Human kidney-derived tubular organoid, tubuloid, recapitulates cellular senescence, inflammation and fibrosis by repeated-cisplatin treatment

Kidney organoids derived from human pluripotent stem cells have been an attracting pathophysiological model recapitulating the response of human kidney to drugs in recent years. Here, we have developed an alternative way to make more homogeneous epithelial-like structures called “tubuloid” based on primary human renal proximal tubular epithelial cells (hRPTECs) cultured from human resected kidneys and tested their efficacy by administering cisplatin at three concentrations of 0.2, 2.0, and 20.0 µg/mL. Tubuloids showed highly differentiated structures composed of proximal tubular epithelial cells with expression of LTL and LRP2/Megalin. Treatment of tubuloids with cisplatin increased γH2AX, a marker for DNA damage, in a dose-dependent manner. Kidney Injury Molecule-1 (KIM-1), a marker of kidney injury, and cleaved caspase-3, a marker for apoptotic signals were expressed due to cisplatin treatment. Repeated administration of cisplatin resulted in upregulation of the cellular senescence marker p16 and enhanced expression of inflammatory cytokines IL-1β and IL-6, indicating an induced senescence-associated secretory phenotype (SASP). Myofibroblast activation was also induced by the supernatant collected from cisplatin-treated tubuloids, which could reflect renal fibrosis. Thus, we succeeded in establishing a model of cisplatin-induced kidney injury based on tubuloids using hRPTECs. Tubuloids have the potential to serve as a novel pathological model and can be utilized to simulate the response of renal epithelial cells to toxins and therapeutic agents. Given its capability to replicate cellular senescence, SASP and the fibrosis, tubuloids could potentially serve as a pathophysiological model for chronic kidney disease (CKD), which is known for fibrosis as a final common pathological pathway.