Effect of hematoporphyrin monomethyl ether-sonodynamic therapy (HMME-SDT) on hypertrophic scarring

OBJECTIVE: The aim of the present study was to explore the potential for hematoporphyrin monomethyl ether-Sonodynamic Therapy (HMME-SDT) treatment of hypertrophic scars within rabbit ears. METHODS: 60 white rabbits were randomly divided into five groups: (1) untreated controls, (2) lesioned, (3) lesioned + HMME, (4) lesioned + US (Ultrasound), and (5) lesioned +HMME-SDT. After induction of a lesion upon the ears of the rabbits, hypertrophic scars were assessed at 14, 28, 42 and 56 days post-lesion +/- treatment. Assessments consisted of visual inspection in the change of the skin, scar formation pathological morphology by hematoxylin and eosin (HE) staining technique with optical microscopy, calculation of a hypertrophic index, fibroblastic density measures, and observation of collagen changes in the scar tissue by Van Gieson's (VG)Stain along with calculation of collagen area density. RESULTS: With continued HMME-SDT treatment there was a gradual improvement in all parameters over the duration of the experiment. The lesion-induced scars of rabbits receiving HMME-SDT treatment were soft, the size was reduced, hyperplasia was flat and the color pale. The fibroblasts and collagens were reduced and the collagens were light red, sparse and orderly. The hypertrophic index was reduced, since the fibroblastic density was lowered and collagen area density was decreased. CONCLUSION: HMME is an effective sonosensitizer and the combination of HMME-SDT treatment can exert significant benefits in reducing the formation of hypertrophic scars.