Implantable sensor provides advanced warning of kidney transplant failure in rats

An implantable sensor provided advanced warning of kidney transplant failure in rats as much as several weeks earlier than commonly used biomarkers of kidney function, researchers report.

The device, tested in a rat model of kidney transplantation, provides real-time continuous monitoring of organ temperature and thermal conductivity, detecting inflammatory processes associated with graft rejection. Although lifesaving for patients with end-stage kidney disease, long-term kidney transplantation survival remains a major challenge. Graft failure can occur anytime, and the early stages of kidney transplant rejection can be difficult to detect. Although organ biopsy is the "gold standard" for diagnosing transplant rejection, it occurs infrequently and can introduce additional risks and complications. As an alternative, blood and urine biomarkers are often used to detect rejection. However, factors unrelated to kidney function can alter these biomarkers, leading to false negative and positive outcomes.

To address the need for a reliable, noninvasive technique to monitor and detect the onset or early stages of rejection, Surabhi Madhvapathy and colleagues developed an implantable bioelectronic device to monitor the thermal characteristics of the organ. The ultrathin, stretchable thermal sensor interfaces directly with the soft surface of the kidney and connects to a miniaturized wireless communication module for long-term, real-time, and continuous measurements of the local temperature and thermal conductivity of the organ, which were used as surrogate markers for kidney inflammation and perfusion, respectively.

In model rat studies, these signals identified the onset of rejection ~3 days before clinically relevant blood biomarkers would, when the animals were not given immunosuppressive therapy, and ~2 to 3 weeks before clinically relevant blood biomarkers would in immunosuppressed animals. "Although several hurdles remain to be overcome, the prospect of integrating continuous monitoring into clinical practice could represent a major step toward personalized organ transplant care," write Mohamad Zaidan and Fadi Lakkis in a related Perspective.