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Background: Human Platelet Lysate (hPL) is a platelet-derived and growth factor-rich supplement for cell culture. It can be prepared from surplus platelet concentrates initially intended for transfusion. Amotosalen-based photochemical pathogen inactivation of platelet concentrates is used in a number of blood establishments worldwide to minimize the risk of pathogen transmission from donor to patient., Methods: This pathogen inactivation method has not been formally validated for direct use on hPL. Here, we have studied the impact of pathogen inactivation on hPL and compared it to untreated hPL prepared from pathogen-inactivated platelet concentrates or control hPL. We used mass spectrometry, ELISA, and in vitro mesenchymal stem cell culture for determining residual amotosalen, final growth factor content, and cell doubling, respectively., Results: The data have shown amotosalen concentrations to be reduced a thousand-fold following pathogen inactivation, leaving trace quantities of photosensitizer molecules in the final hPL product. Some growth factors have been reported to be significantly more impacted in hPL that is directly pathogen-inactivated compared to both control conditions. This has no significant effect on the growth kinetics of adipose-derived mesenchymal stem cells., Conclusion: Direct amotosalen-based pathogen inactivation has a measurable impact on certain growth factors in hPL, but this does not outweigh the likely benefits of reducing the odds of donor-to-patient pathogen transmission., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Human platelet lysate (hPL) is a supplement for cell culture media that can be derived from platelet concentrates. As not-for-profit blood establishments, we endorse the evolution of maximally exploiting the potential of donated blood and its derived components, including platelets. The decision to use platelet concentrates to supply hPL as a cell culture supplement should align with the principles and values that blood establishments hold towards the use of donated blood components in transfusion. As a consequence, questions on ethics, practical standardization of hPL production and logistics as well as on assuring hPL quality and safety need careful consideration. We therefore propose an opinion on some of these matters based on available literature and on discussions within the proceedings of the Working Group on Innovation and New Products of the European Blood Alliance. In addition, we propose collaboration among European blood establishments to streamline efforts of hPL supply to maximize the potential of hPL and its application in the wider field of medicine., (© 2023 International Society of Blood Transfusion.)

Background: We aimed to develop a single step method for the production of human platelet lysate (hPL). The method must result in high hPL yields, be closed system and avoid heparin use., Study Design and Methods: The method aimed at using glass beads and calcium. An optimal concentration of calcium and glass beads was determined by serial dilution. This was translated to a novel method and compared to known methods: freeze-thawing and high calcium. Quality outcome measures were transmittance, fibrinogen and growth factor content, and cell doubling time., Results: An optimal concentration of 5 mM Ca 2+ and 0.2 g/ml glass beads resulted in hPL with yields of 92% ± 1% (n = 50) independent of source material (apheresis or buffy coat-derived). The transmittance was highest (56% ± 9%) compared to known methods (<39%). The fibrinogen concentration (7.0 ± 1.1 μg/ml) was well below the threshold, avoiding the need for heparin. Growth factor content was similar across hPL production methods. The cell doubling time of adipose derived stem cells was 25 ± 1 h and not different across methods. Batch consistency was determined across six batches of hPL (each n = 25 constituting concentrates) and was <11% for all parameters including cell doubling time. Calcium precipitation formed after 4 days of culturing stem cells in media with hPL prepared by the high (15 mM) Ca 2+ method, but not with hPL prepared by glass bead method., Discussion: The novel method transforms platelet concentrates to hPL with little hands-on time. The method results in high yield, is closed system, without heparin and non-inferior to published methods., (© 2022 The Authors. Transfusion published by Wiley Periodicals LLC on behalf of AABB.)

Background: Supplementation of the nicotinamide adenine dinucleotide (NAD) precursor nicotinamide riboside (NR) has recently been shown to increase life-span of cells, tissues, and entire organisms. [Correction added on 13 December 2019, after first online publication: In the preceding sentence, "adenine nicotinamide" was revised to "nicotinamide adenine."] The impact of NR on platelet longevity has not been tested., Study Design and Methods: A pool-and-split design of buffy coat derived platelet concentrates (PCs) was used. One arm was treated with cumulative doses of NR-triflate, the control arm with sodium triflate. Storage lesion was monitored for 23 days. Platelet metabolic and functional parameters were tested. Clearance of human platelets was measured in a mouse model of transfusion., Results: Total intracellular NAD levels in platelets decreased two-fold from 4.8 ± 0.5 fmol (mean ± SD, n = 6) to 2.1 ± 1.8 fmol per 10 3 control cells, but increased almost 10-fold to 41.5 ± 4.1 fmol per 10 3 NR treated platelets. This high intracellular NAD level had no significant impact on platelet count, mean platelet volume, swirling, nor on lactate and glucose levels. Platelet aggregation and integrin α IIb β 3 activation declined steadily and comparably in both conditions. GPIbα levels were slightly lower in NR-treated platelets compared to control, but this was not caused by reduced receptor shedding because glycocalicin increased similarly. Apoptotic markers cytochrome c, Bcl-xL, cleaved caspase-3, and Bak were not different throughout storage for both conditions. Platelet survival in a mouse model of transfusion was not different between NR-treated and control platelets., Conclusion: Platelets carry the cellular machinery to metabolize NR into NAD at rates comparable to other eukaryotic cells. Unlike those cells, platelet life-span cannot be prolonged using this strategy., (© 2019 The Authors. Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.)

Background: Transfusion of cryopreserved platelets (cryoplatelets) is not common but may replace standard liquid-preserved platelets (PLTs) in specific circumstances. To better understand cryoplatelet function, frozen concentrates from different manufacturing sites were compared., Study Design and Methods: Cryoplatelets from Denver, Colorado (DEN); Sydney, Australia (SYD); and Ghent, Belgium (GHE) were compared (n = 6). A paired noncryopreserved control was included in Ghent. Microfluidic-flow chambers were used to study PLT adhesion and fibrin deposition in reconstituted blood. Receptor expression was measured by flow cytometry. Coagulation in static conditions was evaluated by rotational thromboelastometry (ROTEM)., Results: Regardless of the manufacturing site, adhesion of cryoplatelets under shear flow (1000/sec) was significantly (p < 0.05) reduced compared to control. Expression of GPIbα was decreased in a subpopulation of cryoplatelets comprising 45% ± 11% (DEN), 63% ± 9% (GHE), and 94% ± 6% (SYD). That subpopulation displayed increased annexin V binding and decreased integrin activation. PLT adhesion, agglutination, and aggregation were moreover decreased in proportion to that subpopulation. Fibrin deposition under shear flow was normal but initiated faster (546 ± 163 sec GHE) than control PLTs (631 ± 120 sec, p < 0.01), only in the absence of tissue factor. In static conditions, clotting time was faster, but clot firmness decreased compared to control. Coagulation was not different between manufacturing sites., Conclusion: Cryopreservation results in a subset of PLTs with enhanced GPIbα shedding, increased phosphatidylserine expression, reduced integrin response, and reduced adhesion to collagen in microfluidic models of hemostasis. The proportion of this phenotype is different between manufacturing sites. The clinical effects, if any, will need to be verified., (© 2018 The Authors. Transfusion published by Wiley Periodicals, Inc. on behalf of AABB.)