Ewing Sarcoma metastatic invasion dissected through new 3D vascularized human microfluidic models recapitulating endochondral ossification

Ewing’s Sarcoma (EwS) is an aggressive form of childhood cancer and represents the second most common bone tumor in children and adolescents. No significant progress has been made for bone metastatic disease, in which case only 6% of patients survives at 5 years, mainly due to the poor understanding of EwS metastasis formation. Substantial evidences indicate a key role of the bone niche in guiding the metastatic process, but only few works have been published regarding the interactions between cells of bone microenvironment and EwS cells. Recent works show the great potential of innovative 3D models in recapitulating key characteristics of EwS. However, no 3D in vitro model of metastatic EwS (metEwS) based on human cells has been reported, allowing mechanistic and physiologically more accurate investigation of metastatic pathways. Furthermore, present models mimic only fully-mature bone, while EwS originates and thrives in young patients with a developing skeleton, thus subjected to a process of endochondral ossification (ECO), which starts from a cartilage template, finally resulting in bone formation. In this project, we hypothesize that deregulation of developmental pathways and microenvironmental factors specifically active during ECO can be involved or even trigger metEwS cells extravasation and metastases formation. Since no reliable experimental in vitro model of metEwS is available, recapitulating the crosstalk between metEwS cells and a 3D human bone microenvironment, we will generate a fully-human, vascularized microfluidic 3D model of developing bone.