Wak Engineering Evolution

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Abstract

The wearable artificial kidney (WAK) is a device that allows prolonged and frequent dialysis treatments for patients with end stage renal disease. It potentially provides a practical and feasible solution to satisfy the need for an optimal delivered dialysis. Until now, the WAK has already been presented in several models, proposing different therapeutic modalities and engineering approaches. The ideal solution of a WAK may come from a combination of all the prototypes developed and/or those currently in development. Consequently, it is important to have a complete overview and a deep knowledge of the possible engineering solutions in order to achieve the incremental steps necessary to solve the remaining issues of wearable extracorporeal blood purification devices. Since technical advances are continuously evolving and it is important to focus on clinical requirements and needs, a multidisciplinary collaboration has to be coordinated to achieve the final objective of the practical realization of a wearable artificial kidney. In such a context, the main aim of this article was to analyze more in detail the WAK Engineeristic Development.

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Initial clinical results of the bioartificial kidney containing human cells in ICU patients with acute renal failure.

Fresca C Swaniker, E Paganini, J Sobota … (2004)

Acute renal failure (ARF) in intensive care unit patients continues to have mortality rates exceeding 70%, despite hemodialysis or continuous renal replacement therapy (CRRT). The delivery of cellular metabolic function to CRRT may provide more complete renal replacement therapy, thereby changing the natural history of this disease process. An FDA-approved Phase I/II clinical trial on 10 patients has been completed, and demonstrated that this experimental treatment can be delivered safely for up to 24 hours. The bioartificial kidney is a synthetic hemofilter connected in series with a bioreactor cartridge containing approximately 10(9) human proximal tubule cells, as a renal tubule assist device (RAD), within an extracorporeal perfusion circuit utilizing standard hemofiltration pump systems. All 10 patients had ARF and multiorgan failure (MOF), with predicted hospital mortality rates averaging above 85%. Data indicate that the RAD maintains viability, durability, and functionality in this ex vivo clinical setting. The device also demonstrated differentiated metabolic and endocrinologic activity, with glutathione degradation and endocrinologic conversion of 25-OH-D(3) to 1,25-(OH)(2)-D(3). All but one treated patient with more than a 3-day follow-up in the intensive care unit showed improvement as assessed by acute physiologic scores 1 to 7 days following therapy. Six of the 10 treated patients survived past 30 days. One patient expired within 12 hours after RAD treatment due to his family's request to withdraw ventilatory life support. Three other patients died due to complications from acute or chronic comorbidities unrelated to ARF or RAD therapy. Plasma cytokine levels suggest that RAD therapy produced dynamic and individualized responses in patients. For the subset of patients who had excessive proinflammatory levels, RAD treatment resulted in significant declines in granulocyte colony stimulating factor (G-CSF), interleukin (IL)-6, IL-10, and IL-6/IL-10 ratios. The addition of human renal tubule cell therapy to CRRT has been accomplished and demonstrates metabolic activity with systemic effects in patients with ARF and MOF. These initial clinical results are encouraging, so that a randomized, controlled Phase II clinical trial is underway to further assess the clinical safety and efficacy of this new therapeutic approach.

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Tissue engineering of a bioartificial renal tubule assist device: in vitro transport and metabolic characteristics.

Donna Mackay, D Buffington, H Humes … (1999)

Current renal substitution therapy for acute or chronic renal failure with hemodialysis or hemofiltration is life sustaining, but continues to have unacceptably high morbidity and mortality rates. This therapy is not complete renal replacement therapy because it does not provide active transport nor metabolic and endocrinologic functions of the kidney, which are located predominantly in the tubular elements of the kidney. To optimize renal substitution therapy, a bioartificial renal tubule assist device (RAD) was developed and tested in vitro for a variety of differentiated tubular functions. High-flux hollow-fiber hemofiltration cartridges with membrane surface areas of 97 cm2 or 0. 4 m2 were used as tubular scaffolds. Porcine renal proximal tubule cells were seeded into the intraluminal spaces of the hollow fibers, which were pretreated with a synthetic extracellular matrix protein. Attached cells were expanded in the cartridge as a bioreactor system to produce confluent monolayers containing up to 1.5 x 109 cells (3. 5 x 105 cells/cm2). Near confluency was achieved along the entire membrane surface, with recovery rates for perfused inulin exceeding 97 and 95% in the smaller and larger units, respectively, compared with less than 60% recovery in noncell units. A single-pass perfusion system was used to assess transport characteristics of the RADs. Vectorial fluid transport from intraluminal space to antiluminal space was demonstrated and was significantly increased with the addition of albumin to the antiluminal side and inhibited by the addition of ouabain, a specific inhibitor of Na+,K+-ATPase. Other transport activities were also observed in these devices and included active bicarbonate transport, which was decreased with acetazolamide, a carbonic anhydrase inhibitor, active glucose transport, which was suppressed with phlorizin, a specific inhibitor of the sodium-dependent glucose transporters, and para-aminohippurate (PAH) secretion, which was diminished with the anion transport inhibitor probenecid. A variety of differentiated metabolic functions was also demonstrated in the RAD. Intraluminal glutathione breakdown and its constituent amino acid uptake were suppressed with the irreversible inhibitor of gamma-glutamyl transpeptidase acivicin; ammonia production was present and incremented with declines in perfusion pH. Finally, endocrinological activity with conversion of 25-hydroxy(OH)-vitamin D3 to 1,25-(OH)2 vitD3 was demonstrated in the RAD. This conversion activity was up-regulated with parathyroid hormone and down-regulated with increasing inorganic phosphate levels, which are well-defined physiological regulators of this process in vivo. These results clearly demonstrate the successful tissue engineering of a bioartificial RAD that possesses critical differentiated transport, and improves metabolic and endocrinological functions of the kidney. This device, when placed in series with conventional hemofiltration therapy, may provide incremental renal replacement support and potentially may decrease the high morbidity and mortality rates observed in patients with renal failure.

