Contributions
Abstract: O12
Type: Oral presentation
Session Topic: Inherited and acquired disorders of platelets
Presentation during EHA Scientific Conference on Bleeding Disorders:
On Thursday, September 15, 2016 from 09:00 - 10:30
Location: Rossini 1
Background
Transfusion of platelet concentrates (PC) is extensively used either prophylactically to prevent bleeding in high-risk thrombocytopenic patients, or therapeutically to control active bleeding. A good hemostatic potential of platelets in PC is important for a successful transfusion to obtain an effective and rapid hemostatic action in the recipient. PC standard quality is routinely performed by evaluating platelet and leukocyte counts, swirling, volume, and pH changes; however these parameters are not able to define the platelet hemostatic functionality.
Aim
In this study we aim to assess the impact of storage conditions on the hemostatic potential of PC by measuring platelet activation, secretion, and aggregation capacity, both before and after storage.
Methods
Consecutive 70 random PC (O blood group=43, A blood group=27) from 280 blood donors (253M/27F, Median age=41.5 (19-65)) were analyzed at the day of preparation (D0) and after 4 days of storage (D4) at 22°C on lateral agitation. Antigenic levels (i.e ELISA method) of platelet α-granule proteins (i.e. platelet factor-4 (PF4), β-thromboglobulin (β-TG), thrombospondin-1 (TSP-1), vascular-endothelial growth factor (VEGF)), soluble P-selectin and, soluble Glycoprotein V (sGPV) in PC supernatants were evaluated as markers of spontaneous degranulation and platelet membrane shedding. PLT aggregation (300,000 plts/ul) was assessed by light transmission aggregometry (LTA; Born method) in response to collagen, thrombin (i.e.TRAP-6), ristocetin, or arachidonic acid (AA). Statistical analysis was performed using SPSS statistic data editor.
Results
Levels of α-granule proteins increased during the four days of storage with different trends according to the specific marker; particularly a median increase of 141% for PF4 (p<0.01), 110% for β-TG (p<0.01), 179% for VEGF (p<0.01) and 33% for TSP-1 was recorded. Also levels of soluble proteins (P-selectin and GPV) significantly (p<0.01) increased during storage, demonstrating an ongoing shedding of these proteins from platelets. No significant differences between ABO groups were observed concerning the levels of soluble markers. The increased degranulation observed during CP storage was associated to a parallel and significant (p<0.01) decrease in the aggregation response of platelets to collagen (-58.5%), TRAP6 (-35%), ristocetin (-22.4%), but not to AA (-8.5%; p=ns). Platelet aggregation was not different between ABO groups, although a trend to decrease was observed in CP from A compared to O blood group at each time points. A significant (p<0.05) correlation was found between the relative increase (from T0 to T4) in PF4, β-TG and sGPV levels and the decrease in AA-, TRAP6- and ristocetin-induced aggregation. Best correlations were found between β-TG (r=-0.544; p=0.000) or PF4 (r=-0.596; p=0.000) levels and ristocetin-induced aggregation.
Conclusions
During PC storage, platelets change their hemostatic phenotype becoming more activated and less responsive to in vitro stimuli by the aggregation assay. This spontaneous phenomenon was observed in all the 70 CP tested during storage independently from ABO group type. Testing platelets for their hemostatic potential could be useful to identify PCs that might not display full functionality and reactivity in the recipient. However, further studies are necessary to investigate the correlation between platelet functionality in PC and the recovery of the hemostatic balance in the transfused recipient.
Abstract: O12
Type: Oral presentation
Session Topic: Inherited and acquired disorders of platelets
Presentation during EHA Scientific Conference on Bleeding Disorders:
On Thursday, September 15, 2016 from 09:00 - 10:30
Location: Rossini 1
Background
Transfusion of platelet concentrates (PC) is extensively used either prophylactically to prevent bleeding in high-risk thrombocytopenic patients, or therapeutically to control active bleeding. A good hemostatic potential of platelets in PC is important for a successful transfusion to obtain an effective and rapid hemostatic action in the recipient. PC standard quality is routinely performed by evaluating platelet and leukocyte counts, swirling, volume, and pH changes; however these parameters are not able to define the platelet hemostatic functionality.
Aim
In this study we aim to assess the impact of storage conditions on the hemostatic potential of PC by measuring platelet activation, secretion, and aggregation capacity, both before and after storage.
Methods
Consecutive 70 random PC (O blood group=43, A blood group=27) from 280 blood donors (253M/27F, Median age=41.5 (19-65)) were analyzed at the day of preparation (D0) and after 4 days of storage (D4) at 22°C on lateral agitation. Antigenic levels (i.e ELISA method) of platelet α-granule proteins (i.e. platelet factor-4 (PF4), β-thromboglobulin (β-TG), thrombospondin-1 (TSP-1), vascular-endothelial growth factor (VEGF)), soluble P-selectin and, soluble Glycoprotein V (sGPV) in PC supernatants were evaluated as markers of spontaneous degranulation and platelet membrane shedding. PLT aggregation (300,000 plts/ul) was assessed by light transmission aggregometry (LTA; Born method) in response to collagen, thrombin (i.e.TRAP-6), ristocetin, or arachidonic acid (AA). Statistical analysis was performed using SPSS statistic data editor.
Results
Levels of α-granule proteins increased during the four days of storage with different trends according to the specific marker; particularly a median increase of 141% for PF4 (p<0.01), 110% for β-TG (p<0.01), 179% for VEGF (p<0.01) and 33% for TSP-1 was recorded. Also levels of soluble proteins (P-selectin and GPV) significantly (p<0.01) increased during storage, demonstrating an ongoing shedding of these proteins from platelets. No significant differences between ABO groups were observed concerning the levels of soluble markers. The increased degranulation observed during CP storage was associated to a parallel and significant (p<0.01) decrease in the aggregation response of platelets to collagen (-58.5%), TRAP6 (-35%), ristocetin (-22.4%), but not to AA (-8.5%; p=ns). Platelet aggregation was not different between ABO groups, although a trend to decrease was observed in CP from A compared to O blood group at each time points. A significant (p<0.05) correlation was found between the relative increase (from T0 to T4) in PF4, β-TG and sGPV levels and the decrease in AA-, TRAP6- and ristocetin-induced aggregation. Best correlations were found between β-TG (r=-0.544; p=0.000) or PF4 (r=-0.596; p=0.000) levels and ristocetin-induced aggregation.
Conclusions
During PC storage, platelets change their hemostatic phenotype becoming more activated and less responsive to in vitro stimuli by the aggregation assay. This spontaneous phenomenon was observed in all the 70 CP tested during storage independently from ABO group type. Testing platelets for their hemostatic potential could be useful to identify PCs that might not display full functionality and reactivity in the recipient. However, further studies are necessary to investigate the correlation between platelet functionality in PC and the recovery of the hemostatic balance in the transfused recipient.