Temple University School of Podiatric Medicine Journal Review Club

Editor's note: This post is part of the Temple University School of Podiatric Medicine (TUSPM) journal review club blog series. In each blog post, a TUSPM student will review a journal article relevant to wound management and related topics and provide their evaluation of the clinical research therein.

Article title: Molecular events underlying maggot extract promoted rat in vivo and human in vitro skin wound healing.
Authors: Pei-Nan Li MD, PhD; Hong Li MD, PhD; Li-Xia Zhong MD, PhD; Yuan Sun MS; Li-Jun Yu PhD; Mo-Li Wu MD, PhD; Lin-Lin Zhang MS; Qing-You Kong MS; Shou-Yu Wang MD, PhD; and De-Cheng Lv MD, PhD.
Journal name and issue: Wound Repair and Regeneration: The International Journal of Tissue Repair and Regeneration, January-February 2015 (pages 65-73).
Reviewed by: Kristofor Kalvig, Temple University School of Podiatric Medicine Class of 2016

Introduction

Maggot therapy has been shown to be a very effective form of wound therapy as maggots selectively digest necrotic tissue from a wound, leaving the healthy tissue alone. Maggots suffer from a serious self-esteem problem due to practitioner prejudice. Most clinicians, and patients for that matter, do not like the idea of using maggots to treat their wounds. This article wanted to test the effects of maggot extract and excretion/secretion with respect to healing-related signaling transduction. The extract and excretion/secretion was collected and prepared from maggots before and after they had undergone extensive excretion/secretion.

Materials and Methods

The study used two test groups: one was rat skin wounds and the other was human keratinocytes and fibroblasts. 32 rats were broken into four groups: one control and three tests. The rats were 10 weeks old, given wounds under anesthesia, and then treated with a mixture of Vaseline, maggot extract, and maggot secretion/excretion. They underwent regular wound care for 16 days. The cell keratinocytes and fibroblasts were separated into three groups with one control and two tests. Each test group was broken down into A, B, and C. The groups were grown in various mediums containing NaO3, maggot extract, and maggot secretion/excretion.

Results

For the rat subjects, all those in the treatment groups did better than those in the control. The fastest closure healing group were those treated with maggot extracts prepared from maggots before secretion/excretion (extract + S/E) with closure occurring by day 14 or 16. The other test groups achieved closure by day 16 at a greater than 95% rate.

Immunohistochemistry was performed on sections of tissue looking for Ki-67 protein. Treatment groups showed more frequent labeling of Ki-67 both early post-wound and late post-wound.

The keratinocytes and fibroblasts were treated with maggot extract and secretion/excretion concentrations of 200, 150, and 100 µg/ml. They found the cells grew in the media containing the 100 µg/ml and 150 µg/ml. However cells in the 200 µg/ml were cytotoxic. The lower dose, 100 µg/ml, was the best concentration for promoting cell growth.

Following immunohistochemical and western blot experiments on tissue samples it was determined that maggot extracts caused an increase in levels of TGF-8, Smad3, and p-STAT3 proteins. The TGF-8/Smad3 proteins were expressed in both the control and experimental groups but the experimental groups had a higher level of expression. Maggot extract also caused up-regulation of healing-related genes c-Myc, cyclin D1, and VEGF. CD68-positive levels were expressed in low levels in control group and were either not found or expressed in extremely small concentrations in the test group.

Immunohistochemical, western blot and RT-PCR were performed on keratinocytes and fibroblasts. The results were comparable to that of the tissue samples mentioned above. TGF-8, Smad3 and STAT3 were all up-regulated in both cells.

Discussion

The use of maggot extract and secretion/excretion in wound healing shows promise. This article showed that extracts prepared from maggots before excretion/secretion (extract +S/E) was the best at promoting wound healing. The extracts have anti-inflammatory properties by blocking CD68-positive cells. It was shown that part of a maggot’s ability to heal wounds is through the up-regulation of some specific healing factors including TGF-8, STAT3, and Smad3. However, there is "too much of a good thing", resulting in the death of cells when the concentration of the extract is too great. Studying maggots and their healing potential with respect to wounds should be an important part of future wound care research. Understanding maggots or other "natural healers" can only further our understanding of the wound healing process providing strategies for better and faster healing outcomes. Perhaps we can get the benefit of maggots without the bugs.

About the Authors:
Kristofor Kalvig is a fourth year podiatric medical student at Temple University in Philadelphia, Pennsylvania. He has a strong interest in all aspects of podiatry foot care, including wound management and therapeutic interventions.

Dr. James McGuire is the director of the Leonard S. Abrams Center for Advanced Wound Healing and an associate professor of the Department of Podiatric Medicine and Orthopedics at the Temple University School of Podiatric Medicine in Philadelphia.