Three-dimensional matrix stiffness and adhesive ligands affect cancer cell response to toxins.

There is an immediate need to develop highly predictive in vitro cell-based assays that provide reliable information on cancer drug efficacy and toxicity. Development of biomaterial-based three-dimensional (3D) cell culture models as drug screening platforms has recently gained much scientific interest as 3D cultures of cancer cells have been shown to more adequately mimic the in vivo tumor conditions. Moreover, it has been recognized that the biophysical and biochemical properties of the 3D microenvironment can play key roles in regulating various cancer cell fates, including their response to chemicals. In this study, we employed alginate-based scaffolds of varying mechanical stiffness and adhesive ligand presentation to further explore the role of 3D microenvironmental cues on glioblastoma cell response to cytotoxic compounds. Our experiments suggested the ability of both matrix stiffness and cell-matrix adhesions to strongly influence cell responses to toxins. Cells were found to be more susceptible to the toxins when cultured in softer matrices that emulated the stiffness of brain tissue. Furthermore, the effect of matrix stiffness on differential cell responses to toxins was negated by the presence of the adhesive ligand RGD, but regained when integrin-based cell-matrix interactions were inhibited. This study therefore indicates that both 3D matrix stiffness and cell-matrix adhesions are important parameters in the design of more predictive in vitro platforms for drug development and toxicity screening.

Trehalose effectiveness as a cryoprotectant in 2D and 3D cell cultures of human embryonic kidney cells.

Post cryopreservation viability of human embryonic kidney (HEK) cells under two-dimensional (2D) and three-dimensional (3D) culture conditions was studied using trehalose as the sole cryoprotective agent. An L9 (34) Taguchi design was used to optimize the cryoprotection cocktail seeding process prior to slow-freezing with the specific aim of maximizing cell viability measured 7 days post thaw, using the combinatorial cell viability and in-vitro cytotoxicity WST assay. At low (200 mM) and medium (800 mM) levels of trehalose concentration, encapsulation in alginate offered a greater protection to cryopreservation. However, at the highest trehalose concentration (1200 mM) and in the absence of the pre-incubation step, there was no statistical difference at the 95% CI (p = 0.0212) between the viability of the HEK cells under 2D and 3D culture conditions estimated to be 17.9 ± 4.6% and 14.0 ± 3.6%, respectively. A parallel comparison between cryoprotective agents conducted at the optimal levels of the L9 study, using trehalose, dimethylsulfoxide and glycerol in alginate microcapsules yielded a viability of 36.0 ± 7.4% for trehalose, in average 75% higher than the results associated with the other two cell membrane-permeating compounds. In summary, the effectiveness of trehalose has been demonstrated by the fact that 3D cell cultures can readily be equilibrated with trehalose before cryopreservation, thus mitigating the cytotoxic effects of glycerol and dimethylsulfoxide.