Most of you have probably heard about the Frankenstein’s monster, a novel written by the English author Mary Shelley. For those who don’t know it, it is the story of Victor Frankenstein, a scientist who invented a secret technique to impart life to unanimated matter. This technique allowed him to create a monstrous creature with human emotions and sensations.
This is of course only science fiction. However, nowadays, the on-demand growth of human tissues and organs using artificial instruments is becoming reality. One emerging manufacturing technique with promise in tissue engineering and regenerative medicine is 3D printing, which is based on the 3D deposition of material in specific shapes. This technology can be applied in biology (3D bioprinting) to produce 3D scaffolds of our tissues. The cells are directly embedded inside the scaffolds and different cell types can be distributed in different locations. The material loaded with the cells is then 3D printed into the desired shape. This method allows the fabrication of bone and cartilage tissues, skin and cardiac constructs and the regeneration of hepatic tissue.
One of the most important factors in 3D bioprinting is the choice of the material used as ink (or, more specifically, bioink), which should be biocompatible and allow cell survival during the printing process. Beside this, the ink should have an optimal viscosity to allow printing and to avoid the 3D printed shape to collapse. Water based gels (also called hydrogels) are ideal inks for 3D bioprinting. These materials are mainly composed of water (> 99 %) and therefore can closely mimic the natural environment of cells.
Hydrogels can be obtained from a wide range of molecules including natural derivatives such as gelatine, alginate, collagen, hyaluronic acid and cellulose. Being an abundant, renewable, low-cost resource, cellulose represents an ideal candidate for the production of hydrogels for 3D bioprinting. This molecule is formed of long glucose chains and it is obtained by extraction from plants or can be produced by bacteria. Mechanical and chemical treatments of raw materials allow the extraction of cellulose in the form of nanofibers or nanocrystals. The suffix nano- refers to the fact that the extracts have one dimension (length or width) in the nanometre range (1.000.000 smaller than 1 mm).
A variety of bioinks based on cellulose nanofibers and nanocrystals has been created by a number of research groups. These could be applied for the regeneration of human tissues (such as cartilage) or to obtain 3D printed drug delivery systems and wound dressings. Although very promising, this research field is still new and growing. We hope that in the future cellulose will be further exploited to develop new bioinks. Will this be the route towards a new Frankenstein’s monster? Stay tuned!
Want to know more about this? Read this article: http://pubs.rsc.org/en/content/articlepdf/2017/bm/c7bm00510e