Figure 1. Pkd1 null cells preferentially form cysts and hyperproliferate in vitro.

Cells were suspended in a 70:30 collagen:Matrigel mixture and grown for 5 days before quantitation of tubular or cystic structures. (a) Heterozygous PH cells formed mostly linear branching structures with less than 3% cystic structures. (b) Pkd1 null PN cells formed a mixture of cystic structures (arrows) as well as structures that were more linear in shape (arrowheads). (c) Quantitation of the percentage of cystic structures formed for each cell genotype; n=8 for PN (4 each for PN18 and PN24) and n=6 for PH (3 each for PH2 and PH3) cells, respectively, *P<0.001. (d) A total of 1×10⁴ cells from each genotype were plated and cultured for 48 h in the presence of 10% FBS before trypsinization and counting; n=4 for each cell type, *P<0.005 vs the PH2 or PH3 cell lines. (e) Cells were cultured at equal densities and labeled with BrdU for 30 min. BrdU-positive cells were detected by FACS analysis as described; n=4 for each cell type, *P<0.002 vs the PH2 or PH3 cell lines. (f) Cells were cultured at equal densities and serum starved for 48 h before harvest and Annexin V staining and FACS analysis as described; n=3 separate experiments for each cell line, *P<0.01 vs the PH2 or PH3 cell lines.