Artificial kidney

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A representative hollow fiber hemodialyzer Hollow fiber hemodialyzer.jpg
A representative hollow fiber hemodialyzer

Artificial kidney is often a synonym for hemodialyzer, but may also refer to the other renal replacement therapies (with exclusion of kidney transplantation) that are in use and/or in development. This article deals mainly with bio-artificial kidneys featuring cells that are grown from renal cell lines/renal tissue.

Contents

The first successful artificial kidney was developed by Willem Kolff in the Netherlands during the early 1940s: Kolff was the first to construct a working dialyzer in 1943. [1]

Some of the commercial artificial kidney manufacturing companies are Hospal, Asahi Kasei, Medtronic, Baxter, Nipro, Fresenius among many others.

Medical uses

Kidney failure

Kidneys are paired vital organs located behind the abdominal cavity at the bottom of the ribcage corresponding to the levels T12-L3 of the spine vertebrae. They perform about a dozen physiologic functions and are fairly easily damaged. Some of these functions include filtration and excretion of metabolic waste products, regulation of necessary electrolytes and fluids and stimulation of red blood cell-production. [2] These organs routinely filter about 100 to 140 liters of blood a day to produce 1 to 2 liters of urine, composed of wastes and excess fluid. [3]

Kidney failure results in the slow accumulation of nitrogenous wastes, salts, water, and disruption of the body's normal pH balance. This failure typically occurs over a long period of time, and when the patient's renal function declines enough over the course of the disease, is commonly known as end stage renal disease (ESRD; which is also known as Level 5 or 6 kidney disease, depending on whether dialysis or renal replacement therapy is used). Detecting kidney disease before the kidneys start to shut down is uncommon, with high blood pressure and decreased appetite being symptoms that indicate a problem. [4] Diabetes and high blood pressure are seen as the 2 most common causes of kidney failure. [5] Experts predict that the demand for dialysis will increase as the prevalence of diabetes increases. [6] Until the Second World War, kidney failure generally meant death for the patient. Several insights into kidney function and acute kidney failure were made during the war. [7]

One in three American adults are at a risk for developing kidney disease. Over 26 million American adults have kidney disease and most are not aware of it. More than 661,000 of them have kidney failure and 468,000 are on dialysis. The large population of individuals with kidney failure drives continuing advancements in the technology of artificial kidneys so that more people can have access to treatments. [8]

Home hemodialysis has become rare because of its disadvantages. It is expensive, time-consuming and space inefficient. In 1980, 9.7% of the dialysis population was on home hemodialysis but by 1987 the proportion had dropped to 3.6%. [9]

According to a 2011 report by the Organization for Economic Cooperation and Development, the United States of America has the second-highest rate of dialysis among advanced countries after Japan. The United States has the highest mortality rate among patients with ESRD. On average 20% of American ESRD patients die annually, which is more than twice that of Japan. The growth of dialysis facilities in the United States is the result of more Americans developing end-stage renal disease. From 2001 to 2011 the number increased by about 49.7% from 411,000 citizens to 615,000 citizens. In 2001 there were only 296,000 Americans on some form of dialysis. Ten years later that number increased to more than 430,000 as a result of chronic conditions developing such as diabetes and hypertension. [6]

Need for a bioartificial kidney

Over 300,000 Americans are dependent on hemodialysis as treatment for kidney failure, but according to data from the 2005 USRDS 452,000 Americans have end-stage kidney disease (ESKD). [10] Intriguing investigations from groups in London, Ontario and Toronto, Ontario have suggested that dialysis treatments lasting two to three times as long as, and delivered more frequently than, conventional thrice weekly treatments may be associated with improved clinical outcomes. [11] Implementing six-times weekly, all-night dialysis would overwhelm existing resources in most countries. This, as well as scarcity of donor organs for kidney transplantation has prompted research in developing alternative therapies, including the development of a wearable or implantable device. [12]

Proposed solutions

Implantable bioartificial kidney

The implantable bioartificial kidney is a project that is being co-developed by a nephrologist named William H. Fissell IV, MD, from the Vanderbilt University Medical Center with Professor Shuvo Roy, a bioengineer from the University of California, San Francisco. The goal of this project is to create a bio-hybrid device that can remove waste products from the blood stream to keep a patient from needing dialysis or kidney transplant, and also imitate the functions of a healthy kidney, improving QoL and longevity.

The key to the success of this device is the use of silicon nano-pore membrane (SEM) fabricated by MEMS technology similar to the semiconductor manufacturing process. These SEM feature pores that are large enough to allow for fluid and electrolyte transfer, but too small for the immune system to interact with living renal cells contained in the device.

