Formation of Adipose Stromal Vascular Fraction Cell Laden Spheroids Using a 3D Bioprinter and Superhydrophobic Surfaces

The therapeutic infusion of adipose-derived stromal vascular fraction cells (SVF) for the treatment of multiple diseases, has progressed to numerous human clinical trials; however, the often poor retention of the cells following implantation remains a common drawback of direct cell injection. One solution to cellular retention at the injection site has been the use of biogels to encapsulate cells within a microenvironment prior to and upon implantation. The current study utilized 3D bioprinting technology to evaluate the ability to form SVF laden spheroids with collagen I as a gel forming biomatrix. A superhydrophobic surface was created to maintain the bioprinted structures in a spheroid shape. A hydrophilic disc was printed onto the hydrophobic surface to immobilize the spheroids during the gelation process. Conditions for the automated, rapid formation of SVF laden spheroids were explored including time/pressure relationships for spheroid extrusion during bioprinting. The formed spheroids maintain SVF viability in both static culture and dynamic spinner culture. Spheroids also undergo a time dependent contraction with the retention of angiogenic sprout phenotype over the culture period. The use of a biphilic surface exhibiting both superhydrophobicity to maintain spheroid shape and a hydrophilicity to immobilize the spheroid during gel formation produces SVF laden spheroids that can be immediately transplanted for therapeutic applications.