Friday, 18 May 2012

Artificial Tissue

“Living flesh could be constructed by following engineering principles and combining nonliving material with cells”1. This might sound like a crazy sentence pulled out for a future movie, but in fact it is something that is very real nowadays. Thanks to all the research that scientists have made in the past few years, making artificial tissues is something possible, but still, there  are a lot of challenges.
Artificial tissues can go from a thin sheet of cells to a whole organ. And what scientists are trying to achieve right now is to make more complicated tissue structures. But to be able to accomplish that, they have to study how the body works, how it heals and grows. 

Epicel, a permanent replacement epidermis. 
Some tissues like skin and cartilage do not need a lot of internal vasculature, but most tissues do. That is why it is important to design an artificial vascular system that provides cells with blood, so they can get different kind of nutrients and oxygen. By using nano-materials and studying their environment, scientists are able to reproduce them.
They have different techniques for making this systems. They use different kinds of materials to imitate the texture of certain body tissue, they can also use a  membrane filter so that cells can be separated from the blood-carrying channels. Hydrogels, that are made of polymers, can be really helpful, they encapsulate the cells meanwhile the endothelial cells go in channels that run through the gel. 
Once the organ is inside the body, it is important  to connect it with the body´s circulatory system, for that they use chemicals that promote the formation of blood vessels, and while they grow, the artificial vascular system has to keep working, in order to keep the cells alive. 
Adult stem cells are useful for making artificial tissues because they can induce them to reproduce and differentiate into different tissue types. In the other hand, there are embryonic stem (ES) cells, this are capable to produce any type of tissue, but scientists do not know how to fully control them. In order for them to work they need really specific environments, they need to know what materials and chemicals can be used, and what proteins are needed for the process. What they are trying to do now, is reproduce the ES cells from other body tissue. This new cells are called induced pluripotent stem  (iPS) cells, and they are produced by reintroducing master regulatory genes. 

Stem cells

“Cells are smart”2. If you put the right cells together, they will make a desired tissue. But they need an adequate environment, a certain structure, with certain texture. So, what scientists do is to use scaffolds and hydrogels that can be easily manipulated. 
Even if there are still a lot of challenges to overcome, artificial tissues have progressed in a huge way in just a few years. And if scientists continue to use new technologies, to mimic what our body does, there is no question that they will keep improving. 
Natalia Luján Juncua

1,2Khademhosseini, A, Vacanti, J, & Langer, R 2009, `Progress in Tissue Engineering, Scientific American, 300, May 2009, pp. 64-71.
Reece, J, Meyers, N, Urry, L, Cain, M, Wasserman, S, Minorsky, P, Jackson, R & Cooke, B  2012, Campbell Biology, Pearson, Australia pp. 421-426.

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