Taking the Air out of Competition
Typically, the average person breathes between 20-21% oxygen in a normal environment. The oxygen is then redistributed through the body to muscles and tissues with the oxygen they need to survive. However, when an area of the body is deprived of oxygen, there may be a problem. Hypoxia is the relatively low concentration of oxygen in an environment and is associated with certain diseases, such as cancer. Similarly, an anoxic environment, a state with virtually no oxygen, is home to many anaerobic bacteria in the body, both good and bad. For researchers to better understand these kinds of cells or bacteria that exist in parts of the body with relatively low or no oxygen, it is to their benefit to recreate in the lab their environments where they naturally occur.
Northeastern Professor Sidi A. Bencherif, Postdoctoral fellow Thibault Colombani, and PhD student Zachary Rogers have developed a novel method of recreating low-oxygen environments with a biomaterial they call a cryogel. These cryogels are eco-friendly, biodegradable after use, non-toxic, and made from sustainable sources, making them extremely safe for use and leaving behind a negligibly small ecological footprint.
The cryogel was developed as a highly macroporous successor to an existing 3D scaffolding structure called a hydrogel. These cryogels have been engineered to deplete dissolved oxygen through a bioinspired process. Unlike hydrogels which are mesoporous (i.e., small pores), cryogels allow for the rapid diffusion of liquids or oxygen through its structure.
Furthermore, cryogels’ macroporous nature, on the other hand, encourages rapid diffusion of both oxygen and liquids. This key feature of the cryogel allows it to deplete oxygen more effectively from the environment as oxygen and fluid pass through its structure.
To The Aid Of Researchers
Each part of our body contains different amounts of oxygen; our lungs, for example, tend to contain between 14-15% oxygen while our cartilage contains between 1-3%. However, when the amount of oxygen in a particular area drops below 3-5% percent for most tissues, it creates a hypoxic environment where developing diseases, such as cancer, may reside. To better understand how these kinds of diseases work, oxygen-controlling cryogels can be implemented in cell cultures outside of the body, thereby allowing researchers to recreate hypoxic environments in a controlled setting and study the disease in a stable environment.
The cryogel also provides a method of creating cultures where cells that cannot exist in oxygenated environments may be studied. Bacteria in these anoxic cultures exhibit a condition of cellular respiration that is undergone in the absence of oxygen, unlike the cells in human tissues that need oxygen to survive. The bacteria in the gut, called the microbiome, for instance, are known to play a role in many bodily functions, though their role in the body is not entirely understood. They are difficult to study because they cannot exist in an oxygenated environment. However, by creating an oxygen-free environment outside of the body using cryogels, researchers can study the function of these cells with much greater efficacy.
Current Method of Oxygen Removal
As it stands, removing oxygen from cell cultures is an extremely expensive process, costing tens of thousands of dollars in equipment. Currently, inducing hypoxic environments in cell cultures requires a hypoxic chamber, which is a large machine that uses nitrogen to deplete oxygen in the environment. However, once the culture is removed from the hypoxic chamber, it becomes susceptible to being re-oxygenated.
This presents an obvious problem, which is remedied using a device called a glove box. The glove box is a chamber that allows scientists to perform most of their work in within an oxygen-controlled environment. However, the glove box is similarly a very expensive and cumbersome piece of equipment. In some instances, these glove boxes can contain equipment necessary for inducing a low-oxygen environment, which requires a design for the purpose of studying hypoxic and anoxic cell cultures. The glove box can also be difficult to maneuver, which makes it hard to interact with the cultures themselves.
Additionally, in instances where the glove box does not house the equipment necessary to ensure the preservation of the cell culture’s low-oxygen, there is a risk of exposing the culture to oxygen in the room while handling the culture. Should the culture become oxygenated, the results of the data may not be accurate, thus reducing the impact and benefit of expensive research.
Cryogel as an Alternative
The cryogel doesn’t require complex and costly machines or technical training to be used effectively. The cryogels are simply inserted into standard cell culture plates where the cells are housed and begin removing oxygen on contact. There’s no need to preserve the hypoxic state in a special environment since the cryogels can continue to remove oxygen from the culture even when exposed to oxygen in a typical lab setting.
Where the culture from a hypoxic chamber needs a glove box, the hypoxic environment induced using cryogels requires no additional equipment and can be exposed to oxygenated environments without allowing the culture itself to become oxygenated.
Due to the stability of the hypoxic environment provided by the cryogel, the data collected from the cultures are more accurate, consistent, and reliable, thus enabling more fruitful research at a fraction of the cost. With the cryogel, the once costly and complex process of inducing hypoxia or anaerobia in a lab setting can be achieved inexpensively and with ease. No machines. No boxes. Just gel.
Written by Joseph Burns
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