For millions of dialysis patients worldwide, a life-saving vascular access also places continuous strain on the body. Most haemodialysis treatments rely on an arteriovenous fistula (AVF), a surgically created connection between an artery and a vein that allows blood to be removed and returned efficiently during dialysis.

​

XS Innovations, a medical technology start-up emerging from Leiden University Medical Center (LUMC) and TU Delft, is developing a new way to reduce the long-term burden of this access by redesigning how blood flow through the fistula is regulated between dialysis treatments.

​

A valve with a schedule

​

XS Innovations is developing an implantable valve designed to regulate blood flow through the AVF based on when dialysis is actually needed.

​

The patented device is engineered to open during dialysis sessions and close between treatments, allowing blood flow to return closer to physiological levels when dialysis is not taking place. Rather than managing downstream complications, the approach targets a key driver of AVF-related problems: persistent high flow outside treatment hours.

​

“Most vascular access complications are caused by continuous high blood flow through the fistula, which is present 24/7,” CEO Toon Stilma explains. “Existing solutions treat individual problems but do not remove this underlying cause. Dynamic blood-flow regulation allows high flow only during dialysis and normal flow the rest of the time.”

​

By addressing the haemodynamic imbalance itself rather than isolated symptoms, the technology aims to prevent multiple complications and improve patients’ quality of life.

​

From fixed access to flow control

​

Most innovations in dialysis access focus on creating or maintaining an AVF, or intervening once complications occur. XS Innovations’ approach introduces dynamic regulation that adjusts blood flow to align with a patient’s treatment schedule.

If successful, this could reduce cardiovascular strain, prolong access longevity, and decrease the need for repeated surgical interventions. In a field where improvements are often incremental, the idea of time-based flow control introduces a new perspective on access management.

​

Born in the lab, shaped by the clinic

​

XS Innovations emerged from collaborative research between LUMC and TU Delft, combining clinical insight with engineering expertise. Nephrologists and vascular specialists involved in the project brought first-hand experience of the long-term challenges faced by dialysis patients.

​

According to Stilma, this interdisciplinary collaboration was essential from the outset. “The close collaboration resulted in continuous feedback between clinicians and engineers, ensuring functionality, usability, and safety were aligned from the start,” he says. “This has resulted in a clinically relevant, technically feasible, and scalable solution, and allowed us to hit the ground running in the transition from an academic concept to a viable medical device.”

​

What comes next?

​

XS Innovations is now moving beyond early prototyping into more advanced development and validation. A recent public–private partnership with Maastricht University focuses on optimising materials and device design, alongside further in vivo testing to assess long-term performance and biocompatibility.

​

Clear milestones are already in place. “Next year, we will reach design freeze and start formal verification and validation activities,” Stilma notes. “In 2027, we plan to initiate First-in-Human testing. Based on these results, larger pivotal clinical trials in Europe and the United States are planned from 2028 onward.”

​

As the project progresses, XS Innovations continues to build on its academic roots in Leiden, aiming to translate research-driven insight into a medical technology with lasting clinical impact.