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The Vicenza Wearable Artificial Kidney for Peritoneal Dialysis (ViWAK PD)

Claudio Ronco, Luciano Fecondini (2007)

Background: The study describes the structure and operational characteristics of a new wearable system for continuous ambulatory peritoneal dialysis (CAPD) for chronic kidney disease patients. Methods: We designed a wearable system consisting of: (1) a double lumen peritoneal catheter; (2) a dialysate outflow line; (3) a miniaturized rotary pump; (4) a circuit for dialysate regeneration featuring a waterproof container with 4 cartridges in parallel with a mixture of activated carbon and polystyrenic resins; (5) a filter for deaeration and microbiological safety; (6) a dialysate inflow line, and (7) a handheld computer as a remote control. The system has been tested circulating 12 liters of exhausted PD solution through the experimental adsorption unit at a rate of 20 ml/min. Creatinine, β 2 -microglobulin (β 2 -MG) and angiogenin were measured before and after the adsorption unit at baseline, and after 4 and 10 h of use. Results: The cartridges containing polystyrenic resin completely removed β 2 -MG and angiogenin from the fluid batch. Those with the activated carbon removed completely urea and creatinine. The final result was 11.2 liters of net solute clearance. The system is designed to be used as follows: The peritoneal cavity is loaded in the morning with 2 liters of fresh PD solution. After 2 h, when dialysate/plasma equilibration at approximately 50% has occurred, recirculation is activated for 10 h at a rate of 20 ml/min. After this period, recirculation stops and glucose is optionally added to the peritoneal cavity to achieve ultrafiltration if needed. After 2 h the fluid is drained and a 2-liter icodextrin exchange is performed overnight to achieve further ultrafiltration. The clearance provided by the minicycler is further increased by the 2-liter exchange and the overnight exchange. Therefore, the system operates 24 h/day and provides creatinine and β 2 -MG clearance in the range of 15–16 liters/day, corresponding to a weekly clearance of 100–110 liters. The patient reduces the number of exchanges compared to CAPD and uses less fluid than in automated peritoneal dialysis (APD). Furthermore, the handheld computer allows for prescription and assessment of the therapy providing information on cartridge saturation, flow and pressure conditions and offering the possibility of remote wireless control of operations. Some problems still remain to be solved in the present configuration including the addition of an injection system for glucose and bicarbonate when needed, a system to reduce fibrin delivery to the sorbent and finally a more complex mixture of sorbents to make sure a complete removal of small molecules including urea is achieved. Conclusion: The wearable PD system may become a possible alternative to APD or CAPD reducing the time dedicated to perform exchanges and improving peritoneal dialysis adequacy and patient’s rehabilitation.

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Author and article information

Journal

Journal ID (publisher-id): BPU

Journal ID (nlm-ta): Blood Purif

Journal ID (doi): 10.1159/issn.0253-5068

Title: Blood Purification

Publisher: S. Karger AG

ISSN (Print): 0253-5068

ISSN (Electronic): 1421-9735

Publication date Subscription-year: 2015

Publication date (Print): May 2015

Publication date (Electronic): 20 January 2015

Volume: 39

Issue: 1-3

Pages: 110-114

Affiliations

International Renal Research Institute of Vicenza (IRRIV), Department of Nephrology, San Bortolo Hospital, Vicenza, Italy

Author notes

*Prof. Claudio Ronco, Department of Nephrology, Dialysis and Transplantation, San Bortolo Hospital, The International Renal Research Institute, Viale Rodolfi 37, IT-36100 Vicenza (Italy), E-Mail cronco@goldnet.it

Article

Publisher ID: 368955 Other ID: Blood Purif 2015;39:110-114

DOI: 10.1159/000368955

PubMed ID: 25659421

SO-VID: 97f2e0fc-c3be-4d41-8d23-84ef2dd41939

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Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

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Wak Engineering Evolution

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Abstract

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Karger: Nephrology

Most cited references 13

Initial clinical results of the bioartificial kidney containing human cells in ICU patients with acute renal failure.

Tissue engineering of a bioartificial renal tubule assist device: in vitro transport and metabolic characteristics.

The Vicenza Wearable Artificial Kidney for Peritoneal Dialysis (ViWAK PD)

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