A Pacemaker Made From Your Own Cells 54
FiReaNGeL writes to tell us that researchers at the Children's Hospital in Boston are on the road to crafting a pacemaker from living cells instead of an artificial implant. From the article: "When the engineered tissue was implanted into rats, between the right atrium and right ventricle, the implanted cells integrated with the surrounding heart tissue and electrically coupled to neighboring heart cells. Optical mapping of the heart showed that in nearly a third of the hearts, the engineered tissue had established an electrical conduction pathway, which disappeared when the implants were destroyed. The implants remained functional through the animals' lifespan (about 3 years)."
This is awesome (Score:5, Informative)
FYI... (Score:4, Informative)
For those too lazy to go through the registration: (Score:2, Informative)
In complete heart block electrical signals cannot pass from the heart's upper chambers (atria) to the lower chambers (ventricles) leading to heart failure. In normal hearts electrical impulses move first through the atria then pause at the atrioventricular (AV) node. Then after a short delay that allows the ventricles to fill with blood the AV node releases the impulses which move through the ventricles causing them to contract. In this way the beats of the atria and ventricles are synchronized.
Investigators led by Douglas Cowan PhD a cell biologist in Children's Department of Anesthesiology Perioperative and Pain Medicine wanted to create a biological substitute for the AV node that would work in patients who have defective atrioventricular conduction. "The idea was that rather than using a pacemaker we could create an electrical conduit to connect the atria and ventricles" Cowan says.
Collagen and myoblasts (precursor cells derived from skeletal muscle) were cast into molds made up of pieces of tubing and polyester mesh (seen at each end). Once it gels the...
Cowan's team including first author Yeong-Hoon Choi in Children's Department of Cardiac Surgery obtained skeletal muscle from rats and isolated muscle precursor cells called myoblasts. They "seeded" the myoblasts onto a flexible scaffolding material made of collagen creating a 3-dimensional bit of living tissue that could be surgically implanted in the heart.
The cells distributed themselves evenly in the tissue and oriented themselves in the same direction. Tested in the laboratory the engineered tissue started beating when stimulated electrically and its muscle cells produced proteins called connexins that channel ions from cell to cell connecting the cells electrically.
When the engineered tissue was implanted into rats between the right atrium and right ventricle the implanted cells integrated with the surrounding heart tissue and electrically coupled to neighboring heart cells. Optical mapping of the heart showed that in nearly a third of the hearts the engineered tissue had established an electrical conduction pathway, which disappeared when the implants were destroyed. The implants remained functional through the animals' lifespan (about 3 years).
"The advantage of using myoblasts is that they can be taken from skeletal muscle rather than the heart itself--which will be important for newborns whose hearts are so tiny they cannot spare any tissue for the biopsy--and that they're resistant to ischemia meaning they can go without a good blood supply for a relatively long period of time" Cowan says.
Cowan and his team are now working with a large-animal model that more closely simulates pediatric heart block. Further studies will seek to create tissue-engineered grafts that behave more like a natural AV node, for example by providing a built-in delay before sending electrical signals to the ventricles. The team is investigating whether other cell types such as stem cells derived from muscle or bone marrow might be made to behave more like AV node cells.
Complete heart block is present in about 1 in 22000 births. It can also result from congenital heart disease through an injury or scar tissue from heart surgery, or as a side effect of medications. In adults, pacemakers are a good solution
Re:FYI... (Score:2, Informative)
I should know. I have regular heart palpitations. :(
Re:Lots of advantages (Score:2, Informative)
Not quite a "pacemaker" (Score:3, Informative)
In all these cases, you need an electrical pacemaker-- adding conductions cells is unlikely to do anything.
Re:This is awesome (Score:5, Informative)
I find this statement rather strange. I am fairly familiar with MRI - I have worked in MRI scanners regularly for a few years now and everyone down there is fairly aware of just what it means to have a couple of Tesla's of magnetic field strength means (Most are between 0.5 to about 3 Tesla's in strength). It will take a pen and accelerate it up enough to pull it through the donut and either stick to the wall of the magnet or fling it across the room. And the only metal bit in the pen is maybe the nib and the little spring that makes the pen click up an down.
Specifically, we don't let people with all sorts of metal in them go into the scanner. Pacemakers, aneurysm clips in their brains, and so on.
The risks of this to the if you go into a MRI with these sorts of things include:
1. Heating effects. The field is pulsing in enough energy to push alot of electrons into high spin orbitals and then read the energy as they relax (or so I understand - I'm no physicist). This is bad enough when you are just in the scanner for a while ( you can come out a little hot and sweaty in the more powerful magnets), but any coiling of wires (eg the non ferrous conducting carbon leads that we use to read the ECG/EKG) leads to a real risk of alot of heating. This would occur inside a person just as easily as outside.
2. Electrical effects. If you have a pacing wire inside you and you put it in a strong and changing magnetic field you will generate electrical currents. If this is on a pacing lead then they have a direct outlet onto your heart. This would not be a good thing.
3. Interference - pacing boxes would interfere strongly with any imaging near to them, so if they were near to the heart (which they usually are!) then it would be quite hard to image the heart.
4. Movement - a small pacing box probably wouldn't be enough to cause someone to stick to the walls of the magnet. Or then again, it might. I don't know, I've never tried. But it would certainly pull. this might not be good for the bits that screw into the wall of your heart.
All in all, while it is possible that I am the ignorant one here, I am very sceptical that any MRI unit would let someone with a pacemaker anywhere near the magnet. I know for a fact that nobody in our institution with a pacemaker gets anywhere near the magnet - patient or staff.
Would you care to name the institution that lets people with real pacemakers go into MRI units? I think some people might be quite interested in this..
Michael
Re:This is awesome (Score:2, Informative)