Anabolic effects of low-intensity pulsed ultrasound on human gingival fibroblasts☆
Accepted 25 April 2009.
Abstract
Objective
Low-intensity pulsed ultrasound (LIPUS) demonstrated anabolic effects on cementoblasts, odontoblasts, and periodontal ligament cells. However, LIPUS effect on human gingival fibroblasts (HGF) remains to be investigated. Therefore, we evaluated the in vitro effects of LIPUS on HGF proliferation and differentiation to test its feasibility for periodontal therapy.
Design
LIPUS treatment (1.5MHz, 30mW/cm2) was applied to HGF in the experimental groups after 24-h of culture (5 or 10min/day for 28 days) and omitted in the control. Changes in HGF activities were evaluated in response to LIPUS treatment in dose-dependent (5 and 10min) and time-dependent (weeks 1–4) manner. The effects of LIPUS on HGF cell viability (MTT), proliferation (total DNA content and growth pattern), alkaline phosphatase (ALP) activity, and gene expression by reverse-transcriptase polymerase chain reaction (RT-PCR) were determined.
Results
Cell viability remained unchanged after LIPUS treatment during the 4 weeks of treatment as compared to the untreated control group which ensured a safe biological response. Both LIPUS treatments (5–10min/day) did not yield any significant changes in the proliferation, and expression of proliferating cell nuclear antigen (PCNA) and collagen-I (COL-I). Conversely, LIPUS treatment enhanced osteogenic differentiation potential of HGF as determined by significant up-regulation of specific ALP activity and osteopontin (OPN) expression, with optimum effect following 3 weeks of 5min/day LIPUS treatment.
Conclusion
LIPUS treatment at 30mW/cm2 selectively enhanced HGF differentiation but not proliferation. The ability of LIPUS to enhance HGF differentiation is promising for its application in cell-based periodontal therapy.
aDepartment of Dentistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
bDepartment of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
cDepartment of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB, Canada
dFaculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada
Corresponding author at: Faculty of Medicine and Dentistry, Room 4051C, Dentistry/Pharmacy Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2N8. Tel.: +1 780 492 2751; fax: +1 780 492 1624.
☆ Based on a thesis submitted to the Faculty of Medicine and Dentistry, at the University of Alberta in partial fulfilment of the requirements for an MSc Degree.
ABSTRACT