Biomedical Engineering Blog

Biomedical Engineering

The Biomedical Engineering blog is the place for conversation and discussion about topics related to engineering principles of the medical field. Here, you'll find everything from discussions about emerging medical technologies to advances in medical research. The blog's owner, Chelsey H, is a graduate of Rensselaer Polytechnic Institute (RPI) with a degree in Biomedical Engineering.

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Spinning Organs

Posted March 10, 2016 12:00 AM by Chelsey H

You may never look at a cotton candy machine the same again…

At least that's how assistant professor Leon Bellan felt after attending a lecture on tissue engineering. He was doing research on electrospinning and he heard others say that electrospun fibers look like Silly String or cotton candy. Bellan realized during the lecture that electrospoinning can make networks somewhat resembling capillaries but at a much smaller scale, and decided to try it using a cotton candy machine.

The cotton candy machine formed threads that were approximately one tenth the diameter of a human hair - roughly the same size as capillaries. And that's where it all started.

The goal of Bellan's research has been to make fiber networks that can be used as template to produce the capillary systems required to create full-scale artificial organs. The template is made out of a network of tiny threads comparable in size, density, and complexity to the patterns formed by capillaries. According to an article published February 4 by the Advanced Healthcare Materials journal, Bellan and his colleagues have succeeded in producing a three-dimensional artificial capillary system that can keep living cells viable and functional for more than a week - a dramatic improvement over current methods.

Most researchers in this area are using hydrogels, a water-based gel that closely mimics that of the natural extracellular matrix that surrounds cells in the body. While they are able to support diffusion of necessary soluble compounds, oxygen, nutrients, and wastes can only diffuse a limited distance through the gel, so the calls must be close to a source of nutrients and oxygen and a sink for wastes. Image Credit

This need for a network of channels that allow fluids to flow has posed a significant challenge to researchers developing artificial organs. But for Bellan, his cotton-candy spinning method can produce channels ranging from three to 55 microns. He uses a material called Poly (N-isopropylacrylamide), or PNIPAM, a polymer that is not only cell friendly but has the unusual property of being insoluble at temperatures above 32 degrees Celsius and soluble below that temperature.

The team spins a network of PNIPAM threads using a modified cotton candy machine. Then they mix up gelatin, water (at 37 degrees), and human cells with an enzyme that causes the gelatin to irreversibly gel. The warm mixture is poured over the PNIPAM structure and allowed to gel in an incubator at 37 degrees. Finally, the gel contaminating cells and fibers are allowed to cool to room temperature, at which point the embedded fibers dissolve, leaving behind an intricate network of microscale channels. The researchers then attach pumps to the network and begin perfusing them with cell culture media containing necessary chemicals and oxygen.

"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 microchannels," Bellan reported.

The next step is to fine-tune to technique to match the characteristics of the small vessel networks in different types of tissues.

To watch the cotton candy in action click HERE.

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Join Date: Nov 2015
Posts: 133
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Re: Spinning Organs

03/15/2016 8:48 AM

spinning organs for dinner?

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