gms | German Medical Science

Objectives: Bone-derived sarcomas represent a heterogeneous group of rare mesenchymal malignant tumors that originate in bone tissue. Current treatment strategies for sarcomas include a combination of surgery, (neo)adjuvant chemotherapy before and after surgery and radiation therapy. Surgical en bloc resection is the current treatment standard for sarcomas. Before and after surgery, (neo)adjuvant chemotherapy treatments aim to shrink the tumor and kill remaining cancer cells. Despite these treatment options, the survival rate of sarcoma patients remains relatively low, underscoring the high medical need for new individual and effective treatment strategies. Therefore, patient-individual ex vivo screening systems for entity characterization are required. In the recent years three-dimensional cell cultures came into focus of basic research. 3D cultures provide insights into structural conditions and functional aspects of cells in the tissue and mimic phenotypical as well as molecular characteristics of the tissue. In particular, 3D tumor cultures enable functional and mechanistic analyses of the respective entity. For bone-related sarcomas, however, the generation of physiological microenvironments mimicking the bone niche regarding substrate stiffness and bioaccessibility is sophisticated. Although protocols for generating patient-derived 3D tumor cultures have been established for gastrointestinal tumors,optimal processing procedures and culture conditions for sarcomas are pending.

Methods: To address this challenge, sarcoma tissue was obtained from 9 patients including 2 bone-related sarcomas by either biopsy or resection and was processed within 24 h after surgery. Diagnosis was carried out based on biopsy or resected tissue. In a first step, sarcoma tissue was enzymatically digested to prepare single cell suspensions that were seeded as floating spheroid cultures (n=9) or in presence of matrigel to form organoid-like 3D structures (n=7) in serum-free medium supplemented with cytokines that promote cell survival and proliferation. Viable spheroids could be maintained for 20 (synovial sarcoma) to 28 days (liposarcoma); organoids could be viably cultured for 14 (leiomyosarcoma) up to 21 days (liposarcoma). Generated models are assessed histologically and immunohistochemically for marker expression to compare them to the respective primary tumors.

Results and conclusion: For long-term expandability of bone sarcomas, we are currently investigating different media compositions of pathway inhibitors and stimulators tailored to mimic factors present in the human bone environment. In a next step, we aim to utilize stromal cell components and 3D scaffolds to generate an artificial 3D niche that mimics the bone microenvironment to further optimize 3D sarcoma model generation with preserved intra-tumor heterogeneity. These innovative 3D patient-derived sarcoma models will allow gaining novel insights in tumor biology, therapy response and development of resistance in bone sarcomas.