Comparison of low-intensity pulsed ultrasound and pulsed electromagnetic field treatments on OPG and RANKL expression in human osteoblast-like cells.
OBJECTIVE
To compare two clinically applied treatments to stimulate bone healing-low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF)-for their effects on RANKL and OPG expression in osteoblast-like cells in vitro.


METHODS
LIPUS or PEMF was applied to Saos-2 cells for 10 minutes or 3 hours. RANKL and OPG expressions were analyzed at 0, 4, 8, or 12 hours after treatment with real-time PCR. Secreted protein levels in culture supernatant were analyzed at the same posttreatment time points using specific ELISA assays.


RESULTS
Neither LIPUS nor PEMF had an effect on RANKL protein expression. OPG protein was significantly increased by LIPUS after 0 and 4 hours (brief short-term effect) and was increased almost 2.5-fold by PEMF after 8 hours. The mRNA levels of OPG and RANKL were hardly affected by LIPUS treatment at any time point. PEMF induced a fivefold increase in RANKL mRNA expression at t = 0. A brief PEMF treatment of 10 minutes resulted in downregulation of RANKL expression after 0 and 4 hours and upregulation at 12 hours. OPG mRNA was downregulated after 8 hours.


CONCLUSIONS
The effects of LIPUS or PEMF expression on OPG and RANKL are limited. From our experiments, it seems that LIPUS treatment resulted in a quick protein response, while the response of cells to PEMF (3 hours) was delayed. The increase in OPG protein at 8 hours post PEMF treatment is indicative of reduction of osteolysis.
Borsje
Manon A
MA
Department of Orthodontics, University Medical Centre Groningen, University of Groningen, The Netherlands.
Ren
Yijin
Y
de Haan-Visser
H Willy
HW
Kuijer
Roel
R
D002460:Cell Line; D002478:Cells, Cultured; D015536:Down-Regulation / Q000528:radiation effects; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D055909:Magnetic Field Therapy; D010006:Osteoblasts / Q000378:metabolism / Q000528:radiation effects*; D053244:Osteoprotegerin / Q000032:analysis / Q000528:radiation effects*; D016133:Polymerase Chain Reaction / Q000379:methods; D053245:RANK Ligand / Q000032:analysis / Q000528:radiation effects*; D012333:RNA, Messenger / Q000032:analysis / Q000528:radiation effects; D013997:Time Factors; D014464:Ultrasonic Therapy; D015854:Up-Regulation / Q000528:radiation effects; D014945:Wound Healing / Q000528:radiation effects
D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; C505688:TNFSF11 protein, human