Providing direction improves function: Comparison of a radial pore-orientated acellular collagen scaffold to clinical alternatives in a surgically induced rabbit diaphragmatic tissue defect model

Diaphragmatic hernia repair porcine model to compare the performance of biodegradable membranes against Gore-Tex®

BACKGROUND

Patch repair of congenital diaphragmatic hernia (CDH) using Gore-Tex® is associated with infection, adhesions, hernia recurrence, long-term musculoskeletal sequels and poor tissue regeneration. To overcome these limitations, the performance of two novel biodegradable membranes was tested to repair CDH in a growing pig model.

METHODS

Twelve male pigs were randomly assigned to 3 different groups of 4 animals each, determined by the type of patch used during thoracoscopic diaphragmatic hernia repair (Gore-Tex®, polycaprolactone electrospun membrane-PCLem, and decellularized human chorion membrane-dHCM). After 7 weeks, all animals were euthanized, followed by necropsy for diaphragmatic evaluation and histological analysis.

RESULTS

Thoracoscopic defect creation and diaphragmatic repair were performed without any technical difficulty in all groups. However, hernia recurrence rate was 0% in Gore-Tex®, 50% in PCLem and 100% in dHCM groups. At euthanasia, Gore-Tex® patches appeared virtually unchanged and covered with a fibrotic capsule, while PCLem and dHCM patches were replaced by either floppy connective tissue or vascularized and floppy regenerated membranous tissue, respectively.

CONCLUSION

Gore-Tex® was associated with a higher survival rate and lower recurrence. Nevertheless, the proposed biodegradable membranes were associated with better tissue integration when compared with Gore-Tex®.

Development and systematic evaluation of decellularization protocols in different application models for diaphragmatic tissue engineering

BACKGROUND

Tissue engineered bioscaffolds based on decellularized composites have gained increasing interest for treatment of various diaphragmatic impairments, including muscular atrophies and diaphragmatic hernias. Detergent-enzymatic treatment (DET) constitutes a standard strategy for diaphragmatic decellularization. However, there is scarce data on comparing DET protocols with different substances in distinct application models in their ability to maximize cellular removal while minimizing extracellular matrix (ECM) damage.

METHODS

We decellularized diaphragms of male Sprague Dawley rats with 1 % or 0.1 % sodium dodecyl sulfate (SDS) and 4 % sodium deoxycholate (SDC) by orbital shaking (OS) or retrograde perfusion (RP) through the vena cava. We evaluated decellularized diaphragmatic samples by (1) quantitative analysis including DNA quantification and biomechanical testing, (2) qualitative and semiquantitative analysis by proteomics, as well as (3) qualitative assessment with macroscopic and microscopic evaluation by histological staining, immunohistochemistry and scanning electron microscopy.

RESULTS

All protocols produced decellularized matrices with micro- and ultramorphologically intact architecture and adequate biomechanical performance with gradual differences. The proteomic profile of decellularized matrices contained a broad range of primal core and ECM-associated proteins similar to native muscle. While no outstanding preference for one singular protocol was determinable, SDS-treated samples showed slightly beneficial properties in comparison to SDC-processed counterparts. Both application modalities proved suitable for DET.

CONCLUSION

DET with SDS or SDC via orbital shaking or retrograde perfusion constitute suitable methods to produce adequately decellularized matrices with characteristically preserved proteomic composition. Exposing compositional and functional specifics of variously treated grafts may enable establishing an ideal processing strategy to sustain valuable tissue characteristics and optimize consecutive recellularization. This aims to design an optimal bioscaffold for future transplantation in quantitative and qualitative diaphragmatic defects.

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

A Systematic Review Examining the Experimental Methodology Behind In Vivo Testing of Hiatus Hernia and Diaphragmatic Hernia Mesh

INTRODUCTION

Mesh implants are regularly used to help repair both hiatus hernias (HH) and diaphragmatic hernias (DH). In vivo studies are used to test not only mesh safety, but increasingly comparative efficacy. Our work examines the field of in vivo mesh testing for HH and DH models to establish current practices and standards.

METHOD

This systematic review was registered with PROSPERO. Medline and Embase databases were searched for relevant in vivo studies. Forty-four articles were identified and underwent abstract review, where 22 were excluded. Four further studies were excluded after full-text review-leaving 18 to undergo data extraction.

