Cotton Candy Machine and the artificial organs

It may seem absurd, almost grotesque. To make artificial human organs using a cotton candy machine? As such would not be possible, of course, but the principle of functioning of such machines could be adapted for the construction of others capable of making artificial human organs, starting with the simplest ones, such as kidneys, liver and bones.

For several years, Leon Bellan of Vanderbilt University in Nashville, Tennessee, USA, has been tinkering with cotton candy machine, causing them to produce networks of tiny strands comparable in size, density, and complexity to the patterns formed by Capillaries, small thin-walled vessels that supply oxygen and nutrients to the cells and carry away the waste. Its objective has been to fabricate fiber nets that can be used as templates from which to make the capillary systems necessary to create life-size artificial organs.

Bellan and his colleagues have succeeded in using this unorthodox technique to produce a three-dimensional artificial capillary system that can maintain viable and functional cells alive for more than a week, which is a considerable improvement over the methods used today . And one is the cotton candy machine.

Many tissue engineering specialists, including Bellan, are currently focusing their efforts on investigating a class of materials described as hydrogels, and on using these materials as scaffolds to hold cells inside three-dimensional artificial organs.

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Hydrogels are attractive because their properties can be adjusted to closely resemble those of the natural extracellular matrix that surrounds the cells in the body. Unlike solid polymer scaffolds, the hydrogels allow the diffusion of the necessary soluble compounds; However, oxygen, nutrients and residues can only be displaced over a limited distance through the gel. As a result, the cells must be very close (less than the thickness of a human hair) to a source of nutrients and oxygen and to a sink for the waste they produce, otherwise they starve or drown.

Thus, to generate tissues that have the thickness that is normal in real organs, and to keep cells alive throughout the scaffold, researchers must construct a network of channels that allow fluids to flow through the system, simulating the Natural capillary system. And this is very difficult to achieve. Among other things, traditional methods may require weeks for cells to create such a network. So it is not possible to stack many cells or those in the center begin to die before the essential capillary network is formed.

The new technique based on cotton candy machine offers a potential solution to all these problems. The method of spinning cotton candy can produce channels ranging from 3 to 55 microns, with an average diameter of 35 microns.

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The researchers first woven a network of PNIPAM threads using a machine that closely resembled one that made the candy. A solution of gelatin in water (a liquid at 37 degrees) was then mixed and human cells added. The addition of an enzyme commonly used in the food industry (transglutaminase, dubbed “meat glue”) causes the gelatin to acquire a permanent form of gel.

The hot mixture is poured onto the PNIPAM structure and kept in an incubator at 37 degrees. Finally, the gel containing cells and fibers is removed from the incubator and allowed to cool to room temperature, at which time the scaffold-like fibers dissolve, leaving in place an intricate network of micrometer-scale channels . Maybe this is the future cotton candy machine.