Pulsed xenon flash treatment inactivates bacteria in apheresis platelet concentrates while preserving in vitro quality and functionality

UV light-emitting diode (UV-LED) at 265 nm as a potential light source for disinfecting human platelet concentrates

The risk of sepsis through bacterial transmission is one of the most serious problems in platelet transfusion. In processing platelet concentrates (PCs), several methods have been put into practice to minimize the risk of bacterial transmission, such as stringent monitoring by cultivation assays and inactivation treatment by photoirradiation with or without chemical agents. As another potential option, we applied a light-emitting diode (LED) with a peak emission wavelength of 265 nm, which has been shown to be effective for water, to disinfect PCs. In a bench-scale UV-LED exposure setup, a 10-min irradiation, corresponding to an average fluence of 9.2 mJ/cm2, resulted in >2.0 log, 1.0 log, and 0.6 log inactivation (mean, n = 6) of Escherichia coli, Staphylococcus aureus, and Bacillus cereus, respectively, in non-diluted plasma PCs. After a 30-min exposure, platelet counts decreased slightly (18 ± 7%: mean ± SD, n = 7); however, platelet surface expressions of CD42b, CD61, CD62P, and PAC-1 binding did not change significantly (P>0.005), and agonist-induced aggregation and adhesion/aggregation under flow conditions were well maintained. Our findings indicated that the 265 nm UV-LED has high potential as a novel disinfection method to ensure the microbial safety of platelet transfusion.

In vitro thrombus formation and in vivo hemostasis mediated by platelets irradiated with bactericidal ultraviolet C from xenon flash under flow conditions

BACKGROUND

We previously reported a flow path-ultraviolet C (UVC) irradiation system for platelet concentrates (PCs) with platelet additive solution (PAS) to minimize contamination by bacteria. Here, we investigated functionalities of irradiated platelets (PLTs) in in vitro thrombus formation and in vivo hemostasis.

STUDY DESIGN AND METHODS

PAS-PCs were irradiated with flash UVC using the flow path system. Their variables (PLT count, mean platelet volume, pH, glucose, lactate, glycoprotein [GP] Ib, and activated integrin αIIbβ3) were evaluated. Static adhesion to collagen or fibrinogen was analyzed using fluorescent microscopy. Thrombus formation under flow conditions was assessed using a collagen-coated bead column. Adenosine diphosphate (ADP)-induced Akt phosphorylation was determined by western blot. In vivo hemostasis and circulatory survival of PLTs were assessed with a rabbit bleeding model.

RESULTS

All variables, except for GPIb expression, were slightly, but significantly, impaired after flash UVC irradiation throughout the 6-day storage period. No difference was observed in static adhesion to either collagen or fibrinogen between irradiated and nonirradiated PAS-PCs. In vitro thrombus formation of flash UVC-irradiated PAS-PCs was significantly greater than that of nonirradiated PAS-PCs. ADP-induced Akt phosphorylation was enhanced in irradiated PAS-PCs. In vivo hemostatic efficacy was comparable between the groups on Day 1. The efficacy declined in nonirradiated PAS-PCs on Day 5, while it was retained in flash UVC-irradiated PAS-PCs. Circulatory survival of PLTs was lower in irradiated PAS-PCs.

CONCLUSIONS

PAS-PCs irradiated with UVC from xenon flash have favorable properties to achieve hemostasis compared with nonirradiated PAS-PCs.

Correlation between platelet thrombus formation on collagen-coated beads and platelet aggregation induced by ADP

BACKGROUND

The thrombus-forming ability is a critical in vitro parameter to assess platelets (PLTs), but flow-based methods using collagen-coated materials generally require multistep, proficiency, and advanced analysis.

STUDY DESIGN AND METHODS

Commercially available collagen-coated bead columns were examined to assess thrombus-forming ability of PLTs. The retention rate as an index of thrombus formation was calculated using the PLT count before and after column passage. Thrombi were imaged by anti-CD41 using a fluorescent microscope. PLT aggregation was measured by light-transmitting aggregometry.

RESULTS

The retention rate was low when apheresis-collected PLT concentrates (PCs) were suspended in plasma either with or without Ca²⁺. Reconstitution of PCs with red blood cells (RBCs) increased the retention rate with good reproducibility on repeated-measurements, and therefore, PLT samples were reconstructed with RBCs in subsequent experiments. The retention rate of PCs varied widely in a product-dependent manner, and was correlated with the aggregation rate induced by ADP, but not that by collagen. Using platelet-rich-plasma, antagonists of P2Y₁ or P2Y₁₂ receptors for ADP reduced both the retention and aggregation of PLTs. Acetylsalicylic acid reduced retention, although it had no effect on ADP-induced aggregation. Prostaglandin E₁ significantly inhibited both retention and aggregation. These anti-PLT reagents resulted in reduced or no thrombus formation on the beads.

CONCLUSION

The collagen-coated bead column was useful to readily examine the thrombus-forming ability of PLTs. Variance of the PLT retention rate was correlated with responsiveness to ADP. Results from anti-PLT reagents revealed that thrombus formation on collagen-coated beads was similar to in vivo thrombus development.

