Programmpunkt

15:20

Titel: Platelet apheresis as a human model for analysis of platelet subpopulations under increased platelet turnover
ID: VS-7-3
Art: Abstractvortrag
Redezeit: 8 + 5 min
Session:
Sektion Präparative und therapeutische Hämapherese
VS-7

Referent: Martina Wolff (Greifswald)


Abstract - Text

Offenlegung Interessenkonflikt:

MW: No conflicts of interest


SH: No conflicts of interest


AG: Advisor MacoPharma; Clinical Study DRK Blutspendedienst NSTOB; Head of Transfusion Medicine Greifswald producing platelet apheresis concentrates
 
TT: No conflicts of interest regarding this project

Methods

Platelets were isolated before and on days 3, 7 and 10 after double apheresis from ACD-A anticoagulated blood (n=4) and assessed by flow cytometry. Using Cy5-labeled oligo-dT and oligo-dA the relative proportion of RNA-positive (reticulated) platelets was determined. HLA-I expression was quantified using a-human HLA-A, B, C and a-human β2-microglobulin antibodies. Lectins RCA-I and ECL were used to assess platelet desialylation. RNA-content and HLA-I expression were further assessed using defined forward scatter gates.

Results

Platelet apheresis reduced platelet counts by 50.000 platelets/µl. The proportion of reticulated platelets day 0 (mean 4.8) increased until day 3 (mean 15.9) and then decreased on subsequent days to baseline (Fig 1A). Under steady state platelet production, reticulated platelets predominantly distributed in FSC gates for large platelets. However, after increased turnover on day 3, they distributed throughout all FSC gates and therefore showed no correlation between size and platelet age under increased turnover. Expression of HLA-I did not significantly change between days 0, 3, 7 and 10 (Fig. 1B). In contrast, desialylation progressively increased over the 10-day period (Fig. 1C).


 

Background

Human platelets vary in size, function, and age. Young platelets contain more RNA, express more HLA-I and show fewer desialylation as signal for clearance. Little is known about the characteristics of platelets during increased turnover, e.g. after major surgery/bleeding and it is unclear, whether turnover changes the platelet phenotype. We used platelet apheresis to increase platelet turnover in healthy blood donors and aimed to investigate the differences in platelet phenotype and function.

Conclusion

During increased turnover early after apheresis an increased proportion of platelets shows markers of young platelets. At the same time the proportion of desialylated platelets is higher compared to baseline, suggesting an increasing proportion of senescent platelets. Platelet apheresis is a suitable model to study platelet subpopulations during increased turnover without interference of factors caused by severe comorbidities.