Abstract
Unlike red blood cells (RBC) which are stored at 4°C, platelets are stored at 22–24°C (room temperature) due to biophysical and biochemical changes induced by cold temperatures aggregately known as the ‘cold storage lesion’ (CSL). However, 22°C storage greatly increases the risk of microbial growth, thus limiting the safe storage of platelets to only 5–7 days (versus 42 days for RBC). Consequent to the short shelf life of platelets, blood services face chronic shortages of these life-saving cells. To overcome both the risk of microbial contamination and the constrained supplies of platelets, renewed research into attenuating the CSL and/or determining where cold stored platelets are clinically suitable are ongoing. In this chapter, we show that the covalent grafting of methoxypolyethylene glycol (mPEG), a biocompatible polymer, to the membrane of platelets attenuates the CSL. Moreover, the grafted mPEG serves as a potent cryoprotectant allowing platelets to be stored at 4°C, or frozen at −20°C, while retaining normal platelet counts and biologic function. The successful development of platelet PEGylation may provide a means by which the cold storage of platelets can be achieved with a minimal loss of platelet quality while improving both platelet microbial safety and inventory.
Keywords
- cryopreservation
- cryoprotection
- platelets
- blood banking
- cold storage
- PEGylation
- immunocamouflage
- methoxypoly(ethylene glycol)
- polymer
- aggregation
1. Introduction
Platelet adhesion and aggregation at the site of vascular injury are key events required for normal vascular homeostasis and wound repair. [1, 2, 3, 4] Platelets are produced from megakaryocytes in the bone marrow and, while lacking a nucleus, contain a number of specialized granules such as alpha-granules and dense granules. Normal, resting platelets have a discoid morphology which changes upon activation to ‘spiny spheres’ arising from the formation of pseudopodia. This shape change coincides with the rearrangement of the actin cytoskeleton. Upon activation, platelets adhere to the subendothelium at sites of vascular injury, aggregate and initiate coagulation to stop bleeding (
Consequent to this essential role, platelet transfusions have evolved as a crucial therapeutic tool in the treatment of a large number of diverse clinical conditions including acute bleeding, surgery, treatment of a variety of cancers, patients with platelet abnormalities and autoimmune diseases such as Idiopathic Thrombocytopenic Purpura (ITP) [5]. To meet the increasing clinical needs, blood systems within developed countries produce in excess of 5,000,000 transfusion doses annually [6]. However, demand for platelets continues to increase annually while the rate of blood/platelet donations are actually declining leading to an inventory that is chronically constrained [7].
The constraint of platelet inventory is in large part due to an inability to safely store platelet products for greater than 5–7 days. Historically, platelets, like red blood cells (RBC), were stored at 4°C and successfully used clinically. However, multiple studies from the late 1960s to the early 1970s demonstrated that 4°C (
The CSL is multi-dimensional and is best characterized as the sum of all the deleterious changes in platelet morphology, biochemistry and function that arise from the time the blood is withdrawn to the time the cold-stored platelets are transfused. The CSL is characterized, in part, by loss of discoid shape (
However, the warm storage of platelets was not without risk as it was demonstrated that warm storage significantly increased the risk for bacterial growth should bacteria be introduced to the platelet unit during collection [20, 21, 22, 23, 24]. Indeed, numerous North American screening studies have indicated that approximately 1/3500 platelet units (primarily platelet rich plasma; PRP) are bacterially contaminated posing a potential hazard to already at-risk patients [23, 25, 26]. Consequent to this risk, multiple blood systems have implemented costly universal bacteriologic screening of donor platelets. Hence, development of new technologies to improve both platelet safety and inventories will be crucial in meeting the ever increasing demand for platelet products.
