 95% CI, 1.11-2.26; and summary OR, 1.54; 95% CI, 1.11-2.13). The frequency of severe bleeding complications did not differ.

CONCLUSION

The results of the recent RCT are not inconsistent with those of the earlier studies. Introduction of PR technologies in their current stage of development would result in an increase in mild and moderate (albeit not severe) bleeding complications, which the transfusion-medicine community must explicitly tolerate to reap the benefits from PR.