Characterising novel patient tumour tissue-derived organoid models for in vitro research


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Ibrahim Khot1,Roberto Coppo2,Masahiro Inoue2,David Jayne1
1University of Leeds,2Kyoto University

Abstract

Background

Three-dimensional (3D) spheroidal cell cultures have garnered interest in cancer research, as they can better replicate in vivo-like cancers, as compared to two-dimensional (2D) cell cultures. However, 3D spheroid models are generated using commercial cell lines. Primary ex vivo patient specimens provide an alternative, but are difficult to culture for long periods time for experiments. Cancer tissue-originated spheroids (CTOS) are in vitro models of cancer, generated from primary patient tumour tissue samples under specialised conditions. Unlike conventional 3D spheroids and ex vivo specimens, CTOS are able to replicate the features of the primary tumour such as histological architecture and cell arrangement and can be cultured indefinitely whilst retaining their primary characteristics.

Method

Colorectal cancer derived C45 CTOS models were generated and cultured in cell media suspension or embedded into matrigel. Chemosensitivity assays were performed by treating C45 CTOS with 5-FU for 7 days. CTOS viability was assessed using an ATP luminescent cell viability assay and fluorescent imaging using propidium iodide (PI). CTOS were fixed in formalin, embedded into paraffin, sectioned and stained with Haematoxylin and Eosin. Immunohistochemistry was performed to highlight the expression of the breast cancer resistance protein (BCRP).

Results

1µM 5-FU treated C45 CTOS were found to be significantly more sensitive to treatment as compared to untreated CTOS (untreated: 100% viability and no PI staining vs. 1µM treated: 55% viability and PI staining, p<0.05). Histological analysis showed in vivo-like tissue architecture in the CTOS models. BCRP expression was found to be localised, to the luminal apical membranes within the CTOS structures.

Conclusion

Patient-derived CTOS organoid models are an advancement over traditional cell line-based 3D spheroidal and 2D monolayer cell cultures. They provide a more clinically relevant model for anti-cancer evaluations, can potentially be used for developing personalised treatments and serve as a cost-effective alternative to animal models.