Autosomal dominant polycystic kidney disease (
ADPKD) is a common
genetic disorder characterized by the relentless growth of numerous fluid-filled
cysts in the kidneys. Mutations in PKD1 and PKD2, genes that encode
polycystin 1 and 2, respectively, are responsible for most cases of
ADPKD. Currently, the cellular mechanisms responsible for
cyst formation remain poorly understood. In vitro models have been used by researchers to investigate cellular processes for
cyst formation in carefully controlled experimental conditions. Madin-Darby canine kidney (MDCK) cells, a distal tubule epithelial cell line, were first used to form 3-dimensional (3-D)
cysts within a hydrated
collagen gel. This method was applied to epithelial cells cultured from
cysts of human
ADPKD kidneys, allowing investigators to study cellular mechanisms for
cyst growth using cells that harbor the genetic mutations responsible for
ADPKD in humans. Studies using
ADPKD in vitro
cysts have provided insight into cellular processes regulating cell proliferation, fluid secretion, and cell polarity. These assays were used to demonstrate the central role of cAMP agonists, such as
arginine vasopressin, on
cyst growth; and to test the effectiveness of potential therapeutic agents, including
tolvaptan. Results obtained from in vitro
cyst experiments demonstrate the translational value of cell model systems for investigating the mechanisms for
cyst formation in human
ADPKD. In this chapter, we describe protocols for growing
ADPKD cells in a 3-D in vitro
cyst assay and measuring total
cyst volume by microscopy and image analysis.