Comparison of platelet function tests for the in vitro quality assessment of platelet concentrates produced under real-life conditions

Platelet quality in different platelet concentrates (PCs) has been the subject of several studies. Nonetheless, there is a lack of robust data on the correlation and agreement among platelet function tests as a prerequisite for the association of PC functionality in vitro with platelet function in vivo post PC transfusion. The purpose of our study was to correlate a larger panel of platelet function assays in PCs and to assess whether the methods agree sufficiently and can be used interchangeably. Twelve apheresis platelet concentrates in plasma (APC), 16 pooled platelet concentrates in plasma (PPC), and 12 PPC in T-sol (PPCA) were examined on days 1 and 4 after production. PCs were tested for platelet count, light transmission aggregation (LTA) induced by ADP, collagen, or TRAP; platelet ATP release induced by collagen; and spontaneous and ADP and TRAP-induced increase in CD62P and PAC1 expression measured by flow cytometry. All tests were performed in undiluted platelet-rich plasma, recalcified and mixed with an inhibitor of factor Xa and thrombin. Most platelet function parameters correlated significantly with each other, but agreement among methods was insufficient. A proper inverse correlation was observed between ADP-induced LTA and spontaneous platelet activation assessed by CD62P expression (r = -0.61, p < 0.0001). Spontaneous CD62P correlated also significantly with spontaneous PAC1 (r = 0.69, p < 0.0001) and inversely with TRAP-induced CD62P expression (r = -0.86, p < 0.0001). We found significant correlations among all flow cytometric assays measuring platelet CD62P and PAC1 expression induced by ADP or TRAP. Subsequent Bland Altman analysis revealed insufficient agreement between methods. With one exception (collagen-induced LTA compared with TRAP-induced LTA, percentage error = 16%) the limits of agreement expressed as percentage error exceeded the chosen acceptable difference of 30%. In APC, platelet count was 41% and 44% higher, respectively, than in PPC and PPCA (p < 0.0001). Spontaneous CD62P and PAC1 expression were significantly greater, and ADP-induced aggregation and agonist-induced increase in CD62P and PAC1 were significantly lower in PPCA compared to APC and PPC on day 4 of storage. ADP and TRAP-induced CD62P and PAC1 activatability fell significantly during storage between day 1 and day 4 in APC and PPCA, but not in PPC. In conclusion, different platelet function tests capture different aspects of platelet function and do not correlate and agree sufficiently to be used interchangeably.

Restored response to ADP downstream of purinergic P2Y12 receptor in apheresis platelets after pathogen-reducing xenon flash treatment

BACKGROUND

Our previous study revealed that pathogen-reducing filtered xenon flash-treated platelets (fXe-PLTs) showed sustained aggregation in response to adenosine diphosphate (ADP), but apheresis-collected PLTs (Aph-PLTs) showed reversible aggregation.

STUDY DESIGN AND METHODS

Aph-PLTs, fXe-PLTs, and freshly prepared PLTs (PRP-PLTs) from whole blood were used to investigate the following responses to ADP: concentration response and effects of ADP receptor antagonists on aggregation, the cytosolic calcium (Ca²⁺ ) flux downstream of P2Y₁ receptor signaling, and phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and signaling intermediate protein Akt downstream of the P2Y₁₂ receptor.

RESULTS

The aggregation of Aph-PLTs by ADP (10 µM) changed from reversible to sustained in an fXe flash dose-dependent manner. The concentration-response curve of Aph-PLTs showed a fivefold higher 50% effective concentration compared with PRP-PLTs, and fXe treatment decreased it to threefold. While the basal Ca²⁺ level was higher both in Aph- and fXe-PLTs than in PRP-PLTs, the increase of cytosolic Ca²⁺ by ADP remained unchanged in Aph- and PRP-PLTs, but was slightly reduced in fXe-PLTs. Although the forskolin-induced VASP phosphorylation was significantly reduced in Aph-PLTs, and partially restored by the fXe treatment, ADP stimulation attenuated this phosphorylation to an equivalent extent among the three PLT types. The ADP-stimulated time-dependent Akt phosphorylation was weak in Aph-PLTs, whereas fXe-PLTs and PRP-PLTs showed a marked increase.

CONCLUSION

These results indicate that the reversible aggregation of Aph-PLTs is the consequence of insufficient Akt phosphorylation. The fXe treatment restores the increase of phosphorylated Akt, resulting in the sustained aggregation of fXe-PLTs similar to those of PRP-PLTs.

Critical developments of 2017: a review of the literature from selected topics in transfusion. A committee report from the AABB Clinical Transfusion Medicine Committee

BACKGROUND

The AABB compiles an annual synopsis of the published literature covering important developments in the field of Transfusion Medicine. For the first time, an abridged version of this work is being made available in TRANSFUSION, with the full-length report available as an Appendix S1 (available as supporting information in the online version of this paper).

STUDY DESIGN AND METHODS

Papers published in 2016 and early 2017 are included, as well as earlier papers cited for background. Although this synopsis is comprehensive, it is not exhaustive, and some papers may have been excluded or missed.

RESULTS

The following topics are covered: duration of red blood cell storage and clinical outcomes, blood donor characteristics and patient outcomes, reversal of bleeding in hemophilia and for patients on direct oral anticoagulants, transfusion approach to hemorrhagic shock, pathogen inactivation, pediatric transfusion medicine, therapeutic apheresis, and extracorporeal support.

CONCLUSION

This synopsis may be a useful educational tool.