First Successful Transplant of Pulseless Artificial Heart

A pulseless artificial heart was successfully implanted into a Houston man, 55, last month. The man suffered from a rare buildup of amyloid proteins which impaired the function of his heart so severely that he was given roughly one more day to live at the time of transplant.

The device was engineering by heart specialists, surgeons, and inventors Dr. Bud Frazier and Dr. Billy Cohn of Texas Heart Institute. It consists of two continuous flow pumps (named Heartmate II) strapped together and powered by an external battery pack. "Continuous flow" means that
the patient's blood flow is nonpulsatile; the beating of the heart is no longer mimicked and the patient has no pulse. Interestingly, the device required nonconventional methods be used to monitor the patient's blood pressure. Because of the nonpulsatile flow, his blood pressure is a constant value and cannot be determined using a cuff, but must be measured using Doppler ultrasound.

Frazier and Cohn began building a prototype of the device more than 5 years ago, using supplies purchased at local stores like Home Depot. They promote continuous flow pumps because of their simplicity and reduced size and noise. Fewer moving parts are used in continuous flow pumps, which makes them potentially much longer-lasting as there is less friction between parts and thus less wear-and-tear between them. Additionally, continuous flow pumps automatically adjust output based on demand.

I looked up this article after hearing about this in a meeting with Texas Heart Institute, and found it fascinating as well as applicable to our semester project: a pediatric artificial heart. I thought it was interesting that it could finally be used as the man's condition had deteriorated so severely; it seems that finding patients on which to test new devices (particularly unorthodox ones) is a constant dilemma. The device is obviously in its younger stages and needs continued testing and development, but it would be interesting to see how this man fares.

http://www.texasmedicalcenter.org/root/en/TMCServices/News/2011/04-01/Houston+Man+First+in+World+to+be+Successfully+Implanted+with+Pulseless+Artificial+Heart.htm
April 21, 2011

Miracle Grow

Above: Synthetic scaffold of an ear (photo credit: Rebecca Hale, NGM Staff)

Bioartificial organs, or organs grown from a patient's own cells, are seeing advances in an effort to overcome the problems of transplant rejection and the shortage of organs. Recently, Anthony Atala worked with a team of researchers at the Wake Forest Institute for Regenerative Medicine have developed a technique for a lab-grown bladder. A balloon-shaped scaffold is created from collagen and seeded with healthy bladder cells from a patient's diseased bladder, then incubated at body temperature for six to eight weeks. At least two different types of cells are used: urothelial and muscle. They are seeded in the appropriate locations, urothelial on the inside and muscle on the outside. At least 30 people to date have received lab-grown bladders.

This technique, however, has limitations: the bladder's vasculature is far less extensive than that of solid organs such as kidneys or livers. Angiogenesis is a complex process, and the direction of growth is less predictable than layers of cells surrounding hollow organs. Despite this hurdle, Atala's team produced a piece of liver using a technique analogous to a jet printer, which "prints" a layer of cells on the scaffold one at a time.

Additionally, using a patient's cells may not be an option if the organ is too diseased, as may be the case with advanced cancers. The usage of embryonic stem cells has long been a controversy, primarily because the embryo is damaged or destroyed in the process - but Atala's team has proven a way that leaves the embryo unharmed by using amniotic fluid in the womb. They subsequently have grown a variety of cell types, although not necessarily complete organs. In a bank of stem cell types, it could be possible to have a "library" from which to order organs from in the future.

Other bioartificial organs of notable mention in this article include a jawbone at Columbia University, a lung at Yale, and a non-implantable kidney at the University of Michigan.

After the SNBAL on a regenerated lung, I was curious about the progress of other bioartificial organs. Apparently, the idea of using a decellurized bioscaffold is not exactly new, with Taylor's heart being grown on its scaffold in 2008. Additionally, I found the author's view on embryonic stem cell usage to be thought-provoking: if we aren't harming the embryo while extracting the cells, will the number of ethical objections be just as high? I could see a potential "God-complex" argument. Finally, growing organs has been of interest to me since I discovered the field of biomedical engineering, and it's interesting to know that so many successful techniques are based off of using bioscaffolds. Perhaps I should consider a different track if the idea of working with stem cells is unappealing.

National Geographic, March 2011
"Miracle Grow", Josie Glausiusz
http://ngm.nationalgeographic.com/2011/03/big-idea/organ-regeneration-text