Abstract 4214: Tissue-engineered 3D model for elucidating the role of the bone niche in osteosarcoma therapy response
Authors: Peasah Abena Darkwah , Monette Callan , Lee Jeehee , Tai Michelle , Sweet-Cordero E. Alejandro , Yang Fan 
Published: March 2024

Abstract
Introduction. Osteosarcoma (OS) is an aggressive pediatric bone cancer whose 5-year survival rate has remained stagnant for nearly 40 years, and often exhibits high therapy resistance. Experimental models that can elucidate how the OS bone niche modulates OS signaling and drug response could accelerate discovery of new targeted therapies. Our group has recently reported a biomaterials-based 3D in vitro model of OS with bone matrix mimicking cues: a gelatin microribbon scaffold coated with hydroxyapatite particles (GelHA µRBs). We demonstrated this 3D OS model can better mimic in vivo signaling and drug responses than standard 2D culture. However, the potential of this 3D model for probing OS-bone niche crosstalk has not yet been investigated. We hypothesize that OS-bone crosstalk will modulate OS drug response and signaling. To test this hypothesis, here we aim to establish a 3D model to assess the effect of tissue engineered (TE) bone on OS drug response and signaling.
Methods. Gel µRBs were fabricated by wet spinning as previously described. To generate tissue engineered bone, human mesenchymal stem cells (hMSCs) were encapsulated (15 M/mL) in GelHA µRBs and cultured in osteogenic medium for 28 days. A PDX-derived OS line (OS052) was used. Three groups were studied: OS monoculture, separate coculture (paracrine only), and OS cells seeded directly on TE bone (paracrine plus direct contact). For all groups, 96K OS cells were seeded per sample. OS cells were labeled with firefly luciferase to allow tracking of OS cell viability and proliferation using bioluminescence. Gemcitabine, a standard chemotherapy drug for OS, was used as the model drug (0.001 to 1 uM). Outcome analyses include cell viability, proliferation, gene expression, and immunostaining.
Results. TE bone enhances OS resistance to gemcitabine in both separate coculture and direct seeding on bone, as shown by bioluminescence. At 1 uM, OS cell death in monoculture, separate coculture, and seeding on bone was on average 98.19%, 82.05%, and 64.44%. These results indicate that both paracrine signaling from osteoblasts and direct contact with bone ECM contribute to OS drug resistance. TE bone did not significantly impact OS proliferation over 7 days as shown by bioluminescence. Ongoing studies will assess the effect of TE bone on OS expression of key proteins in the bone niche (RANK/RANKL/OPG) and OS response to cabozantinib, a cMET inhibitor whose antiproliferative effect may be osteoblast-mediated.
Conclusions. Here we report a tissue engineered 3D model to study the crosstalk between OS cells and bone niche. The results support our hypothesis that bone niche contributes to OS drug resistance, which is mediated through both paracrine signals and ECM. This model can be used to further elucidate the mechanisms through which the bone niche influences OS progression and drug resistance, and for screening potential drug candidates that target such crosstalk.
Citation Format: Abena Darkwah Peasah, Callan Monette, Jeehee Lee, Michelle Tai, E. Alejandro Sweet-Cordero, Fan Yang. Tissue-engineered 3D model for elucidating the role of the bone niche in osteosarcoma therapy response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4214.