In vitro modeling of the microvascular occlusion and thrombosis that occur in hematologic diseases using microfluidic technology
Michelle Tsai, Ashley Kita, Joseph Leach, Ross Rounsevell, James N. Huang, Joel Moake, Russell E. Ware, Daniel A. Fletcher, Wilbur A. Lam
Michelle Tsai, Ashley Kita, Joseph Leach, Ross Rounsevell, James N. Huang, Joel Moake, Russell E. Ware, Daniel A. Fletcher, Wilbur A. Lam
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Technical Advance Hematology

In vitro modeling of the microvascular occlusion and thrombosis that occur in hematologic diseases using microfluidic technology

Abstract

In hematologic diseases, such as sickle cell disease (SCD) and hemolytic uremic syndrome (HUS), pathological biophysical interactions among blood cells, endothelial cells, and soluble factors lead to microvascular occlusion and thrombosis. Here, we report an in vitro “endothelialized” microfluidic microvasculature model that recapitulates and integrates this ensemble of pathophysiological processes. Under controlled flow conditions, the model enabled quantitative investigation of how biophysical alterations in hematologic disease collectively lead to microvascular occlusion and thrombosis. Using blood samples from patients with SCD, we investigated how the drug hydroxyurea quantitatively affects microvascular obstruction in SCD, an unresolved issue pivotal to understanding its clinical efficacy in such patients. In addition, we demonstrated that our microsystem can function as an in vitro model of HUS and showed that shear stress influences microvascular thrombosis/obstruction and the efficacy of the drug eptifibatide, which decreases platelet aggregation, in the context of HUS. These experiments establish the versatility and clinical relevance of our microvasculature-on-a-chip model as a biophysical assay of hematologic pathophysiology as well as a drug discovery platform.

Authors

Michelle Tsai, Ashley Kita, Joseph Leach, Ross Rounsevell, James N. Huang, Joel Moake, Russell E. Ware, Daniel A. Fletcher, Wilbur A. Lam

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Figure 4

Application of the microvasculature on a chip to vasoocclusion in SCD.

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Application of the microvasculature on a chip to vasoocclusion in SCD. (...
(A) Under identical initial hemodynamic conditions comparable to postcapillary venules using a microdevice cultured with HLMVECs, the microchannel velocity (n = 32 microchannels/device) of a whole blood sample taken from a healthy volunteer was compared with that of a whole blood sample taken from an SCD patient treated with HU and a whole blood sample from an SCD patient not treated with HU. Flow patterns of both sickle cell samples were much less steady than that of the control sample, and velocities of the sickle cell samples were lower than that of the control. Within 20 minutes of the start of the experiment until the end of the experiment, the velocity of the sickle cell HU– sample was consistently lower than that of the sickle cell HU+ sample (P < 0.03). (B) These differences became more apparent when the average of velocity curves of blood samples taken from 5 different HU+ sickle cell blood samples were compared with the average of velocity curves of 5 different HU– sickle cell blood samples (P < 0.008). (C) Similarly, a sickle cell HU– whole blood sample exhibited a higher rate of microchannel obstruction than a sickle cell HU+ whole blood sample, and microchannel obstruction in the HU– sample was even higher when compared with that of a healthy control. (D) Again, the differences became more apparent when the average of 5 obstruction curves from different HU+ sickle cell blood samples was compared with the average of 5 HU– sickle cell blood samples (P < 0.032). All SCD patients in this study had hemoglobin SS (Hb SS), whereas health controls had hemoglobin AA (Hb AA). All error bars represent SD.