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Abstract: PO0879

Kidney Organoids Derived from a Pediatric Patient with Type 1 Diabetes and Steroid-Dependent Nephrotic Syndrome Show Losses of Podocyte Podocalyxin and Increased Proximal Tubule Injury

Session Information

Category: Development, Stem Cells, and Regenerative Medicine

  • 500 Development, Stem Cells, and Regenerative Medicine

Authors

  • Lee, Nathan, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Choi, Kyung hwa, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Cheng, Shun-Yang, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Riella, Leonardo V., Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham and Women's Hospital, Boston, Massachusetts, United States
Background

Whole exome sequencing of a pediatric patient, who at age 3 developed Type 1 diabetes mellitus and steroid-dependent nephrotic syndrome, revealed a de novo heterozygous mutation of the GREM1 gene. Gremlin is a BMP antagonist crucial for kidney development and also implicated later in life in diabetic kidney disease. Specifically, gremlin has been associated with kidney inflammation, Notch activation and fibrosis, and proposed to be a mediator of diabetic nephropathy and other progressive kidney diseases. 3D kidney organoids differentiated from induced pluripotent stem cells (hiPSCs) provide a platform technology to explore the effects of genetic changes on pathobiology of human tissue.

Methods

An induced pluripotent stem cell (iPSC) line was created from the patient. Organoids were generated from iPSCs by modifications of our laboratory’s prior published techniques without use of undefined matrices. Structures of kidney organoids were imaged by immunostaining for LTL, CDH1, GATA3, PODXL, NPHS1, NPHS2, and CD31. Organoids were also stained for gremlin, SGLT2, and KIM-1 to investigate phenotypes.

Results

A de novo heterozygous mutation of the GREM1 gene was identified. The GREM1 mutation specifically eliminates one of the three known GREM1 splicing isoforms while leaving the other two intact. When compared to organoids generated from embryonic stem cells or BJFF iPSCs the patient-derived organoids had several kidney disease phenotypes including decreased expression of podocalyxin, aberrant expression of SGLT2, and pronounced expression of KIM-1, an indicator of proximal tubule injury. The phenotypes could be rescued by treatment of the kidney organoids with recombinant GREM1 protein, altering the balance of long and short forms of gremlin.

Conclusion

Organoids derived from a patient with a GREM1 heterozygous mutation demonstrated decreased podocalyxin, aberrant SGLT2 staining, and increased proximal tubule injury. Better understanding of the relative roles for GREM1 isoforms could lead to better understanding of diabetic progressive kidney disease and organoids can be used to find potential therapies.

Funding

  • NIDDK Support