Morphological observations of knot-induced inflammation at different anatomic levels in mouse abdominal wall

Abstract

Objective Knot-induced inflammatory response is noted in percutaneous extracorporeal knotting for laparoscopic inguinal inner ring closure in children.The present study was intended to explore the correlation between knot-induced inflammation and different knot locations in mouse abdominal wall. Methods Three vertical and parallel incisions with a length of 0.5 cm were created in abdominal wall in the same Balb/C mice, followed by saturation with 1mm stitch using MERSILK © non-absorbable suture.The knots were located in subcutaneous, intramuscular and extra peritoneal space in abdominal wall.Knot segments of each group were harvested at Day 7 and 14 post operatively.Hematoxylin & eosin, immunohistochemical and Masson stains were conducted to examine the location of knots in each group and degree of inflammation by inflammatory cell infiltration and expression of pro-cytokines, as well as collagen deposition around knots in each group. Results Hematoxylin & eosin staining indicated that knot was located in subcutaneous, intramuscular and extra peritoneal space of abdominal wall.Immunohistochemical staining and quantitative evaluations revealed less macrophage infiltration and decreased production of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in extra peritoneal space.On the contrary, there were more macrophage infiltration and increased production of IL-6 and TNF-α in subcutaneous layer.The significant biological difference of the above cytokines among three groups further confirmed a correlation between knot-induced inflammation and differential knot location in murine abdominal wall.Masson staining showed relative less collagen deposition and fibrosis in subcutaneous layer as compared with intramuscular layer and extra peritoneal space. Conclusions There is a correlation between knot-induced inflammation and differential knot location in murine abdominal wall.Knot in extra peritoneal space induced slight inflammation in abdominal wall as compared with other subcutaneous and intramuscular layers.Knot in extra peritoneal space is more likely to lower knot-induced inflammation and potential complications caused by extracorporeal knotting for laparoscopic inguinal inner ring closure in children.Long-term clinical trials are still required for further confirmations. Key words: Abdominal wall; Animal experimentation; Suture techniques