In the 1960's film The Fantastic Voyage (or its homage episode in the PBS KIDS classic The Magic School Bus!) a miniaturized crew pilots a ship inside the body of an incapacitated scientist. The mission? Find and destroy a threatening blood clot. Science fiction is rife with portrayals of microscopic medicine like this but the question is, can it ever be a reality?
Clot-busting nanovehicles like those in the movies do hold a grain of truth. There is now an entire field devoted to the use of nanotechnology in treating and detecting cardiovascular disease. It’s called cardiovascular nanomedicine.
Cardiovascular disease is the root cause of approximately 610,000 deaths per year in the United States. That is approximately 1 out of every 4 deaths! New and improved therapies must be developed to help treat these life-threatening diseases. And nanotechnology is an exciting new resource for cardiovascular disease research.
In nanomedicine, nanoparticles are targeted drug carriers. Nanoparticles can deliver large amounts of medication to a specific target site, providing high therapeutic activity at a disease site, and hopefully avoiding many systemic side effects that persist with current drugs on the market.
So how would this work for our clot-busting example from above? Sometimes clots can form inside of blood vessels. A clot that blocks an artery results in ischemia—the reduction of oxygen supply to the surrounding tissue. In the case of the brain, this is known as a stroke. In the heart, we know this as a heart attack.
Currently, the only FDA approved therapy for acute ischemic stroke is a drug known as a tissue plasminogen activator. Tissue plasminogen activators aid the activation of enzymes. These enzymes help to rapidly dissolve the clot, restoring the supply of oxygen to the deprived surrounding tissue.
In rare cases, some patients that receive tissue plasminogen activator may have serious side effects. Since the drug acts on all clots (not just the ones causing trouble), necessary clots—like those formed through the natural healing of an injury—can also be also dissolved, putting patients at risk of bleeding out.
Similarly, patients with chronic heart conditions are often placed on anticoagulant medications, sometimes for years. These prevent the recurrence of strokes or heart attacks, but they also prevent the body from developing clots when they are needed. For example, if you accidentally cut your finger while chopping vegetables or need emergency surgery after a car accident!
In both acute and chronic cases like these, nanomedicine aims to package clot-busting and clot-preventing drugs onto nanoparticles for specific delivery to target sites. This means they only go to precisely where they are needed and don’t effect clot-forming in other parts of the body.
Nanomedicine is also being used to treat the underlying cause for many of these clots: atherosclerosis. Atherosclerosis is a disease where plaques form over time in the walls of blood vessels. Overtime, these plaques can erode or rupture, resulting in the formation of problematic clots. Current treatments for atherosclerosis often involve cholesterol-lowering therapies. These therapies are generally effective and widely prescribed, but the systemic side effects leave much room for improvement.
As a graduate student, I was part of a team trying to target and treat specific plaque components using nanoparticles. Our objective was to reduce the local inflammation that results in plaque formation. In our research, we used nanoparticles to deliver drugs directly to the plaque site. In our research, this increased the effect of these drugs where we needed them and diminished side effects elsewhere in a patient.
Clearly, the potential of nanomedicine in providing the next generation of cardiovascular disease therapies is immense. Future work in this area will undoubtedly aid the development of new therapies and hopefully revolutionize the standard of care. The research being conducted in this field is only the beginning of the "Fantastic Voyage" ahead of us!