Background: Secondary lymphedema is a clinically incurable disease that commonly occurs following surgical cancer treatment and/or radiation. Microcurrent therapy (MT) has been shown to decrease inflammation and promote wound healing. This study aimed to investigate the therapeutic effect of MT in a rat model for forelimb lymphedema induced by axillary lymph node dissection.
Methods: The model was created by dissecting the right axillary lymph node. Two weeks after surgery, 12 Sprague-Dawley rats were randomly divided into two groups: one that underwent MT in the lymphedematous forelimb (MT, n=6) and a sham MT group (sham MT, n=6). MT was applied daily for 1 h in each session for two weeks. The circumferences of the wrist and 2.5 cm above the wrist were measured 3 days and 14 days after surgery, weekly during MT and 14 days after the last MT. Immunohistochemical staining of pan-endothelial marker (CD31), Masson's trichrome, and western blot analysis of vascular endothelial growth factor C (VEGF-C) and vascular endothelial growth factor receptor-3 (VEGFR3) were performed 14 days after the last MT. Quantification of the area covered by blood vessels (CD31+) and fibrotic tissue area were measured using an image analysis program (ImageJ software).
Results: The circumference of the carpal joint in the MT group was significantly decreased 14 days after the last MT compared to that in the sham MT group (P=0.021). The area covered by blood vessels (CD31+) was significantly higher in the MT group than in the sham MT and contralateral control group (P<0.05). The extent of fibrotic tissue was significantly attenuated in the MT group compared to the sham MT group (P<0.05). The expression of VEFGR3 was 2.02-fold higher for MT group, compared for the contralateral control group, which was statistically significant (P=0.035). VEGF-C expression was 2.27-fold higher for MT group than that for contralateral control group; however, the difference between the groups was not significant (P=0.051).
Conclusions: Our findings indicate that MT promotes angiogenesis, and improves fibrosis in secondary lymphedema. Therefore, MT may be a novel and non-invasive treatment modality for secondary lymphedema.
Keywords: Microcurrent therapy (MT); immunohistochemical staining; secondary lymphedema; western blot analysis.