LP9 cell culture

[LP9 cells]

I have been cultivating LP( cells (human peritoneal mesothelial cells) for over a year now, but they never reach confluence. They are newly purchased, mycoplasma-free cells, and I've tried cultivating them on different plastics and coating the plates with fibronectin. I use new EGF in the medium and I even increased its concentration to encourage growth, but the LP9 cell still aren't confluent. How can I solve this problem? Any help would be greatly appreciated!