Dry needling of a healthy rat achilles tendon increases its gene expressions: a pilot study

Abstract

Background: Tendon dry needling is a potential treatment for tendinopathies. Several hypotheses have been proposed to explain its underlying mechanisms. No studies (to the best of our knowledge) have investigated changes in gene expression. Objective: To investigate histological and gene expression changes after the application of dry needling to the healthy Achilles tendons of rats. Methods: Six Sprague-Dawley male rats were randomly divided into two groups: no intervention or dry needling. Dry needling consisted of three sessions (once per week) to the Achilles tendon. Molecular expression of several genes involved in tendon repair and remodeling (e.g., Cox2, Mmp2, Mmp9, Col1a1, Col3a1, Vefg, and Scx) was assessed 7 days after the last needling session (day 28) or 28 days after for the no-intervention group. Histological tissue changes were determined with hematoxylin-eosin analyses. Results: The hematoxylin-eosin-stained images revealed no substantial differences in collagen structure or the presence of inflammatory cells between the dry needling and no-intervention groups. A significant increase in the molecular expression of Cox2, Mmp2, Col3a1, and Scx genes was observed in Achilles tendons treated with dry needling when compared with the no-intervention group. Conclusion: This animal pilot study found that the application of dry needling to the healthy Achilles tendons of rats is able to increase the expression of genes associated with collagen regeneration and tissue remodeling of the extracellular matrix with no further histological damage to the tendon.