Effect of Metformin on HIF-1α Signaling and Postoperative Adhesion Formation.

BACKGROUND: Peritoneal adhesion formation is common after abdominal surgery and results in severe complications. Tissue hypoxia is one of the main drivers of peritoneal adhesions. Thus, we determined the clinical role of hypoxia-inducible factor (HIF)-1 signaling in peritoneal adhesions and investigated whether the biguanide antidiabetic drug metformin shows HIF-inhibitory effects and could be repurposed to prevent adhesion formation. STUDY DESIGN: As part of the ReLap study (DRKS00013001), adhesive tissue from patients undergoing relaparotomy was harvested and graded using the adhesion grade score. HIF-1 signaling activity within tissue biopsies was determined and correlated with adhesion severity. The effect of metformin on HIF-1 activity was analyzed by quantification of HIF target gene expression and HIF-1 protein stabilization in human mesothelial cells and murine fibroblast under normoxia and hypoxia. Mice were treated with vehicle or metformin 3 days before and until 7 days after induction of peritoneal adhesions; alternatively, metformin treatment was discontinued 48 hours before induction of peritoneal adhesions. RESULTS: HIF-1 signaling activity correlated with adhesion severity in patient biopsies. Metformin significantly mitigated HIF-1 activity in vitro and in vivo. Oral treatment with metformin markedly prevented adhesion formation in mice even when the treatment was discontinued 48 hours before surgery. Although metformin treatment did not alter macrophage polarization, metformin reduced proinflammatory leucocyte infiltration and attenuated hypoxia-induced profibrogenic expression patterns and myofibroblast activation. CONCLUSIONS: Metformin mitigates adhesion formation by inhibiting HIF-1-dependent (myo)fibroblast activation, conferring an antiadhesive microenvironment after abdominal surgery. Repurposing the clinically approved drug metformin might be useful to prevent or treat postoperative adhesions.

Standard of Care and Outcomes of Primary Laparotomy Versus Laparotomy in Patients with Prior Open Abdominal Surgery (ReLap Study; DRKS00013001).

BACKGROUND: Patients undergoing relaparotomy are generally underrepresented in trials, despite how common the procedure is in clinical practice. The aim of this trial was to determine standard of care and gain evidence of intra- and postoperative outcomes for patients undergoing relaparotomy compared to primary laparotomy. METHODS: In this single-center controlled clinical trial, adult patients scheduled for elective abdominal surgery via relaparotomy or primary laparotomy were consecutively screened for eligibility. The perioperative course was monitored prospectively in five study visits during hospital stay and one study visit 1 year after surgery. Intraoperative standards, short and long-term outcomes were statistically explored at a level of significance of 5%. RESULTS: A total of 131 patients with relaparotomy and 50 patients with primary laparotomy were analyzed. In the relaparotomy group, the access to the abdomen took longer (23.5 min vs. 8.8 min; p = < 0.001) and the peritoneal adhesion index was higher (10.8 vs. 0.4; p = < 0.001). Inadvertent enterotomies were more frequent in the relaparotomy group (relaparotomy 0.3 versus primary laparotomy: 0.0; p = 0.002). The overall comprehensive complication index and rates of surgical site infection and wound dehiscence with evisceration were not different between the two groups. At long-term follow-up, rates of incisional hernia did not differ (relaparotomy: n = 12/104 (11.5%); primary laparotomy: n = 7/35 (20.0%); p = 0.208). DISCUSSION: In this first prospective comparison of relaparotomy with primary laparotomy, inadvertent enterotomies were more frequent in the relaparotomy group. However, contrary to previous retrospective studies, the risk of complications and incisional hernias was not increased compared to primary laparotomy. TRIAL REGISTRATION: Deutsches Register Klinischer Studien ( www.germanctr.de ): DRKS00013001.

Randomised-controlled feasibility trial on abdominal wall closure techniques in patients undergoing relaparotomy (ReLap study; DRKS00013001).

BACKGROUND: Patients undergoing relaparotomy are generally underrepresented in clinical trials, despite how common the procedure is in clinical practice. Specifically, techniques for re-do abdominal wall closure have never been evaluated in a randomised-controlled trial. The aim of this trial was to identify the optimal abdominal wall closure technique in patients undergoing relaparotomy. METHODS: In this monocentric, randomised feasibility trial, patients scheduled for elective relaparotomy were randomised to abdominal wall closure with either the small stitches technique, using Monomax® 2-0, or the large stitches technique, using PDS II® 1 loop. Patients' postoperative courses were followed for 1 year after the index operation. Effectiveness and safety outcomes were compared at a level of significance of 5% between the two techniques. RESULTS: A total of 100 out of 131 patients (76.3%) were evenly randomised to the small stitches and large stitches groups. The time for abdominal wall closure did not differ between the two techniques (small stitches 27.5 ± 9.5 min versus large stitches 25.3 ± 12.4 min; p = 0.334). The overall comprehensive complication index was 14.4 ± 15.5 in the small stitches group and 19.9 ± 23.4 in the large stitches group (p = 0.168). Specifically, rates of surgical site infection (small stitches 30.0% versus large stitches 36.0%; p = 0.524) and burst abdomen (small stitches 4.0% versus large stitches 0.0%; p = 0.495) did not differ. After 1 year, incisional hernia rate was 7.5% in the small stitches group and 10.0% in the large stitches group (p > 0.999). DISCUSSION: Both abdominal wall closure techniques investigated in this trial were feasible in relaparotomy patients. This exploratory trial revealed no noticeable difference in the effectiveness or safety of the small stitches technique with Monomax® 2-0 versus the large stitches technique with PDS II® 1 loop. Therefore, surgeons should stay with their preferred suture technique in relaparotomy patients. TRIAL REGISTRATION: Deutsches Register Klinischer Studien ( www.germanctr.de ): DRKS00013001.

Prospective mixed-methods study of patients undergoing relaparotomy (ReLap study; DRKS00013001).

BACKGROUND: Patients undergoing relaparotomies are underrepresented in clinical trials. Standard of care, relative outcomes compared to primary laparotomy, and the ideal fascial closure technique are unknown. OBJECTIVE: The ReLap study has three objectives: First, to determine standard of care and gain evidence of intra-/postoperative outcomes for patients undergoing relaparotomy compared to patients undergoing primary laparotomy. Second, to gain evidence of an association between biomarkers and adhesion grade in a clinical-translational approach in patients undergoing relaparotomy or primary laparotomy. Third, to gain evidence of the feasibility and comparative effectiveness of fascial closure after relaparotomy using the small stitches technique with Monomax 2-0 versus the large stitches technique with PDS 1 loop. METHODS: The ReLap study is a monocentric, prospective, mixed-methods, exploratory study with three steps: health care research, translational research, and randomized controlled trial. All patients scheduled for elective laparotomies or relaparotomies at the University of Heidelberg will be screened for eligibility. There will be five study visits during the hospital stay and one study visit one year after surgery. The clinical course will be followed and outcomes necessary to answer the study objectives will be captured prospectively. Relaparotomy patients eligible for closure with the small and large stitches technique will be randomized intraoperatively to one technique. DISCUSSION: The ReLap study will bridge a significant knowledge gap regarding patients undergoing relaparotomy. Differences in the standard of care between relaparotomies and primary laparotomies will be determined. The relation between biomarkers and manifestation of adhesions will be explored and evidence for the comparative effectiveness of fascial closure after relaparotomy will be gained.