Accordingly, the SEM will not only function as hemo-filters, but as a platform for which living kidney cells can reside and thrive within the unit. These cells can thereby perform the metabolic and endocrine functions of a healthy kidney. By virtue of being protected by the SEM, the kidney cells will remain healthy and viable inside the device. An added benefit of the iBAK is that patients using the device will not need to take lifelong immune suppression drugs as needed by kidney transplant recipients. Also, because the kidney cells in the iBAK will perform hormone regulation functions like a natural kidney, the recipients will be healthier and suffer fewer morbidities than dialysis patients. The device will be designed to be small enough to fit inside a patient's body and will be powered by the natural blood flow. In other words the device requires no batteries, electronics or maintenance. The device will also create urine like a natural kidney and will be connected to the bladder; recipients will regain the ability to urinate naturally.

In 2020, a proof-of-concept experiment showed that the prototype iBAK devices remained blood-clot and rejection free. The prototypes contained human renal cells which stayed healthy for the duration of the 7 day trial implantation in healthy juvenile Yucatan pigs (n=5). Further testing with a greater number of kidney cells in the devices on pigs with kidney failure will be needed to show the bioreactor can perform physiologically similar functions to a natural kidney. Profs. Roy and Fissell and research team continue to make progress and they hope for the device to have completed FDA trials by 2030. [13]

Wearable artificial kidney

A wearable artificial kidney is a wearable dialysis machine that a person with end-stage kidney disease could use daily or even continuously. A wearable artificial kidney (WAK) is not available, but research teams are in the process of developing such a device. The goal is to develop a portable device that will be able to imitate the functions of the regular kidney. This device would allow for a patient to be treated twenty-four hours a day. With the development of miniature pumps, the hope of an effective wearable hemodialysis device has become realizable. Some patients already receive continuous peritoneal dialysis treatment which allows them to remain ambulatory. However, only a small portion of dialysis patients use peritoneal dialysis treatment because it requires large amounts of dialysate to be stored and disposed. A healthy individual's kidneys filter blood 24 hours/day, 168 hours/week compared to an individual with end-stage renal disease whose dialysis treatment plan is approximately 12 hours a week. The treatment results in a lower quality of life as well as a higher mortality rate for patients with end stage renal disease (ESRD). Therefore, there is a need for an around-the-clock device that will allow ESRD patients to receive dialysis continuously while maintaining a normal life. [14] [15] [16] The FDA approved the first human clinical trial in the United States for a wearable artificial kidney designed by Blood Purification Technologies Inc. The prototype of the WAK is a 10-pound device, powered by nine-volt batteries, which connects to a patient via a catheter, and should use less than 500mL of dialysate. [14] It is designed to run continuously on batteries, allowing patients to remain ambulatory when wearing the device, leading to a greater quality of life. The device is designed to improve other physiological aspects of the patient's health such as improved volume control, decreased hypertension and sodium retention, as well as a decreased rate of cardiovascular disease and stroke. [14] [15] [16]

Experiments of the wearable artificial kidney

The wearable artificial kidney (WAK) has constantly been modified throughout the years for the better of people who have kidney failure. To try and make the WAK usable, several experiments have been conducted. While conducting these experiments for the WAK, similar goals are trying to be achieved. For example, a main goal that these experiments are trying to achieve is to make sure that the WAK can function like a regular kidney. [14]

One experiment that took place included eight people who wore the WAK for four to eight hours. As the participants wore the WAK, several outcomes occurred. For example, one outcome during the experiment was that the fluid removal for the WAK was controlled correctly by an ultrafiltration pump. Another outcome that took place during this experiment was that a needle connected to the WAK ended up disconnecting itself. When this happened, the WAK was able to recognize this, and the blood stopped pumping. When the blood stopped pumping, the needle could be reinserted without the body losing a large amount of blood. [14] As other research has been conducted, it has been argued that using an ultrafiltration pump may not be the best pump for the WAK. For example, research has found that by using a peristaltic pump instead, would allow a person to know their blood flow rate without having a sensor, which is needed in an ultrafiltration pump used in the experiment mentioned above. A change in the type of pump used for the WAK may be crucial because it could help make the device cheaper and more reliable for the public by not having a sensor. [17]

After a considerable amount of research on the WAK, several research questions have been answered. For example, researchers have found out that the WAK can work without an outlet because it has been able to function on a nine-volt battery. [14] Although, it has been argued by researchers that using nine-volt batteries are not effective enough for the WAK because it does not power the device long enough and indirectly it makes the WAK less affordable when having to constantly change the batteries. [18] Due to this, other energy sources are being explored, for example, researchers are seeing if fuel cells, wireless transmission of energy from an active source, or harvesting energy from the environment would be better ways to power the WAK for longer periods of time. [18] Several questions have been answered about the WAK, but many research questions are still left unanswered. Researchers are still trying to figure out if the WAK can be energy efficient, affordable, and if it can reuse small amounts of dialysate. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Nephrology</span> Medical study concerned with the kidneys

