Standing waves to pattern tissue constructs

Pattern generation by sonic vibrations is a well-known phenomenon often used in physics demonstrations (see this entertaining video by UCSD’s own Physics Girl, recent winner of Alan Alda’s Flame Challenge). However, it has only recently been applied to the challenge of patterning engineered tissues, which is surprising given its simplicity and the tolerance of cells for these vibrations.

A team led by Utkan Demirci at Stanford University recently showed in Advanced Materials that standing waves in a liquid can cause cultured cells to assemble into sub-millimeter scale patterns, which can be immobilized using blood clotting proteins (including fibrinogen in the cell solution and adding thrombin after pattern generation). As this approach is bottom-up rather than top-down, it is far less time- and resource-intensive than many methods of cell patterning, such as bioprinting and micromolding. Further, it employs equipment available in most biology labs, and could thus be easily adopted by many researchers if it proves able to generate structures similar to those of native tissues. This method, termed liquid-based templated assembly (LBTA) by the researchers, can generate an enormous variety of patterns depending on the combination of frequency and geometry of the chamber.

Pattern generated by vibrating a solution of NIH 3T3 fibroblasts in OptiPrep/ PBS (also containing fibrinogen). Cells were later fixed with thrombin and stained with cell tracker CFSE. Image used with permission from Wiley and Sons Publishing, © 2014.

According to the New Scientist, the team is currently pursuing application of LBTA to engineering liver tissue.