Atherosclerosis is a condition in which plaques accumulate in the arteries of the heart, limiting blood flow to cardiac muscle and possibly resulting in a heart attack. Coronary artery disease – which is usually caused by atherosclerosis – is the leading cause of death worldwide. As such, developing drugs to combat atherosclerosis is a global health priority. Animal models are the gold-standard for testing drugs because of their relative low cost and convenience. However, animals do not have an anatomy or disease process similar to humans and are therefore not the most representative models.

Researchers are beginning to turn to microfluidic devices, or “organ-on-a-chip” technology, to recreate human physiological processes outside of a living organism. If microfluidic technology proves successful in this regard, it can serve as a more accurate representation of human disease processes and be more predictive of drug efficacy. More important to animal advocates, if microfluidic devices gain necessary traction, pharmaceutical research will be less reliant on animal models, thus sparing more animals from experimentation.

However, the replacement of animal models with microfluidic devices relies on the ability of microfluidic devices to accurately replicate human pathology. The authors of this study investigate some of the limitations and potential uses of microfluidic technology. At its most basic level, a microfluidic device for atherosclerosis would consist of various channels representing the arteries. The channels would be lined with human cells, particularly the same endothelial cells that line arteries in the body. Fluid would be pumped into the device from an external source, and the rate of flow as well as other properties of the fluid could be controlled. While microfluidic devices lend an extra level of control to researchers, this technology has limitations that both the medical and animal rights communities must be aware of.

For one, research is emerging that shows the fluid dynamics during atherosclerosis is different than expected. We used to think the smaller the opening in the coronary artery, the higher the risk to the patient, because there is a smaller channel for blood to flow through. However, recent findings show that it is not the size of the opening, but rather the duration of time that blood flows at high force, which determines the risk to the patient. Microfluidic devices have yet to model these newly-discovered fluid dynamic parameters. Nonetheless, microfluidic models are more flexible than animal models when it comes to integrating new findings. As we continue to learn more about atherosclerosis, we can redesign microfluidic devices to reflect our new knowledge. 

The strength of microfluidic models is their capability to recreate different stages of the disease process. The authors of this paper write that a microfluidic device can provide a platform for personalized medicine. By designing a microfluidic device that replicates the fluid dynamics of a particular patient, and running the patient’s own blood through the device, we get an incredibly realistic model for whether a drug will work in the specific patient we are studying. This will help patients avoid the unnecessary complications they may face if administered incompatible drugs. The authors continue to discuss various applications of the microfluidic device, emphasizing each time the value of the rapid testing and repeated refinement that microfluidic devices enable. 

However, animal advocates should be aware that microfluidic devices are still in-the-works. It will require patience as the medical community refines this technology to achieve the tasks that animal models are generally commissioned to do, and in the meantime, advocates may want to push for different alternatives, or further reductions in experiments. Big changes do not tend to happen all at once, but the culture of animal experimentation in medicine is slowly giving way to novel technologies such as microfluidic devices. Members of the animal advocacy community must recognize the hurdles that are still present in the world of animal testing alternatives, and adjust strategy to best suit the current landscape.