Daphne Siozios ’23
3-D bioprinting is a novel field that continues to pave the way in establishing alternative forms of medicine to otherwise traditional techniques of tissue remodeling. Bio-ink, the material used to produce artificial live tissue through three-dimensional means, must meet certain requirements in resolution, shape, and biocompatibility (the material must not cause an adverse response in the host organism). While certain biomaterials used for bio-ink composition can enhance oxygen levels and provide nutrients to cells, there is a need to further improve their porosity to increase surface area for cell adhesion. Researchers previously have used substances like gelatin and fibrin to create hydrogels, but these carbohydrate-based mediums possess low mechanical properties. To combat these issues of batch-to-batch reproducibility or the high cost of modifying proteins, scientists at the University of Bordeaux and members of the L’Oréal research group in France have been examining the supposed implications of a specific, elastin-like polypeptide (ELP) bio-ink on cell adhesion properties.
The researchers began by synthesizing the ELP bio-ink using complex recombinant DNA and protein engineering techniques. They chose the type MW-ELP[V3M1-40], which contains valine and methionine, due to its ability to be tailored through chemoselective postmodification (changing the properties of a protein by altering the modifying groups). Indeed, the group then modified this bioink with the protein sequence GRGDS to foster the formation of a cell network as well as with collagen I to promote cell adhesion. This ink was then analyzed under a variety of conditions, including in culture with human fibroblast cells, in the bioprinter, and in an aqueous environment. Results of this analysis showed that the ELP-based bioink has superior mechanical properties during bioprinting and does not experience undue or significant swelling over time, marking it as a stable hydrogel. Additionally, biocompatibility tests showed that the bio-ink was able to support cell growth due to collagen modification. However, since collagen is an animal product additive, the researchers noted that there could be some variability from batch to batch.
The results indicate that ELPs can indeed be altered to produce specific ELP-based bio-inks for 3-D bioprinting in tissue reconstruction. Still, there are some synthesis caveats to this process that must be addressed with further research. Pursuing a greater knowledge of bio-ink properties is a key to further aid in treating complex, current clinical maladies, such as organ shortages.
M. Dai, et al., Elastin-like polypeptide-based bioink: a promising alternative for 3d bioprinting. Biomacromolecules 5, 1-11 (2021). doi: 10.1021/acs.biomac.1c00861.
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