(P 18) ESTABLISHMENT AND CHARACTERIZATION OF A NOVEL PRIMARY CELL LINE FROM A BONE METASTASIS OF OSTEOSARCOMA

Objective: Bone metastasis from osteosarcoma (OS) occurs in only 10% of patients as first relapse. Here, we report the case of a 62-year-old man, presenting a pelvic OS in 2022 followed by a metachronous scapular metastasis in 2024. We grab the opportunity to develop a preclinical model, which, to the best of our knowledge, is not available yet for bone metastasis from OS.

Methods: We enzymatically digested fresh tumour tissue to obtain a primary cell culture, namely OS-MET-R-092, which has now been cultured in vitro for over a year. We characterized OS-MET-R-092 cells in terms of growth and clonogenic potential, ability to form spheroids under 3D non-adherent culture conditions, migratory abilities and osteogenic differentiation.

Results: OS-MET-R-092 cells displayed a very slow proliferation ability and no clonogenic and osteogenic differentiative potentials. In relation to OS cell lines, OS-MET-R-092 displayed spheroid formation ability intermediate between Saos-2 and U2OS and migratory abilities comparable to Saos-2. Functionally, OS-MET-R-092 cells showed a multi-drug resistant phenotype when exposed to doxorubicin, cisplatin, gemcitabine and docetaxel (all included in the therapeutic regimen of the patient), with overexpression of ABCB1, a known chemoresistance marker in OS. As a surrogate measurement of in vivo tumorigenic ability, OS-MET-R-092 cells were seeded on the chick chorioallantoic membrane (CAM) and were allowed to grow for 7 days. Cells engrafted in 100% of CAMs, growing in bundles and forming a thick and opaque tissue, where it was possible to recognize OS cells, positive for SATB2 expression. In parallel, lively stocked tumour specimens were also engrafted on the CAM, which allowed their maintenance and growth as well as the spread of cells from the graft onto the CAM.

Conclusion: Altogether, OS-MET-R-092 could represent a useful tool for studying bone metastasis from bone sarcoma in diverse experimental settings and could be the first building block for more composite and translatable 3D models.