DEVELOPMENT OF A HUMAN-SPECIfiC 3D IN VITRO PAEDIATRIC CEREBELLAR TUMOUR MODEL USING DECELLULARISED BRAIN AUTOPSY TISSUE

Abstract

Abstract AIMS Group-3 medulloblastoma (MB) is a paediatric cerebellar tumour with a dismal prognosis. Our objective was to establish a 3D in vitro model termed ‘tumoursphere matrix’ to recapitulate physiologically-relevant communication between tumour cells and reactive brain elements, aiming to discern differential gene expression in cancer cells upon co-culture with astrocytes and human brain extracellular matrix (ECM). METHOD Non-disease human autopsy brain was decellularised to generate ECM and extensively characterised to show DNA reduction, ECM ligand retention and compatibility with different cell lines. D283, D341 and D425 cells were co-cultured with primary human cerebellar astrocytes within a PEGDA hydrogel containing decellularised ECM. Following 7 days of culture, co-cultured cells were separated using fluorescence activated cell sorting to generate individual cell populations for transcriptomic analysis. RESULTS ECM characterisation showed a significant reduction in cellular material whilst retaining ECM ligands. Reduction of DNA content to 174 ng/mg was corroborated by an absence of nuclei in immunohistochemical staining. Colorimetric assays indicated collagen and glycosaminoglycan retention in decellularised ECM, and immunofluorescence confirmed retention of fibronectin, laminin and hyaluronic acid. Detection of all ECM ligands was cross-validated by Orbitrap-Secondary Ion Mass Spectrometry. Primary human cerebellar astrocytes, D283, D341 and D425 cells were cultured as spheroids within the ECM/PEGDA hydrogel for 7 days with no significant decrease in cellular viability. Cytokine and Human Matrix Metalloproteinase (MMP) Antibody Arrays showed retained cytokine and MMP expression in all three cell lines in the presence of ECM material. CONCLUSION We have developed a bespoke 3D model which can co-culture cells for over 7 days, whilst recapitulating the in vivo tumour environment. RNA sequencing on all 3 cell lines in mono and co-culture is currently in progress to identify differentially expressed genes in medulloblastoma cells upon astrocytic and brain ECM crosstalk. We hypothesise that biochemical signalling underlying this communication network will reveal putative therapeutic vulnerabilities.