Joshua Moskow

Introduction. The kidneys are a main source of homeostatic control in the body. Chronic kidney disease (CKD) has a number of criteria but all represent a decline in kidney function. The most common causes are diabetes and hypertension^1,2. In addition to a failing glomerular filtration barrier, the kidneys also lose several homeostatic functions^3-5. The best treatment for progressive CKD is a kidney transplant; however, there is a severe lack of donor tissue⁶. The current work focuses on the state of artificial kidneys as renal replacement therapy (RRT) and highlights shortcomings, specifically related to inadequate regulatory function of the replacement. Methods. First, dysfunctions in renal regulation as a result of CKD were identified. Next, the current state of RRT research was analyzed. Information for analysis was gained from first-hand research based on clinical trials, animal studies, and some bench-top work found on PubMed. Additionally, several review articles were included for background and insights used for interpretation. Results. Several dysregulations in CKD were identified. An in human study showed inadequate renin angiotensin aldosterone system (RAAS) deactivation in acute salt and water loading⁵. Patients with CKD were also found to have high serum phosphate levels leading to vascular calcifications and adverse cardiovascular events⁷. Finally, CKD often results in a secondary hyperparathyroidism contributing to adverse cardiovascular events as well^8,9. A number of studies to advance RRT were found. Absorbents called MXenes were shown to absorb up to 94% of urea from solutions on the bench-top thus reducing the need for high fluid volumes and associated weight currently present in dialysis¹⁰. Analysis on flow patterns revealed a lower likelihood of thrombosis potential for a parallel versus a serpentine layout in a live porcine model¹¹. Last, three artificial kidney systems were of note. These were the automated artificial wearable kidney, the wearable artificial kidney, and the implantable artificial kidney¹². All of these technologies were innovative in creating a device that achieved peritoneal or hemodialysis in a wearable form factor. Conclusion. CKD is known to cause dysfunction in the regulation of salt, water, phosphate, and parathyroid hormone. Current studies in RRT are focused on improvements in filtrations, especially in reducing the required volumes for dialysis. Extremely lacking was any work focused on making an artificial kidney that was able to compensate for the lost regulation of salt, water, phosphate, or parathyroid hormone. This presents a significant area for opportunity in developing a fully functional artificial kidney.

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