Monocyte-biomaterial interaction inducing phenotypic dynamics of monocytes: a possible role of monocyte subsets in biocompatibility

Long-term outcomes after Lichtenstein repair using titanium-coated mesh: A retrospective cohort study

OBJECTIVE

To examine the long-term outcomes such as recurrence, foreign body feeling and chronic pain of titanium-coated mesh (TCM) versus standard polypropylene mesh (PM) after Lichtenstein repair (LR).

METHODS

In this retrospective cohort study, patients who underwent TCM and PM in LR were evaluated between May 2014 and January 2018 at Ordu University Training and Research Hospital in Turkey. Primary outcomes (age, gender, body mass index, smoking habits, comorbid diseases, American Society of Anesthesiologists score, hernia type, side of hernia, duration of hernia presentation and operative time) and secondary outcomes (surgical site occurence, recurrence, foreign body feeling and chronic pain) were analyzed. Patients were divided into two groups according to the mesh elected (TCM and PM); titanium group (TG) and polypropylene group (PG), respectively.

RESULTS

In this study, 221 patients were analyzed; TCM was used in 72 (32.6%) patients and PM was used in 149 (67.4%) patients. No difference was found between groups in terms of primary outcomes (p>0.05). In the analysis of secondary outcomes, surgical site occurence was similar in both groups (p>0.05). Recurrence was observed in 1.39% (n=1) of TG and 2.01% (n=3) of PG. No difference was found between groups in terms of recurrence (p=0.606). Foreign body feeling was observed in 15.3% (n=11) of TG and 27.5% (n=41) of PG. Chronic pain was observed in 4.2% (n=3) of TG and 12.8% (n=9) of PG. Significant differences were found between groups in terms of chronic pain and foreign body feeling (p=0.046 and p=0.044, respectively).

CONCLUSION

The result of this study shows that in LR, TCM leads to less foreign body feeling and chronic pain than PM. However, there was no difference in terms of recurrence between these meshes.

Delayed primary closure of contaminated abdominal wall defects with non-crosslinked porcine acellular dermal matrix compared with conventional staged repair: a retrospective study

INTRODUCTION

Synthetic mesh has been used traditionally to repair abdominal wall defects, but its use is limited in the case of bacterial contamination. New biological materials are now being used successfully for delayed primary closure of contaminated abdominal wall defects. The costs of biological materials may prevent surgeons from using them. We compared the conventional staged repair of contaminated abdominal wall defects with a single-stage procedure using a non-crosslinked porcine acellular dermal matrix.

METHODS

A total of 14 cases with Grade 3 contaminated abdominal wall defects underwent delayed primary closure of the abdomen using a non-crosslinked porcine acellular dermal matrix (Strattice™ Reconstructive Tissue Matrix, LifeCell Corp., Branchburg, NJ, USA). The results were compared with a group of 14 patients who had received conventional treatment for the repair of contaminated abdominal wall defects comprising a staged repair during two separate hospital admissions employing synthetic mesh. Treatment modalities, outcomes, and costs were compared.

RESULTS

In all cases treated with delayed primary closure employing non-crosslinked porcine acellular dermal matrix, there were no complications related to its use. Two patients died due to unrelated events. Although treatment costs were estimated to be similar in the two groups, the patients treated with porcine acellular dermal matrix spent less time as an inpatient than those receiving conventional two-stage repair.

CONCLUSIONS

Delayed primary closure of contaminated abdominal wall defects using a non-crosslinked porcine acellular dermal matrix may be a suitable alternative to conventional staged repair. In our patients, it resulted in early restoration of abdominal wall function and shorter hospitalization. The costs for treating contaminated abdominal wall defects using porcine acellular dermal matrix during a single hospital admission were not higher than costs for conventional two-stage repair. Further randomized studies are needed to expand upon these findings.

