Mechanical strength vs. degradation of a biologically-derived surgical mesh over time in a rodent full thickness abdominal wall defect

Effect of Compressive Modulus of Porous PVA Hydrogel Coating on the Preventing Adhesion of Polypropylene Mesh

PP mesh is a widely used prosthetic material in hernia repair. However, visceral adhesion is one of the worst complications of this operation. Hence, an anti-adhesive PP mesh is developed by coating porous polyvinyl alcohol (PVA) hydrogel on PP surface via freezing-thawing process method. The compressive modulus of porous PVA hydrogel coating is first regulated by the addition of porogen sodium bicarbonate (NaHCO3) at various quality ratios with PVA. As expected, the porous hydrogel coating displayed modulus more closely resembling that of native abdominal wall tissue. In vitro tests demonstrate the modified PP mesh show superior coating stability, excellent hemocompatibility, and good cytocompatibility. In vivo experiments illustrate that PP mesh coated by the PVA4 hydrogel that mimicked the modulus of native abdominal wall could prevent adhesion effectively. Based on this, the rapamycin (RPM) is loaded into the porous PVA4 hydrogel coating to further improve anti-adhesive property of PP mesh. The Hematoxylin and eosin (H&E) and Masson trichrome (MT) staining results verified that the resulting mesh could alleviate the inflammation response and reduce the deposition of collagen around the implantation zone. The biomimetic mechanical property and anti-adhesive property of modified PP mesh make it a valuable candidate for application in hernioplasty.

A Review of Advanced Abdominal Wall Hernia Patch Materials

Tension-free abdominal wall hernia patch materials (AWHPMs) play an important role in the repair of abdominal wall defects (AWDs), which have a recurrence rate of <1%. Nevertheless, there are still significant challenges in the development of tailored, biomimetic, and extracellular matrix (ECM)-like AWHPMs that satisfy the clinical demands of abdominal wall repair (AWR) while effectively handling post-operative complications associated with abdominal hernias, such as intra-abdominal visceral adhesion and abnormal healing. This extensive review presents a comprehensive guide to the high-end fabrication and the precise selection of these advanced AWHPMs. The review begins by briefly introducing the structures, sources, and properties of AWHPMs, and critically evaluates the advantages and disadvantages of different types of AWHPMs for AWR applications. The review subsequently summarizes and elaborates upon state-of-the-art AWHPM fabrication methods and their key characteristics (e.g., mechanical, physicochemical, and biological properties in vitro/vivo). This review uses compelling examples to demonstrate that advanced AWHPMs with multiple functionalities (e.g., anti-deformation, anti-inflammation, anti-adhesion, pro-healing properties, etc.) can meet the fundamental clinical demands required to successfully repair AWDs. In particular, there have been several developments in the enhancement of biomimetic AWHPMs with multiple properties, and additional breakthroughs are expected in the near future.

Soft, Long-Lived, Bioresorbable Electronic Surgical Mesh with Wireless Pressure Monitor and On-Demand Drug Delivery

Current research in the area of surgical mesh implants is somewhat limited to traditional designs and synthesis of various mesh materials, whereas meshes with multiple functions may be an effective approach to address long-standing challenges including postoperative complications. Herein, a bioresorbable electronic surgical mesh is presented that offers high mechanical strength over extended timeframes, wireless post-operative pressure monitoring, and on-demand drug delivery for the restoration of tissue structure and function. The study of materials and mesh layouts provides a wide range of tunability of mechanical and biochemical properties. Dissolvable dielectric composite with porous structure in a pyramidal shape enhances sensitivity of a wireless capacitive pressure sensor, and resistive microheaters integrated with inductive coils provide thermo-responsive drug delivery system for an antibacterial agent. In vivo evaluations demonstrate reliable, long-lived operation, and effective treatment for abdominal hernia defects, by clear evidence of suppressed complications such as adhesion formation and infections.

