Development of a Mechanical Culture System for Stem Cell Stimulation in Bioprinted Scaffolds

Mechanical forces promote stem cell differentiation, tissue and organ development. Research has shown that stem cells stimulated by tensile strain can lead to higher regulation of self-renewal genes and higher proliferation rates. Our goal is to develop a culture system to mechanically stimulate stem cells in three-dimensional scaffolds using bioprinting. Bioinks are used as a scaffold and extracellular matrix where the cells will grow. In this work, we used a custom-made tensile stress bioreactor to grow bioprinted structures containing adipose-derived stem cells using a bioink made of alginate, cellulose and clay. We tested different concentrations of each component under tensile stress and analyzed the different strains for each bioink. We varied the concentrations of each material from 1% to 5%, and found that the optimal mixture for extrusion to keep shape consisted of 3% alginate, 3% cellulose, and 3% laponite. Adding clay to the mixture ensured that structure can be maintained after printing. Cellulose added tensile strength to the alginate mixture. The alginate fibers were strengthened when added with both cellulose and laponite, making the mixture of the three preferred over a bioink made of only alginate materials for tensile loading experiments.