Methods for keloid spheroid formation, viability, composition, and propagation assays are detailed, involving fibroblasts and endothelial cells. Fibroblasts from commercial lines and keloid patients, and HUVECs, were cultured and mixed to form spheroids. Viability, composition, and propagation of spheroids were assessed using fluorescent staining and microscopy. Gene expression analysis by RT-PCR and drug assays with triamcinolone, fluorouracil, and bleomycin were conducted. Statistical analysis was performed using Prism 9.3.1, with significance set at p < 0.05.