Abstract
Pulsed electromagnetic field (PEMF) has been successfully applied to accelerate fracture repair since 1979. Recent studies suggest that PEMF might be used as a nonoperative treatment for the early stages of osteonecrosis. However, PEMF treatment requires a minimum of ten hours per day for the duration of the treatment. In this study, we modified the protocol of the single-pulsed electromagnetic field (SPEMF) that only requires a 3-minute daily treatment. In the in vitro study, cell proliferation and osteogenic differentiation was evaluated in the hBMSCs. In the in vivo study, new bone formation and revascularization were evaluated in the necrotic bone graft. Results from the in vitro study showed no significant cytotoxic effects on the hBMSCs after 5 days of SPEMF treatment (1 Tesla, 30 pulses per day). hBMSC proliferation was enhanced in the SPEMF-treated groups after 2 and 4 days of treatment. The osteogenic differentiation of hBMSCs was significantly increased in the SPEMF-treated groups after 3–7 days of treatment. Mineralization also increased after 10, 15, 20, and 25 days of treatment in SPEMF-treated groups compared to the control group. The 7-day short-course treatment achieved similar effects on proliferation and osteogenesis as the 25-day treatment. Results from the in vivo study also demonstrated that both the 7-day and 25-day treatments of SPEMF increased callus formation around the necrotic bone and also increased new vessel formation and osteocyte numbers in the grafted necrotic bone at the 2nd and 4th weeks after surgery. In conclusion, the newly developed SPEMF accelerates osteogenic differentiation of cultured hBMSCs and enhances bone repair, neo-vascularization, and cell growth in necrotic bone in mice. The potential clinical advantage of the SPEMF is the short daily application and the shorter treatment course. We suggest that SPEMF may be used to treat fractures and the early stages of osteonecrosis.
Highlights
The clinical application of Pulsed electromagnetic field (PEMF) for treatment of fracture healing has been known for nearly 30 years [1]
Alkaline Phosphatase (ALP) Activity Assay hBMSCs cultured in osteo-induction medium showed significantly increased ALP activity by single-pulsed electromagnetic field (SPEMF) stimulation in both donors at day 3, day 5 and day 7 compared to the control group (Fig. 1, C)
Another study indicated that extremely low-frequency PEMF stimulation induced osteogenesis at early stages of hBMSC differentiation, but suppressed proliferation of hBMSCs [16]
Summary
The clinical application of PEMF for treatment of fracture healing has been known for nearly 30 years [1]. Many studies have confirmed the osteogenic effects of PEMF on long bone nonunion repair [1,2,3,4]. There are still problems with clinical applications. The main drawback of PEMF treatment is time consumption. The U.S Food and Drug Administration (FDA) suggested that the stimulating duration of PEMF (EBI Bone Healing System) requires a minimum of ten hours per day for the duration of the treatment. This study aimed to search for a better module of electromagnetic field (EMF) that can more efficiently stimulate osteogenesis for bone repair
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