The Effects of Pectin-Honey Hydrogel in a Contaminated Chronic Hernia Model in Rats

Incisional hernia is a frequent complication after abdominal surgery. A previous study on rats evaluated the use of a Pectin-Honey Hydrogel (PHH)-coated polypropylene (PP) mesh for the healing of acute hernias. However, there are no studies investigating the use of PHH in association with PP mesh in chronic contaminated hernia. The aims of this study are to assess the effectiveness of PHH in promoting abdominal hernia repaired with PP mesh and in counteracting infection. Twenty Sprague Dawley male rats were enrolled and a full thickness defect was made in the abdominal wall. The defect was repaired after 28 days using a PP mesh, and a culture medium (Tryptone Soy Broth, Oxoid) was spread onto the mesh to contaminate wounds in both groups. The rats were randomly assigned to a treated or untreated group. In the treated group, a PHH was applied on the mesh before skin closure. At euthanasia-14 days after surgery-macroscopical, microbiological and histopathological evaluations were performed, with a score attributed for signs of inflammation. An immunohistochemical investigation against COX-2 was also performed. Adhesions were more severe (p = 0.0014) and extended (p = 0.0021) in the untreated group. Bacteriological results were not significantly different between groups. Both groups showed moderate to severe values (score > 2) in terms of reparative and inflammatory reactions at histopathological levels. The use of PHH in association with PP mesh could reduce adhesion formation, extension and severity compared to PP mesh alone. No differences in terms of wound healing, contamination and grade of inflammation were reported between groups.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

Decellularized-disc based allograft and xenograft prosthesis for the long-term precise reconstruction of temporomandibular joint disc

Currently, no effective disc reconstruction treatment strategy is clinically available for temporomandibular joint (TMJ) disc-related diseases. To address this, we developed a prosthesis construct with laser-drilled decellularized natural disc reinforced by polycaprolactone, which mimics the natural morphology, and structural, biomechanical and biological property of the TMJ disc. The construct demonstrated good biocompatibility, safety and immunological tolerance both in vitro, and in a rat subcutaneous model. During 6 months implantation in an allogeneic rabbit TMJ disc reconstruction model, the disc prosthesis maintained its integrity, collagen fiber-orientation, mechanical property, joint structural stability and prevented articular cartilage and bone from damage. Furthermore, the "upgraded" disc prosthesis obtained from decellularized porcine disc was implanted into a goat TMJ disc reconstruction model. The xenograft prosthesis, with strength and viscoelasticity similar to a natural TMJ disc, was able to restore the structure and function of TMJ up to 20 weeks. These results demonstrate the translational feasibility of an allogeneic or xenogeneic decellularized disc prosthesis for treatment of advanced TMJ disc-related diseases. STATEMENT OF SIGNIFICANCE: This study makes a significant contribution to TMJ disc disease treatment both in theory and in clinics, because: (1) it provided an innovative approach to prepare an artificial TMJ disc with decent mechanical properties and long-term condyle-protecting effect; (2) it specified an advanced decellularized method for fibrocartilage decellularization and xenograft application; (3) it developed a facile and reproducible TMJ disc reconstruction model not only for middle size animal but also for large animal study; (4) the comprehensive and unreported biomechanical tests on the natural TMJ discs would act as a valuable reference for further research in the field of artificial TMJ disc materials or TMJ disc tissue engineering; (5) it suggested a potential treatment for patients with severe TMJ diseases that were commonly met but difficult to treat in clinics.

Preparation and Use of Decellularized Extracellular Matrix for Tissue Engineering

The multidisciplinary fields of tissue engineering and regenerative medicine have the potential to revolutionize the practise of medicine through the abilities to repair, regenerate, or replace tissues and organs with functional engineered constructs. To this end, tissue engineering combines scaffolding materials with cells and biologically active molecules into constructs with the appropriate structures and properties for tissue/organ regeneration, where scaffolding materials and biomolecules are the keys to mimic the native extracellular matrix (ECM). For this, one emerging way is to decellularize the native ECM into the materials suitable for, directly or in combination with other materials, creating functional constructs. Over the past decade, decellularized ECM (or dECM) has greatly facilitated the advance of tissue engineering and regenerative medicine, while being challenged in many ways. This article reviews the recent development of dECM for tissue engineering and regenerative medicine, with a focus on the preparation of dECM along with its influence on cell culture, the modification of dECM for use as a scaffolding material, and the novel techniques and emerging trends in processing dECM into functional constructs. We highlight the success of dECM and constructs in the in vitro, in vivo, and clinical applications and further identify the key issues and challenges involved, along with a discussion of future research directions.

