Heart attacks and cancer account for nearly half of all deaths in the United States - they're the two biggest killers walking the streets, but MIT isn't afraid. Michael Cima and his team developed an implantable sensor that uses antibodies attached to nanoparticles to detect cancer related biomarkers. In 2009 Cima showed that he could implant these devices into human tumors in mice and then 'read' the cancer growth using MRI. No biopsies need. Over the past few years, Cima and his team have adapted their work to create a very similar device that measures biomarkers related to heart damage. This month they published work in Nature that demonstrated how their implant could detect heart attacks in mice. Watch Cima discuss some of the potential of this technology in the video below. While these implants aren't ready for the clinic (Cima thinks 5 years for some applications) they are just too cool to ignore. Once fully realized, implants like these could be inserted into cells via a needle and read with a hand held scanner. Heart attacks, cancer...those bastards would never have the chance to sneak up on you again.
Biopsies, the standard method for testing clumps of cells for cancer, is an invasive procedure. Mild heart attacks can go unnoticed or ignored, but still leave behind serious damage that could later lead to death. What is needed in both cases is a method of safely and reliably monitoring the body, preferably from the inside where signals are stronger. That's why the MIT implants are so ingenious. They can detect small changes in cells and relate that information to a medical professional without having to be removed. Developed by Cima and his team, graduate student Christophoros Vassiliou was able to get the devices small enough to fit inside a biopsy needle. You can inject them into the tissue you want to monitor. Once there, they not only can warn you of dangerous changes, they can help you directly control the treatment of patients so that their therapy matches their current needs. Cima describes this further in the following video:
While they have a different shape, and monitor for vastly different biomarkers, the two sensors share a common technique. Each implant is filled with magnetic nanoparticles (iron-oxide) that are bonded to antibodies. Those antibodies will respond to different biomarkers around them and cause the nanoparticles to clump together. This changes the magnetic properties of the implant. When you scan the body with MRI, a change in the device's magnetic response alerts you to the presence of the biomarkers you were looking for.
Many cancers produce characteristically high levels of certain hormones that can be monitored. In a 2009 article in the journal Biosensors and Bioelectronics, Cima and his team found that implants in cancerous tumors showed a signal that was about 20% stronger than in control cases. The bigger the signal, the more cancer cells you're likely to have in the region.
In the more recent 2011 article in Nature, the MIT team (along with associates at Harvard Medical and Mass General Hospital) were looking for three proteins heart cells release when they are damaged. Implants inside mice were used to detect these biomarkers up to 72 hours after a heart attack was induced. Sure enough, the stronger the signal seen in the MRI, the more damage caused. Not only that, but the signal was cumulative. These implants could help us see not just how cells are being damaged now, but how much they've been damaged recently - a very necessary distinction if you want to detect patients who have injured hearts but who may not be actively showing signs of distress.
This work is very exciting, but still very early in development. As we've said many times before, successes with mice experiments and successes with human experiments can be miles apart. The 5mm cylindrical cancer implant and the 8mm heart monitoring disk both need more time to be perfected. The antibodies used to detect biomarkers have a limited lifetime in the body. Currently an implant probably wouldn't last much longer than two months. Also, while MRI is non-invasive, it's also not portable. Cima and his colleagues are working on upgrading the implants so that they can be read by handheld magnetic instruments.
If MIT continues to see good results with these early prototypes, there's a good chance we'll see similar devices in clinical trials in the near future. Cima thinks that such experiments could be as little as five years away. The lowest hanging fruit are implants that could monitor for pH levels - acidity is often a hallmark of cancer cells. After that, we may see versions that can accurately detect hormone levels and drug responses.
Cancer and heart attacks may be vicious killers, but they're also really dumb. They leave traces of their presence we can watch for, and they often rely upon a patient's ignorance to succeed. We need to be smarter than these bullies, and to know more about what they are up to. The implants out of the Cima Lab are a great solution and they're not alone. We've seen handheld testing devices and lab-on-chip technology that will likewise help us track cancer in our cells and damage in our hearts. Along with a more general trend towards continuous body monitoring, these systems will help us stay vigilant against the most prevalent causes of death. One day we'll all have these technologies inside us, implanted well ahead of time so that we'll know the second something goes wrong. Information well used is the best weapon in medicine, and with developments like the ones we've seen from MIT, we'll soon have more than enough to help keep us alive for a very long time.
[image credit: Michael Cima/MIT via New Scientist]