It has to be one of the more unusual calls a plastics fabricating company could get: MIT is on the phone, and wants help building a tiny, fake liver from polycarbonate.
Larry Dawson, vice president of marketing at Eastern Plastics Inc., said the plastics machining company in Bristol, Conn., jumped at the chance.
``Our first reaction was, `Yeah, this sounds pretty cool,' '' he said.
Eastern had worked with MIT researchers before, and liked tackling tricky assignments. This one certainly promised challenges: the Massachusetts Institute of Technology scientists wanted to make a miniature bioreactor no bigger than a fingertip where they could, for the first time, grow and sustain human liver cells.
The end result would be a way to test how liver cells react to drugs, making it possible to avoid animal testing. Such a breakthrough would allow doctors to learn enough about liver functions to fight infections better and avoid some organ transplants.
The task required some new technology in plastics, Dawson said - a way to join thin strips of PC together in a process called diffusion bonding. While such technology was common in metals and some other plastics, it was untested in polycarbonate.
After two years of work, MIT has been able to build its artificial liver. Well, actually, it's a miniature device for growing the cells.
The device, which measures just under an inch long, is filled with a nutrient-rich fluid that feeds the liver cells. Eastern's job was to machine the device to MIT specs, with tolerances as small as 0.0004 inch.
``There are very strict demands on the reactors,'' said Karel Domansky, an MIT research scientist who oversaw the device design for the team of researchers. ``It's quite a difficult process because the tolerances are very, very tight.''
The device had to be diffusion-bonded to make it extremely flat so cells could be studied with a microscope, Domansky said.
The curved channels in the reactor were important, Dawson said. The device, sometimes called a ``liver chip,'' requires a constant flow of fluid to simulate conditions in the human liver.
That's harder than it sounds, Domansky said. Simply growing liver cells in a petri dish, for example, would not create the right conditions to infect the cells and then see how they react to different drugs, he said.
At first, only about 30 percent of the devices Eastern made worked, Domansky said. Now, the process has been improved and Dawson estimates that about 70 percent of them work. To date, he said, the company has shipped about 55 devices to MIT.
Domansky said the school hopes to find a way to mass-produce the units, either through injection molding or photopolymerization, to make them available to other universities and researchers. The same technique could be used to make a bioreactor heart or lung cells, he said.
Eastern, which machines plastics for the medical, clinical and semiconductor industries, said it hopes to be part of future work on the project. Dawson said the company is happy that it was able to find a project to develop its technology for bonding polycarbonate.
``We were waiting for that one application where we could say it's worth the investment and we want to be able to tell the world about it,'' Dawson said.