2. What was ‘OLD’ is ‘NEW’ again
Consequent to the clinical demand and supply chain issues, several studies over the last several years have re-explored the potential use of ‘cold-stored’ platelets. Initial excitement regarding cold-stored platelets arose in 2003, Hoffmeister et al. investigated the mechanism(s) underlying the CSL and experimentally demonstrated that the shape change alone induced by cold storage itself did not result in poor platelet survival in a murine model [18, 19]. Instead, Hoffmeister et al. hypothesized that poor platelet survival resulted from an irreversible membrane clustering of alpha subunits of glycoprotein Ib (GPIbα). Their studies reported that exposed, terminal, beta-linked N-acetylglucosamine (βGlcNAc) residues on clustered GPIbα were recognized by the lectin domain of type 3 complement receptors (CR3; αMβ2; CD11b/CD18) on liver and splenic macrophages. This immunorecognition resulted in the rapid clearance of cold stored donor platelets via phagocytosis. Hoffmeister also demonstrate that phagocytosis of briefly chilled murine platelets could be inhibited and
More recently, the ‘old’ (1960) has become ‘new’ (2019) as transfusion scientists have begun to reexamine the clinical utility of platelets stored at 4°C. Indeed, the original 1960’s/70’s studies that initially discovered the platelet CSL, also reported that ‘cold-stored’ platelets were still effective
3. Hypothesis: attenuating the CSL via membrane-grafted mPEG
Consequent to our earlier work on polymer grafting to intact cells (
4. Polymer engineering of platelets
All human experiments were done in accordance with the approval of the University of British Columbia Clinical Research Ethics Board and the Canadian Blood Services Ethics Review Board in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki). Following informed consent, fresh platelet rich plasma (PRP) and, in some cases, buffy coat platelets (the standard of care in Canada and Western Europe) were obtained from volunteer donors or the Canadian Blood Services Network Centre for Applied Development (NetCAD) Laboratory (Vancouver, BC). PRP samples are similar to the platelet preparations used clinically and have an advantage of a lower level of manipulation (
Based on our previous studies, platelets were PEGylated using a semi-automated PEGylation device to maintain a constant platelet:polymer ratio (Figure 2) in a micromixing chamber to assure uniform polymer grafting [50, 52, 56, 71]. Platelets were modified with monofunctional (
Control and PEGylated mini-units (approximately 50 ml/unit; ~500 × 109/L) of platelets were stored at 4 or 22°C with agitation per Canadian Blood Services standard operating procedures. Storage at −80°C was done separately in the sample mini-unit blood banking bags. Storage was done for up to 12 days under the prescribed conditions (note: normal storage at 22°C is only allowed for 7 days). Storage bags were sampled aseptically in biosafety cabinets; washing and lysis procedures were performed as described previously [80, 81, 82]. Platelet counts were determined using an Advia 120 Hematology Analyzer (Bayer Inc., Toronto, Canada).
5. Effect of 4°C storage on mPEG-platelets
The covalent grafting of mPEG to PRP platelets resulted in the efficient immunocamouflage of CD9 (Figure 3A). As demonstrated in Figure 3A, virtually 100% of control platelets were CD9+, while the mPEG grafting to the platelets exhibited dose effect on the immunocamouflage of CD9. More importantly, the grafted polymer significantly decreased the aggregation of human platelets at 4°C. As microscopically demonstrated in Figure 3B, temperature exerted a significant effect on the morphology and microaggregation of control PRP preparations. As anticipated, minimal differences were observed in the control platelets at 37° (
The mPEG-mediated inhibition of cold-induced platelet aggregation was also not a short term effect. As demonstrated in Figure 4, unmodified control platelets demonstrated significant shape change, microaggregation, and a dramatic (~30%) decrease in platelet count. In contrast, minimal microaggregation was noted in the PEGylated samples following 12 days storage at 4°C. PEGylated platelets also retained a more discoid shape (though some pseudopod formation was noted). Due to the inhibition of microaggregation and inhibition of activation induced shape change, the mPEG-grafted platelets also resulted in a significantly improved platelet count.
Importantly, PEGylated platelets were functionally normal as evidenced by their
Clinically, visual inspection for ‘swirl’ may be the only pre-transfusion ‘quality’ test of the platelet unit—though even this is rarely done. The swirl test is a noninvasive method that literally works by swirling the bag and looking for light diffraction (
6. Effect of −80°C storage on mPEG-platelets
To further assess the cryoprotective effects of the grafted mPEG polymer, freezing studies were conducted on the control and SCmPEG platelets. While previous work on PEG as a cryoprotectant utilized a soluble form, work with PEG and other cryoprotectants (DMSO and Trehalose) demonstrated that the primary site of protection was at the level of the cell membrane [72, 73, 74, 75, 76, 77, 78, 79]. As shown in Figure 7, following 12 days storage at −80°C, covalently bound SCmPEG provided significant cryoprotection as reflected by both platelet morphology and improved cell counts. This finding is in stark contrast to control platelets which exhibited significant fragmentation and dramatically reduced cell counts post storage and thawing.
The covalent grafted mPEG exerted additional benefits post thaw. As shown in Figure 8, SCmPEG-grafted platelets exhibited improved morphology, and less fragmentation, immediately post-thaw when compared to control cells. Indeed, the grafted polymer provided comparable (or better) cryoprotection than DMSO. Moreover, following washing and re-concentration of the freeze-thaw control and SCmPEG platelets, control platelets demonstrated significant aggregation when stored at 22°C overnight (12 hours). In contrast, the SCmPEG-platelets demonstrated no aggregation over the same 12 hour time frame.
