Autosomal dominant polycystic kidney disease (ADPKD) is the most common life- threatening genetic disease in humans, affecting between 1:400 and 1:1000 people worldwide. ADPKD patients suffer from massive cysts in the kidney, leading to eventual renal failure, as well as specific cardiovascular problems, in particular intracranial aneurysms which can rupture and cause mortality. ADPKD is caused by heterozygous mutations in either PKD1 or PKD2 encoding polycystin-1 and polycystin-2, respectively, which form a flow-sensing channel complex at the primary cilium of renal epithelial and blood vessel endothelial cells. Since animals models are low-throughput and do not fully recapitulate human biology, more accurate and higher-throughput laboratory models are required to study human ADPKD. Induced pluripotent stem (iPS) cells have revolutionized our ability to develop patient-specific in vitro disease models. Our laboratory has recently generated six iPS cell lines from two ADPKD patients (ADPKD- iPS). We will first demonstrate that these are true pluripotent iPS cell lines capable of generating cell types from each of the three germ layers in embryoid bodies (EBs). We will also characterize the genetic mutations and polycystin expression levels in these cells. To develop ADPKD-iPS cells into an in vitro disease model, ADPKD-iPS cells or their derivative EBs will be inspected for phenotypes relating to ciliary function or cystogenesis. We will measure the morphology of ADPKD-iPS or EB cilia compared to healthy iPS lines and quantify ciliary polycystin levels by quantitative fluorescence intensity co-localization. In addition, ADPKD-iPS will be differentiated into either renal tubular epithelial cells, which form ADPKD cysts in vivo, or alternatively endothelial cells, which may give rise to intracranial aneurysms. These cell types will be screened for disease phenotypes related to epithelialization and tubulogenesis, ciliogenesis, and calcium release, since polycystins function as flow-sensory calcium channels at the primary cilium. Finally, we will model 'second hit'somatic mutations using siRNA polycystin knockdown to exacerbate phenotypes, and model gene therapy using wild- type over-expression to rescue them. Establishment of a human, in vitro model for ADPKD will enhance our understanding of disease pathology, allow for the testing of candidate therapeutic agents, and facilitate high-throughput therapeutics screens.
Autosomal dominant polycystic kidney disease (ADPKD) is the most common life- threatening genetic disease, affecting ~1:500 people. Our group has recently engineered induced pluripotent stem cells from ADPKD patients. We will develop these cell lines into laboratory models of human ADPKD in multiple tissues, to investigate the causes of the disease and test potential cures.
