Highly Filled Compositions Based on Alginate Gel and Fine Tricalcium Phosphate for 3D Printing of Tissue-Engineered Matrices

In order to obtain hydrogel matrices for bone tissue engineering, the process of formation of highly filled alginate-calcium phosphate structures by 3D printing was developed. Optimal conditions for the formation of three-dimensional structures from Ca 2+ crosslinked alginate hydrogels and highly filled alginate compositions with fine (5–30 μm) α-tricalcium phosphate (TCP) were determined. Comparative analysis of physicomechanical properties of crosslinked alginate hydrogels showed lower strength and higher elastic modulus of the TCP-filled composite in comparison with pure hydrogel. The difference between the mechanical characteristics of the filled and pure gels increases with the crosslinking density. It was found that, because of the significant content of the mineral dispersed phase, the α-TCP-filled hydrogel does not shrink during crosslinking, unlike pure alginate hydrogel. Using cultures of human umbilical cord mesenchymal stem cells, it was shown in vitro that all the studied samples of both pure and highly filled composite alginate matrices with α-TCP do not have short-term cytotoxic effects.