While the maintenance of morphology and platelet numbers post −80 storage was promising, the key question was whether these platelets were functional. To assess platelet function, thrombin (2 IU/ml) induced aggregation was assessed. As shown in Figure 9, thawed control platelets exhibited a poor response to thrombin (see Figure 5B for a normal response) as demonstrated by very limited aggregation. Moreover, the aggregation of the control platelets was very slow as seen by the slope of the aggregation curve. In contrast, the thawed SCmPEG platelets demonstrated significant, and rapid, thrombin mediated aggregation. Indeed, near maximal aggregation was achieved within approximately 3 minutes and very closely resembled the thrombin activation curves of fresh control and SCmPEG PRP (see Figure 5B).
7. Discussion
Platelet transfusions are a critical component in the treatment of both traumatic acute injury and a number of chronic diseases. However, unlike RBC which are stored at 4°C, platelets are stored at 22–24°C (room temperature) due to the induction of the CSL at temperatures below ~18°C. While the CSL encompasses a multitude of biophysical and biochemical changes, perhaps the most apparent effect is the production of platelet aggregates. To prevent the CSL, blood services worldwide have successfully stored platelets at 22°C. However, warm storage has its own risks as it greatly increases the risk for microbial growth limiting the safe storage of platelets to only 5–7 days (versus 42 days for RBC) and the outdating of a significant number of donor units. Consequent to the short shelf life of platelets, blood services face chronic shortages of these life-saving cells. To overcome both the risk of microbial contamination and the constrained supplies of platelets, renewed research into attenuating the CSL and/or determining where cold stored platelets are clinically suitable are ongoing.
To circumvent the microbial risk, and improve platelet inventory, our research has examined the potential use of cold stored, mPEG-grafted, platelets. As demonstrated by our
Interestingly, while not a focus of this chapter, polymer size (
8. Conclusions
PEGylation of donor platelets with short chain (2–5 kDa) mPEG effectively prevent the overt morphological changes arising from the CSL. Moreover, the polymer-grafted platelets retained their normal haemostatic function following both cold storage (4°C) and freezing (−80°C) as evidenced by thromboelastography and aggregation studies. Importantly, cold storage of platelets would improve transfusion safety as it would diminish the risk of microbial growth in a blood product destined for use in at risk patients. Also of potential clinical and economic importance was the finding that mPEG-grafted platelets withstood freezing in the absence of other cryoprotectants such as DMSO. The use of frozen platelets, requiring no DMSO removal step, could expand the availability of platelet transfusions to geographic regions in which they are not currently available or where donor recruitment or production facilities do not exist. The successful implementation of this technology for the cold storage of platelets would be of significant benefit to transfusion recipients by increasing the availability of platelets for transfusion.
Acknowledgments
This work was supported by grants from the Canadian Blood Services (MDS; EMS and MDS) and Health Canada (MDS). The views expressed herein do not necessarily represent the view of the federal government of Canada. We thank the Canada Foundation for Innovation and the Michael Smith Foundation for Health Research for infrastructure funding at the University of British Columbia Centre for Blood Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Conflict of interest
The Canadian Blood Services (Ottawa, ON, Canada) has patents relating to the cold storage of platelets [48, 49]. MDS, NN and EMS are inventors cited on said patents.
References
- 1.
Slichter SJ. Platelet transfusion therapy. Hematology/Oncology Clinics of North America. 1990; 4 :291-311. DOI: 10.1016/S0889-8588(18)30517-3 - 2.
Murphy S, Varma M. Selecting platelets for transfusion of the alloimmunized patient: A review. Immunohematology. 1998; 14 :117-123 - 3.
Hartwig JH. The platelet: Form and function. Seminars in Hematology. 2006; 43 :S94-S100. DOI: 10.1053/j.seminhematol.2005.11.004 - 4.
Wohner N. Role of cellular elements in thrombus formation and dissolution. Cardiovascular & Hematological Agents in Medicinal Chemistry. 2008; 6 :224-228. DOI: 10.2174/187152508784871972 - 5.
Cobain TJ, Vamvakas EC, Wells A, Titlestad K. A survey of the demographics of blood use. Transfusion Medicine. 2007; 17 :1-15. DOI: 10.1111/j.1365-3148.2006.00709.x - 6.
Stroncek DF, Rebulla P. Platelet transfusions. Lancet. 2007; 370 :427-438. DOI: 10.1016/S0140-6736(07)61198-2 - 7.
