Cells can respond to different topographical cues in their natural microenvironment. Hence, scientists have employed microfabrication techniques and materials to generate culture substrates containing topographies for cell-based assays. However, one of the limitations of custom topographical platforms is the lack of adoption by the broad research community. These techniques and materials have high costs, require high technical expertise, and can leach components that may introduce artifacts. In this study, we developed an array of culture surfaces on polystyrene using razor printing and sanding methods to examine the impact of microscale topographies on cell behavior. The proposed technology consists of culture substrates of defined roughness, depth, and curvature on polystyrene films bound to the bottom of a culture well using double-sided medical-grade tape. Human monocytes and adult mesenchymal stem cells (hMSCs) were used as test beds to demonstrate the applicability of the array for cell-based assays. An increase in cell elongation and Arg-1 expression was detected in macrophages cultured in grooves and on rough substrates as compared to flat surfaces. Also, substrates with enhanced roughness stimulated the proliferation of hMSCs. This effect correlated with the secretion of proteins involved in cell proliferation and the downregulation of those associated with cell differentiation. Our results showed that the polystyrene topography sticker array supports cellular changes guided by microscale surface roughness and geometries. Consequently, microscale surface topographies on polished and razor-printed polystyrene films could leverage the endogenous mechanisms of cells to stimulate cellular changes at the functional level for cell-based assays.

Cell culture technologies have provided biomedical researchers with fast and accessible tools to probe the breast tumor microenvironment. Exponential progress in fabrication methods combined with multiparametric approaches have enabled the development of cell culture model systems with enhanced biological complexity to identify key aspects that regulate breast cancer (BC) progression and therapeutic response. Yet, the culture parameters and conditions employed influence the behavior of tumor cells, thereby affecting its tissue biomimetic capabilities. In this chapter we review the wide range of culture platforms employed for the generation of breast tumor models and summarize their biomimetic capabilities, advantages, disadvantages and specific applications.

Researchers and practitioners of many areas of knowledge frequently struggle with missing data. Missing data is a problem because almost all standard statistical methods assume that the information is complete. Consequently, missing value imputation offers a solution to this problem. The main contribution of this paper lies on the development of a random forest-based imputation method (TI-FS) that can handle any type of data, including high-dimensional data with nonlinear complex interactions. The premise behind the proposed scheme is that a variable can be imputed considering only those variables that are related to it using feature selection. This work compares the performance of the proposed scheme with other two imputation methods commonly used in literature: KNN and missForest. The results suggest that the proposed method can be useful in complex scenarios with categorical variables and a high volume of missing values, while reducing the amount of variables used and their corresponding preliminary imputations.

Introduction: Cancer stem cells (CSC), a major culprit of drug-resistant phenotypes and tumor relapse, represent less than 2 % of the bulk of TNBC cells, making them difficult to isolate, study, and thus, limiting our understanding of the pathogenesis of the disease. Current methods for CSC enrichment, such as 3D spheroid culture, genetic modification, and stem cell conditioning, are time consuming, expensive, and unsuitable for high-throughput assays. One way to address these limitations is to use topographical stimuli to enhance CSC populations in planar culture. Physical cues in the breast tumor microenvironment can influence cell behavior through changes in the mechanical properties of the extracellular matrix (ECM). In this study, we used topographical cues on polystyrene films to investigate their effect on the proteome and stemness of standard TNBC cell lines.Methods: The topographical polystyrene-based array was generated using razor printing and polishing methods. Proteome data were analyzed and enriched bioprocesses were identified using R software. Stemness was assessed measuring CD44, CD24 and ALDH markers using flow cytometry, immunofluorescence, detection assays, and further validated with mammosphere assay. EGF/EGFR expression and activity was evaluated using enzyme-linked immunosorbent assay (ELISA), immunofluorescence and antibody membrane array. A dose-response assay was performed to further investigate the effect of surface topography on the sensitivity of cells to the EGFR inhibitor.Results: Surface roughness enriched the CSC population and modulated epidermal growth factor receptor (EGFR) signaling activity in TNBC cells. Enhanced proliferation of MDA-MB-468 cells in roughness correlated with upregulation of the epidermal growth factor (EGF) ligand, which in turn corresponded with a 3-fold increase in the expression of EGFR and a 42% increase in its phosphorylation compared to standard smooth culture surfaces. The results also demonstrated that phenotypic changes associated with topographical (roughness) stimuli significantly decreased the drug sensitivity to the EGFR inhibitor gefitinib. In addition, the proportion of CD44+/CD24−/ALDH+ was enhanced on surface roughness in both MDA-MB-231 and MDA-MB-468 cell lines. We also demonstrated that YAP/TAZ activation decreased in a roughness-dependent manner, confirming the mechanosensing effect of the topographies on the oncogenic activity of the cells.Discussion: Overall, this study demonstrates the potential of surface roughness as a culture strategy to influence oncogenic activity in TNBC cells and enrich CSC populations in planar cultures. Such a culture strategy may benefit high-throughput screening studies seeking to identify compounds with broader tumor efficacy.