3D printed skin may be stronger than mother nature’s.
I first heard about this while I was watching Grey’s Anatomy. Meredith was trying to print a 3D model of a liver, and I thought “That’s cool, but it will never happen.” As it turns out, I was wrong – it’s already happening. A group in China is using bioprinting to grow small livers.
3D printing is a relatively new process. To make 3D objects, people have traditionally used subtractive methods. To make a statue, a sculptor would remove pieces of stone until he got the image he wanted.
3D printing is an additive method. Layers of material, with changing shapes, are laid down and gradually combined to produce a three-dimensional object in the desired form. And the best part about 3D printing is that not only can you print in plastic or paper, but also with living cells.
Printing human skin
A group of scientists from the Rensselaer Polytechnic Institute in New York have developed a method to print human skin. While skin seems to be a fairly simple organ to print in 3D because it’s flat, it’s actually much more complex than it sounds.
Skin is composed of two main layers, the dermis and the epidermis. Additionally, the epidermis is composed of five different layers, and skin contains almost a dozen different types of cells. So how is skin made by 3D bioprinting?
The materials used for 3D printing are very important. The scientists used a collagen hydrogel as a scaffold material. Then layers of cells called fibroblasts and more collagen were stacked on top of each other, and cells called keratinocytes were laid on top. This recreates the dermal and epidermal compartments found in skin.
Cell density varies between these two layers, so the group had to figure out how to control this during the printing process. They addressed this by changing the number of cells in each drop of ‘ink’ and the spacing between the drops in the 3D matrix.
Better than nature
The authors found that 3D bioprinted skin retained its shape and resisted shrinking far better than 3D skin constructs created by manual deposition. They hypothesize that printing may allow more uniform gelling conditions, and may allow the collagen to more evenly disperse the contractile forces of fibroblasts.
Fibroblast differentiation and contraction is very important in scar formation, so printed skin grafts may be less likely to shrink and scar.
While 3D bioprinting is just beginning, the potential benefits are endless. Manufactured organs could mean the end of the transplant list.
Photo: Flickr, RobiNZ
Lee VK, Singh G, Trasatti JP, Bjornsson C, Tran TN, Xu G, Yoo SS, Dai G, & Karande P (2013). Design and Fabrication of Human Skin by 3D Bioprinting. Tissue engineering. Part C, Methods PMID: 24188635
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