Goldman M, Steele WR, Di Angelantonio E, van den Hurk K, Vassallo RR, Germain M, et al. Biomedical EFSTCBESTI. Comparison of donor and general population demographics over time: A BEST collaborative group study. Transfusion. 2017; 57 :2469-2476. DOI: 10.1111/trf.14307 - 8.
Murphy S, Gardner FH. Effect of storage temperature on maintenance of platelet viability--deleterious effect of refrigerated storage. The New England Journal of Medicine. 1969; 280 :1094-1098. DOI: 10.1056/NEJM196905152802004 - 9.
Murphy S, Gardner FH. The effect of temperature on platelet viability. Vox Sanguinis. 1969; 17 :22 - 10.
Murphy S, Sayar SN, Gardner FH. Storage of platelet concentrates at 22 degrees C. Blood. 1970; 35 :549-557 - 11.
Murphy S, Gardner FH. Maintenance of platelet viability and functional integrity during storage. Vox Sanguinis. 1971; 20 :427-428. DOI: 10.1111/j.1423-0410.1971.tb01814.x - 12.
Murphy S, Gardner FH. Platelet storage at 22 degrees C; metabolic, morphologic, and functional studies. The Journal of Clinical Investigation. 1971; 50 :370-377. DOI: 10.1172/JCI106504 - 13.
Becker GA, Tuccelli M, Kunicki T, Chalos MK, Aster RH. Studies of platelet concentrates stored at 22 C and 4 C. Transfusion. 1973; 13 :61-68. DOI: 10.1111/j.1537-2995.1973.tb05442.x - 14.
Slichter SJ, Harker LA. Preparation and storage of platelet concentrates. Transfusion. 1976; 16 :8-12 - 15.
Holme S, Vaidja K, Murphy S. Platelet storage at 22 degrees C: Effect of type of agitation on morphology, viability, and function in vitro. Blood. 1978; 52 :425-435 - 16.
Slichter SJ. Preservation of platelet viability and function during storage of concentrates. Progress in Clinical and Biological Research. 1978; 28 :83-100 - 17.
Winokur R, Hartwig JH. Mechanism of shape change in chilled human platelets. Blood. 1995; 85 :1796-1804 - 18.
Hoffmeister KM, Josefsson EC, Isaac NA, Clausen H, Hartwig JH, Stossel TP. Glycosylation restores survival of chilled blood platelets. Science. 2003; 301 :1531-1534. DOI: 10.1126/science.1085322 - 19.
Hoffmeister KM, Felbinger TW, Falet H, Denis CV, Bergmeier W, Mayadas TN, et al. The clearance mechanism of chilled blood platelets. Cell. 2003; 112 :87-97. DOI: 10.1016/S0092-8674(02)01253-9 - 20.
Wagner SJ, Friedman LI, Dodd RY. Transfusion-associated bacterial sepsis. Clinical Microbiology Reviews. 1994; 7 :290-302. DOI: 10.1128/CMR.7.3.290 - 21.
Blajchman MA. Bacterial contamination of blood products and the value of pre-transfusion testing. Immunological Investigations. 1995; 24 :163-170. DOI: 10.3109/08820139509062770 - 22.
Dumont LJ, AuBuchon JP, Whitley P, Herschel LH, Johnson A, McNeil D, et al. Seven-day storage of single-donor platelets: Recovery and survival in an autologous transfusion study. Transfusion. 2002; 42 :847-854. DOI: 10.1046/j.1537-2995.2002.00147.x - 23.
Hillyer CD, Josephson CD, Blajchman MA, Vostal JG, Epstein JS, Goodman JL. Bacterial contamination of blood components: Risks, strategies, and regulation: Joint ASH and AABB educational session in transfusion medicine. Hematology. American Society of Hematology. Education Program. 2003; 2003 :575-589. DOI: 10.1182/asheducation-2003.1.575 - 24.
Benjamin RJ, Wagner SJ. The residual risk of sepsis: Modeling the effect of concentration on bacterial detection in two-bottle culture systems and an estimation of false-negative culture rates. Transfusion. 2007; 47 :1381-1389. DOI: 10.1111/j.1537-2995.2007.01326.x - 25.
Blajchman MA, Goldman M, Baeza F. Improving the bacteriological safety of platelet transfusions. Transfusion Medicine Reviews. 2004; 18 :11-24. DOI: 10.1016/j.tmrv.2003.10.002 - 26.
Blajchman MA, Beckers EA, Dickmeiss E, Lin L, Moore G, Muylle L. Bacterial detection of platelets: Current problems and possible resolutions. Transfusion Medicine Reviews. 2005; 19 :259-272. DOI: 10.1016/j.tmrv.2005.05.002 - 27.
