Cytokine production following experimental implantation of xenogenic dermal collagen and polypropylene grafts in mice

Association of systemic antibody response against polyethylene terephthalate with inflammatory serum cytokine profile following implantation of differently coated vascular prostheses in a rat animal model

Experimental studies demonstrated antibodies against matrix and coating of polyester-based vascular prostheses. Thus, this study examined associations of these antibodies with serum cytokines (IL-2, IL-4, and IL-10) and local inflammatory reactions. Rats (n = 8/group) intramuscularly received prosthesis segments [PET-C, PET-G, and PET-A groups: polyethylene terephthalate (PET)-based prostheses coated with bovine collagen and gelatin or human serum albumin, respectively; uncoated polytetrafluoroethylene-based (PTFE) prosthesis], with sham-operated controls. Blood was drawn pre-operatively and weekly until day 22. Polymer-specific or coating-specific antibodies and cytokines were detected by enzyme immunoassays, inflammatory reactions were immunohistochemically evaluated on day 23. Polymer-specific antibodies were detected in all PET-groups using uncoated PET as antigenic target, but not for PTFE or controls, coating-specific antibodies only for PET-A. IL-10 was increased in all PET-groups and correlated with polymer-specific antibodies for PET-G and PET-A. IL-2 was increased for PET-A, but overall correlated with PET-specific antibodies. IL-4 remained unchanged in all groups. Intense local inflammatory reactions (ED1⁺ /ED2⁺ macrophages and T lymphocytes) were found within all PET-groups, but only minor for PTFE or controls. In conclusion, PET-specific antibodies were associated with increased IL-10 and along with concurrent coating-specific antibodies also with increased IL-2, indicating a specific T cell response. Thus, matrix and/or coating of polymeric vascular prostheses elicit distinct systemic immune reactions, probably influencing local inflammatory reactions.

Host inflammatory response to polypropylene implants: insights from a quantitative immunohistochemical and birefringence analysis in a rat subcutaneous model

Objectives

To describe acute and sub acute aspects of histological and immunohistochemical response to PP implant in a rat subcutaneous model based on objective methods.

Materials and Methods

Thirty rats had a PP mesh subcutaneously implanted and the same dissection on the other side of abdomen but without mesh (sham). The animals were euthanized after 4 and 30 days. Six slides were prepared using the tissue removed: one stained with hematoxylin-eosin (inflammation assessment); one unstained (birefringence evaluation) and four slides for immunohistochemical processing: IL-1 and TNF-α (pro-inflammatory cytokines), MMP-2 (collagen metabolism) and CD-31 (angiogenesis). The area of inflammation, the birefringence index, the area of immunoreactivity and the number of vessels were objectively measured.

Results

A larger area of inflammatory reaction was observed in PP compared to sham on the 4th and on the 30^th day (p=0.0002). After 4 days, PP presented higher TNF (p=0.0001) immunoreactivity than sham and no differences were observed in MMP-2 (p=0.06) and IL-1 (p=0.08). After 30 days, a reduction of IL-1 (p=0.010) and TNF (p=0.016) for PP and of IL-1 (p=0.010) for sham were observed. Moreover, area of MMP-2 immunoreactivity decreased over time for PP group (p=0.018). Birefringence index and vessel counting showed no differences between PP and sham (p=0.27 and p=0.58, respectively).

Conclusions

The implantation of monofilament and macroporous polypropylene in the subcutaneous of rats resulted in increased inflammatory activity and higher TNF production in the early post implant phase. After 30 days, PP has similar cytokines immunoreactivity, vessel density and extracellular matrix organization.

