Department of Biomedical EngineeringCardiovascular diseases are one of the leading causes of disability and mortality worldwide and directly associated with the enhanced reactivity of platelets. Platelet is the smallest (1 ~ 4 ??m) cells in the circulation, comprising the second largest volume fraction of blood, responsible for the maintenance of the circulatory systems in normal condition. However, platelets can significantly contribute to the formation of thrombus which blocks the blood flow if hyper-functional, or result in bleeding, if dysfunctional. Aside from its hemostatic role, platelets are also involved in other essential and versatile functions of immunity, wound healing, and inflammation. Its pathophysiological involvements in cancer, Alzheimer???s disease, cardiovascular disease, diabetes and viral infections were recently established and have gained much attention for its potential use in both diagnostics and therapy.
Conventional platelet isolation uses density-based centrifugation, which lacks global standard, hence, high variations that influence clinical decision have been reported. In addition, platelet activation due to high shear stress during the centrifugation, and WBC contamination limited the use of platelet in bio-assays for protein quantification and RNA analysis. The conventional isolation approach also suffers from handling errors, long processing time, and labour intensiveness. Hence, microfluidics based technological interventions have been developed to overcome above limitations but was not able to achieve the optimal platelet isolation of uncompromised high purity, throughput, and recovery with minimal activation in short time from undiluted whole blood. Still, isolation of platelets for molecular diagnosis in small blood volume remains a challenging task.
Therefore, we developed a fully automated lab-on-a-disc device to isolate platelets for downstream analysis. By integration of sequential filtration on disc with 3 ??m and 600 nm pore size membranes, highly pure platelet isolation was achieved. From our results, the disc based isolation significantly increased platelet count by 3~4 fold, while simultaneously lowering activation even in the absence of inhibitors. The flow cytometry and RT-PCR analysis of isolated platelets revealed that our disc platform results in ~ 99 % pure platelets free from WBC contamination having WBC specific gene undetected. In summary, the experimental result confirmed that disc is capable of separating platelets ideal for downstream analysis having high purity and recovery with minimal activation in time efficient manner.
Prior to downstream analysis, platelet function test for screening of multiple platelet related disorders or conditions are commonly requested in clinical settings. As a proof of concept, we demonstrated the potential of full integration of light transmission aggregometry - the reference gold standard of addressing platelet function - on lab on a disc platform as a point of care testing device to improve time efficiency, overall cost, and higher precision without restriction to the staff and facilities.ope
