The promising regenerative potential of pulsed electromagnetic fields toward tendon differentiation : a hamstring tendon explant culture study.

Hamstring tendons are commonly used autografts for anterior cruciate ligament (ACL) reconstruction. They represent an optimal source for in vitro testing of new approaches that may improve tendon regeneration and, likely, ligamentization after ACL reconstruction. We assessed ex vivo, in a 3D explant culture, the anabolic effect of pulsed electromagnetic fields (PEMF) on hamstring tendons in an experimental setting as close as possible to that of common clinical applications, suggesting a potential new therapeutic strategy to improving tendon remodelling. We exposed tendon explants from nine donors to PEMF for 21 days, eight hours/day, with an intensity similar to that used in clinical practice, and evaluated specific gene expression by immunofluorescence and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analyses. Increased expression of tendon-related markers (scleraxis, collagen types I and VI) and important players of tenogenic differentiation (c-Fos and mammalian target of rapamycin) was evidenced by immunofluorescence analysis upon PEMF exposure and confirmed by qRT-PCR analysis. Our results demonstrate that PEMF enhances tendon differentiation, which suggests that PEMF exposure could have clinical relevance as a new non-invasive adjuvant treatment for improving the early phases of hamstring autograft remodelling after ACL reconstruction, as well as possibly for hastening the repair of injured tendons.