Experimental evaluation of four biologic prostheses for ventral hernia repair

Extracellular matrix biomaterials for soft tissue repair

The biological and physical augmentation provided by extracellular matrix (ECM) derived implants continues to challenge and refine the conventional wisdom of biomaterials. It is now appreciated that different tissue-processing methodologies can produce ECM devices with characteristic post-implantation responses ranging from the classic foreign body encapsulation of a permanent implant, to one where the implant is degraded and resorbed, to one where the processed ECM implant is populated by local fibroblasts and supporting vasculature to generate a new, metabolically active tissue (gTissue). This article reviews the multiple ECM devices available clinically and highlights the impact of tissue source and processing on physicomechanical properties and host-implant interactions, with regard to surgical applications and clinical considerations.

Reconstruction of complex abdominal wall hernias using acellular human dermal matrix: a single institution experience

BACKGROUND

Acellular human dermal matrix (AHDM) has mechanical properties suitable for complex abdominal wall reconstructions and physiologic properties that allow more resistance to infection in contaminated fields. The purpose of this study was to determine which patient and technical factors lead to optimal surgical outcomes.

METHODS

A retrospective review was conducted of 144 abdominal wall reconstructions using AHDM over a 33-month period. Data were recorded and analyzed.

RESULTS

Fifty-three percent were women. The average age was 55 years, with an average body mass index of 35 kg/m(2). Thirty percent were smokers at the time of repair, and 24% had diabetes. Forty-three percent of the operative fields had some degree of contamination. The indication for operation in half the patients was to reconstruct a previously failed hernia repair. The recurrence rate was 27.1%. The significant factors that affected the recurrence rate were female gender (P = .02), reconstructing a failed prior repair (P = .025), and high body mass index (P = .004). An underlay mesh placement trended to a lower recurrence rate (P = .053). Average follow-up time was 23 weeks (range, 0-100 weeks).

CONCLUSIONS

Three patient factors contributed significantly to the recurrence rate in this study: gender, above-normal body mass index, and repairing a recurrent hernia. Placing the matrix as an underlay appears to decrease recurrence rates. Long-term follow-up is needed to further determine the durability of hernia repairs with AHDM. AHDM offers a viable option with acceptable morbidity in complex abdominal wall reconstructions in high-risk patient populations.

Macrophage phenotype as a determinant of biologic scaffold remodeling

Macrophage phenotype can be characterized as proinflammatory (M1) or immunomodulatory and tissue remodeling (M2). The present study used a rat model to determine the macrophage phenotype at the site of implantation of two biologic scaffolds that were derived from porcine small intestinal submucosa (SIS) and that differed mainly according to their method of processing: the Restore device (SIS) and the CuffPatch device (carbodiimide crosslinked form of porcine-derived SIS (CDI-SIS)). An autologous tissue graft was used as a control implant. Immunohistologic methods were used to identify macrophage surface markers CD68 (pan macrophages), CD80 and CCR7 (M1 profile), and CD163 (M2 profile) during the remodeling process. All graft sites were characterized by the dense population of CD68+ mononuclear cells present during the first 4 weeks. The SIS device elicited a predominantly CD163+ response (M2 profile, p < 0.001) and showed constructive remodeling at 16 weeks. The CDI-SIS device showed a predominately CD80+ and CCR7+ response (M1 profile, p < 0.03), and at 16 weeks was characterized by chronic inflammation. The autologous tissue graft showed a predominately CD163+ response (M2) at 1 week, with a dual M1/M2 population (CD80+, CCR7+, and CD163+) by 2 and 4 weeks and moderately well organized connective tissue by 16 weeks. The processing methods used during the manufacturing of a biologic scaffold can have a profound influence upon the macrophage phenotype profile and downstream remodeling events. Routine histologic examination alone is inadequate to determine the phenotype of mononuclear cells that participate in the host response to the scaffold.

Permacol: a potential biologic patch alternative in congenital diaphragmatic hernia repair

PURPOSE

Recurrence is a well-known complication after patch repair of congenital diaphragmatic hernia (CDH). We propose that a newer, "bioprosthetic" material may lower recurrence rates. The purpose of this study is to compare outcomes of CDH repair with synthetic Gore-Tex (W. L. Gore and Associates, Neward, Del) to the bioprosthetic Permacol (Tissue Science Laboratories Inc, Andover, Mass).

METHODS

We performed a retrospective review of 100 consecutive patients with CDH with survival more than 30 days at Children's Medical Center of Dallas (Dallas, Tex) from 1999 to 2007. The incidence and timing of recurrence, as well as comorbidities were assessed.

RESULTS

Primary repair was performed in 63 patients and patch repair in 37, divided between Gore-Tex (29) and Permacol (8). Overall recurrences were as follows: 1 (2%), 8 (28%), and 0 in the primary, Gore-Tex, and Permacol groups, respectively. Median follow-up was 57 months for Gore-Tex and 20 months for Permacol. Median time to recurrence in the Gore-Tex group was 12 months, with no Permacol recurrences. Both the Gore-Tex and Permacol groups had similar comorbidities, including prematurity, congenital heart disease (76% and 63%, respectively), and the need for extracorporeal membrane oxygenation support (38% and 25%).

CONCLUSION

Our results suggest that Permacol may have lower recurrence rates compared to Gore-Tex and is a promising alternative biologic graft for CDH repair.

Use of a porcine dermal collagen graft (Permacol) in parotid surgery

Our aim was to present the results of the use of porcine dermal collagen graft (Permacol) in the prevention of Frey's syndrome and face-contouring aesthetic deformities after operations on the parotid. We treated 19 patients with parotid tumours. After resection, a Permacol sheet was applied to the perimeter of the tissue deficit so that it was fully covered, and was sutured firmly. This technique produced satisfactory aesthetic results with good facial contouring in all patients. It also protected the exposed parotid nerve plexus, and none of the patients developed Frey's syndrome. Permacol produced good results in both postoperative facial contouring and prevention of Frey's syndrome.

The use of porcine dermal collagen implants in assisting abdominal wall closure of pediatric renal transplant recipients with donor size discrepancy

Children may have kidneys transplanted from donors larger than themselves. Abdominal wall closure may be difficult, with risks of abdominal compartment syndrome and graft compromise. Meshes used to facilitate closure may cause dense intra-abdominal adhesions, making further surgery or peritoneal dialysis difficult. We present five cases in which abdominal wall closure was facilitated by porcine dermal collagen implant. Five children (2-15 yr) received transplanted kidneys from adult donors of significantly greater weight. In four recipients, the kidney was transplanted onto the aorta and vena cava intra-abdominally using a midline incision. In the fifth, the kidney was anastomosed onto the iliac vessels. The skin overlying the implant was closed normally. Maximum follow-up was three yr. In all cases, primary closure was achieved. One child received a second intra-abdominal transplant as an emergency, which later failed. The other kidneys are functioning well. One recipient developed a small incisional hernia three yr post-transplant. Another developed a skin dehiscence over the implant 23 days post-operatively. The implant was removed and skin closed. The other two recipients recovered well. Porcine dermal collagen implant is a helpful adjunct to abdominal wall closure following organ transplantation in children with donor size discrepancy.