RESULTS

Of 18 studies identified, 9 used an in vivo HH model and 9 a DH model. Five studies undertook mechanical testing on tissue samples-all uniaxial in nature. Testing strip widths ranged from 1-20 mm (median 3 mm). Testing speeds varied from 1.5-60 mm/minute. Upon histology, the most commonly assessed structural and cellular factors were neovascularisation and macrophages respectively (n = 9 each). Structural analysis was mostly qualitative, where cellular analysis was equally likely to be quantitative. Eleven studies assessed adhesion formation, of which 8 used one of four scoring systems. Eight studies measured mesh shrinkage.

DISCUSSION

In vivo studies assessing mesh for HH and DH repair are uncommon. Within this relatively young field, we encourage surgical and materials testing institutions to discuss its standardisation.

Promoting endogenous repair of skeletal muscle using regenerative biomaterials

Skeletal muscles normally have a remarkable ability to repair themselves; however, large muscle injuries and several myopathies diminish this ability leading to permanent loss of function. No clinical therapy yet exists that reliably restores muscle integrity and function following severe injury. Consequently, numerous tissue engineering techniques, both acellular and with cells, are being investigated to enhance muscle regeneration. Biomaterials are an essential part of these techniques as they can present physical and biochemical signals that augment the repair process. Successful tissue engineering strategies require regenerative biomaterials that either actively promote endogenous muscle repair or create an environment supportive of regeneration. This review will discuss several acellular biomaterial strategies for skeletal muscle regeneration with a focus on those under investigation in vivo. This includes materials that release bioactive molecules, biomimetic materials and immunomodulatory materials.

Polydopamine Functionalization: A Smart and Efficient Way to Improve Host Responses to e-PTFE Implants

Among the different materials used as protheses for the treatment of Congenital Diaphragmatic Hernia, expanded polytetrafluoroethylene (e-PTFE) plays a leading role owing to its mechanical properties as explained in the first part of this review. However, this material is poorly cell adhesive, which is expected for its contact on the abdominal face, but should display specific tissue adhesion on its thoracic exposed faced. A side specific functionalization method is hence required. The deposition of a nanosized polydopamine film on PTFE is known to be possible but immersion of the e-PTFE membrane in an aerated dopamine solution leads to a functionalization not only on both faces of the membrane but also in its porous volume. The fact that polydopamine also forms at the water/air interface has allowed to transfer a polydopamine film on only one face of the e-PTFE membrane. The deposition method and applications of such Janus like membranes are reviewed in the second part of the review.

One-year follow-up study of iBTA-induced allogenic biosheet for repair of abdominal wall defects in a beagle model: a pilot study

PURPOSE

We evaluated the usefulness of biosheet, an in-body tissue-engineered collagenous membrane, as a novel repair material for abdominal wall defects in a beagle model.

METHODS

Biosheets were prepared by embedding molds into subcutaneous pouches in two beagle dogs for 2 months, with subsequent storage in 70% ethanol. The obtained biosheets (thickness 0.5 mm, size 25 cm²) were implanted to replace same-size defects in the abdominal wall of two beagles in an allogenic manner.

RESULTS

The biosheets were not stressed during suturing and did not split; moreover, patch implantation into the defective wound was easy. No complications such as anastomotic leaks or infections occurred during implantation. One year post-implantation, the thickness of the biosheet implantation section increased to approximately 2.5 mm, corresponding to approximately 70% of the native abdominal wall. A section of the abdominal wall muscle elongated from the periphery of the newly formed collagen layer, and the peritoneum was entirely formed on the peritoneal cavity surface, resulting in partial regeneration of the three-layered abdominal wall. The mechanical strength of the newly formed wall was approximately fivefold higher than the native wall. The elasticity of the biosheet in the low-strain region decreased to approximately 10% post-implantation, similar to the native wall.

CONCLUSIONS

This pilot study demonstrated that biosheet maintained the abdominal wall without any complications for 1 year post-implantation, and partial regeneration was observed. Although this experiment was limited to two cases, the results indicated that biosheet may serve as a reliable abdominal wall restorative material.