The effects of adipose‐derived stem cells on CD133‐expressing bladder cancer cells

Mesenchymal stem cells (MSCs) hold great promise as therapeutic agents in regenerative medicine. They are also considered as a preferred cell source for urinary tract reconstruction. However, as MSCs exhibit affinity to tumor microenvironment, possible activation of tumor‐initiating cells remains a major concern in the application of stem cell‐based therapies for patients with a bladder cancer history. To analyze the influence of adipose‐derived stem cells (ASCs) on bladder cancer cells with stem cell‐like properties, we isolated CD133‐positive bladder cancer cells and cultured them in conditioned medium from ASCs (ASC‐CM). Our results showed that parental 5637 and HB‐CLS‐1 cells showed induced clonogenic potential when cultured in ASC‐CM. Soluble mediators secreted by ASCs increased proliferation and viability of unsorted cells as well as CD133+ and CD133− subpopulations. Furthermore, incubation with ASC‐CM modulated activation of intracellular signaling pathways. Soluble mediators secreted by ASCs increased phosphorylation of AKT1/2/3 (1.4‐fold, P