Impairment of chondrocyte biosynthetic activity by exposure to 3-tesla high-field magnetic resonance imaging is temporary

Ilse-Gerlinde Sunk,Josef S Smolen,Carl-Walter Steiner,Klaus Bobacz,Winfried B Graninger,Love Amoyo,Birgit Tuerk,Siegfried Trattnig

doi:10.1186/ar1991

Abstract

The influence of magnetic resonance imaging (MRI) devices at high field strengths on living tissues is unknown. We investigated the effects of a 3-tesla electromagnetic field (EMF) on the biosynthetic activity of bovine articular cartilage. Bovine articular cartilage was obtained from juvenile and adult animals. Whole joints or cartilage explants were subjected to a pulsed 3-tesla EMF; controls were left unexposed. Synthesis of sulfated glycosaminoglycans (sGAGs) was measured by using [35S]sulfate incorporation; mRNA encoding the cartilage markers aggrecan and type II collagen, as well as IL-1β, were analyzed by RT–PCR. Furthermore, effects of the 3-tesla EMF were determined over the course of time directly after exposure (day 0) and at days 3 and 6. In addition, the influence of a 1.5-tesla EMF on cartilage sGAG synthesis was evaluated. Chondrocyte cell death was assessed by staining with Annexin V and TdT-mediated dUTP nick end labelling (TUNEL). Exposure to the EMF resulted in a significant decrease in cartilage macromolecule synthesis. Gene expression of both aggrecan and IL-1β, but not of collagen type II, was reduced in comparison with controls. Staining with Annexin V and TUNEL revealed no evidence of cell death. Interestingly, chondrocytes regained their biosynthetic activity within 3 days after exposure, as shown by proteoglycan synthesis rate and mRNA expression levels. Cartilage samples exposed to a 1.5-tesla EMF remained unaffected. Although MRI devices with a field strength of more than 1.5 T provide a better signal-to-noise ratio and thereby higher spatial resolution, their high field strength impairs the biosynthetic activity of articular chondrocytes in vitro. Although this decrease in biosynthetic activity seems to be transient, articular cartilage exposed to high-energy EMF may become vulnerable to damage.

Highlights

The imaging of articular cartilage in clinical practice relies mainly on conventional radiography and ultrasound
In contrast to the planar images provided by conventional radiographic techniques, MRI permits the assessment of the MRI techniques require patients to be exposed to an intense electromagnetic field (EMF) of a strength not BM = basal medium; bp = base pairs; EMF = electromagnetic field; IL = interleukin; MRI = magnetic resonance imaging; PBS = phosphate-buffered saline; RT–PCR = reverse transcriptase-mediated polymerase chain reaction; sulfated glycosaminoglycans (sGAGs) = sulfated glucosaminoglycan; TUNEL = terminal deoxynucleotidyl-transferase (TdT)-mediated dUTP nick end labelling
The exposure of whole joints to a 3-tesla EMF affects cartilage biosynthetic activity Because low-energy EMFs have been reported to increase cartilage matrix synthesis, we investigated the effects of a high-energy 3-tesla EMF on the biosynthetic activity of articular cartilage

Summary

Introduction

The imaging of articular cartilage in clinical practice relies mainly on conventional radiography and ultrasound. This allows one to evaluate cartilage defects and thinning in regions of the joint not visible to radiography or ultrasound, which provides greater sensitivity to change. In contrast to the planar images provided by conventional radiographic techniques, MRI permits the assessment of the MRI techniques require patients to be exposed to an intense electromagnetic field (EMF) of a strength not BM = basal medium; bp = base pairs; EMF = electromagnetic field; IL = interleukin; MRI = magnetic resonance imaging; PBS = phosphate-buffered saline; RT–PCR = reverse transcriptase-mediated polymerase chain reaction; sGAG = sulfated glucosaminoglycan; TUNEL = TdT-mediated dUTP nick end labelling

Results

Discussion

Conclusion