Wandall HH, Hoffmeister KM, Sorensen AL, Rumjantseva V, Clausen H, Hartwig JH, et al. Galactosylation does not prevent the rapid clearance of long-term, 4 degrees C-stored platelets. Blood. 2008; 111 :3249-3256. DOI: 10.1182/blood-2007-06-097295 - 28.
Milford EM, Reade MC. Comprehensive review of platelet storage methods for use in the treatment of active hemorrhage. Transfusion. 2016; 56 (Suppl 2):S140-S148. DOI: 10.1111/trf.13504 - 29.
Johnson L, Tan S, Wood B, Davis A, Marks DC. Refrigeration and cryopreservation of platelets differentially affect platelet metabolism and function: A comparison with conventional platelet storage conditions. Transfusion. 2016; 56 :1807-1818. DOI: 10.1111/trf.13630 - 30.
Getz TM, Montgomery RK, Bynum JA, Aden JK, Pidcoke HF, Cap AP. Storage of platelets at 4°C in platelet additive solutions prevents aggregate formation and preserves platelet functional responses. Transfusion. 2016; 56 :1320-1328. DOI: 10.1111/trf.13511 - 31.
Spinella PC, Cap AP. Whole blood: Back to the future. Current Opinion in Hematology. 2016; 23 :536-542. DOI: 10.1097/MOH.0000000000000284 - 32.
Stubbs JR, Tran SA, Emery RL, Hammel SA, Haugen AL, Zielinski MD, et al. Cold platelets for trauma-associated bleeding: Regulatory approval, accreditation approval, and practice implementation-just the “tip of the iceberg”. Transfusion. 2017; 57 :2836-2844. DOI: 10.1111/trf.14303 - 33.
Berzuini A, Spreafico M, Prati D. One size doesn’t fit all: Should we reconsider the introduction of cold-stored platelets in blood bank inventories. F1000Res. 2017; 6 :95. DOI: 10.12688/f1000research.10363.1 - 34.
Wu X, Darlington DN, Montgomery RK, Liu B, Keesee JD, Scherer MR, et al. Platelets derived from fresh and cold-stored whole blood participate in clot formation in rats with acute traumatic coagulopathy. British Journal of Haematology. 2017; 179 :802-810. DOI: 10.1111/bjh.14999 - 35.
Stolla M, Fitzpatrick L, Gettinger I, Bailey SL, Pellham E, Christoffel T, et al. In vivo viability of extended 4°C-stored autologous apheresis platelets. Transfusion. 2018; 58 :2407-2413. DOI: 10.1111/trf.14833 - 36.
Ng MSY, Tung JP, Fraser JF. Platelet storage lesions: What more do we know now. Transfusion Medicine Reviews. 2018; 32 :144-154. DOI: 10.1016/j.tmrv.2018.04.001 - 37.
Humbrecht C, Kientz D, Gachet C. Platelet transfusion: Current challenges. Transfusion Clinique et Biologique. 2018; 25 :151-164. DOI: 10.1016/j.tracli.2018.06.004 - 38.
Waters L, Cameron M, Padula MP, Marks DC, Johnson L. Refrigeration, cryopreservation and pathogen inactivation: An updated perspective on platelet storage conditions. Vox Sanguinis. 2018; 113 :317-328. DOI: 10.1111/vox.12640 - 39.
Reddoch-Cardenas KM, Sharma U, Salgado CL, Montgomery RK, Cantu C, Cingoz N, et al. An in vitro pilot study of apheresis platelets collected on Trima Accel system and stored in T-PAS+ solution at refrigeration temperature (1-6°C). Transfusion. 2019; 59 :1789-1798. DOI: 10.1111/trf.15150 - 40.
Reddoch-Cardenas KM, Bynum JA, Meledeo MA, Nair PM, Wu X, Darlington DN, et al. Cold-stored platelets: A product with function optimized for hemorrhage control. Transfusion and Apheresis Science. 2019; 58 :16-22. DOI: 10.1016/j.transci.2018.12.012 - 41.
Leeper CM, Yazer MH, Cladis FP, Saladino R, Triulzi DJ, Gaines BA. Cold-stored whole blood platelet function is preserved in injured children with hemorrhagic shock. Journal of Trauma and Acute Care Surgery. 2019; 87 :49-53. DOI: 10.1097/TA.0000000000002340 - 42.
Braathen H, Sivertsen J, Lunde THF, Kristoffersen EK, Assmus J, Hervig TA, et al. In vitro quality and platelet function of cold and delayed cold storage of apheresis platelet concentrates in platelet additive solution for 21 days. Transfusion. 2019; 58 :2652-2661. DOI: 10.1111/trf.15356 - 43.
