A humble cotton candy machine is about to revolutionize the field of tissue engineering and build artificial organs, paving the way forward for organ transplantation, research suggests.
Leon Bellan, assistant professor of mechanical engineering at Vanderbilt University in Tennesse, has developed a process using cotton candy machines, to spin out networks of tiny threads comparable to capillaries. His goal is to eventually build fiber networks that can be used as templates to create full-scale artificial organs. His work, along with that of his colleagues, was published in an article by the Advanced Healthcare Materials journal.
"Some people in the field think this approach is a little crazy. 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."
Many tissue engineering researchers, including Bellan, are currently focusing their efforts on hydrogels and using them as scaffolds to support cells within three-dimensional artificial organs.
There are two basic methods that researchers use to create artificial capillary systems, bottom-up and top-down. In the bottom-up process, scientists culture cells in a thin slab of gel. After some time, the cells spontaneously begin creating capillaries. But this is a time consuming process running into weeks. Hence, Bellan is using the top-down apporoach, using his cotton-candy spinning method, which can produce channels ranging from three to 55 microns, with a mean diameter of 35 microns.
"So far the other top-down approaches have only managed to create networks with microchannels larger than 100 microns, about ten times the size of capillaries," he said.
"The analogies everyone uses to describe electrospun fibers are that they look like silly string, or Cheese Whiz, or cotton candy. 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."
The path from that point to creating artificial capillaries that work was not easy, as Bellan described.
"First, the material has to be insoluble in water when you make the mold so it doesn't dissolve when you pour the gel. Then it must dissolve in water to create the microchannels because cells will only grow in aqueous environments."
The researchers experimented with a number of different materials before they discovered one that worked PNIPAM, Poly (N-isopropylacrylamide).
"Our experiments show that, after seven days, 90 percent of the cells in a scaffold with perfused microchannels remained alive and functional compared to only 60 to 70 percent in scaffolds that were not perfused or did not have micro channels," Bellan explained.
Now Bellan and his team aim to fine-tune the method to match the characteristics of the small vessel networks in different types of tissues, and explore a variety of cell types. Popular Science reported that in future studies the researchers hope to test their cotton candy technique with other types of cells to create tissues similar to those found in several different organs in the body.
"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.
Co-authors on the paper are postdoctoral researchers Jung Bok Lee, Xintong Wang, and Shannon Faley, doctoral students Bradly Baer and Daniel Balikov, and Associate Professor of Biomedical Engineering Hak-Joon Sung.
The history of the cotton candy machine goes back more than a hundred years. It was invented by a Nashville dentist in 1897 and made its debut at the 1904 World's Fair in St. Louis. Cotton candy has since been a hot favorite of kids and grown ups alike. Who would have thought that it would revolutionize the way we would be looking at organ transplants in the future.