Hydrogel microstructure live-cell array for multiplexed analyses of cancer stem cells, tumor heterogeneity and differential drug response at single-element resolution.

Specific phenotypic subpopulations of cancer stem cells (CSCs) are responsible for tumor development, production of heterogeneous differentiated tumor mass, metastasis, and resistance to therapies. The development of therapeutic approaches based on targeting rare CSCs has been limited partially due to the lack of appropriate experimental models and measurement approaches. The current study presents new tools and methodologies based on a hydrogel microstructure array (HMA) for identification and multiplex analyses of CSCs. Low-melt agarose integrated with type I collagen, a major component of the extracellular matrix (ECM), was used to form a solid hydrogel array with natural non-adhesive characteristics and high optical quality. The array contained thousands of individual pyramidal shaped, nanoliter-volume micro-chambers (MCs), allowing concomitant generation and measurement of large populations of free-floating CSC spheroids from single cells, each in an individual micro-chamber (MC). The optical live cell platform, based on an imaging plate patterned with HMA, was validated using CSC-enriched prostate and colon cancer cell lines. The HMA methodology and quantitative image analysis at single-element resolution clearly demonstrates several levels of tumor cell heterogeneity, including morphological and phenotypic variability, differences in proliferation capacity and in drug response. Moreover, the system facilitates real-time examination of single stem cell (SC) fate, as well as drug-induced alteration in expression of stemness markers. The technology may be applicable in personalized cancer treatment, including multiplex ex vivo analysis of heterogeneous patient-derived tumor specimens, precise detection and characterization of potentially dangerous cell phenotypes, and for representative evaluation of drug sensitivity of CSCs and other types of tumor cells.

[The immunity generated in white rats vaccinated with strains of the Venezuelan equine encephalomyelitis virus]. / Immunitet, sozdavaemyi u belykh krys, vaktsinirovannykh shtammami virusov venesuél'skogo éntsefalomielita loshadei.

The existence of virulence gradient in the main members of Venezuelan equine encephalomyelitis virus complex (VEE) was established by subcutaneous inoculation of immunologically competent outbred rats weighing 50-70 g. The virulence of the strains may be judged by a parameter such as the weight of the animal in 5 or 10 days after inoculation. The highest degree of protection was observed in the animals immunized with strain 15, the least in those immunized with strain 230. The above results indicate that adult white rats may be used as a model for the evaluation of the efficacy of protective preparations against viruses of the VEE complex.