Bringing Molecular Biology to Bear on Adhesion Prevention: Postsurgical Adhesion Reduction Using Intraperitoneal Inoculation of Hyaluronic Acid–Inducing Adenoviral Vector in a Murine Model

Objective: Seprafilm (Genzyme, Cambridge, MA) an absorbable adhesion barrier incorporating hyaluronic acid (HA), a high molecular mass glycosaminoglycan and important component of the extracellular matrix, has been shown to prevent adhesions in both experimental models and human subjects. Yet, the application of HA as a sheet at the time of surgery has several important logistic limitations. Recently, our laboratory has identified and cloned the genes encoding murine hyaluronic acid synthase 2 (mHAS2) and 3 (mHAS3) and engineered adenoviruses incorporating these genes, which, on intraperitoneal injection, significantly increases HA in peritoneal fluid. We hypothesized that intraperitoneal gene therapy with mHAS2 or mHAS3 via an adenoviral vector prior to a standardized cecal abrasion surgery would lead to a reduction in postoperative adhesion severity. Methods: Mice were assigned to one of four groups: (1) intraperitoneal inoculation with adenovirus encoding mHAS2; (2) mHAS3; (3) a control reporter adenovirus (RV) encoding GFP; or (4) intraoperative placement of a commercially available and murine-validated hyaluronic acid adhesion barrier (Seprafilm, SF). An a priori sample size calculation was performed. Mice in groups 1, 2, and 3 underwent injection of 2 x 107 viral particles in 1 ml of fluid on day -1. Sham injection was performed on group 4 SF mice. On day 0, laparotomy was performed in random sequence by surgeon blinded to the experimental group. On day 7, adhesion scores (0-3) were assigned independently by two blinded investigators. Results: Mean adhesion scores (n = 247) were 0.68 (mHAS2), 0.91 (mHAS3), 1.28 (RV), and 0.47 (SF). Pairwise comparisons using Wilcoxon rank-sum test revealed significant reduction in severity of adhesions between mHAS2, mHAS3, and SF compared to RV (p = 0.0004, 0.039, and 0.0001, respectively). Significance persisted despite correction for multiple comparisons (p = 0.0002, Kruskal-Wallis). There was a direct relationship between intraperitoneal HA concentration and adhesion reduction. Only one death (RV) was secondary to adhesive disease; differential risk of death between groups was statistically significant (p = 0.008) (highest in mHAS2 group). Conclusions: In a dose-response relationship, an intraperitoneal gene therapy approach to adhesion prevention in a murine model was successful, with adenoviruses most productive of HA resulting in the most significant reduction in adhesion scores compared to empty virus (RV). Although SF best reduced postoperative adhesions, the adenoviral gene delivery approach may prove to be more effective in clinical use when peritoneal injury is less localized or at laparoscopy where the application of SF is not possible. Further studies to elucidate the reason for the differential death rates (time bias may have played a role) and to validate results are in progress

Validation of a Mouse Adhesion Reduction Model Using Seprafilm®

Introduction: Most initial trials of antiadhesion technologies are currently carried out in rats or rabbits. This paper describes a simple, reliable technique for producing intraperitoneal adhesions in the mouse. This model has been validated using a hyaluronan/carboxymethylcellulose (HA/CMC) barrier (Seprafilm, Genzyme, Somerville, NJ) currently in clinical use. Methods: Adult, FVB mice were anesthetized with isoflurane. Celiotomy was performed in each mouse and the cecum and abdominal wall were abraded with sandpaper in a standardized manner. The mice either received no treatment or the cecum was wrapped in the HA/CMC membrane. Treatment groups were assigned, after abrasion, by coin toss. One (1) week later, the mice were euthanized and the adhesions were scored by two trained investigators blinded to the treatment group of each animal and the other investigator\u27s adhesion score. Results: Maximum adhesion grades were significantly lower (p = 0.009, Wilcoxon rank-sum) for the HA/CMC group (median = 0; s = 1.21; n = 18) than for the control group (mean = 2; s = 0.85; n = 24). The risk of any adhesion formation for the HA/CMC group was only half (relative risk [RR] = 0.51, 95% confidence interval [CI] = 0.30-0.87) as large as the risk of adhesion formation in the control group. Eight (8) mice (16%) died during the experiment. The risk of death was 8 times higher for mice treated with HA/CMC membrane than for the controls (RR = 7.7; 95% CI = 1.0-57), suggesting that treatment with HA/CMC could have increased the risk of mortality. Conclusions: This simple technique for adhesion formation is reliable and allows fast throughput of animals. The extent of adhesion prevention with HA/CMC membrane suggests that trials of adhesion prevention technologies in this model system may mirror those seen in humans

Prevention of Postoperative Nausea and Vomiting in Elective Hysterectomy: A Prospective, Randomized, Placebo Controlled Outcomes Trial of Aprepitant NK-1-Receptor Antagonist

Objectives: Current prophylactic interventions fail to completely eliminate postoperative nausea and vomiting (PONV) for a substantial number of patients. A new antiemetic (aprepitant) has been effective in preventing chemotherapy induced nausea and vomiting (CINV). We hypothesized that adding aprepitant to our current prophylactic regimen of dexamethasone and ondansetron would reduce the incidence of PONV in our elective hysterectomy population. Methods: 256 patients un-dergoing elective hysterectomy were enrolled in this prospective, randomized, double blinded, placebo controlled trial. Subjects received either oral aprepitant 40 mg or oral placebo 30 minutes prior to induction of standardized anesthesia. The primary outcome was vomiting within the first 24 hours after surgery. Postoperative nausea, vomiting, and use of rescue antiemetics were docu-mented over a 24 h period. Additionally, adverse events, hospitalization days, and readmission