Wearable kidney

A wearable kidney is a portable dialysis machine that a patient with end-stage renal disease could use daily or even continuously. As of May 2008, no wearable kidney is commercially available, but many research teams are in the process of developing such devices.

History & motivation

Chronic Kidney Disease (CKD) affects 26 million people in the United States, and around 400,000 of these patients have end-stage renal disease requiring dialysis or transplantation. The mortality rate for patients with end-stage renal disease is around 22% per year, and at the moment, dialysis is the only therapeutic option for these people. Dialysis therapy is usually given three times a week for four hours at a time, and it involves many risks such as bleeding, clotting, and infection. For patients and society in general, the emotional and financial costs of dialysis therapy are very high. The quality of life for patients on dialysis is often very low, and the yearly cost of treating end-stage renal disease is around $27 billion.

Technology

Today’s dialysis machines are far from perfect. Their efficiency is only around 10% of that of a functioning kidney, and when used three times per week, they are incapable of controlling unhealthy fluctuations in the concentrations of metabolites such as urea in the blood. Many researchers are seeking to design an artificial, wearable kidney that would make dialysis a more effective therapy.

Nanotechnology offers enticing possibilities in this area. Thin nanomembranes would be more permeable to solutes in the blood than thicker conventional membranes, and these nanomembranes could be carefully engineered to contain highly selective pores, instead of the randomly sized pores present in membranes used today. Particular pores, forexample, could be designed to selectively filter middle-sized molecules from the blood. Some middle-sized molecules, such as beta-microglobulin, can cause debilitating health problems when they accumulate in the body, and traditional dialysis machines do a poor job of filtering these molecules from the blood. Eventually, researchers hope to create a library of engineered pores that would allow nephrologists to come up with customized dialysis regimens specifically tailored to their individual patients.

Researchers [Jeffrey Borenstein, Harvard University] are also seeking to combine engineered structures with engineered tissue. Some current designs for a wearable kidney involve microfluidic networks in which each tube is coated with endothelial tissue. These networks are designed to have smooth flow patterns, and the endothelial tissue helps to reduce the chance of a clot forming in the device.

Financial considerations

From a venture capital perspective, investing in the development of a wearable kidney has both advantages and disadvantages. If an artificial kidney were ever brought to market, it could potentially be very lucrative, for per capita spending on patients with end-stage renal disease is enormous, yet investors also see reasons to be wary of backing research to develop this technology. Continuous dialysis devices, like traditional dialysis machines, would involve risks associated with blood access, such as bleeding, clotting, and infection. Additionally, some believe that there is a perception among investors that nephrologists are not aggressive adopters of new technology. Finally, and perhaps most importantly, daily or continuous dialysis therapies are not currently reimbursed by insurers.

References

Conference references

* CIMIT Forum. January 15, 2007.

Video references

* [http://flashplayer.streamos.com/flvplayer.php?url=http://partnerhc.edgeboss.net/flash/partnerhc/cimit/forum2006fall/flash/011508bonventre_256k.flvThe Impact of Chronic Kidney Disease Joseph Bonventre, MD, PhD, Harvard Medical School]
* [http://flashplayer.streamos.com/flvplayer.php?url=http://partnerhc.edgeboss.net/flash/partnerhc/cimit/forum2006fall/flash/011508steinman_256k.flvCreating an Artificial Kidney Theodore I. Steinman, MD, Harvard Medical School]
* [http://flashplayer.streamos.com/flvplayer.php?url=http://partnerhc.edgeboss.net/flash/partnerhc/cimit/forum2006fall/flash/011508erman_256k.flvBringing a Wearable Kidney to Market Greg Erman, MBA, former president and CEO of Renalworks Medical Corporation]
* [http://flashplayer.streamos.com/flvplayer.php?url=http://partnerhc.edgeboss.net/flash/partnerhc/cimit/forum2006fall/flash/011508borenstein_256k.flvEngineering an Artificial Kidney Jeffrey Borenstein, PhD, Drapers Labs]

Additional video references

* [http://flashplayer.streamos.com/flvplayer.php?url=http://partnerhc.edgeboss.net/flash/partnerhc/cimit/forum2006fall/flash/011508panel_256k.flv Panel Discussion on Wearable Kidney CIMIT]

External links

* [http://www.cimit.org CIMIT Center for Intigration of Medicine and Innovative Technology]