A clinically relevant in vivo model for the assessment of scaffold efficacy in abdominal wall reconstruction

Copyright © The Author(s) 2017. An animal model that allows for assessment of the degree of stretching or contraction of the implant area and the in vivo degradation properties of biological meshes is required to evaluate their performance in vivo. Adult New Zealand rabbits underwent full thickness subtotal unilateral rectus abdominis muscle excision and were reconstructed with the non-biodegradable Peri-Guard®, Prolene® or biodegradable Surgisis® meshes. Following 8 weeks of recovery, the anterior abdominal wall tissue samples were collected for measurement of the implant dimensions. The Peri-Guard and Prolene meshes showed a slight and obvious shrinkage, respectively, whereas the Surgisis mesh showed stretching, resulting in hernia formation. Surgisis meshes showed in vivo biodegradation and increased collagen formation. This surgical rabbit model for abdominal wall defects is advantageous for evaluating the in vivo behaviour of surgical meshes. Implant area stretching and shrinkage were detected corresponding to mesh properties, and histological analysis and stereological methods supported these findings.This study was financially supported by the Enterprise Ireland (Technology Development Grant). This publication has emanated from research conducted with the financial support of Science Foundation Ireland (SFI) and is co-funded under the European Regional Development Fund under grant no. 13/RC/2073. This study was also supported by the Centre for Microscopy & Imaging funded by NUI Galway and PRTLI, Cycles 4 and 5, National Development Plan 2007–2013

Artificial vs biological meshes: can in vitro cellular responses predict the outcome in patients?

Synthetic and biological matrices for abdominal wall repair have been developed and commercialized in recent years. Biological meshes have been proposed as an alternative when synthetic implants are not indicated, as in the case of contaminated surgical field and may present fewer complications such as chronic pain and visceral adhesions after hernia repair. However, their use is still debated, due to high cost to benefit ratio. Moreover, knowledge of the molecular pathways activated in the different types of cells by their use is still lacking. This study aimed to investigate the molecular processes activated by fibroblasts during their interaction with different types of biological and synthetic matrices, comparing the fibroblast-matrix interactions morphologically, monitoring cell proliferation and the expression of genes involved in the deposition and reabsorption of collagen, as well as some cytokines and markers of differentiation into myofibroblasts. We found that fibroblasts grew differently on the different biological meshes. Few fibroblasts grew on the synthetic mesh, impairing gene expression analysis. Fibroblasts on biological meshes induced specific metalloproteinases and reduced expression of collagen genes compared to control cells. Expression of markers for myofibroblast differentiation was also reduced. We found limited differences in gene expression programs among the different biological meshes

Recent Innovations & Daily Problems. A new prosthesis in inguinal hernia repair:preliminary results of a pilot study.

Introduction: Elective surgery for inguinal hernia is affected by very low mortality « 1 per 10000 operation); in contrast, when surgery is carried out for complicated inguinal hernia, risks of postoperative complication are higher. TAPP is a world-wide accepted surgical practice in the treatment of elective bilateral or recurrent inguinal hernia, above all in young patients. Few exploratory studies were published on laparoscopic approach in the treatment of urgent complicated inguinal hernia. Aim of this study was to analyze feasibility (operative time, conversion rate), safety (postoperative morbidity, length of hospital stay) and quality of life (acute and chronic pain, return to work) of trans-abdominal pre-peritoneal laparoscopic hernia repair in acute incarcerated inguinal hernia. Rationale of laparoscopic trans-abdominal approach is the easier hernia reduction under vision and a better exploration of the abdominal cavity. Methods: from September 2012 to September 2013, 15 consecutive patients admitted in emergency at the Division of General Surgery of University "Sapienza", Polo Pontino, for acute incarcerated inguinal hernia were submitted to TAPP using 3 trocars (1 of 10 mm and 2 of 5mm) and polyester prosthesis fixed by fibrin glue. Exclusion criteria for laparoscopic approach were age III, previous abdominal surgery, signs of strangulated hernia. All of them were evaluated for operative time, conversion rate, postoperative morbidity, organ resection or other surgery required. All patients were scored for pain by Visual Analogic Scale (VAS) during postoperative in hospital stay at 7 days, 1,6 and 12 months after surgery. Results: median follow-up was 16 months and 12 as minimum. In all cases reduction of hernia was always possible and none conversion to open surgery was recorded, median operative time was 89 minutes (55-137 as range), omental resection was carried out in one patient (6,6%), no other organ resections needed, whereas contralateral hernia was diagnosed and repaired at the same time in 4 patients (26,6%). No major complications were observed, median blood loss was 100 ml, minor morbidity was contained to 18% represented by fever and wound infection of surgical umbilical scar. Median in hospital stay was 1,5 days with 1-5 days as range. Postoperative median acute pain, measured by visual analogic scale (VAS), was 2 (range:0-4), none patient referred any pain during follow-up. Median time of return to work was 6,5 days, ranged between 3 to 15 days. Patients' compliance to treatment and to follow-up was complete as well their satisfaction. Conclusions: In centres skilled for laparoscopy in emergency, TAPP could be considered a feasible and safe technique. In well-selected patients (especially if emolled in controlled clinical trial) TAPP could represent an alternative surgical approach for complicated incarcerated inguinal hernia to conventional open surgery even in urgency. The main advantages of laparoscopic approach are the ability to perform surgical hernia reduction under vision, a better exploration and evaluation of abdominal cavity and diagnosis and treatment of eventual contralateral defect of wall, otherwise often missed. Finally, the good control of acute and chronic pain, faster return to normal activity and work, better aesthetic results contributed to total satisfaction and compliance of the patients

Effects of collagen prosthesis crosslinking on long-term tissue regeneration following the repair of an abdominal wall defect

22 p.Collagen prostheses used to repair abdominal wall defects, depending on their pretreatment (noncross-linked vs. cross-linked), besides repair may also achieve tissue regeneration. We assessed the host tissue incorporation of different bioprostheses using a new tool that combines immunofluorescence confocal microscopy with differential interference contrast images, making it possible to distinguish newly formed collagen. Partial hernial defects in the abdominal wall of rabbits were repaired using cross-linked/noncross-linked bioprostheses. Expanded polytetrafluoroethylene (ePTFE) was used as control. After 14/30/90/180 days of implant, specimens were taken for microscopy, immunohistochemistry, and quantitative-reverse transcription-polymerase chain reaction to determine host tissue ingrowth and collagen I/III protein and 1a1/3a1 gene expression. Shrinkage and stress resistance were also examined. At 14 days, crosslinked prostheses had suffered significantly lessshrinkage than ePTFE or noncross-linked prostheses. Significantly higher shrinkage was recorded for ePTFE in the longer term. Microscopy revealed encapsulation of ePTFE by neoformed tissue, while the bioprostheses became gradually infiltrated byhost tissue. Noncross-linked prosthesis showed better tissue ingrowth, more intense inflammatory reaction and more rapid degradation than the cross-linked prostheses. At 14 days, cross-linked prostheses induced up-regulated collagen 1a1 and 3a1 geneexpression, while noncross-linked only showed increased collagen III protein expression at 90 days postimplant. At 6 months, the tensile strengths of cross-linked prostheses were significantly greater compared with ePTFE. Our findings demonstrate that despite the cross-linked collagen prostheses promoting lesstissue ingrowth than the noncross-linked meshes, they became gradually replaced by good quality host tissue and were less rapidly degraded, leading to improved stress resistance in the long term.Fundación Mutua MadrileñaMinisterio de Ciencia y Tecnologí