Scorer T, Williams A, Reddoch-Cardenas K, Mumford A. Manufacturing variables and hemostatic function of cold-stored platelets: A systematic review of the literature. Transfusion. 2019; 59 :2722-2732. DOI: 10.1111/trf.15396 - 44.
Getz TM. Physiology of cold-stored platelets. Transfusion and Apheresis Science. 2019; 58 :12-15. DOI: 10.1016/j.transci.2018.12.011 - 45.
Ketter PM, Kamucheka R, Arulanandam B, Akers K, Cap AP. Platelet enhancement of bacterial growth during room temperature storage: Mitigation through refrigeration. Transfusion. 2019; 59 :1479-1489. DOI: 10.1111/trf.15255 - 46.
Scott MD, Eaton JW. Antigenic modulation of cells. US Patent Number: 5,908,624. Albany, NY, USA: Assignee Albany Medical College. 1999 - 47.
Scott MD, Eaton JW. Antigenic modulation of cells. US Patent Number: 8,007,784. Assignee Albany Medical College. 2011 - 48.
Scott MD, Maurer E. Cold Storage Of Modified Platelets At >0°C. US Patent Number: 7,964,339. Assignee Canadian Blood Services. 2011 - 49.
Maurer E, Scott MD, Kitamura N. Cold storage of pegylated platelets at about or below 0°C. US Patent Number: 8,067,151. Assignee Canadian Blood Services. 2011 - 50.
Scott MD, Murad KL, Koumpouras F, Talbot M, Eaton JW. Chemical camouflage of antigenic determinants: Stealth erythrocytes. Proceedings of the National Academy of Sciences of the United States of America. 1997; 94 :7566-7571. DOI: 10.1073/pnas.94.14.7566 - 51.
Murad KL, Gosselin EJ, Eaton JW, Scott MD. Stealth cells: Prevention of major histocompatibility complex class II-mediated T-cell activation by cell surface modification. Blood. 1999; 94 :2135-2141 - 52.
Murad KL, Mahany KL, Brugnara C, Kuypers FA, Eaton JW, Scott MD. Structural and functional consequences of antigenic modulation of red blood cells with methoxypoly(ethylene glycol). Blood. 1999; 93 :2121-2127 - 53.
Scott MD, Bradley AJ, Murad KL. Camouflaged blood cells: Low-technology bioengineering for transfusion medicine? Transfusion Medicine Reviews. 2000; 14 :53-63. DOI: 10.1016/S0887-7963(00)80115-7 - 54.
Chen AM, Scott MD. Current and future applications of immunological attenuation via pegylation of cells and tissue. BioDrugs. 2001; 15 :833-847. DOI: 10.2165/00063030-200115120-00005 - 55.
Bradley AJ, Test ST, Murad KL, Mitsuyoshi J, Scott MD. Interactions of IgM ABO antibodies and complement with methoxy-PEG-modified human RBCs. Transfusion. 2001; 41 :1225-1233. DOI: 10.1046/j.1537-2995.2001.41101225.x - 56.
Bradley AJ, Murad KL, Regan KL, Scott MD. Biophysical consequences of linker chemistry and polymer size on stealth erythrocytes: Size does matter. Biochimica et Biophysica Acta. 2002; 1561 :147-158 - 57.
Bradley AJ, Scott MD. Separation and purification of methoxypoly(ethylene glycol) grafted red blood cells via two-phase partitioning. Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences. 2004; 807 :163-168. DOI: 10.1016/j.jchromb.2004.03.054 - 58.
Chen AM, Scott MD. Comparative analysis of polymer and linker chemistries on the efficacy of immunocamouflage of murine leukocytes. Artificial Cells, Blood Substitutes, and Immobilization Biotechnology. 2006; 34 :305-322. DOI: 10.1080/10731190600683845 - 59.
Bradley AJ, Scott MD. Immune complex binding by immunocamouflaged [poly(ethylene glycol)-grafted] erythrocytes. American Journal of Hematology. 2007; 82 :970-975. DOI: 10.1002/ajh.20956 - 60.
Le Y, Scott MD. Immunocamouflage: The biophysical basis of immunoprotection by grafted methoxypoly(ethylene glycol) (mPEG). Acta Biomaterialia. 2010; 6 :2631-2641. DOI: 10.1016/j.actbio.2010.01.031 - 61.
Wang D, Toyofuku WM, Chen AM, Scott MD. Induction of immunotolerance via mPEG grafting to allogeneic leukocytes. Biomaterials. 2011; 32 :9494-9503. DOI: 10.1016/j.biomaterials.2011.08.061 - 62.