Polymeric Biomaterials for Medical Implants and Devices

In this review article, we focus on the various types of materials used in biomedical implantable devices, including the polymeric materials used as substrates and for the packaging of such devices. Polymeric materials are used because of the ease of fabrication, flexibility, and their biocompatible nature as well as their wide range of mechanical, electrical, chemical, and thermal behaviors when combined with different materials as composites. Biocompatible and biostable polymers are extensively used to package implanted devices, with the main criteria that include gas permeability and water permeability of the packaging polymer to protect the electronic circuit of the device from moisture and ions inside the human body. Polymeric materials must also have considerable tensile strength and should be able to contain the device over the envisioned lifetime of the implant. For substrates, structural properties and, at times, electrical properties would be of greater concern. Section 1 gives an introduction of some medical devices and implants along with the material requirements and properties needed. Different synthetic polymeric materials such as polyvinylidene fluoride, polyethylene, polypropylene, polydimethylsiloxane, parylene, polyamide, polytetrafluoroethylene, poly(methyl methacrylate), polyimide, and polyurethane have been examined, and liquid crystalline polymers and nanocomposites have been evaluated as biomaterials that are suitable for biomedical packaging (section 2). A summary and glimpse of the future trend in this area has also been given (section 3). Materials and information used in this manuscript are adapted from papers published between 2010 and 2015 representing the most updated information available on each material.

Acute in vivo response to an alternative implant for urogynecology

Purpose. To investigate in vivo the acute host response to an alternative implant designed for the treatment of stress urinary incontinence (SUI) and pelvic organ prolapse (POP). Methods. A biodegradable scaffold was produced from poly-L-lactic acid (PLA) using the electrospinning technique. Human and rat adipose-derived stem cells (ADSCs) were isolated and characterized by fluorescence-activated cell sorting and differentiation assays. PLA scaffolds were seeded and cultured for 2 weeks with human or rat ADSCs. Scaffolds with and without human or rat ADSCs were implanted subcutaneously on the abdominal wall of rats. After 3 and 7 days, 6 animals from each group were sacrificed. Sections from each sample were analyzed by Haematoxylin and Eosin staining, Sirius red staining, and immunohistochemistry for CD68, PECAM-1, and collagen I and III. Results. Animals responded to the scaffolds with an acute macrophage response. After 7 days of implantation, there was extensive host cell penetration, new blood vessel formation, and new collagen deposition throughout the full thickness of the samples without obvious differences between cell-containing and cell-free scaffolds. Conclusions. The acute in vivo response to an alternative implant (both with and without cells) for the treatment of SUI and POP showed good acute integration into the host tissues.

Molecular Biocompatibility Evaluation of Poly-L-Ornithine-Coated Alginate Microcapsules by Investigating mRNA Expression of Pro-Inflammatory Cytokines

Following a polyelectrolytical complex reaction, the poly-L-ornithine (PLO)-alginate microcapsules were prepared by coating PLO on calcium alginate beads which were produced by a high-voltage electrostatic droplet generator. The biocompatibility of the microcapsules at the molecular level was evaluated through investigating the mRNA expression of pro-inflammatory cytokines; that is, the effect of the PLO coating of alginate beads on the mRNA expression of TNF-α, IL-1β, and IL-6 were measured using the RT-PCR method. The resulting PLO-coated alginate microcapsules have a smooth surface with a mean diameter of 309µm. The molecular biocompatibility studies show that coating microcapsules with PLO has no significant effect on the biocompatibility of alginate microcapsules (p>0.05), and both alginate microcapsules and PLO-coated microcapsules are significantly different from the positive control (p<0.05); however, both are also capable of causing an inflammatory response at a molecular level since both are significantly different from the blank control (p<0.05). Furthermore, with the increase in concentration of microcapsules or co-cultured time, part of the mRNA expression of cytokines is significantly increased. The results also demonstrate that the method used in this study, co-incubating the microcapsules with macrophages and measuring the mRNA expression of cytokines by RT-PCR, may be a useful method for evaluating the biocompatibility of coating materials of microcapsules.

