Alginate is widely used as a biomaterial in 3D bioprinting due to its biocompatibility, biodegradability, high accessibility, shear thinning behavior, and cross-linking speed. The rheological properties of the bioink are the key factor influencing printability (ability to form and maintain the design shape), therefore investigations are conducted to enhance the weak mechanical properties of alginate gel in order to obtain hybrid hydrogels with high printability. Indeed, when using 3D bioprinting, the objective is to obtain a multilayer construction that retains its mechanical stability over time and, in order to produce relevant in vitro tissue models, the final goal is to match the native mechanical properties of the tissue.
In the review ‘Alginate based hydrogel inks for 3D bioprinting of engineered orthopedic tissues’, Murab et al. provide an overview of the different parameters such as printing method, concentration of alginate and crosslinker, and shape of the printed structures on the properties of the alginate-based printed construct. Specifically, they reviewed different strategies used in the last few years to increase the mechanical and biological performances of alginate-based hydrogels for bioprinting of bone and cartilage. For example, the advantageous properties of alginate and type I collagen have been combined to create a lattice structure with improved mechanical properties and higher expression of cartilage-specific genes in primary rat articular cartilage chondrocytes compared to the alginate control.
Another example of cartilage tissue engineering using alginate combined the latter with polycaprolactone (PCL) to create a stable PCL support scaffold with bioprinted alginate in between. The resulting construct exhibits good mechanical stability and the goat cartilage cells embedded in alginate were found to have high viability with the production of a cartilage-like matrix. Although encouraging results are presented in the literature, there is still a long way to go to use the alginate-based hydrogels for in vitro orthopedic models.
References
Murab, Sumit, et al. “Alginate based hydrogel inks for 3D bioprinting of engineered orthopedic tissues.” Carbohydrate Polymers (2022): 119964.
This article was written by Marie Moulin as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Marie is researching the Bioprinting of Bone and Cartilage at Uppsala University, Sweden.