The Dynamic Platelet Function Assay (DPFA): Assessment of platelet translocation behaviour on von Willebrand Factor (VWF) in pregnancy, neonates and adults

Platelets are a key constituent in haemostasis and thrombosis. Platelet function testing has clinical benefit, through identifying those who are potentially at risk to bleeding or thrombosis. Empirically, the challenge is to produce tests that can effectively replicate the flow and shear environment that platelets experience in vivo.

Our research group, previously developed a Dynamic Platelet Function Assay (DPFA), that uses novel parallel plate flow chambers coated with purified human VWF and custom-designed platelet tracking software (Kent et al., 2010, Lincoln et al., 2010). This custom-designed platelet tracking software was capable of deriving novel parameters of platelet function that related to the biological activity of platelets in vivo. However, the reliability and the clinical relevance of the measured parameters of the DPFA were unclear, and there were errors in its platelet tracking process. A primary objective of this PhD thesis was to investigate the above issues through validation and clinical evaluation of the DPFA. Validation of the assay was achieved computationally using an ideal data set, which determined the percentage systematic error for each measured parameter of platelet behaviour, and biologically using a P2Y₁ receptor inhibitor MRS2179. Clinical evaluation was performed in adults, neonates, healthy pregnancy and pregnancy with utero-placental disease, through observation and recording of subtle changes in the behavior of platelets translocating on VWF.

The results conveyed in this thesis, validated, clinically evaluated and enhanced the DPFA, through the refinement and adaptation of its platelet tracking software and parameter outputs. It is concluded that the DPFA is capable of detecting subtle changes in platelet function. These changes in platelet function are cognizant to the behaviours of platelets in vivo. It is recommended that future work should seek to enhance and further understand the assays outputs.