Durability of biologic implants for use in hernia repair: a review

In the past 10 years, hernia repair has evolved from primarily using suture closure to using mesh repair. Synthetic mesh implants were the initial gold standard, but the rate of complications such as infection, adhesions, and erosion was higher with synthetics than has been observed with newer biologic implants. As efforts to develop the ideal implant continue, the advantages of biologics for hernia and other soft-tissue repair become increasingly apparent. Animal-sourced biologics have the potential advantage over human dermis of being more amenable to standardization, and porcine dermal collagen architecture closely resembles that of human dermis. Cross-linking the collagen adds strength and durability to the implant that facilitates healing of surgical wounds, just as endogenous collagen, which is cross-linked, has innate durability that enhances natural wound healing. This review defines and assesses durability of the acellular collagen (biologic) implant options available for hernia repair. The factors that affect wound healing-and hernia repair--are summarized. Additionally, the particular features that enhance durability are described, and durability-related clinical outcomes discussed in the literature are cited to aid clinicians in making informed surgical choices.

Sacrocolpopexy using xenogenic acellular collagen in patients at increased risk for graft-related complications

AIMS

We studied the long-term anatomical and functional outcome following sacrocolpopexy for apical vaginal prolapse using xenogenic grafts in a population at increased risk for graft-related complications (GRCs).

METHODS

Twenty-two consecutive patients with symptomatic apical prolapse were scheduled for laparoscopic sacrocolpopexy (LSC) with porcine grafts because they were presumed to be at risk for GRC, because of pre-existing vaginal ulcerations (n = 4), concomitant vaginal prolapse repair (n = 15), total hysterectomy (n = 1), or intra-operative abdominal contamination due to accidental laceration of the vagina, bowel perforation (n = 1) or the presence of infection (n = 1). Either small intestinal submucosa (n = 8) or dermal collagen (n = 14) was used. Outcome measures were GRCs, anatomical cure (<or=Stage I at any compartment), subjective cure, impact on bowel, bladder, and sexual function measured by a standardized interview.

RESULTS

At study closure 20 (91%) patients were available for functional evaluation and 16 (73%) for anatomical evaluation at a mean follow-up period of 27.4 months. The GRC rate was 25% (n = 4) prompting reintervention in half, and including two patients with spondylodiscitis. The anatomical cure rate was 31.5%. Failures at the vault, anterior, and posterior compartments occurred in, respectively, 31%, 18.8%, and 50% of patients. The subjective cure rate was 60% and three patients (15%) underwent redo-LSC.

CONCLUSION

The strategy of using xenografts in patients at risk for GRC, did not prevent these to occur and was associated with a high anatomical and functional failure rate as well as reoperation rate.

Conservative management of mesh-site infection in hernia repair

BACKGROUND

Mesh hernioplasty is the preferred surgical procedure for large abdominal wall hernias. Infection remains one of the most challenging complications of this operation. Salvaging infected prosthetic material after ventral hernia repair is rarely successful. Most cases require mesh excision and complex abdominal wall reconstruction, with variable success rates. In this article, we report 3 cases of mesh salvage after laparoscopic ventral herniorrhapy with a novel use of percutaneous drainage and antibiotic irrigation.

RESULTS

Three patients developed infected seromas after laparoscopic ventral hernia repair. The fascial defect of the first patient was repaired with a commercially available 20 x 18 cm polytetrafluoroethylene (PTFE) mesh. A complex fluid collection developed the following month in the anterior abdominal wall overlying the patient's mesh. The cultures grew Staphylococcus aureus. The second patient had a 30 x 20 cm PTFE mesh placed, which developed a fluid collection with Enterococcus faecalis and Escherichia coli. The third case underwent repair, using a another commercially available 22 x 28 cm PTFE mesh. A fluid collection measuring 20 x 10 cm in the anterior abdominal wall developed, growing Staphylococcus lugdunensis. In all 3 cases, a percutaneous drain was placed within the fluid collection and long-term intravenous (i.v.) access was obtained. I.v. antibiotics were initiated. In addition, gentamicin (80 mg) with 20 mL of saline was infused through the drain 3 times a day. All patients have remained free of clinical signs of infection following the completion of therapy.

