The prevention of incisional hernia formation using a delayed-release polymer of basic fibroblast growth factor

Abstract

Objective: We sought to reduce the high incidence of abdominal wall incisional hernias using sustained release growth factor therapy.

Summary background data: Incisional hernias complicate 11% of abdominal wall closures, resulting in 200,000 incisional hernia repairs in the United States each year. Mechanical improvements alone in mesh, suture material, and surgical technique have failed to reduce the high rate of fascial wound failure.

Methods: Sprague-Dawley rats underwent midline celiotomies that were closed with fast-absorbing suture to induce early biomechanical wound failure and incisional hernia formation. In primary wounds, fascial incisions were closed adjacent to a continuous release polygalactone polymer rod containing basic fibroblast growth factor (bFGF), no growth factor (control-rod), or without rods. In a second group, incisional hernias were repaired with either bFGF or control-rod therapy. Breaking strength was measured on postoperative day (POD) 7, and the incidence of incisional hernia formation was determined on POD 28.

Results: Treatment with bFGF rods significantly increased fascial wound breaking strength. In the "hernia-prevention" experiments, incisional hernias developed in 90% of untreated incisions, 60% of control-rod incisions, and only 30% of bFGF-rod incisions (P < 0.05). In the "hernia-treatment" experiments, recurrent incisional hernias developed in 86% of control-rod incisions compared with only 23% of bFGF-rod treated incisions (P < 0.05). Immunohistochemistry demonstrated increased angiogenesis and collagen protein production in bFGF treated incisions.

Conclusion: The treatment of abdominal fascial incisions with a sustained-release bFGF polymer significantly lowered the incidence of incisional hernias and the recurrence rate after repair.

FIGURE 1. A, The ventral abdominal wall incisional hernia model. A 5-cm celiotomy incision is placed through the fascia of the midline linea alba and it is repaired with a single, 5-O plain catgut suture. In the untreated rat, rapid absorption of the catgut suture results in intentional acute fascial wound failure and herniation. Previous experience with this model predicts an 80% incidence of fascial incisional hernias after 28 days without biologic intervention. B, In the polygalactone rod-treated groups, the polymer was incorporated to the ventral edge of the fascial wound closure. The overlying 6-cm wide by 3-cm long skin flap is known to be viable. It functions to isolate the fascial wound from the dermal wounds and to secure abdominal contents into a hernia sac.

FIGURE 2. Fascial breaking strength was measured with an Instron Tensiometer on POD 7. Values are the mean ± SEM of 10 wound biopsies each from the vehicle control and the bFGF-treated groups.

FIGURE 3. Prominent angiogenesis in the bFGF-treated healing fascial incision demonstrated on this trichrome-stained photomicrograph taken adjacent to a bFGF-impregnated polyglactone rod.

FIGURE 4. Relative expression of type I collagen mRNA in bFGF-treated, empty rod control, and hernia model control fascial incisions. Values expressed in arbitrary units, P > 0.05).

FIGURE 5. A, Immunostaining for type I collagen was significantly increased in POD 28 fascial incisions treated with bFGF 100X. B, Control wounds stained weakly for type I collagen and contained more herniated preperitoneal fat.