A systematic review and meta-analysis evaluating the effectiveness of lightweight mesh against heavyweight mesh in influencing the incidence of chronic groin pain following laparoscopic inguinal hernia repair

BACKGROUND

A systematic analysis was conducted of randomized controlled trials (RCTs) comparing lightweight mesh (LWM) with heavyweight mesh in laparoscopic inguinal hernia repair.

METHODS

Data extracted from the included RCTs were analyzed according to the principles of meta-analysis.

RESULTS

Eleven RCTs encompassing 2,189 patients were analyzed. In a fixed-effects model, operating time, postoperative pain, and recurrence rate were statistically similar between LWM and heavyweight mesh. LWM was associated with fewer perioperative complications and a reduced risk for developing chronic groin pain. There was also a reduced risk for developing other groin symptoms, such as foreign body sensations, but it was not statistically significant.

CONCLUSIONS

The use of LWM for laparoscopic inguinal hernia repair is not associated with an increased risk for hernia recurrence. LWM reduces the incidence of chronic groin pain, groin stiffness, and foreign body sensations. Therefore, LWM may routinely be used in laparoscopic inguinal hernia repair. However, high-quality RCTs with longer follow-up periods are required to validate these findings.

Gentamicin supplemented polyvinylidenfluoride mesh materials enhance tissue integration due to a transcriptionally reduced MMP-2 protein expression

Background

A beneficial effect of gentamicin supplemented mesh material on tissue integration is known. To further elucidate the interaction of collagen and MMP-2 in chronic foreign body reaction and to determine the significance of the MMP-2-specific regulatory element (RE-1) that is known to mediate 80% of the MMP-2 promoter activity, the spatial and temporal transcriptional regulation of the MMP-2 gene was analyzed at the cellular level.

Methods

A PVDF mesh material was surface modified by plasma-induced graft polymerization of acrylic acid (PVDF+PAAc). Three different gentamicin concentrations were bound to the provided active sites of the grafted mesh surfaces (2, 5 and 8 μg/mg). 75 male transgenic MMP-2/LacZ mice harbouring the LacZ reporter gene under control of MMP-2 regulatory sequence -1241/+423, excluding the RE-1 were randomized to five groups. Bilateral of the abdominal midline one of the five different meshes was implanted subcutaneously in each animal. MMP-2 gene transcription (anti-ß-galactosidase staining) and MMP-2 protein expression (anti-MMP-2 staining) were analyzed semiquantitatively by immunohistochemistry 7, 21 and 90 days after mesh implantation. The collagen type I/III ratio was analyzed by cross polarization microscopy to determine the quality of mesh integration.

Results

The perifilamentary ß-galactosidase expression as well as the collagen type I/III ratio increased up to the 90^th day for all mesh modifications, whereas no significant changes could be observed for MMP-2 protein expression between days 21 and 90. Both the 5 and 8 μg/mg gentamicin group showed significantly reduced levels of ß-galactosidase expression and MMP-2 positive stained cells when compared to the PVDF group on day 7, 21 and 90 respectively (5 μg/mg: p < 0.05 each; 8 μg/mg: p < 0.05 each). Though the type I/III collagen ratio increased over time for all mesh modifications significant differences to the PVDF mesh were only detected for the 8 μg/mg group at all 3 time points (p < 0.05 each).

Conclusions

Our current data indicate that lack of RE-1 is correlated with increased mesh induced MMP-2-gene expression for coated as well as for non-coated mesh materials. Gentamicin coating reduced MMP-2 transcription and protein expression. For the 8 μg/mg group this effect is associated with an increased type I/III collagen ratio. These findings suggest that gentamicin is beneficial for tissue integration after mesh implantation, which possibly is mediated via RE-1.

Systematic review and meta-analysis of the use of lightweight versus heavyweight mesh in open inguinal hernia repair

BACKGROUND

The objective of this study was systematically to analyse published randomized trials comparing lightweight mesh (LWM) with heavyweight mesh (HWM) in open inguinal hernia repair.

