A $40 cotton candy machine could save lives.
Hydrogels are what scientists currently use to emulate human tissues. They are gelatinous fibers, much like hair-gel, that can function “as scaffolds to support cells within three-dimensional artificial organs.” Unfortunately, the current processes for making them, called electrospinning, can takes weeks at a time and sometimes they don’t dry or cool properly.
Researcher Leon Bellan, assistant professor of mechanical engineering at Vanderbilt University, came up with the idea of using a cotton candy machine to spin the fibers.
"The analogies everyone uses to describe electrospun fibers are that they look like silly string, or Cheese Whiz, or cotton candy," said Bellan. "So I decided to give the cotton candy machine a try. I went to Target and bought a cotton candy machine for about $40. It turned out that it formed threads that were about one tenth the diameter of a human hair — roughly the same size as capillaries — so they could be used to make channel structures in other materials."
He has been perfecting the technique for a number of years, with the goal of making fiber networks usable as templates to create the capillary systems necessary for full-scale artificial organs. These moist fibers make it possible for oxygen and necessary nutrients to travel to and from the cells.
After all their hard work, Bellan and his team reported on February 4, in an article in the Advanced Healthcare Materials journal, that they have been successful!
"Some people in the field think this approach is a little crazy," said Bellan, "But now we've shown we can use this simple technique to make microfluidic networks that mimic the three-dimensional capillary system in the human body in a cell-friendly fashion. Generally, it's not that difficult to make two-dimensional networks, but adding the third dimension is much harder; with this approach, we can make our system as three-dimensional as we like."
How did they do it? They used a material called PNIPAM, Poly(N-isopropylacrylamide), a polymer that is insoluble above 89.6 degrees Fahrenheit (32 degrees Celsius), but soluble below that temperature. They spun a network of threads made of this material using a device similar to a cotton candy machine. Then, they added human cells and an enzyme to a gelatin solution, the latter causing it to transform from liquid to gel form. By pouring the gel over the PNIPAM structure, incubating it at 98.6 degrees Fahrenheit (37 degrees Celsius), and then allowing it to cool, they ended up with “an intricate network of microscale channels” left behind by dissolved embedded fibers.
The last step was to pump them full of the oxygen and nutrients necessary to keep the cells alive. After seven days, 90 percent of the cells were still alive, compared to 60 or 70 percent using other methods.
"Our goal is to create a basic 'toolbox' that will allow other researchers to use this simple, low-cost approach to create the artificial vasculature needed to sustain artificial livers, kidneys, bone and other organs," Bellan said.
That sounds pretty sweet!
Information provided in a press release from Vanderbilt University