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Abstract: SA-PO734

Human iPSC-Derived Podocytes to Study APOL1 High-Risk Variants

Session Information

Category: Glomerular Diseases

  • 1304 Glomerular Diseases: Podocyte Biology

Authors

  • Haines, Lauren, Cleveland Clinic, Cleveland, Ohio, United States
  • Tran, Uyen, Cleveland Clinic, Cleveland, Ohio, United States
  • O'Toole, John F., Cleveland Clinic, Cleveland, Ohio, United States
  • Sedor, John R., Cleveland Clinic, Cleveland, Ohio, United States
  • Wessely, Oliver, Cleveland Clinic, Cleveland, Ohio, United States
Background

Podocytes within the glomerulus are integral to forming the filtration barrier needed for kidney function. The CDC estimates 15% of adults in the US have chronic kidney disease (CKD), but there are no curative treatment options for CKD and patients must resort to time-consuming dialysis or undergo a kidney transplant to maintain a quality of life during disease progression. The African American population of sub-Saharan descent has a 3.5-fold increased risk for end-stage kidney disease compared to populations of European descent. This incidence discrepancy is, in part, due to two pathogenic variants G1 and G2 in the apolipoprotein L1 (APOL1) gene. Individuals with the presence of one high-risk allele are resistant to African sleeping sickness, but the presence of two high-risk alleles significantly predisposes to kidney disease.

Methods

As APOL1 is only present in humans and some higher-order primates, to model its biology we have generated a series of isogenic human induced pluripotent stem cell lines (iPSCs) genetically engineered to contain APOL1 reference (G0) and high-risk (G1, G2) variant genotypes. In addition, the lab has also developed a protocol to directly differentiate iPSCs into pure populations of podocytes. Combined with our new iPSC cell lines, this provides a novel cellular model to study APOL1 high-risk variants in the cell type affected in human patients. A pure population of human high-risk APOL1 podocytes will enable additional discovery not feasible through prior means of research.

Results

Variant APOL1 iPSC lines successfully differentiate into pure podocyte populations using our podocyte differentiation protocol. These podocytes robustly express FOXD1, MAFB, and WT1. They form foot process-like cytoplasmic extensions, marked by slit diagram proteins NPHS1 and NPHS2. Upon stimulation with IFN-γ, the podocytes express APOL1. These podocytes do not demonstrate differential cell death upon induction of APOL1.

Conclusion

This research allows the integration of human-specific aspects of podocyte biology in a representative and homogenous cell population. It provides an opportunity to gain an understanding of APOL1 and the mechanism underlying APOL1-mediated diseases. Data generated using this model will help to provide directly translatable and desperately needed therapeutic intervention to kidney disease injury and progression.

Funding

  • NIDDK Support