Comparison of Two Porcine-Derived Materials for Repairing Abdominal Wall Defects in Rats

OBJECTIVE: The purpose of this study was to compare the mechanical properties, host responses and incorporation of porcine small intestine submucosa (PSIS) and porcine acellular dermal matrix (PADM) in a rat model of abdominal wall defect repair. MATERIALS AND METHODS: Prior to implantation, PSIS and PADM were prepared and evaluated in terms of structure and mechanical properties. Full-thickness abdominal wall defects were created in 50 Sprague-Dawley rats, and were repaired using either PSIS or PADM. Rats were sacrificed 1, 2, 4, 8 and 12 weeks post-repair and examined for herniation, infection, adhesions, contraction, and changes in the thickness and strength of the tissues incorporated at the defect sites. Histopathology and immunohistochemistry were performed to analyze inflammatory responses, collagen deposition and vascularization. RESULTS: PADM showed more dense collagen deposition and stronger mechanical properties than PSIS prior to implantation (P<0.01). However, the mechanical properties observed after integration with the surrounding native tissues was similar for PADM and PSIS. Both PADM and PSIS showed significant contraction by week 12. However, PADM tissue induced less adhesion and increased in thickness more slowly, and showed less infiltration by foreign giant cells, polymorphonuclear cells, and mononuclear cells. Improved remodeling of host tissue was observed after PSIS implantation, which was apparent from the orientation of bands of fibrous connective tissue, intermixed with newly formed blood vessels by Week 12. CONCLUSION: PSIS showed weaker mechanical properties prior to implantation. However, after implantation PSIS induced more pronounced host responses and showed better incorporation into host tissues than PADM

The effects of neoadjuvant chemoradiotherapy and an in-hospital exercise training programme on physical fitness and quality of life in locally advanced rectal cancer patients (The EMPOWER Trial): Study protocol for a randomised controlled trial

Background: The standard treatment pathway for locally advanced rectal cancer is neoadjuvant chemoradiotherapy (CRT) followed by surgery. Neoadjuvant CRT has been shown to decrease physical fitness, and this decrease is associated with increased post-operative morbidity. Exercise training can stimulate skeletal muscle adaptations such as increased mitochondrial content and improved oxygen uptake capacity, both of which are contributors to physical fitness. The aims of the EMPOWER trial are to assess the effects of neoadjuvant CRT and an in-hospital exercise training programme on physical fitness, health-related quality of life (HRQoL), and physical activity levels, as well as post-operative morbidity and cancer staging. Methods/Design: The EMPOWER Trial is a randomised controlled trial with a planned recruitment of 46 patients with locally advanced rectal cancer and who are undergoing neoadjuvant CRT and surgery. Following completion of the neoadjuvant CRT (week 0) prior to surgery, patients are randomised to an in-hospital exercise training programme (aerobic interval training for 6 to 9 weeks) or a usual care control group (usual care and no formal exercise training). The primary endpoint is oxygen uptake at lactate threshold ( V · o 2 at δ L ) measured using cardiopulmonary exercise testing assessed over several time points throughout the study. Secondary endpoints include HRQoL, assessed using semi-structured interviews and questionnaires, and physical activity levels assessed using activity monitors. Exploratory endpoints include post-operative morbidity, assessed using the Post-Operative Morbidity Survey (POMS), and cancer staging, assessed by using magnetic resonance tumour regression grading. Discussion: The EMPOWER trial is the first randomised controlled trial comparing an in-hospital exercise training group with a usual care control group in patients with locally advanced rectal cancer. This trial will allow us to determine whether exercise training following neoadjuvant CRT can improve physical fitness and activity levels, as well as other important clinical outcome measures such as HRQoL and post-operative morbidity. These results will aid the design of a large, multi-centre trial to determine whether an increase in physical fitness improves clinically relevant post-operative outcomes