Exercise in tissue engineering, Halloween decoration, or mad scientist show piece? Take your pick...
Some people like to make their Halloween decorations from papier mache. We used raw, bleeding pig's hearts!
Last year, we tried to decellularize some chicken hearts and gizzards
for Halloween. This year, we tackled a full-size pig heart, with members of Counter Culture Labs
, our new DIYbio
group in the SF East Bay, with some help from friends at BioCurious.
Decellularization is a tissue engineering technique designed to strip out all the cells from a donor organ, leaving nothing but the connective tissue that used to hold the cells in place. This scaffold of connective tissue - called a "ghost organ" for its pale and almost translucent appearance - can then be reseeded with a patient's own cells, with the goal of regenerating an organ that can be transplanted into the patient
without fear of tissue rejection. A decellularized mouse heart regenerated with human heart precursor cells will actually start beating autonomously
! Here's some amazing videos on this work by Doris Taylor at U. Minnesota:Creating a beating heart in the labSurprising Beauty, Holding A Pig's Heart
Getting all the cells to coordinate correctly in a large heart is still a big challenge. That part is still years away from clinical use. We're just doing the first part though: decellularization of a pig heart. Why? Well, what self-respecting mad scientist wouldn't want to have a Ghost Heart in a Jar!
If any of this seems way too challenging to you - note that none of us had ever done anything like this before
! We just read up on what it took to do this, figured out where to get a pig heart, got a few pieces of equipment, ordered some chemicals, and got to it! The results look absolutely spectacular, and we learned tons along the way. Yes, this project is a bit complex, and there's lots of long words in the steps below - but don't let that scare you away! The whole thing can be accomplished in a single day, and we'll tell you about DIY alternatives for all the equipment and chemicals used here.
The decellularization is achieved using enzymes and detergents to break open the cells and flush out the cellular content. The solutions need to be perfused throughout the heart muscle using a pump. Not just through the chambers of the heart, mind you, but actually through the coronary arteries that provide blood supply to the muscle of the heart itself. The published protocol takes approximately 10 hours, but since we are planning this as a show piece and not to reseed them with cells, we have taken some shortcuts.
Please use appropriate safety equipment and measures. One of the nice aspects of this experiment is that all the chemicals you're working with are fairly non-toxic. But you're also working with lots of fluids under pressure, and you really, really don't want assorted pig heart juices squirting into your eyes - trust me on that! So make sure to wear some goggles at least. A lab coat to protect your clothes from giant blood stains wouldn't hurt either (unless you're into that kinda thing).
If you use something like an aquarium pump please note the problems the solutions used could cause the pump, as well as contamination issues. A fountain pump from the hardware store might be another interesting alternative for high volume and relative high pressure. But most fountain pumps are immersion pumps, and are *not* designed to handle salty, conductive water - try at your own risk!
Check out the timelapse video we made we made of the whole procedure: