Session: Status and Advances in the Development of the Artificial Wearable Kidney (May 9, 2019)
Presenter: William Fissell, MD
An implantable bioartificial kidney can be the solution for organ scarcity, immunosuppressants, and poor quality of life associated with dialysis. The idea of combining technological with biological materials to create an implantable artificial kidney has fermented for over 20 years and it bubbled with excitement at the recent NKF Spring Clinical Meeting in Boston, MA. The auditorium where this topic was discussed was overflowing with people long before the talk started.
Dr William Fissell, MD, Associate Professor at the Vanderbilt University Medical Center, co-leader of this project, delivered an engaging presentation on this topic, sharing with the audience how his career trajectory motivated his thinking process and how his closeness to patient suffering shaped his goals.
Half a million Americans need hemodialysis three times a week in order to survive. The procedure consists of circulating the patient’s blood though a device that uses hydrostatic pressure to get rid of harmful wastes and extra fluids. The concentration of waste, such as urea and phosphorus, needs to be high in order to drive the diffusion in the device – low concentrations of waste products leads to no concentration gradient to move the products out of the blood.
In the 2-3 days prior to dialysis, these concentrations rise four or five times the normal value, leading to patients feeling sick before their treatments. “This leaves us stuck in the middle, between sickness and health,” Dr Fissell remarked. In addition, patients on dialysis need to endure food restrictions, he said: “Every single dialysis patient is walking this ugly tightrope, balancing starvation with intoxication.” He also discussed harmful consequences to patients’ blood pressure and heart functioning due to dialysis.
A decrease in quality of life, including psychosocial aspects, and high costs to the health system are key elements to consider when creating alternative treatments for people with kidney failure. With this in mind, over the course of 20 years, this group created a device which combines silicon nanopore membranes with renal tubule epithelial cells grown in vitro. The idea was to create an artificial kidney that can mimic the native organ. The silicon membrane filtrates the blood with high efficiency (just like glomeruli do) while tubule cells process the blood, returning salt, water, and glucose to the circulation, concentrating toxins into a small volume of fluid similar to urine.
This device does not require electrical pumps, as it is connected to arterial vasculature, leading the patient’s own blood pressure to pump blood through the filter. In addition, it does not require dialysate, because the device maintains approximately neutral fluid balance while excreting concentrated wastes. Interestingly, the silicon membrane can also be used as a scaffold where the tubule cells are grown, creating a barrier between the tubule cells and the patient’s immune system. Thus, no immunosuppressant drugs are necessary when this device is implanted. However, the limitation of the implantable artificial kidney is that it may require repeated invasive procedures.
Dr Fissell and his group successfully implanted this device in animals for up to one month. Their expectation is to have it studied in clinical trials this year and therapeutically implanted in humans within five years. Despite the paucity of funding, which is the major limitation, there is much excitement surrounding the potential behind this technology.
– Post prepared by Andrea Blotta, PhD, AJKD Special Projects Coordinator. Follow her @BlottaAndrea.
To learn more about this topic: Portable and Implantable Artificial Kidneys: AWAK, WAK, and IAK, oh my!