| This document reports the results for the in vitro validation of the WAKD
(wearable artificial kidney device) laboratory prototype which is under
development within the Nephron+ project. The device is intended to be used for
continuous home treatment and will offer the patients more mobility and
flexibility. The detoxification of the patients’ blood is conducted by an electrooxidation
unit which degrades urea and other nitrogen-containing toxins as well
as an adsorbent unit which adsorbs unwanted oxidation products as well as other
uremic toxins. In order to remove excessive fluid, an ultrafiltration unit with a
waste bag is introduced into the device.
The WAKD was characterized regarding its efficiency of the removal for uremic
toxins as well as for biocompatibility and cell toxicity. The efficiency and
biocompatibility experiments were carried out with freshly drawn human blood
which was spiked with target substances such as urea, creatinin and phosphate.
Biocompatibility tests were carried out by contacting human cells in with fluid
which was previously treated with the WAKD and, therefore, came in contact both
with the adsorbent unit as well as with the electrooxidation unit.
The in vitro experiments show that uremic toxins can be reduced significantly by
the WAKD. However, even when taking into account that the WAKD is intended to
be used continuously or at least for several hours every day, the detoxification
efficiency is currently not comparable to conventional chronic dialysis treatment
(3 times per week for 4 hours, total Kt/V ≥ 3.6) and most probably not sufficient
to keep the toxins at an acceptable level. Further improvements have to be
introduced for the final system.
For the biocompatibility tests, basic parameters such as protein adsorption,
removal of clotting parameters and hemolysis rates were assessed. Furthermore,
advanced methods such as testing for oxidative stress, MTT test, Live-Dead assay
and FACS analysis were conducted in order to check the impact of the electrooxidation
on cells. The overall biocompatibility was good. No negative impact
from electro-oxidation on the tested cells could be found with the applied
methods. However, hemolysis is still high compared to conventional roller pumps,
especially when taking into account that the system is intended to be used |