Sodium/glucose co-transporter-2 inhibitor (SGLT2i) or dipeptidyl peptidase IV inhibitor (DPP4i) is a newer anti-diabetic drug in type II diabetes mellitus (DM), but their use in tacrolimus (TAC)-induced DM is still undetermined. We performed this study to evaluate the effect of these two drugs in TAC-induced DM and nephrotoxicity in ex vivo and in vivo. In the experimental Sprague Dawley rat model of TAC-induced DM and nephrotoxicity, dual inhibition of DPP4 and SGLT2 significantly decreased blood glucose level, HbA1C and increased plasma insulin levels and pancreatic islet size compared with each drug. In the kidney, dual inhibition improved renal function decreased interstitial fibrosis and profibrotic cytokines compared with DPP4i and SGLT2i alone. Increased oxidative stress by TAC was remarkably decreased with DPP4i or SGLT2i in serum, pancreatic and renal tissues and this decrease was much more significant in the combination group. In in vitro study, TAC decreased the cell viability of human kidney-2(HK-2) cells and insulin-secreting beta-cell-derived line(INS-1) cells. SGLT2i protected TAC-induced cell death in HK-2 cells, but not in INS-1 cells. The addition of DPP4i to SGLT2i compensated for a lack of protective effect of SGLT2i on INS-1 cells. This finding provides the rationale for the combined treatment of SGLG2i and DPP4i in TAC-induced DM and nephrotoxicity.

Tissue kallikrein has protective function against various types of injury. In this study, we investigated whether exogenous pancreatic kininogenase (PK) conferred renoprotection in a rat model of unilateral ureteral obstruction (UUO) and H₂O₂-treated HK-2 cells in vitro. SD rats were subjected to UUO surgery, then PK (7.2 U/g per day, ip) was administered for 7 or 14 days. After the treatment, rats were euthanized; the obstructed kidneys were harvested for further examination. We found that PK administration significantly attenuated interstitial inflammation and fibrosis, and downregulated the expression of proinflammatory (MCP-1, TLR-2, and OPN) and profibrotic (TGF-β1 and CTGF) cytokines in obstructed kidney. UUO-induced oxidative stress, closely associated with excessive apoptotic cell death and autophagy via PI3K/AKT/FoxO1a signaling, which were abolished by PK administration. We further showed that PK administration increased the expression of bradykinin receptors 1 and 2 (B1R and B2R) mRNA and the production of NO and cAMP in kidney tissues. Coadministration with either B1R antagonist (des-Arg9-[Leu8]-bradykinin) or B2R antagonist (icatibant) abrogated the renoprotective effects of PK, and reduced the levels of NO and cAMP in obstructed kidney. In H₂O₂-treated HK-2 cells, addition of PK (6 pg/mL) significantly decreased ROS production, regulated the expression of oxidant and antioxidant enzymes, suppressed the expression of TGF-β1 and MCP-1, and inhibited cell apoptosis. Our data demonstrate that PK treatment protects against the progression of renal fibrosis in obstructed kidneys.

The aim of this study is to explore the possibility of modeling Gitelman’s disease (GIT) with human-induced pluripotent stem cell (hiPSC)-derived kidney organoids and to test whether gene correction using CRISPR/Cas9 can rescue the disease phenotype of GIT. To model GIT, we used the hiPSC line CMCi002 (CMC-GIT-001), generated using PBMCs from GIT patients with SLC12A3 gene mutation. Using the CRISPR-Cas9 system, we corrected CMC-GIT-001 mutations and hence generated CMC-GIT-001^corr. Both hiPSCs were differentiated into kidney organoids, and we analyzed the GIT phenotype. The number of matured kidney organoids from the CMC-GIT-001^corr group was significantly higher, 3.3-fold, than that of the CMC-GIT-001 group (12.2 ± 0.7/cm² vs. 3.7 ± 0.2/cm², p < 0.05). In qRT-PCR, performed using harvested kidney organoids, relative sodium chloride cotransporter (NCCT) mRNA levels (normalized to each iPSC) were increased in the CMC-GIT-001^corr group compared with the CMC-GIT-001 group (4.1 ± 0.8 vs. 2.5 ± 0.2, p < 0.05). Consistently, immunoblot analysis revealed increased levels of NCCT protein, in addition to other tubular proteins markers, such as LTL and ECAD, in the CMC-GIT-001^corr group compared to the CMC-GIT-001 group. Furthermore, we found that increased immunoreactivity of NCCT in the CMC-GIT-001^corr group was colocalized with ECAD (a distal tubule marker) using confocal microscopy. Kidney organoids from GIT patient-derived iPSC recapitulated the Gitelman’s disease phenotype, and correction of SLC12A3 mutation utilizing CRISPR-Cas9 technology provided therapeutic insight.

Genetic or hereditary kidney disease stands as a pivotal cause of chronic kidney disease (CKD). The proliferation and widespread utilization of DNA testing in clinical settings have notably eased the diagnosis of genetic kidney diseases, which were once elusive but are now increasingly identified in cases previously deemed CKD of unknown etiology. However, despite these diagnostic strides, research into disease pathogenesis and novel drug development faces significant hurdles, chiefly due to the dearth of appropriate animal models and the challenges posed by limited patient cohorts in clinical studies. Conversely, the advent and utilization of human-induced pluripotent stem cells (hiPSCs) offer a promising avenue for genetic kidney disease research. Particularly, the development of hiPSC-derived kidney organoid systems presents a novel platform for investigating various forms of genetic kidney diseases. Moreover, the integration of the CRISPR/Cas9 technique into this system holds immense potential for efficient research on genetic kidney diseases. This review aims to explore the applications of in vitro kidney organoids generated from hiPSCs in the study of diverse genetic kidney diseases. Additionally, it will delve into the limitations of this research platform and outline future perspectives for advancing research in this crucial area.

Endothelial cell (EC) dysfunction is a frequent feature in patients with end-stage renal disease (ESRD). The aim of this study was to generate human induced pluripotent stem cells, differentiate ECs (hiPSC-ECs) from patients with ESRD, and appraise the usefulness of hiPSC-ECs as a model to investigate EC dysfunction. We generated hiPSCs using peripheral blood mononuclear cells (PBMCs) isolated from three patients with ESRD and three healthy controls (HCs). Next, we differentiated hiPSC-ECs using the generated hiPSCs and assessed the expression of endothelial markers by immunofluorescence. The differentiation efficacy, EC dysfunction, and molecular signatures of EC-related genes based on microarray analysis were compared between the ESRD and HC groups. In both groups, hiPSCs and hiPSC-ECs were successfully obtained based on induced pluripotent stem cell or EC marker expression in immunofluorescence and flow cytometry. However, the efficiency of differentiation of ECs from hiPSCs was lower in the ESRD-hiPSCs than in the HC-hiPSCs. In addition, unlike HC-hiPSC-ECs, ESRD-hiPSC-ECs failed to form interconnecting branching point networks in an in vitro tube formation assay. During microarray analysis, transcripts associated with oxidative stress and inflammation were upregulated and transcripts associated with vascular development and basement membrane extracellular matrix components were downregulated in ESRD-hiPSC-ECs relative to in HC-hiPSC-ECs. ESRD-hiPSC-ECs showed a greater level of EC dysfunction than HC-hiPSC-ECs did based on functional assay results and molecular profiles. hiPSC-ECs may be used as a disease model to investigate the pathophysiology of EC dysfunction in ESRD.