Background and Objective: Hypertrophic scar is a pathological scar that grows aberrantly by excessive deposition of
collagens in the dermis. It is known that photodynamic therapy (PDT) contributes to a variety of diseases, however, the
use of inhibiting scar formation has not been fully explored. The purpose of this study is to investigate the effect of
HMME-PDT (Photodynamic therapy induced by Hematoporphyrin Monomethyl Ether) with different parameters on
hypertrophic scar in rabbit ear.
Materials and Methods: After the placement of 7-mm diameter dermal wounds on each ear, the acute model of dermal
hypertrophic scar in the New Zealand white rabbits was established. Scar wounds were randomly separated into 2 groups:
the experimental group received HMME-PDT with different parameters, and the control group received no special
treatment. Specimens were harvested from scar wounds on postoperative day 28. Scar and hypertrophic index (HI) were
observed by haematoxylin-eosin staining.
Results: Compared with the control group, scar formation was inhibited by HMME-PDT in the experimental group
with parameters as follows: photosensitizer dose 10mg/kg, power density 20mw/cm<sup>2</sup>, fluence 5J/cm<sup>2</sup>, meanwhile, HI
was decreased significantly.
Conclusion: HMME-PDT may play a role in inhibiting hypertrophic scarring in rabbit ear. The biological effect is
determined by the dose of photosensitizer, interval between the injection of photosensitizer and irradiation, power
density and energy fluence.