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Pulsed electromagnetic fields increase growth factor release by nonunion cells.
H H Guerkov1, C H Lohmann, Y Liu
1Department of Orthopaedics, University of Texas Health Science Center at San Antonio, 78229-3900, USA.
Clinical Orthopaedics and Related Research
|March 16, 2001
Summary
Pulsed electromagnetic field stimulation increases transforming growth factor-beta 1 in human nonunion cells. This early event suggests a cascade of regulatory events leading to healing in nonunions.
Area of Science:
- Biomedical Engineering
- Orthopedic Research
- Cell Biology
Background:
- The precise mechanisms by which pulsed electromagnetic fields (PEMF) promote bone healing in nonunions remain unclear.
- Previous studies in animal and cell models indicate PEMF may stimulate endochondral ossification via increased cartilage production and transforming growth factor-beta 1 (TGF-β1).
Purpose of the Study:
- To investigate the effect of PEMF stimulation on cells derived from human hypertrophic and atrophic nonunion tissues.
- To determine if TGF-β1 production is an early response to PEMF in these human nonunion cells.
Main Methods:
- Human hypertrophic (n=3) and atrophic (n=4) nonunion cells were cultured.
- Cells were exposed to a PEMF (4.5-ms bursts, 20 pulses/15 Hz) for 8 hours/day over 1, 2, or 4 days.
- Conditioned media were analyzed for TGF-β1 levels, cell number, DNA synthesis, alkaline phosphatase, collagen, prostaglandin E2, and osteocalcin.
Main Results:
- A time-dependent increase in TGF-β1 was observed in PEMF-treated hypertrophic nonunion cells by Day 2 and in atrophic nonunion cells by Day 4.
- PEMF stimulation did not significantly affect cell number, DNA synthesis, alkaline phosphatase activity, collagen synthesis, or prostaglandin E2 and osteocalcin production.
- TGF-β1 production was identified as an early response, with a delayed onset (>24 hours) in both cell types.
Conclusions:
- Human nonunion cells exhibit a response to PEMF stimulation in vitro.
- PEMF treatment initiates an early increase in TGF-β1 production, suggesting its role in the therapeutic mechanism.
- The delayed response indicates that PEMF likely triggers a cascade of regulatory events leading to growth factor synthesis and release, contributing to nonunion healing.