Computational modeling of drug transport and mixing in the chemofilter device: enhancing the removal of chemotherapeutics from circulation

Transport of nitrite from large arteries modulates regional blood flow during stress and exercise

Background

Acute cardiovascular stress increases systemic wall shear stress (WSS)-a frictional force exerted by the flow of blood on vessel walls-which raises plasma nitrite concentration due to enhanced endothelial nitric oxide synthase (eNOS) activity. Upstream eNOS inhibition modulates distal perfusion, and autonomic stress increases both the consumption and vasodilatory effects of endogenous nitrite. Plasma nitrite maintains vascular homeostasis during exercise and disruption of nitrite bioavailability can lead to intermittent claudication.

Hypothesis

During acute cardiovascular stress or strenuous exercise, we hypothesize enhanced production of nitric oxide (NO) by vascular endothelial cells raises nitrite concentrations in near-wall layers of flowing blood, resulting in cumulative NO concentrations in downstream arterioles sufficient for vasodilation.

Confirmation and implications

Utilizing a multiscale model of nitrite transport in bifurcating arteries, we tested the hypothesis for femoral artery flow under resting and exercised states of cardiovascular stress. Results indicate intravascular transport of nitrite from upstream endothelium could result in vasodilator-active levels of nitrite in downstream resistance vessels. The hypothesis could be confirmed utilizing artery-on-a-chip technology to measure NO production rates directly and help validate numerical model predictions. Further characterization of this mechanism may improve our understanding of symptomatic peripheral artery occlusive disease and exercise physiology.

3D-Printed Drug Capture Materials Based on Genomic DNA Coatings

The toxic side effects of chemotherapy have long limited its efficacy, prompting expensive and long-drawn efforts to develop more targeted cancer therapeutics. An alternative approach to mitigate off-target toxicity is to develop a device that can sequester chemotherapeutic agents from the veins that drain the target organ before they enter systemic circulation. This effectively localizes the chemotherapy to the target organ, minimizing any hazardous side effects. 3D printing is ideal for fabricating these devices, as the geometric control afforded allows us to precisely dictate its hemodynamic performance in vivo. However, the existing materials compatible with 3D printing do not have drug-binding capabilities. Here, we report the stable coating of genomic DNA on a 3D-printed structure for the capture of doxorubicin. Genomic DNA is an effective chemotherapeutic-agent capture material due to the intrinsic DNA-targeting mechanism of action of these drugs. Stable DNA coatings were achieved through a combination of electrostatic interactions and ultraviolet C (UVC, 254 nm) cross-linking. These UVC cross-linked DNA coatings were extremely stable-leaching on average 100 pg of genomic DNA per mm2 of 3D-printed structure over a period of 30 min. In vitro studies of these materials in phosphate buffered saline and human serum demonstrated that they were able to capture, on average, 72 and 60 ng of doxorubicin per mm2 of structure, respectively. The stability and efficacy of these genomic DNA-coated 3D-printed materials represent a significant step forward towards the translation of these devices to clinical applications for the potential improvement of chemotherapy treatment.