Contribution of aldose reductase to diabetic hyperproliferation of vascular smooth muscle cells

Area of Science:

• Biochemistry
• Vascular Biology
• Diabetic Complications

Background:

• Diabetes mellitus is associated with vascular abnormalities, including abnormal vascular smooth muscle cell (SMC) growth.
• The polyol pathway, particularly the enzyme aldose reductase, is implicated in mediating these diabetes-related vascular dysfunctions.

Purpose of the Study:

• To investigate the role of aldose reductase in mediating diabetes-induced vascular SMC growth.
• To evaluate the therapeutic potential of aldose reductase inhibition in preventing vascular abnormalities in diabetes.

Main Methods:

• Cultured rat aortic SMCs were exposed to high glucose conditions.
• Aldose reductase inhibitors (tolrestat, sorbinil) or antisense aldose reductase mRNA were used to inhibit enzyme activity.
• In vivo studies involved balloon-injured carotid arteries in streptozotocin-induced diabetic rats treated with tolrestat.
• Vascular smooth muscle cell proliferation, intimal hyperplasia, and oxidative stress markers were assessed.

Main Results:

• High glucose induced SMC hyperproliferation in vitro, which was prevented by aldose reductase inhibitors or antisense mRNA.
• Tolrestat treatment blocked high glucose-induced cell cycle progression, causing G0-G1 phase arrest.
• In vivo, diabetes increased SMC growth and intimal hyperplasia; tolrestat treatment significantly reduced these effects.
• Tolrestat treatment increased markers of oxidative stress but did not lead to increased lesion fibrosis.

Conclusions:

• Aldose reductase inhibition effectively prevents high glucose-induced SMC proliferation in both cell culture and in vivo models.
• Inhibition of aldose reductase may be a viable strategy for preventing abnormal vascular SMC growth and intimal hyperplasia in diabetic patients.
• Despite increasing vascular oxidative stress, aldose reductase inhibition shows promise for managing diabetic vascular complications.