Figure 4. 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.