Establishment of conditionally immortalised human glomerular mesangial cells in culture, with unique migratory properties

Background The aim of this study was to establish an immortalized human mesangial cell line similar to mesangial cells in vivo for use as a tool for understanding glomerular cell function. Methods Mesangial cells were isolated from glomerular outgrowths from a normal human kidney, then retrovirally transfected with a temperature sensitive SV40T antigen + human telomerase (hTERT). Results Mesangial cells exhibited features of compact cells with small bodies in a confluent monolayer at 33°C but the cell shape changed to flat and stellate after 5 days in growth restrictive conditions (37°C). Western blot and immunofluorescence analysis showed that podocyte markers (nephrin, CD2AP, podocin, WT1) and an endothelial specific molecule (VE- cadherin) were not detectable in this cell line, whereas markers characteristic of mesangial cells (α-SMA, Fibronectin and PDGFβ-R were strongly expressed. In migration assays, a significant reduction in wound surface was observed in podocyte and endothelial cells as soon as 12 hours (75% and 62% respectively) and complete wound closure after 24 hours. In contrast, no significant change was observed in mesangial cells after 12 hours and even after 48 hours the wounds were not completely closed. Discussion Until now conditionally immortalized podocyte and endothelial cell lines derived from mouse and human have been described and this has greatly boosted research on glomerular physiology and pathology. We have established the first conditionally immortalized human glomerular mesangial cell line, which will be an important adjunct in studies of representative glomerular cells, as well as in co-culture studies. Unexpectedly mesangial cells ability to migrate seems to be slower than other glomerular cells suggesting this line will demonstrate functional properties distinct from previously available mesangial cell cultures. Conclusion This conditionally immortalized human mesangial cell line represents a new tool for the study of human mesangial cell biology in vitro.