Inductive Remodeling of Extracellular Matrix Scaffolds in the Temporomandibular Joint of Pigs

The temporomandibular joint (TMJ) disc is a fibrocartilaginous tissue located between the condyle of the mandible and glenoid fossa and articular eminence of the temporal bone. Damage or derangement of the TMJ disc can require surgical removal (discectomy) to restore function. Removal of the TMJ disc, however, leaves the joint space vulnerable to condylar remodeling and degradation, potentially leading to long-term complications. No consistently effective clinical option exists for repair or replacement of the disc following discectomy. This study investigates the use of an acellular scaffold composed of extracellular matrix (ECM) derived from small intestinal submucosa (SIS) as a regenerative template for the TMJ disc in a porcine model. Acellular SIS ECM scaffolds were implanted following discectomy and allowed to remodel for 2, 4, 12, and 24 weeks postimplantation. Remodeling of the implanted device was assessed by longitudinal magnetic resonance imaging (MRI) over the course of 6 months, as well as gross morphologic, histologic, biochemical, and biomechanical analysis (tension and compression) of explanted tissues (disc and condyle) at the time of sacrifice. When the scaffold remained in the joint space, longitudinal MRI demonstrated that the scaffolds promoted new tissue formation within the joint space throughout the study period. The scaffolds were rapidly populated with host-derived cells and remodeled with formation of new, dense, aligned fibrocartilage resembling native tissue as early as 1 month postimplantation. De-novo formation of peripheral muscular and tendinous attachments resembling those in native tissue was also observed. The remodeled scaffolds approached native disc biochemical composition and compressive modulus, and possessed 50% of the tensile modulus within 3 months postimplantation. No degradation of the condylar surface was observed. These results suggest that this acellular bioscaffold fills a medical need for which there is currently no effective treatment and may represent a clinically relevant "off-the-shelf" implant for reconstruction of the TMJ disc.

Mast Cell-Biomaterial Interactions and Tissue Repair

Tissue engineers often use biomaterials to provide structural support along with mechanical and chemical signals to modulate the wound healing process. Biomaterials that are implanted into the body interact with a heterogeneous and dynamic inflammatory environment that is present at the site of injury. Whether synthetically derived, naturally derived, or a combination of both, it is important to assess biomaterials for their ability to modulate inflammation to understand their potential clinical use. One important, but underexplored cell in the context of biomaterials is the mast cell (MC). MCs are granulocytic leukocytes that engage in a variety of events in both the innate and adaptive immune systems. Although highly recognized for their roles in allergic reactions, MCs play an important role in wound healing by recognizing antigens through pattern recognition receptors and the high-affinity immunoglobulin E receptor (FceRI) and releasing granules that affect cell recruitment, fibrosis, extracellular matrix deposition, angiogenesis, and vasculogenesis. MCs also mediate the foreign body response, contributing to the incorporation or rejection of implants. Studies of MC-biomaterial interactions can aid in the elucidation of MC roles during the host tissue response and tissue repair. This review is designed for those in the tissue engineering and biomaterial fields who are interested in exploring the role MCs may play in wound-biomaterial interactions and wound healing. With this review, we hope to inspire more research in the MC-biomaterial space to accelerate the design and construction of optimized implants. Impact statement Mast cells (MCs) are highly specialized inflammatory cells that have crucial, but not fully understood, roles in wound healing and tissue repair. Upon stimulation, they recognize foreign antigens and release granules that help orchestrate the inflammatory response after tissue damage or biomaterial implantation. This review summarizes the current use of MCs in biomaterial research along with literature from the past decade focusing on MC interactions with materials used for tissue repair and regeneration. Studying MC-biomaterial interactions will help (i) further understand the process of inflammation and (ii) design biomaterials and tissue-engineered constructs for optimal repair and regeneration.

Self-Assembling Hydrogel Structures for Neural Tissue Repair

Hydrogel materials have been employed as biological scaffolds for tissue regeneration across a wide range of applications. Their versatility and biomimetic properties make them an optimal choice for treating the complex and delicate milieu of neural tissue damage. Aside from finely tailored hydrogel properties, which aim to mimic healthy physiological tissue, a minimally invasive delivery method is essential to prevent off-target and surgery-related complications. The specific class of injectable hydrogels termed self-assembling peptides (SAPs), provide an ideal combination of in situ polymerization combined with versatility for biofunctionlization, tunable physicochemical properties, and high cytocompatibility. This review identifies design criteria for neural scaffolds based upon key cellular interactions with the neural extracellular matrix (ECM), with emphasis on aspects that are reproducible in a biomaterial environment. Examples of the most recent SAPs and modification methods are presented, with a focus on biological, mechanical, and topographical cues. Furthermore, SAP electrical properties and methods to provide appropriate electrical and electrochemical cues are widely discussed, in light of the endogenous electrical activity of neural tissue as well as the clinical effectiveness of stimulation treatments. Recent applications of SAP materials in neural repair and electrical stimulation therapies are highlighted, identifying research gaps in the field of hydrogels for neural regeneration.

