Rejuvenated Kidney Stem Cells Model APOL1 Disease and Test Baricitinib

Chronic kidney disease (CKD) afflicts roughly 850 million people globally, yet studying its cellular mechanisms is hampered by the inability of key kidney cells—especially podocytes—to divide in vivo. Existing models rely on mouse systems, HEK293 overexpression constructs, or temperature-sensitive SV40 immortalized lines, none of which authentically recapitulate the human disease context, particularly for APOL1 high-risk variants prevalent in people of West African ancestry.

To address this gap, the research team isolated urine-derived renal progenitor cells from a healthy 30-year-old West African male and partially reprogrammed them using non-integrative episomal plasmids carrying OCT4, SOX2, NANOG, c-MYC, and KLF4, together with SV40 large T antigen and small molecule pathway inhibitors (SB431245, PD0325901, CHIR99021). Rather than pursuing full iPSC colonies, the team selected rapidly proliferating, mesenchymal-like partially reprogrammed clusters that retained the renal progenitor identity of the donor cells. The resulting line, UM30-OSN, has been maintained stably for over one year.

Characterization confirmed robust renal progenitor identity: immunofluorescence, FACS, and qPCR all detected SIX2, CD133, and CD24, alongside the pluripotency-associated surface marker SSEA4. Critically, senescence markers p21 and p53 were downregulated while proliferation and telomere-maintenance genes PCNA, KI67, and TERT were upregulated, confirming functional rejuvenation. Upon seven-to-fourteen-day differentiation in retinoic acid-supplemented medium on collagen I, cells expressed canonical podocyte markers NPHS1 (Nephrin), NPHS2 (Podocin), SYNPO (Synaptopodin), and CD2AP. Whole-transcriptome comparison with the gold-standard immortal podocyte line AB 8/13 yielded a correlation coefficient of R²=0.88, validating physiological relevance.

Because the donor carries the APOL1 G1/G0 genotype—associated with elevated CKD risk—the team used UM30-OSN-derived podocytes to model IFN-γ-induced APOL1 activation. Stimulation with 100 ng/ml IFN-γ for 24 hours triggered STAT1 phosphorylation via the JAK/STAT pathway and upregulated APOL1 expression. Downstream, pro-inflammatory cytokine IL-6, the profibrotic factor TGF-β, and mesenchymal/fibrotic matrix proteins Vimentin and Fibronectin were all elevated. Cells also displayed morphological stress changes consistent with podocyte injury. Pre-treatment with 1 µM Baricitinib (a clinically approved JAK1/JAK2 inhibitor) for 24 hours before IFN-γ exposure effectively blocked STAT1 phosphorylation, reduced expression of all pro-inflammatory and fibrosis-associated genes, and preserved normal podocyte morphology—demonstrating the therapeutic potential of JAK inhibition in APOL1-related nephropathy.

The UM30-OSN line offers several advantages over current models: it retains the endogenous APOL1 regulatory context absent from overexpression systems, maintains stable phenotype without repeated reprogramming, and is derived from a donor group disproportionately affected by APOL1-associated CKD. Limitations include single-donor origin, lack of a matched G2/G2 high-risk control line, and the in vitro nature of the system, which cannot replicate the full complexity of glomerular biology including immune cell crosstalk and hemodynamic forces.