METHODS

Randomized trials on LWM versus HWM were selected from the standard electronic databases. Reported outcomes were analysed systematically using RevMan. Pooled risk ratios were calculated for categorical outcomes, and mean differences for secondary continuous outcomes, using the fixed-effects and random-effects models for meta-analysis.

RESULTS

Nine randomized trials containing 2310 patients were included. There was significant heterogeneity among trials. There was no difference in duration of operation, postoperative pain, recurrence rate, testicular atrophy and time to return to work between LWM and HWM groups. The two mesh types had a similar risk of perioperative complications, but LWM was associated with a reduced risk of developing chronic groin pain (risk ratio (RR) 0·61, 95 per cent confidence interval 0·50 to 0·74) and a reduced risk of developing other groin symptoms, such as stiffness and foreign body sensations (RR 0·64, 0·50 to 0·81).

CONCLUSION

The use of LWM for open inguinal hernia repair was not associated with an increased risk of hernia recurrence. LWM reduced the incidence of chronic groin pain as well as the risk of developing other groin symptoms.

A fibroblast/macrophage co-culture model to evaluate the biocompatibility of an electrospun Dextran/PLGA scaffold and its potential to induce inflammatory responses

Fibroblasts and macrophages are the two major types of cells responding to implanted biomaterials. They play crucial roles in inflammatory responses, host-material interactions and tissue remodeling. However, the synergistic interactions of these two cell types with biomaterials are not fully understood. In this investigation, an in vitro fibroblast/macrophage co-culture system was utilized to examine the biocompatibility and the potential to induce inflammatory responses of an electrospun Dextran/PLGA scaffold. The scaffold did not affect the morphologies, attachments, proliferations and viabilities of both the fibroblasts and macrophages, cultured separately or together. Moreover, it only activated a small subset of the macrophages implicating a low potential to induce either severe acute or chronic inflammatory response. Additionally, fibroblasts played a role in prolonging macrophage activation in the presence of the scaffolds. Using antibody arrays, IL-10, SDF-1, MIP-1 gamma and RANTES were found to be up-regulated when the cells were incubated with the scaffolds. The results of subdermal implantation of the Dextran/PLGA scaffolds confirmed its biocompatibility and low inflammatory potential.

Biocompatibility of prosthetic meshes in abdominal surgery

Surgical meshes today represent a group of implants mainly used for hernia repair. Modern hernia surgery is no longer imaginable without the application of these special biomaterials leading to millions of implantations each year worldwide. Because clinical trials are insufficient to evaluate the distinct effects of modified mesh materials in regard to tissue biocompatibility and functionality, a basic understanding of the physicochemical properties of mesh materials, as well as the underlying cause for hernia formation, is essential for a rational selection of the most appropriate device. The most important properties of meshes were found to be the type of filament, tensile strength, and experimental data, which indicate that particularly the mesh's porosity is of outstanding importance.

Polyglactine/polypropylene mesh vs. propylene mesh: is there a need for newer prosthesis in inguinal hernia?

BACKGROUND/AIM

To compare outcomes of light and heavy weight mesh for repair of inguinal hernia.

MATERIALS AND METHODS

This study was conducted at the Department of Surgery; Lady Reading Hospital, Peshawar from January 1, 2007 to December 31, 2008. Patients were divided into two groups based on the type of mesh implanted for inguinal hernia repair. Group 1 included patients in whom light weight composite (VyproII ) mesh is implanted: Group 2 included patients in whom polypropylene (Prolene R ) mesh is implanted. Data concerning the complications and post operative pain in the perioperative and postoperative period were collected and analyzed. Categorical data were presented as percentages with 95% confidence intervals and compared using a chi2 test and P 0.05 were considered significant.

RESULTS

Following allocation and exclusion of violating cases, 111 patients in group 1 and 138 patients in group 2 were analyzed. The mean age in group 1 was 38.20 +/- 13.34 years and in group 2 was 39.55 +/- 13.70 (P = 0.434). In group 1, hematoma formation was observed in four cases (3.6%), while it was observed in six cases (4.2%) in group 2 (P = 0.766). During the entire study, ten patients in all developed urinary retention, three of which required transient catheterization. One year post operation, there was a recurrence in only five cases overall, while only two patients complained of pain (P = 0.826).