In Vivo Evaluation of a Pectin-Honey Hydrogel Coating on Polypropylene Mesh in a Rat Model of Acute Hernia

Investigations about ventral hernia repair are focused on improving the quality, resistance, and biocompatibility of mesh. This study compared plain polypropylene mesh with a pectin-honey hydrogel-coated polypropylene mesh in an acute hernia model in rats. Forty Wistar rats, randomly assigned to two groups, were submitted to laparotomy, and a 1 cm × 2 cm fascial defect was created, centered on the midline. Uncoated (group C) or coated mesh (group T) was inserted in an inlay fashion to repair the defect. After 30 days, the rats were euthanized, and the presence of adhesions to the mesh was macroscopically evaluated. Histology and measurement of COX-2 as tissue inflammation markers were used to assess fascia tissue healing. Grades of adhesion were not different between groups. Histological score and COX-2 expression were not significantly different between groups, except for the higher inflammatory response demonstrated in group T. The pectin-hydrogel coated mesh could not reduce adhesion formation compared to uncoated polypropylene mesh but improved peritoneal regeneration and tissue healing.

Extracellular Matrix Patches for Endarterectomy Repair

Patch repair is the preferred method for arteriotomy closure following femoral or carotid endarterectomy. Choosing among available patch options remains a clinical challenge, as current evidence suggests roughly comparable outcomes between autologous grafts and synthetic and biologic materials. Biologic patches have potential advantages over other materials, including reduced risk for infection, mitigation of an excessive foreign body response, and the potential to remodel into healthy, vascularized tissue. Here we review the use of decellularized extracellular matrix (ECM) for cardiovascular applications, particularly endarterectomy repair, and the capacity of these materials to remodel into native, site-appropriate tissues. Also presented are data from two post-market observational studies of patients undergoing iliofemoral and carotid endarterectomy patch repair as well as one histologic case report in a challenging iliofemoral endarterectomy repair, all with the use of small intestine submucosa (SIS)-ECM. In alignment with previously reported studies, high patency was maintained, and adverse event rates were comparable to previously reported rates of patch angioplasty. Histologic analysis from one case identified constructive remodeling of the SIS-ECM, consistent with the histologic characteristics of the endarterectomized vessel. These clinical and histologic results align with the biologic potential described in the academic ECM literature. To our knowledge, this is the first histologic demonstration of SIS-ECM remodeling into site-appropriate vascular tissues following endarterectomy. Together, these findings support the safety and efficacy of SIS-ECM for patch repair of femoral and carotid arteriotomy.

Dose optimization of decellularized skeletal muscle extracellular matrix hydrogels for improving perfusion and subsequent validation in an aged hindlimb ischemia model

Peripheral artery disease (PAD) affects more than 27 million individuals in North America and Europe, and current treatment strategies mainly aim to restore blood perfusion. However, many patients are ineligible for existing procedures, and these therapies are often ineffective. Previous studies have demonstrated success of an injectable decellularized skeletal muscle extracellular matrix (ECM) hydrogel in a young rat hindlimb ischemia model of PAD, but further pre-clinical studies are necessary prior to clinical translation. In this study, varying concentrations of a skeletal muscle ECM hydrogel were investigated for material properties and in vivo effects on restoring blood perfusion. Rheological measurements indicated an increase in viscosity and mechanical strength with the higher concentrations of the ECM hydrogels. When injecting dye-labelled ECM hydrogels into a healthy rat, differences were also observed for the spreading and degradation rate of the various concentrations. The three concentrations for the ECM hydrogel were then further examined in a young rat hindlimb ischemia model. The efficacy of the optimal ECM hydrogel concentration was then further confirmed in an aged mouse hindlimb ischemia model. These results further validate the use of decellularized skeletal muscle ECM hydrogels for improving blood perfusion in small animal models of PAD.