Nephrology is a specialty for both adult internal medicine and pediatric medicine that concerns the study of the kidneys, specifically normal kidney function and kidney disease, the preservation of kidney health, and the treatment of kidney disease, from diet and medication to renal replacement therapy. The word "renal" is an adjective meaning "relating to the kidneys", and its roots are French or late Latin. Whereas according to some opinions, "renal" and "nephro" should be replaced with "kidney" in scientific writings such as "kidney medicine" or "kidney replacement therapy", other experts have advocated preserving the use of renal and nephro as appropriate including in "nephrology" and "renal replacement therapy", respectively.

<span class="mw-page-title-main">Kidney dialysis</span> Removal of nitrogenous waste and toxins from the body in place of or to augment the kidney

Kidney dialysis is the process of removing excess water, solutes, and toxins from the blood in people whose kidneys can no longer perform these functions naturally. This is referred to as renal replacement therapy. The first successful dialysis was performed in 1943.

<span class="mw-page-title-main">Kidney failure</span> Disease where the kidneys fail to adequately filter waste products from the blood

Kidney failure, also known as end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may resolve; and chronic kidney failure, which develops slowly and can often be irreversible. Symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications of acute and chronic failure include uremia, hyperkalemia, and volume overload. Complications of chronic failure also include heart disease, high blood pressure, and anaemia.

<span class="mw-page-title-main">Uremia</span> Excess urea in the blood due to kidney dysfunction

Uremia is the term for high levels of urea in the blood. Urea is one of the primary components of urine. It can be defined as an excess in the blood of amino acid and protein metabolism end products, such as urea and creatinine, which would be normally excreted in the urine. Uremic syndrome can be defined as the terminal clinical manifestation of kidney failure. It is the signs, symptoms and results from laboratory tests which result from inadequate excretory, regulatory, and endocrine function of the kidneys. Both uremia and uremic syndrome have been used interchangeably to denote a very high plasma urea concentration that is the result of renal failure. The former denotation will be used for the rest of the article.

<span class="mw-page-title-main">Hemodialysis</span> Medical procedure for purifying blood

Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of filtering the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatinine and urea and free water from the blood when the kidneys are in a state of kidney failure. Hemodialysis is one of three renal replacement therapies. An alternative method for extracorporeal separation of blood components such as plasma or cells is apheresis.

<span class="mw-page-title-main">Acute kidney injury</span> Sudden decrease in kidney function that develops within 7 days

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a sudden decrease in kidney function that develops within 7 days, as shown by an increase in serum creatinine or a decrease in urine output, or both.

<span class="mw-page-title-main">Chronic kidney disease</span> Abnormal kidney structure or gradual loss of kidney function

Chronic kidney disease (CKD) is a type of long-term kidney disease, in which either there is a gradual loss of kidney function occurs over a period of months to years, or abnormal kidney structure. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications can relate to hormonal dysfunction of the kidneys and include high blood pressure, bone disease, and anemia. Additionally CKD patients have markedly increased cardiovascular complications with increased risks of death and hospitalization.

<span class="mw-page-title-main">Peritoneal dialysis</span> Type of dialysis

Peritoneal dialysis (PD) is a type of dialysis that uses the peritoneum in a person's abdomen as the membrane through which fluid and dissolved substances are exchanged with the blood. It is used to remove excess fluid, correct electrolyte problems, and remove toxins in those with kidney failure. Peritoneal dialysis has better outcomes than hemodialysis during the first couple of years. Other benefits include greater flexibility and better tolerability in those with significant heart disease.

<span class="mw-page-title-main">Diabetic nephropathy</span> Chronic loss of kidney function

Diabetic nephropathy, also known as diabetic kidney disease, is the chronic loss of kidney function occurring in those with diabetes mellitus. Diabetic nephropathy is the leading causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD) globally. The triad of protein leaking into the urine, rising blood pressure with hypertension and then falling renal function is common to many forms of CKD. Protein loss in the urine due to damage of the glomeruli may become massive, and cause a low serum albumin with resulting generalized body swelling (edema) so called nephrotic syndrome. Likewise, the estimated glomerular filtration rate (eGFR) may progressively fall from a normal of over 90 ml/min/1.73m2 to less than 15, at which point the patient is said to have end-stage renal disease. It usually is slowly progressive over years.

