Investigation and Characterization of Cell Aggregation During and After Inkjet-Based Bioprinting of Cell-Laden Bioink

Abstract

Recently, 3D bioprinting techniques have been broadly recognized as a promising tool to fabricate functional tissues and organs. The bioink used for 3D bioprinting consists of biological materials and cells. Because of the dominant gravitational force, the suspended cells in the bioink sediment resulting in the accumulation and aggregation of cells. This study primarily focuses on the quantification of cell sedimentation-induced cell aggregation during and after inkjet-based bioprinting. The major conclusions are summarized as follows: (1) as the printing time increases from 0 min to 60 min, the percentage of the cells forming cell aggregates at the bottom of the bioink reservoir increases significantly from 3.6% to 54.5%, indicating a severe cell aggregation challenge in 3D bioprinting, (2) during inkjet-based bioprinting, at the printing time of only 15 min, more than 80% of the cells within the nozzle have formed cell aggregates. Both the individual cells and cell aggregates tend to migrate to the vicinity of the nozzle centerline mainly due to the weak shear-thinning properties of the bioink, and (3) after the bioprinting process, the mean cell number per microsphere increases significantly from 0.38 to 1.05 as printing time increases from 0 min to 15 min. The maximum number of cells encapsulated within one microsphere is ten, and 29.8% of the microspheres with cells encapsulated have contained small or large cell aggregates at the printing time of 15 min.

Engineering biomaterials by inkjet printing of hydrogels with functional particulates

“…As the biomaterial inks become more complex, however, an increased difficulty in printing may arise. Studies have shown that the aggregation of cells and other ink additives can become sufficient to clog the nozzle during long prints resulting in decreased print quality or the inability to print entirely [ 76 ]. Although this phenomenon can be mitigated to some degree using inkjet circulation or by ink additives such as polyvinylpyrrolidone, the pursuit of enhanced ink additives and capabilities must be carefully balanced to ensure that printability remains sufficient to allow a high level of architecture control [ 77 ].…”

Inkjet Printing of Pharmaceuticals

“…A recent study primarily focused on the comprehensive quantification of cell sedimentation‐induced aggregation during and following inkjet‐based bioprinting. [ 217 ] It was revealed that extending the printing time by 60 min results in a significant increase in the percentage of cells forming aggregates at the bottom of the bioink reservoir (i.e., from 3.6% to 54.5%). This escalation underscores the profound challenge posed by cell aggregation in the realm of 3D bioprinting.…”

Investigation of Cell Aggregation on the Printing Performance in Inkjet-Based Bioprinting of Cell-Laden Bioink

“…Later, the same group presented a study characterizing cell aggregation both during and after the inkjet-based bioprinting process. 46 It was observed that the percentage of cells forming cell aggregates at the bottom of the bioink reservoir increased significantly from 3.6% to 54.5% within 60 min of printing time. In addition, a huge percentage of cells have been found to adhere to form cell aggregates both within the inkjet nozzle during printing and formed microspheres after printing.…”

“…It was reported that only within 40 min of printing time, almost all of the cells within the bioink containing 0.5% (w/v) sodium alginate have sedimented to the bottom, significantly increasing the cell concentration and facilitating cell aggregation. Later, the same group presented a study characterizing cell aggregation both during and after the inkjet-based bioprinting process . It was observed that the percentage of cells forming cell aggregates at the bottom of the bioink reservoir increased significantly from 3.6% to 54.5% within 60 min of printing time.…”