Improved functionality of hepatic spheroids cultured in acoustic levitation compared to existing 2D and 3D models.

Hepatic spheroids are of high interest in basic research, drug discovery and cell therapy. Existing methods for spheroid culture present advantages and drawbacks. An alternative technology is explored: the hepatic spheroid formation and culture in an acoustofluidic chip, using HepaRG cell line. Spheroid formation and morphology, cell viability, genetic stability, and hepatic functions are analyzed after 6 days of culture in acoustic levitation. They are compared to 2D culture and non-levitated 3D cultures. Sizes of the 25 spheroids created in a single acoustofluidic microphysiological system are homogeneous. The acoustic parameters in our system do not induce cell mortality nor DNA damage. Spheroids are cohesive and dense. From a functional point of view, hepatic spheroids obtained by acoustic levitation exhibit polarity markers, secrete albumin and express hepatic genes at higher levels compared to 2D and low attachment 3D cultures. In conclusion, this microphysiological system proves not only to be suitable for long-term culture of hepatic spheroids, but also to favor differentiation and functionality within 6 days of culture.