<span class="mw-page-title-main">Home hemodialysis</span>

Home hemodialysis (HHD) is the provision of hemodialysis to purify the blood of a person whose kidneys are not working normally, in their own home. One advantage to doing dialysis at home is that it can be done more frequently and slowly, which reduces the "washed out" feeling and other symptoms caused by rapid ultrafiltration, and it can often be done at night, while the person is sleeping.

In medicine, Kt/V is a number used to quantify hemodialysis and peritoneal dialysis treatment adequacy.

<span class="mw-page-title-main">Hemofiltration</span> Medical procedure

Hemofiltration, also haemofiltration, is a renal replacement therapy which is used in the intensive care setting. It is usually used to treat acute kidney injury (AKI), but may be of benefit in multiple organ dysfunction syndrome or sepsis. During hemofiltration, a patient's blood is passed through a set of tubing via a machine to a semipermeable membrane where waste products and water are removed by convection. Replacement fluid is added and the blood is returned to the patient.

Renal replacement therapy (RRT) is therapy that replaces the normal blood-filtering function of the kidneys. It is used when the kidneys are not working well, which is called kidney failure and includes acute kidney injury and chronic kidney disease. Renal replacement therapy includes dialysis, hemofiltration, and hemodiafiltration, which are various ways of filtration of blood with or without machines. Renal replacement therapy also includes kidney transplantation, which is the ultimate form of replacement in that the old kidney is replaced by a donor kidney.

Hemoperfusion or hæmoperfusion is a method of filtering the blood extracorporeally to remove a toxin. As with other extracorporeal methods, such as hemodialysis (HD), hemofiltration (HF), and hemodiafiltration (HDF), the blood travels from the patient into a machine, gets filtered, and then travels back into the patient, typically by venovenous access.

<span class="mw-page-title-main">Northwest Kidney Centers</span>

Northwest Kidney Centers is a regional, not-for-profit community-based provider of kidney dialysis, public health education, and research into the causes and treatments of chronic kidney disease. Established in Seattle in 1962, it was the world's first out-of-hospital dialysis provider. It offers dialysis throughout the greater Seattle area in 20 free-standing clinics, eight hospitals and its home dialysis program. It opened its first clinic in Everett in 2020, the organization's first in Snohomish county.

<span class="mw-page-title-main">Dialysis disequilibrium syndrome</span> Complication of dialysis

Dialysis disequilibrium syndrome (DDS) is the collection of neurological signs and symptoms, attributed to cerebral edema, during or following shortly after intermittent hemodialysis or CRRT.

Nathan W. Levin is an American physician and founder of the Renal Research Institute, LLC., a research institute dedicated to improving the outcomes of patients with kidney disease, particularly those requiring dialysis. Levin is one of the most prominent and renowned figures in clinical nephrology as well as nephrology research. He has authored multiple book chapters and over 350 peer-reviewed publications, including articles in leading journals such as Nature, the New England Journal of Medicine, and The Lancet.

Aluminium toxicity in people on dialysis is a problem for people on haemodialysis. Aluminium is often found in unfiltered water used to prepare dialysate. The dialysis process does not efficiently remove excess aluminium from the body, so it may build up over time. Aluminium is a potentially toxic metal, and aluminium poisoning may lead to mainly three disorders: aluminium-induced bone disease, microcytic anemia and neurological dysfunction (encephalopathy). Such conditions are more prominently observed in people with chronic kidney failure and especially in people on haemodialysis.

A liver support system or diachysis is a type of therapeutic device to assist in performing the functions of the liver. Such systems focus either on removing the accumulating toxins, or providing additional replacement of the metabolic functions of the liver through the inclusion of hepatocytes to the device. This system is in trial to help people with acute liver failure (ALF) or acute-on-chronic liver failure.

<span class="mw-page-title-main">Rockwell Medical</span>

Rockwell Medical Inc. is a publicly traded pharmaceutical company based in Wixom, Michigan and founded in 1996 that focuses on development and commercialization of treatments against diseases such as end-stage renal disease (ESRD) and chronic kidney disease (CKD).