Greco CA, Maurer-Spurej E, Scott MD, Kalab M, Nakane N, Ramirez-Arcos SM. PEGylation prevents bacteria-induced platelet activation and biofilm formation in platelet concentrates. Vox Sanguinis. 2011; 100 :336-339. DOI: 10.1111/j.1423-0410.2010.01419.x - 63.
Wang D, Kyluik DL, Murad KL, Toyofuku WM, Scott MD. Polymer-mediated immunocamouflage of red blood cells: Effects of polymer size on antigenic and immunogenic recognition of allogeneic donor blood cells. Science China. Life Sciences. 2011; 54 :589-598. DOI: 10.1007/s11427-011-4190-x - 64.
Le Y, Li L, Wang D, Scott MD. Immunocamouflage of latex surfaces by grafted methoxypoly(ethylene glycol) (mPEG): Proteomic analysis of plasma protein adsorption. Science China. Life Sciences. 2012; 55 :191-201. DOI: 10.1007/s11427-012-4290-2 - 65.
Wang D, Toyofuku WM, Scott MD. The potential utility of methoxypoly(ethylene glycol)-mediated prevention of rhesus blood group antigen RhD recognition in transfusion medicine. Biomaterials. 2012; 33 :3002-3012. DOI: 10.1016/j.biomaterials.2011.12.041 - 66.
Kyluik-Price DL, Li L, Scott MD. Comparative efficacy of blood cell immunocamouflage by membrane grafting of methoxypoly(ethylene glycol) and polyethyloxazoline. Biomaterials. 2014; 35 :412-422. DOI: 10.1016/j.biomaterials.2013.09.016 - 67.
Li L, Noumsi GT, Kwok YY, Moulds JM, Scott MD. Inhibition of phagocytic recognition of anti-D opsonized Rh D+ RBC by polymer-mediated immunocamouflage. American Journal of Hematology. 2015; 90 :1165-1170. DOI: 10.1002/ajh.24211 - 68.
Kyluik-Price DL, Scott MD. Effects of methoxypoly (ethylene glycol) mediated immunocamouflage on leukocyte surface marker detection, cell conjugation, activation and alloproliferation. Biomaterials. 2016; 74 :167-177. DOI: 10.1016/j.biomaterials.2015.09.047 - 69.
Le Y, Toyofuku WM, Scott MD. Immunogenicity of murine mPEG-red blood cells and the risk of anti-PEG antibodies in human blood donors. Experimental Hematology. 2017; 47 :36-47.e2. DOI: 10.1016/j.exphem.2016.11.001 - 70.
Kang N, Toyofuku WM, Yang X, Scott MD. Inhibition of allogeneic cytotoxic T cell (CD8(+)) proliferation via polymer-induced Treg (CD4(+)) cells. Acta Biomaterialia. 2017; 57 :146-155. DOI: 10.1016/j.actbio.2017.04.025 - 71.
Scott M, Toyofuku W, Yang X, Raj M, Kang N. Immunocamouflaged RBC for alloimmunized patients. In: Koopman-van Gemert A, editor. Transfusion Medicine and Scientific Developments. Croatia: INTECH; 2017. pp. 23-42. DOI: 10.5772/intechopen.68647 - 72.
Takahashi T, Hirsh A, Erbe E, Williams RJ. Mechanism of cryoprotection by extracellular polymeric solutes. Biophysical Journal. 1988; 54 :509-518. DOI: 10.1016/S0006-3495(88)82983-7 - 73.
Tormanen CD. Cryoprotection of purified rat kidney transamidinase by polyethylene glycol. Cryobiology. 1992; 29 :511-518. DOI: 10.1016/0011-2240(92)90054-6 - 74.
Banker MC, Layne JRJ, Hicks GLJ, Wang TC. Freezing preservation of the mammalian cardiac explant. II. Comparing the protective effect of glycerol and polyethylene glycol. Cryobiology. 1992; 29 :87-94. DOI: 10.1016/0011-2240(92)90008-P - 75.
Banker MC, Layne JRJ, Hicks GLJ, Wang T. Freezing preservation of the mammalian heart explant. III. Tissue dehydration and cryoprotection by polyethylene glycol. The Journal of Heart and Lung Transplantation. 1992; 11 :619-623 - 76.
Coundouris JA, Grant MH, Engeset J, Petrie JC, Hawksworth GM. Cryopreservation of human adult hepatocytes for use in drug metabolism and toxicity studies. Xenobiotica. 1993; 23 :1399-1409. DOI: 10.3109/00498259309059449 - 77.
