Maggot homogenate is associated with neural regeneration and wound healing in the rat

BACKGROUND：Live delivery limits the clinical application of maggot therapy. To date in China, there are no in vivo reports regarding wound healing mechanisms of maggot therapy or the effects of maggot homogenate on wound nerve regeneration.OBJECTIVE：To avoid complications due to the use of live maggots, an aseptic maggot homogenate was applied. Substance P （SP） and gene protein product 9.5 expression in a cutaneous wound was analyzed to explore possible mechanisms of neural regeneration and wound healing in the rat.DESIGN, TIME AND SETTING：A random grouping and controlled animal study was performed at the laboratory of the Department of Orthopedic Surgery, First Affiliated Hospital, Dalian Medical University from August 2008 to April 2009.MATERIALS：Live maggots were cultured and provided by the laboratory of the Department of Orthopedic Surgery of the First Affiliated Hospital, Dalian Medical University, China.METHODS：A total of 48 adult rats were selected and two acute, full-thickness wounds （round, 1.5 cm diameter） were created on the back of each rat. The two wounds were randomly assigned to homogenate product and control groups. Following two-step disinfection of maggots, a homogenate was produced from 10 maggots and applied to the wound area in the homogenate product group, while the wounds in the control group were treated with normal saline alone.MAIN OUTCOME MEASURES：On days 1,3, 7, 10, 14, and 21 following injury, the wound tissue was excised. Histological examination of the wound was observed by hematoxylin and eosin staining or Masson＇s Trichrome staining. SP and protein gene product 9.5 expressions were examined by immunohistochemistry to evaluate wound neural regeneration.RESULTS：On days 7, 10, and 14, the rate of wound healing was significantly greater in the homogenate product group compared with the control group （P 〈 0.05）, and homogenate healing was better than that seen in the control group. On days 3, 7, and 10, SP expression in cells and regenerative nerves was significantly greater in the homogenate product group compared with the control group （P 〈 0.05）. On days 7 and 10, protein gene product 9.5 expression was detected in the regenerative nerve, and expression level was significantly greater in the homogenate product group compared with the control group （P 〈 0.05）.CONCLUSION：Maggot homogenate resulted in upregulated SP and protein gene product 9.5 expressions, thereby promoting neural regeneration and wound healing.