Artificial kidney

Artificial kidney. An artificial kidney is a device designed to replace the critical blood-filtering functions of a natural kidney, primarily for patients with end-stage renal disease. These devices aim to replicate key physiological tasks such as waste removal, electrolyte balance, and fluid regulation, offering an alternative to conventional dialysis or organ transplantation. Significant research is driven by organizations like the National Institute of Biomedical Imaging and Bioengineering and the Kidney Health Initiative, seeking to create more portable and biocompatible systems.

Overview

The primary function is to mimic the selective filtration and regulatory roles of the nephron, the kidney's functional unit. This involves processes like ultrafiltration and active transport, often utilizing advanced membrane technology and living renal tubule cells. Unlike standard hemodialysis machines, which are large and stationary, next-generation devices aim for miniaturization and implantability. Key development goals include improving biocompatibility to reduce immune response and creating a device that operates continuously, akin to a natural organ.

History and development

Early concepts emerged in the 1940s, with Willem Kolff pioneering the first working rotating drum kidney in the Netherlands, a precursor to modern dialysis. The 1960s saw the development of the Scribner shunt by Belding Scribner, enabling long-term vascular access for repeated hemodialysis. The National Institutes of Health established the Artificial Kidney-Chronic Uremia Program in the 1970s to accelerate device innovation. In the 21st century, projects like The Kidney Project at the University of California, San Francisco and the Vanderbilt University medical center have advanced bio-hybrid designs. The Food and Drug Administration has granted several devices, including those from Xcorporeal, the breakthrough device designation to expedite clinical evaluation.

Types and technologies

Current research focuses on three main paradigms. The wearable artificial kidney is a miniaturized, portable version of hemodialysis, with prototypes tested in trials at the David Geffen School of Medicine. The implantable artificial kidney, a goal of initiatives like the National Kidney Foundation Innovation Fund, integrates silicon nanotechnology membranes with cultured cells. The bioartificial kidney typically combines a hemofilter with a cartridge containing human renal proximal tubule cells, developed by entities such as the Nephros Therapeutics and researchers at the Mayo Clinic. These technologies often employ nanotechnology from institutions like the Massachusetts Institute of Technology to enhance membrane precision and durability.

Clinical applications and trials

Clinical evaluation is ongoing to assess safety and efficacy. The REDY sorbent dialysis system was an early commercial attempt at portability. More recently, the Wearable Artificial Kidney trial, presented at the American Society of Nephrology annual meeting, demonstrated feasibility but highlighted challenges with component reliability. The Bioartificial Renal Epithelial Cell System underwent phase II trials coordinated by the University of Michigan. Regulatory milestones include the European Medicines Agency granting priority status to certain devices, while the National Institute of Diabetes and Digestive and Kidney Diseases funds pivotal preclinical studies through programs like the SBIR.

Challenges and future directions

Major hurdles include preventing thrombosis and biofouling on device surfaces, ensuring long-term stability of living cells, and achieving a compact, efficient power supply. Research at the Cleveland Clinic and Stanford University explores novel anticoagulant coatings and improved biomaterials. Future directions involve leveraging tissue engineering advances from the Wake Forest Institute for Regenerative Medicine and integrating with precision medicine approaches. The ultimate goal, supported by advocacy from the American Association of Kidney Patients, is to develop a fully implantable device that liberates patients from dialysis machines and the waiting list for a United Network for Organ Sharing donor organ.

Category:Medical equipment Category:Nephrology Category:Artificial organs