“Class I biocompatible DLP printed acrylate impairs adhesion and proliferation of human mesenchymal stromal cells in indirect cytotoxicity assay”

The popular method of direct light processing 3D printing (DLP) for complex and individual laboratory equipment requires materials that are as inert as possible for use in contact with cells for subsequent investigations. However, the per se incomplete curing of acrylate resins by UV light leaves residues that are not suitable for cell culture application. Therefore, we evaluated four commercially available acrylate resins for their cytotoxicity with bone marrow-derived human mesenchymal stromal cells (BM-hMSC) in an indirect cytotoxicity test by incubation the printed cylinders in TransWell inserts for 7 days. While the degree of crosslinking did not increase significantly between freshly printed and stored samples (3 weeks in ambient conditions), the storage improved the materials performance in terms of cytocompatibility. A resin specific DNA amount and LDH activity showed a direct influence of the resin residuals on cell adhesion. The Class I acrylate Surgical Guide left no adherent cells after 7 days, regardless of previous storage. In comparison, the Basic Ivory resin after storage allowed same amount of adherent cells after 7 days as the polystyrene reference. Depending on the formulation, the resin residuals are released with storage time and the material can be used in indirect contact with cells.