Gene

Alkaline phosphatase

Molecular biology

Type I collagen

Biology

Messenger RNA

Western blot

Type II collagen

Chromatography

Endocrinology

Extracellular matrix

Cartilage

Biochemistry

Collagen, type I, alpha 1

Hydroxyproline

Chondrocyte

Matrix (chemical analysis)

Organic chemistry

Anatomy

In vitro

Enzyme

Matrix metalloproteinase

Strontium

Chemistry

Gene expression

Biological Trace Element Research

Strontium stimulates cartilage matrix formation in vitro. However, the mechanisms governing these effects have not yet been extensively reported. In this study, chondrocytes were isolated from rat articular cartilage by enzymatic digestion and cultured for 24–72 h with 1–5 mM strontium. We investigated the effects of different concentrations of strontium on collagen content, type II collagen, insulin-like growth factor (IGF-1) and matrix metalloproteinase (MMP)-13 expression in rat cultured articular chondrocytes in vitro. The collagen content of the chondrocytes, determined as hydroxyproline, was measured by a colorimetry method. Type II collagen, IGF-1, and MMP-13 mRNA abundance and protein expression levels were determined by real-time polymerase chain reaction (real-time PCR) and western blot, respectively. The results showed that collagen content from the chondrocytes extracellular matrix increased with increasing strontium concentration. Moreover, 3 and 5 mM strontium strongly stimulated protein expression and mRNA levels of type II collagen and IGF-1. Conversely, MMP-13 expression in chondrocytes decreased dose-dependently with increasing strontium concentration. These results should provide insight into the ability of strontium to promote chondrocyte extracellular matrix synthesis. Strontium could promote collagen synthesis and suppress collagen degradation via the repression of MMP-13 expression.

Effects of Strontium on Collagen Content and Expression of Related Genes in Rat Chondrocytes Cultured In Vitro