Identify the protein contents within the fluids secreted by transplanted human vascularized lung organoid

We recently established a hPSC-derived 3D organoid system to mimic the vascularization process during lung differentiation. To further mature the organoid, we embedded them into the mouse kidney capsule for three months and observed the accumulation of fluid within the growing organoids. Therefore, we aim to understand if there are any proteins related to lung function are being secreted in this case.