CONCLUSION

The frequency of postoperative pain and complications in patients was similar in both groups.

The lightweight and large porous mesh concept for hernia repair

In modern hernia surgery, there are two competing mesh concepts which often lead to controversial discussions, on the one hand the heavyweight small porous model and on the other, the lightweight large porous hypothesis. The present review illustrates the rationale of both mesh concepts and compares experimental data with the first clinical data available. In summary, the lightweight large porous mesh philosophy takes into consideration all of the recent data regarding physiology and mechanics of the abdominal wall and inguinal region. Furthermore, the new mesh concept reveals an optimized foreign body reaction based on reduced amounts of mesh material and, in particular, a significantly decreased surface area in contact with the recipient host tissues by the large porous model. Finally, recent data demonstrate that alterations in the extracellular matrix of hernia patients play a crucial role in the development of hernia recurrence. In particular, long-term recurrences months or years after surgery and implantation of mesh can be explained by the extracellular matrix hypothesis. However, if the altered extracellular matrix proves to be the weak area, the decisive question is whether the amount of material as well as mechanical and tensile strength of the surgical mesh are really of significant importance for the development of recurrent hernia. All experimental evidence and first clinical data indicate the superiority of the lightweight large porous mesh concept with regard to a reduced number of long-term complications and particularly, increased comfort and quality of life after hernia repair.

Biological responses to cationically charged phosphorylcholine-based materials in vitro

Phosphorylcholine (PC)-based polymers have been used in a variety of medical device applications to improve biocompatibility. The use of PC-based materials for biomaterials is associated with low protein adsorption, reduced complement activation, low inflammatory response and cell adhesion. For some medical device applications however, materials that support cell adhesion are also beneficial, allowing host interaction and encouraging full incorporation within the body. As previous studies have suggested that cell adhesion to materials is enhanced by the addition of charge, PC-based polymers have therefore been modified to incorporate various concentrations of cationic charge. In this study, the affect of cationic charge on a range of biological responses was investigated. In vitro assays have been used to assess the adsorption of protein onto the materials surface, the adhesion of mouse fibroblasts and rabbit corneal epithelial cells and the adhesion of human mononuclear cells and granulocytes. The results corroborate previous work showing that PC without charge significantly reduces protein adsorption, cell adhesion and inflammatory cell activation. The addition of cationic charge to PC polymers however, resulted in an increase in all of the above responses. This increase did not however, increase linearly with cationic monomer concentration. The differences in cell adhesion are discussed in terms of differences in protein adsorption, cytotoxicity and/or stability of the different cationic polymer coatings.

Secretion of IL-1 and H2O2 by human mononuclear cells in vitro

The secretion of hydrogen peroxide (H2O2) and interleukin-1alpha (IL-1alpha) was evaluated during in vitro culturing of human monocytes. The oxidative metabolism and cytokine secretion were correlated to the cell distribution (number of surface-associated cells), the DNA content and their integrity, evaluated by lactate dehydrogenase (LDH) assay. The differentiation of cultured monocytes was determined by the expression of CD14, 27E10 and RM3/1. After 24 h cultivation, unstimulated cells had a low production of H2O2 and IL-1alpha. A four-fold increase in the production of H2O2 was detected with 5 and 10 microg/ml of lipopolysaccharide (LPS) and polystyrene (PS) particles. PS particles induced a concentration-dependent increase in IL-1alpha after 24 h. In contrast, cultivation for 48 h, did not result in any measurable production of H2O2, irrespective of the type of stimulus. A decreased viability of monocytes was shown after stimulation with PS particles in high concentrations. Our results indicate that the phenotype expression, adhesion, integrity and secretory pattern of human monocytes is dependent on the culture time and the type and concentration of stimulus.