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Growth abnormalities in cultured mesangial cells from rats with spontaneous glomerulosclerosis
F Pugliese1, R G Ferrario, A Ciavolella
1Department of Medicine, University of Rome La Sapienza, Italy.
Abstract:
Age-related glomerulosclerosis (GS) occurs in normotensive rats of the Milan strain (MNS), but not in genetically-matched hypertensive animals (MHS). Altered mesangial cell (MC) proliferation and matrix expansion are common features of the glomerular scarring process. We evaluated proliferation and matrix protein synthesis of cultured MC from MNS and MHS animals aged 1 and 8 months, that is, before and after the occurrence of GS. [3H]-thymidine (TdR) incorporation into DNA of MC from MNS rats stimulated by 10% FBS serum increased with donor aging from 115 +/- 6.0 to 176 +/- 15, P < 0.01 (% cpm/well over quiescent controls +/- SEM). Under the same experimental conditions, cell counts changed from 101 +/- 4.0 to 146 +/- 5.0, P < 0.01 (% cells/well over quiescent controls). Additionally, cytosolic Ca2+ concentration ([Ca2+]i) rised from 115 +/- 19 to 220 +/- 32 nM and from 112 +/- 24 to 734 +/- 136 nM when fura-2-loaded cells from young and old MNS rats, respectively, were stimulated with 1% FBS. The rate of collagen production also increased with donor age, as well as collagen IV and laminin B1 mRNA expression. In contrast, in MC from MHS rats both DNA synthesis and cell replication rate declined as function of donor age. No differences in the [Ca2+]i responses to FBS were observed, nor collagen production changed with MHS rat senescence. We conclude that the age-associated decline of proliferative activity in MC from MHS animals could actually reflect a normal process of cell aging, possibly protecting from the occurrence of GS.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Mesangial cell (MC) proliferation and matrix synthesis differ between aging normotensive (MNS) and hypertensive (MHS) rats. MNS rats show increased MC proliferation and matrix production with age, unlike MHS rats, suggesting a protective mechanism against glomerulosclerosis in MHS.
Area of Science:
- Nephrology
- Cell Biology
- Genetics
Background:
- Age-related glomerulosclerosis (GS) is a kidney scarring process affecting mesangial cells (MC).
- Milan normotensive (MNS) rats develop GS with age, while genetically similar Milan hypertensive (MHS) rats do not.
- Understanding MC behavior in aging is crucial for explaining these differences.
Purpose of the Study:
- To investigate age-related changes in MC proliferation and matrix protein synthesis.
- To compare these changes between MNS and MHS rats.
- To elucidate potential mechanisms underlying the absence of GS in MHS rats.
Main Methods:
- Cultured MCs from 1-month-old (young) and 8-month-old (old) MNS and MHS rats.
- Assessed DNA synthesis ([3H]-thymidine incorporation) and cell counts.
- Measured cytosolic calcium ([Ca2+]i) using fura-2.
- Quantified collagen production and collagen IV/laminin B1 mRNA expression.
Main Results:
- In MNS rats, MC proliferation, DNA synthesis, [Ca2+]i response, collagen production, and related mRNA expression increased with age.
- In MHS rats, MC DNA synthesis and proliferation declined with age.
- No significant age-related changes in [Ca2+]i or collagen production were observed in MHS MCs.
Conclusions:
- Aging MNS rats exhibit increased MC proliferative activity and matrix synthesis, correlating with GS development.
- Aging MHS rats show a decline in MC proliferative capacity, potentially a protective mechanism against GS.
- Differential regulation of MC aging processes may explain the absence of GS in MHS rats.