0135
EFFECT OF LDL
ON THE PROLIFERATION OF RAT GLOMERULAR MESANGIAL CELLS IN VITRO Wu L, Wang L, Wang YW, et al. Department of Pediatrics, Changzheng Hospital,
Shanghai, China Objective: To study the effect of low density lipoprotein (LDL)on the
expression of transforming growth factor-β(TGF-β) and fibronectin (FN )mRNA
in rat glomerular mesangial cells (MsC). Methods: Mesangial cells were isolated from the
glomeruli of male Sprague- Dawley rats (Shanghai experiment animal center) aged
4 to 6 weeks, weighing 100 to 150 gm using a differential sieving
technique. Isolated glomeruli were then digested with IV collagenase (Sigma
Inc, USA). MsC were cultured in RPMI-1640 medium containing 20% fetal
bovine serum (FBS) in CO2 incubator for 2 to 3 weeks. Cells were
subcultured at one to two-week intervals. Cells between passages 3 throngh
4 were used for experiments. Cultured mesangial cells were exposed to
medium with LDL prepared from normal human plasma(50, 100, 200ug/ml) for 24
hours and with LDL 150ug/ml for 24, 48, 72 hours. 3H-TdR incorporation was
used for the detection of MsC proliferation.Anti-TGF-β antibody 10ug/ml was
added to MsC treated with LDL at concentration of 50 to 200 ug /ml for 24
hours, and 150 ug/ml for 24 to 72 hours at the end of incubation
,respectively. According to the standard method ,Northern blot and Dot blot analysis were
performed with TGF-β cDNA(2.138 kb) and FN cDNA(1.3 kb) and were used to determine
the expression of TGF-βmRNA and FN mRNA. The autoradiographs were scanned with a laser
densitometer to determine relative mRNA levels. Results: (1) LDL had biphasic effect on MsC proliferation. Low
concentration stimulated MsC proliferation in concentration-dependent (50
to 150ug/ml) and time-dependent (24 to 72 hours) manner(P<0.05),whereas
high concentration (200ug/ml) inhibited MsC proliferation (P<0.05). (2)
Northern blot analysis revealed an increase of TGF-βmRNA and FN mRNA
levels in concentration-dependent and time-dependent manner in MsC
stimulated by LDL.The expression of TGF-β mRNA was 24 hours
earlier than that of FN mRNA. (3) Dot blot analysis showed that the
expression of FN mRNA in MsC cultured with medium containing anti-TGF-βantibody decreased
significantly. Conclusion: Our results clearly demonstrate that LDL stimulates mesangial
cells proliferation and enhances TGF-βmRNA and FN mRNA expression.It is
possible that LDL may play an important role in the development and
progression of glomerular injury.Our study also suggests that TGF-βhas several potential
roles in renal disease by promoting extracellular matrix accumulation in
renal cells in vitro.