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Updated: Aug 28, 2025
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Wound healing in weaning, adult, and old rats with provoked incisional hernias. A comparative study
Raphael Nogueira do Amaral1, Ana Cristina Aoun Tannuri2, Junia Marielle Teixeira Rodrigues Neri1
1Medical Researcher, Pediatric Surgery Division, Pediatric Liver Transplantation Unit and Laboratory of Research in Pediatric Surgery (LIM 30), Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil.
Insights
Pediatric patients experience fewer incisional hernias due to more efficient wound healing. Younger rats showed greater fibroblast proliferation and specific gene expression, suggesting a biological basis for better healing in the young.
Area of Science:
- Biomedical Science
- Surgical Research
- Pediatric Surgery
Background:
- Incisional hernias are more common in adults than children.
- Pediatric healing efficiency is hypothesized to be superior.
- Factors like neovascularization, inflammation, collagen, fibroblasts, and gene expression may contribute to this difference.
Purpose of the Study:
- To investigate age-related differences in incisional hernia formation and healing.
- To explore the biological mechanisms underlying superior healing in younger populations.
- To compare healing in weaning, adult, and old rats across different incision types.
Main Methods:
- Seventy-one rats across three age groups (weaning, adult, old) underwent simulated incisional hernia surgery.
- Three incision types (vertical, oblique, horizontal) were used.
- Scar tissue was measured, and histological, immunohistochemical, and molecular analyses were performed.
Main Results:
- Weaning rats developed shorter hernias than old rats with horizontal incisions (p=0.03).
- Younger rats exhibited greater fibroblast proliferation irrespective of incision type.
- The Lox gene showed higher expression in weaning rats with vertical and oblique incisions.
Conclusions:
- Age-related differences in healing, including fibroblast proliferation and gene expression, may explain lower hernia incidence in children.
- Further research is needed to confirm these findings and their clinical implications.
Background:
Incisional hernias are more frequent in adults than in children. It is hypothesized that a more efficient healing process in pediatric patients could explain this difference in incidence. Certain elements of healing such as neovascularization, degree of inflammation, percentage of mature and immature collagen, the proliferation of fibroblasts, and expression of certain genes could explain why healing in children is more efficient when compared to the adult and elderly populations.
Materials And Methods:
Seventy-one rats of 3 different age groups (weaning, adult, and old) underwent surgery with 3 different incisions (vertical, oblique, and horizontal). During the procedure, the skin and abdominal wall of the animal were sectioned and only the skin was sutured to mimic incisional hernia in the animals. Four weeks after surgery, the rats were euthanized, their skin was removed, and the extent of scar tissue formed in the muscle opening was measured. In addition, samples of the scar tissue were collected for histological, immunohistochemical, and molecular analyzes. Nine rats served as controls.
Results:
Shorter-length hernias were formed in weaning rats when compared to old ones when the surgical incision was horizontal (p = 0.03). There was a greater proliferation of fibroblasts in rats in the younger age groups, regardless of the type of incision. The Lox gene was more expressed in weaning rats with vertical and oblique incisions.
Conclusions:
These differences could explain the better healing and lower incidence of hernias in the pediatric population, although this aspect requires further studies.