References

  1. ↑ Twardowski, Zbylut J. (2008). "History of hemodialyzers' designs". Hemodialysis International. 12 (2): 173–210. doi:10.1111/j.1542-4758.2008.00253.x. ISSN   1492-7535.
  2. ↑ Kidney Anatomy at eMedicine
  3. ↑ "The Kidneys and How They Work". www.niddk.nih.gov. Retrieved 2015-11-30.
  4. ↑ "Kidney Overview". WebMD. Retrieved 2015-12-02.
  5. ↑ "Key Points: About Dialysis For Kidney Failure". www.kidney.org. National Kidney Foundation. 2016.
  6. 1 2 Johnson, Steven (2014-10-11). "Dialysis Demand Strong as Kidney Disease Grows". www.modernhealthcare.com. Modern Healthcare.
  7. ↑ Bywaters EGL, Beall D (1941). "Crush injuries with impairment of renal function". British Medical Journal. 1 (4185): 427–32. doi:10.1136/bmj.1.4185.427. PMC   2161734 . PMID   20783577.
  8. ↑ "Fast Facts". The National Kidney Foundation. National Kidney Foundation. 2014-08-12. Retrieved 2016-11-13– via kidney.org.
  9. ↑ Twardowski, Zbylut J. (Aug 9, 1994). "Artificial kidney for frequent (daily) Hemodialysis". United States Patent.
  10. ↑ Fissell WH, Humes HD, Fleischman AJ, Roy S (2007). "Dialysis and Nanotechnology: Now, 10 years, or Never?". Blood Purification. 25 (1): 12–17. doi:10.1159/000096391. PMID   17170531. S2CID   42050968.
  11. ↑ Lindsay RM, Le itch R, Heidenham AP, Kortas C (2003). "The London daily/nocturnal Hemodialysis study: Study design, morbidity, and mortality results". Am J Kidney Dis. 42 Supp 1 (1 Suppl): S5–S12. doi:10.1016/S0272-6386(03)00531-6. PMID   12830437.
  12. ↑ Fissell W, Manley S, Westover A, Humes HD, Fleischman AJ, Roy S (2006). "Differentiated Growth of Human Renal Tubule Cells on Thin-Film and Nanostructured Materials". ASAIO Journal. 52 (3): 221–227. doi: 10.1097/01.mat.0000205228.30516.9c . PMID   16760708. S2CID   9494223.
  13. ↑ Kim, Eun Jung; Chen, Caressa; Gologorsky, Rebecca; Santandreu, Ana; Torres, Alonso; Wright, Nathan; Goodin, Mark S.; Moyer, Jarrett; Chui, Benjamin W.; Blaha, Charles; Brakeman, Paul; Vartanian, Shant; Tang, Qizhi; David Humes, H.; Fissell, William H.; Roy, Shuvo (29 August 2023). "Feasibility of an implantable bioreactor for renal cell therapy using silicon nanopore membranes". Nature Communications. 14 (1): 4890. Bibcode:2023NatCo..14.4890K. doi:10.1038/s41467-023-39888-2. PMC   10465514 . PMID   37644033.
  14. 1 2 3 4 5 6 7 Ronco, Claudio; Davenport, Andrew; Gura, Victor (2008-07-01). "Toward the wearable artificial kidney". Hemodialysis International. 12: S40–S47. doi:10.1111/j.1542-4758.2008.00295.x. ISSN   1542-4758. PMID   18638240. S2CID   5721553.
  15. 1 2 Gura, Victor; Rivara, Matthew B.; Bieber, Scott; Munshi, Raj; Smith, Nancy Colobong; Linke, Lori; Kundzins, John; Beizai, Masoud; Ezon, Carlos (2016). "A wearable artificial kidney for patients with end-stage renal disease". JCI Insight. 1 (8). doi:10.1172/jci.insight.86397. ISSN   2379-3708. PMC   4936831 . PMID   27398407.
  16. 1 2 Gura, Victor; Macy, Alexandra S.; Beizai, Masoud; Ezon, Carlos; Golper, Thomas A. (2016-12-07). "Technical Breakthroughs in the Wearable Artificial Kidney (WAK)". Clinical Journal of the American Society of Nephrology. 4 (9): 1441–1448. doi:10.2215/CJN.02790409. ISSN   1555-9041. PMC   2736696 . PMID   19696219.
  17. ↑ Markovic, M.; Rapin, M.; Correvon, M.; Perriard, Y. (2013-09-01). "Design and Optimization of A Blood Pump for A Wearable Artificial Kidney Device". IEEE Transactions on Industry Applications. 49 (5): 2053–2060. doi:10.1109/TIA.2013.2260851. ISSN   0093-9994. S2CID   16399324.
  18. 1 2 Kim, Jeong Chul; Garzotto, Francesco; Nalesso, Federico; Cruz, Dinna; Kim, Ji Hyun; Kang, Eungtaek; Kim, Hee Chan; Ronco, Claudio (2011). "A wearable artificial kidney: technical requirements and potential solutions". Expert Review of Medical Devices. 8 (5): 567–579. doi:10.1586/erd.11.33. PMID   22026622. S2CID   38028816.
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