Modeling Tumor Microenvironment Interactions of Imid Sensitive and Resistant Cells in 3D Organotypic Culture Models
Authors: Ahsan Aarif , Jeyaraju Danny , Bisht Kamlesh , Hagner Patrick R. , Bjorklund Chad C. , Pierceall William E , Thakurta Anjan 
Published: October 2019

Abstract
Background: Organotypic culture models developed using 3D conditions recapitulate tissue-specific structural features and cell-cell interactions more accurately than conventional 2D cultures. Our ultimate goal is to optimize culture conditions which promote the survival and proliferation of multiple myeloma (MM) cells and could serve as a platform for molecular mechanistic, clinical biomarker and pharmacodynamic marker studies using immune-modulatory compounds (IMIDs) and other myeloma drugs alone and in combination.
Design/Results: Using gas permeable microfluidic devices, we cultured and compared growth/morphologic properties of six multiple myeloma cell lines, MM1.S, MM1.SPR, H929, H929PR, H929-220R and RPMI-8226 in 2D and 3D conditions. Collagen type IV was used as an extra-cellular matrix source to grow these cells. Cell growth and morphology was captured at regular intervals. Ten days post culture, cells were harvested from the device and stained for proliferation (Ki67 staining) index and expression of key MM oncogenic molecules, CD138, CD38 and BCMA. Cell lines grown in 3D conditions had, with some exceptions, higher proliferation index compared to 2D conditions. Thus, Ki67-mean fluorescence intensity (MFI) for 3D vs 2D were: 2038 vs 1130 for MM1.S; 1614 vs 1912 for MM1.PR; 2067 vs 1169 for H929; 2057 vs 1702 for H929PR; 2300 vs 1889 for H929-220R; 2018 vs 1220 for RPMI-8226. Similar trends for higher proliferation under 3D conditions were observed for the CD138, CD38 and BCMA cell subsets. Expression of FOXM1, a potential marker of IMID resistance, was reduced in Pomalidomide sensitive non-synchronous cells compared to resistant cells, although a few clusters with higher FOXM1 expression were observed among sensitive cells. To further study the effects of other components of MM tumor micro-environment on Pomalidomide response, we optimized the culture conditions to co-culture MM cell lines with bone marrow stromal cells. The co-culture of bone marrow stromal cells, HS5 with MM cell line H929 protected Ikaros degradation induced by Pomalidomide. Interestingly, CD44 expression in H929 cells was upregulated in co-culture conditions with stromal cells.
Future Directions: These culture conditions are currently being optimized to study the (1) drug effects in MM and immune cells alone and in combination and (2) use the co-culture derived cells for single cell level evaluation of genetic, transcriptomic or proteomic changes associated with drug treatment and (3) ultimately grow primary Myeloma cells in these conditions for ex vivo manipulation and downstream molecular and biological effects.
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Disclosures
Ahsan: celgene: Employment, Equity Ownership. Jeyaraju:Celgene Corporation: Employment, Equity Ownership. Bisht:Celgene Corporation: Employment, Equity Ownership. Hagner:Celgene Corporation: Employment, Equity Ownership. Bjorklund:Celgene Corporation: Employment, Equity Ownership. Pierceall:Celgene: Employment, Equity Ownership. Thakurta:Celgene Corporation: Employment, Equity Ownership.