CONCLUSIONS

Infected mesh after laparoscopic ventral herniorrhapy without systemic sepsis may be amenable to nonoperative treatment. A conservative approach that includes percutaneous drainage followed by antibiotic irrigation is a potential alternative to prosthetic removal in carefully selected patients. Further evaluation of this technique is warranted to define the most appropriate management strategies for these patients.

Clinicopathological study of patients requiring reintervention after sacrocolpopexy with xenogenic acellular collagen grafts

PURPOSE

We describe the operative and histopathological findings of patients requiring reintervention because of symptomatic vault prolapse or graft related complications following sacrocolpopexy using xenografts.

MATERIALS AND METHODS

A total of 13 patients underwent secondary sacrocolpopexy because of failure (8) or vaginal revision (5) because of a graft related complication after the initial sacrocolpopexy with porcine dermal collagen (9) or small intestinal submucosa (4). Outcome measures were operative findings and histology of specimens obtained at reintervention. Sections were semiquantitatively scored for the presence of infection, foreign body reaction and fibrosis by a pathologist blinded to the outcome and graft type.

RESULTS

Reinterventions for failure and graft related complications were performed a median of 33 and 15 months, respectively, after the initial operation. Pathology of porcine dermal collagen failures (6) revealed local degradation associated with a minimal foreign body reaction. Porcine dermal collagen remnants were surrounded by minimal fibrosis and neovascularization. Small intestinal submucosa implants of failures (2) were entirely replaced by collagen rich and moderately vascularized connective tissue. Pathology of 3 erosions (all 3 porcine dermal collagen) revealed a locally degraded implant that was surrounded by histiocytes and a polymorphonuclear infiltrate. Pathology of 2 early infections, both small intestinal submucosa, revealed a massive polymorphonuclear infiltration with the implant material remodeled and replaced by loose connective tissue.

CONCLUSIONS

In these clinical recurrences porcine dermal collagen implants were usually locally degraded but still recognizable several years after implantation. Small intestinal submucosa implants were fully replaced by connective tissue. Therefore, the cause of recurrence remains unclear. Porcine dermal collagen erosions displayed features of infection and degradation.

[Mid-term results of the grade 3-4 genital prolapse cure by vaginal route using a total hammock of porcine skin implant associated with bilateral sacro-spinofixation]

OBJECTIVE

To evaluate the feasibility, morbidity and mid-term results of genital prolapse cure by vaginal route using a total hammock of porcine skin implant (Pelvicol) and bilateral sacro-spinofixation.

PATIENTS AND METHODS

From May 2001 to June 2006, 101 patients with grade 3-4 genital prolapse, using the POPQ classification, were treated by vaginal route. One patient refused the use of porcine skin implant for religious reasons. Anterior fixation of the total hammock was performed by transobturator route and the posterior fixation was done on sacrospinous ligaments associated with a bilateral Richter operation. Intra- and postoperative complications, anatomical results, as well as global satisfaction, have been evaluated.

RESULTS

The technique was always feasible. With a mean follow-up of 29 months, anatomical results were optimal in 73.3% while 16.8% of recurrences were observed. Mean operating time was 112+/-39 min (range: 40-310). Intraoperative complication rate was 4.9% (three bladder injuries, one rectal injury, one unfundibulo pelvic ligament injury during hysterectomy). Postoperative complication rate was 11.9% (four cases of urinary retention, one urethral plication and five pararectal haematomas including two cases requiring a second surgery complicated by an urethrovaginal fistula in one case and one urinary infection). With a mean follow-up of 29+/-12 months (74-12), optimal anatomical results and recurrence rate were 73.3 and 16.8%, respectively. Global satisfaction rate was 87.7%. This rate decreased to 60% for patients with a 4- to 6-year follow-up.

CONCLUSION

Our results confirmed the feasibility of genital prolapse cure using a total hammock of porcine skin and bilateral sacro-spinofixation with a similar rate of complications to vaginal surgery without implant. However, anatomical results at mid-term raise the issue on the permanence of biological meshes.