Tsitsanou KE, Oikonomakos NG, Zographos SE, Skamnaki VT, Gregoriou M, Watson KA, et al. Effects of commonly used cryoprotectants on glycogen phosphorylase activity and structure. Protein Science. 1999; 8 :741-749. DOI: 10.1110/ps.8.4.741 - 78.
Mi Y, Wood G, Thoma L. Cryoprotection mechanisms of polyethylene glycols on lactate dehydrogenase during freeze-thawing. The AAPS Journal. 2004; 6 :e22. DOI: 10.1208/aapsj060322 - 79.
Chen YF, Tate MW, Gruner SM. Facilitating protein crystal cryoprotection in thick-walled plastic capillaries by high-pressure cryocooling. Journal of Applied Crystallography. 2009; 42 :525-530. DOI: 10.1107/S0021889809011315 - 80.
Thon JN, Schubert P, Duguay M, Serrano K, Lin S, Kast J, et al. Comprehensive proteomic analysis of protein changes during platelet storage requires complementary proteomic approaches. Transfusion. 2008; 48 :425-435. DOI: 10.1111/j.1537-2995.2007.01546.x - 81.
Thon JN, Schubert P, Devine DV. Platelet storage lesion: A new understanding from a proteomic perspective. Transfusion Medicine Reviews. 2008; 22 :268-279. DOI: 10.1016/j.tmrv.2008.05.004 - 82.
Schubert P, Thon JN, Walsh GM, Chen CH, Moore ED, Devine DV, et al. A signaling pathway contributing to platelet storage lesion development: Targeting PI3-kinase-dependent Rap1 activation slows storage-induced platelet deterioration. Transfusion. 2009; 49 :1944-1955. DOI: 10.1111/j.1537-2995.2009.02224.x - 83.
Maurer-Spurej E, Brown K, Labrie A, Marziali A, Glatter O. Portable dynamic light scattering instrument and method for the measurement of blood platelet suspensions. Physics in Medicine and Biology. 2006; 51 :3747-3758. DOI: 10.1088/0031-9155/51/15/010 - 84.
Maurer-Spurej E, Chipperfield K. Past and future approaches to assess the quality of platelets for transfusion. Transfusion Medicine Reviews. 2007; 21 :295-306. DOI: 10.1016/j.tmrv.2007.05.005 - 85.
Maurer-Spurej E, Labrie A, Pittendreigh C, Chipperfield K, Smith C, Heddle N, et al. Platelet quality measured with dynamic light scattering correlates with transfusion outcome in hematologic malignancies. Transfusion. 2009; 49 :2276-2284. DOI: 10.1111/j.1537-2995.2009.02302.x - 86.
Maurer-Spurej E, Pittendreigh C, Yakimec J, De Badyn MH, Chipperfield K. Erroneous automated optical platelet counts in 1-hour post-transfusion blood samples. International Journal of Laboratory Hematology. 2010; 32 :e1-e8. DOI: 10.1111/j.1751-553X.2008.01097.x - 87.
Xu Y, Nakane N, Maurer-Spurej E. Novel test for microparticles in platelet-rich plasma and platelet concentrates using dynamic light scattering. Transfusion. 2011; 51 :363-370. DOI: 10.1111/j.1537-2995.2010.02819.x - 88.
Labrie A, Marshall A, Bedi H, Maurer-Spurej E. Characterization of platelet concentrates using dynamic light scattering. Transfusion Medicine and Hemotherapy. 2013; 40 :93-100. DOI: 10.1159/000350362 - 89.
Maurer-Spurej E, Chipperfield K. Could microparticles Be the universal quality indicator for platelet viability and function. Journal of Blood Transfusion. 2016; 2016 :6140239. DOI: 10.1155/2016/6140239 - 90.
Maurer-Spurej E, Larsen R, Labrie A, Heaton A, Chipperfield K. Microparticle content of platelet concentrates is predicted by donor microparticles and is altered by production methods and stress. Transfusion and Apheresis Science. 2016; 55 :35-43. DOI: 10.1016/j.transci.2016.07.010 - 91.
Kanzler P, Mahoney A, Leitner G, Witt V, Maurer-Spurej E. Microparticle detection to guide platelet management for the reduction of platelet refractoriness in children - a study proposal. Transfusion and Apheresis Science. 2017; 56 :39-44. DOI: 10.1016/j.transci.2016.12.016 - 92.
Millar D, Murphy L, Labrie A, Maurer-Spurej E. Routine screening method for microparticles in platelet transfusions. Journal of Visualized Experiments. 2018:e56893. DOI: 10.3791/56893