Abstract
Preoperative radiation is associated with an increased risk of wound complications. However, the influences of radiation on musculofascial wound healing remains unclear. The purpose of the study was to investigate the short-term effects of preoperative local radiation on the musculofascial healing of laparotomy incisions in a rat model. Eighteen Fischer 344 rats received radiation doses of 0, 10, or 20 Gy to the abdominal wall and underwent laparotomy 4 weeks later. Two weeks after laparotomy, samples of irradiated muscle were harvested for mechanical tests, histological (Hematoxylin & Eosin, and Masson’s Trichrome) and immunohistochemical analyses using KI67, CD31, TGF-β, and MYOD1 antibodies. The elastic modulus (EM), maximum strain (MS), and ultimate tensile strength (UTS) in the 20-Gy group were significantly weaker than those in the 0-Gy group. The EM and UTS in the 20-Gy group were significantly lower than those in the 10-Gy group. The UTS and MS in the 10-Gy group were significantly lower than those in the 0-Gy group. The mean number of inflammatory cells per mm2 in the 20-Gy group was significantly larger than those in the 10- and 0-Gy groups. The mean numbers of CD31-, KI67-, and MYOD1-positive cells, the optical density of TGF-β, and the microvessel density in the 20-Gy group were significantly smaller than those in the 10- and 0-Gy groups. These results indicated that radiation delays musculofascial healing and decreases mechanical strength of the laparotomy incision by creating a chronic inflammatory environment, inhibiting cell proliferation, angiogenesis, granulation maturation, collagen deposition, and muscular regeneration in a dose-dependent manner. The impaired biomechanical, histological and molecular properties may be associated with the higher risk of wound complications in patients who undergo radiotherapy prior to laparotomy.
Highlights
Wound healing is a complicated process that includes inflammation, proliferation, regeneration, and remodeling, involving interactions among a variety of cells, chemokines, cytokines, growth factors, and extracellular matrix[1]
Within the first 3 days after laparotomy, the rats were extremely fatigued with decreased activity, appetite and weight
Our results collectively indicated that radiation reduced the ultimate tensile strength (UTS), maximum strain (MS), and elastic modulus (EM) in a dose-dependent manner, which might be the biomechanical weakness of an incisional hernia in patients with previous radiotherapy and laparotomy
Summary
Wound healing is a complicated process that includes inflammation, proliferation, regeneration, and remodeling, involving interactions among a variety of cells, chemokines, cytokines, growth factors, and extracellular matrix[1]. Incisional hernia, one of the most significant challenges after abdominal wall surgery, occurs most frequently through previous incision or scar within one year postoperatively with a high incidence of 10–20% and recurrence rate up to 20%6. Compared with abundant studies in skin wound healing, few studies have investigated the post-radiation musculofascial healing of a laparotomy. The knowledge gap of short-term influences of radiation on the musculofascial healing needs to be elucidated to optimize radiotherapy and surgery plans for effective prevention of incisional hernia and other wound complications. The purpose of this study is to investigate the impact of radiation on the musculofascial healing of a laparotomy incision in a rat model and to explore the biomechanical and histopathological change in post-radiation musculofascial incisional healing. We tested our hypothesis through the following specific aims: (1) to develop a post-radiation laparotomy rat model; (2) to compare the biomechanical, histopathological and molecular properties of laparotomy incisions exposed to no radiation, 10-Gy, and 20-Gy radiation
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