Impairment of chondrocyte biosynthetic activity by exposure to 3-tesla high-field magnetic resonance imaging is temporary.
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-1beta, 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-1beta, 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.
Sunk
Ilse-Gerlinde
IG
Department of Internal Medicine III, Division of Rheumatology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. ilse-
Trattnig
Siegfried
S
Graninger
Winfried B
WB
Amoyo
Love
L
Tuerk
Birgit
B
Steiner
Carl-Walter
CW
Smolen
Josef S
JS
Bobacz
Klaus
K
D053674:Aggrecans / Q000235:genetics; D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002417:Cattle; D002470:Cell Survival / Q000528:radiation effects; D019902:Chondrocytes / Q000378:metabolism* / Q000502:physiology; D015536:Down-Regulation; D004574:Electromagnetic Fields; D015870:Gene Expression / Q000528:radiation effects; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D066298:In Vitro Techniques; D053583:Interleukin-1beta / Q000235:genetics; D046911:Macromolecular Substances / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008662:Metacarpophalangeal Joint / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D010012:Osteogenesis / Q000528:radiation effects; D013997:Time Factors
D053674:Aggrecans; D006025:Glycosaminoglycans; D053583:Interleukin-1beta; D046911:Macromolecular Substances; C013786:A73025