Device for early detection of organ rejection

Bio-electronic implants detecting kidney transplant rejection early.


The study introduces a groundbreaking medical device designed to monitor transplanted organs and detect early signs of rejection. Organ transplantation is a life-saving procedure for patients with end-stage organ failure, but the risk of rejection poses a significant challenge to the success of these procedures. Timely detection of rejection is crucial for patient outcomes, and this study explores the development and potential impact of the new monitoring device.

Researchers at Northwestern University have created a unique electronic device that can monitor transplanted organs in real time. It sits on top of the transplanted kidney and can be noticed when there are temperature problems caused by inflammation or rejection. It sends this information to a smartphone or tablet, alerting the patient or doctor.

In a recent test on animals with transplanted kidneys, this device spotted signs of rejection nearly three weeks earlier than the current methods. This extra time could help doctors act faster, making patients feel better and increasing the chances of saving donated organs in high demand.

The study authors said, “Rejection can occur anytime after a transplant — immediately after the transplant or years down the road. It is often silent, and patients might not experience symptoms”.

Dr. Lorenzo Gallon, a Northwestern Medicine transplant nephrologist who led the clinical portion of the study, said, “I have noticed many of my patients feel constant anxiety — not knowing if their body is rejecting their transplanted organ or not. They may have waited years for a transplant and finally received one from a loved one or deceased donor. Then, they spend the rest of their lives worrying about the health of that organ. Our new device could offer protection, and continuous monitoring could provide reassurance and peace of mind.”

John A. Rogers from Northwestern University, who led the creation of this device, emphasizes the importance of spotting rejection early. If rejection is detected quickly, doctors can give treatments to help the patient and protect the donated organ from harm. Ignoring rejection can even be life-threatening. The device was made to catch rejection as soon as possible.

Surabhi Madhvapathy, a graduate student in Rogers’ lab, points out that each person responds differently to anti-rejection treatments. Monitoring the transplanted organ’s health in real-time is crucial for giving each patient the right medicine at the correct dose.

Over 250,000 people in the U.S. have transplanted kidneys, and keeping an eye on their kidney health is a continuous task. The usual way to do this is by checking certain things in the blood. Doctors look at creatinine and blood urea nitrogen levels to understand how the kidneys work. However, these levels can change for reasons unrelated to organ rejection, making them unreliable. Sometimes, they can show problems when there are none, or they might not show problems when there are.

The best way to detect rejection is through a biopsy, where a doctor takes a tiny piece of tissue from the transplanted organ and examines it for signs of rejection. However, biopsies are invasive and can lead to complications like bleeding, infection, and pain.

Some new blood markers can be used alongside creatinine and blood urea nitrogen levels, but they could be better.

The problem with these tests is that they can take a long time, and the results might need to come back more quickly to make critical patient care decisions. Waiting for these results could be a problem for the patient.

Northwestern University’s new implant keeps it simple by monitoring temperature. When there’s inflammation, temperature tends to rise, so the researchers thought unusual temperature changes might signal early transplant rejection.

Their animal study confirmed this idea. They found that the temperature of a transplanted kidney can go up, sometimes by as much as 0.6 degrees Celsius, before rejection happens.

In animals not taking immune-suppressing drugs, temperature changes happened two or three days before changes in blood tests. In animals on these drugs, temperature changes occurred up to three weeks before changes in creatinine and blood urea nitrogen levels.

The device spots these unusual temperature changes that aren’t part of the average daily cycle. This is important because even when creatinine levels are normal, rejection can still happen. Doctors can monitor things in real-time with the new device, whereas patients might have to wait for weeks between checks and blood tests.

Dr. Joaquin Brieva, a Northwestern Medicine dermatologist, knows what waiting and worrying are like. He had a kidney transplant in September 2022 because he was born with a kidney problem.

He said, “My new kidney worked perfectly two days after my transplant. But then you start worrying about the possibility of the body rejecting it. To prevent that, you take strong drugs and steroids. It’s like walking a tightrope because you’re anxious about infections, drug side effects, and, most importantly, your body rejecting the kidney. You can manage some of these worries by adjusting your medication, but the fear of rejection is always there because the transplanted kidney is precious.”

A transplant specialist, Dr. Gallon, explains that increasing anti-rejection drugs to prevent rejection isn’t an easy solution because these drugs have risks. They can weaken the immune system and lead to infections and even cancer. They only want to use them when it’s vital.

For people like Brieva, who have had organ transplants, having a device that constantly checks the organ’s health could be a game-changer. It would mean they don’t have to take unnecessary medications, and it would offer peace of mind.

Now, the device itself is tiny, smaller than a pinky fingernail. It fits snugly under the kidney’s protective layer, so it doesn’t harm the organ. The device can detect even tiny temperature changes in the kidney, which is a sign of trouble. It also measures blood flow, but temperature is a better indicator.

The device is connected to a small electronics package, including a tiny battery, using Bluetooth to send data to external devices. It’s made of soft, body-friendly materials.

The plan is to have surgeons implant this device right after a transplant surgery while the patient is still in the operating room. This way, it can monitor the kidney without needing more procedures.

The researchers successfully tested it on small animals and are now trying it on larger animals. They are also figuring out how to make the battery last a lifetime. While starting with kidney transplants, they think it could work for other organ transplants and diseases.

Journal Reference:

  1. Surabhi R. Madhvapathy, Jiao-Jing Wang, et al., Implantable bioelectronic systems for early detection of kidney transplant rejection. Science. DOI: 10.1126/science.adh7726.
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