The Antimicrobial Effectiveness and Cytotoxicity of the Antibiotic-Loaded Chitosan: ECM Scaffolds

Background: The development of multifunctional wound dressings with the ability to control hemostasis, limit infection and promote rapid wound healing and constructive tissue remodeling has been a challenge for many years. In view of these challenges, a hybrid scaffold platform was developed that combined two different extracellular matrices (ECM): ECM from decellularized mammalian tissue and ECM (chitosan) from crustaceans. Both types of ECM have well established clinical benefits that support and promote wound healing and control hemostasis. This scaffold platform could also be augmented with antibiotics to provide bactericidal activity directly to the wound site. Methods: Four different scaffold formulations were developed containing chitosan supplemented with either 20% or 50% urinary bladder matrix (UBM) hydrogel or 1% (w/v) or 10% (w/v) UBM–ECM particulates. 100% chitosan scaffolds were used as controls. The scaffolds were augmented with either minocycline or rifampicin. Escherichia Coli and Staphylococcus Aureus were used to assesses antimicrobial efficacy and duration of activity, while neutral red uptake assays were performed to establish direct and indirect cytotoxicity. Results: Results showed that scaffold handling properties, scaffold integrity over time and the efficacy and release rate of loaded antibiotics could be modified by altering scaffold composition. Moreover, antibiotics were easily released from the scaffold and could remain effective for up to 24 h by modifying the scaffold composition. Variable results with cytotoxicity testing show that further work is required to optimize the scaffold formulations but these proof of principle experiments suggest that these scaffolds have potential as bioactive wound dressings.

Evolution From the U-shaped to Keyhole-shaped Mesh Configuration in the Repair of Paraesophageal and Recurrent Hiatal Hernia

BACKGROUND

Paraesophageal hernia (PEH) and recurrent hiatal hernia (RHH) are prone to recurrences. One adjunct used to reduce recurrences is mesh reinforcement. The optimal configuration is yet to be determined. We present our evolution from the U-shaped to the keyhole pattern.

METHODS

All patients undergoing PEH/RHH repair with mesh between 2013 and 2019 were reviewed for demographic information, perioperative/intraoperative details, postoperative complications, and recurrences.

RESULTS

Of patients undergoing PEH/RHH repair between 2013 and 2019, 138 were repaired using mesh. Of these, 88 were repaired using the U-shaped configuration and 50 using the keyhole configuration. The U-shaped configuration was used for PEH in 72% and RHH in 28%, while the keyhole configuration was used for PEH in 66% and RHH in 34%. Thirty patients suffered postoperative complications, although there was no difference between the groups. Overall, 28 patients in the U-shaped configuration group (31.8%) had a recurrence of their hiatal hernia identified, compared with 7 patients (14.6%) in the keyhole group (P=0.039). The median time to last follow-up was 21 months (range: 1 to 85) in the U-shaped group and 8 months (range: 1 to 23) in the keyhole group. There was no difference in median time to recurrence, postoperative dysphagia, dilations, or strictures.

CONCLUSIONS

The keyhole pattern mesh was not associated with a higher complication rate compared with the U-shape pattern. Although this study was not a direct comparison between the configurations, it does suggest that the keyhole pattern may lead to fewer recurrences.

Biochemical and biomechanical comparisions of decellularized scaffolds derived from porcine subcutaneous and visceral adipose tissue

Decellularized adipose tissue (DAT) is a promising biomaterial for adipose tissue engineering. However, there is a lack of research of DAT prepared from xenogeneic porcine adipose tissue. This study aimed to compare the adipogenic ability of DAT derived from porcine subcutaneous (SDAT) and visceral adipose tissue (VDAT). The retention of key collagen in decellularized matrix was analysed to study the biochemical properties of SDAT and VDAT. For the biomechanical study, both DAT materials were fabricated into three-dimensional (3D) porous scaffolds for rheology and compressive tests. Human adipose-derived stem cells (ADSCs) were cultured on both scaffolds to further investigate the effect of matrix stiffness on cellular morphology and on adipogenic differentiation. ADSCs cultured on soft VDAT exhibited significantly reduced cellular area and upregulated adipogenic markers compared to those cultured on SDAT. In vivo results revealed higher adipose regeneration in the VDAT compared to the SDAT. This study further demonstrated that the relative expression of collagen IV and laminin was significantly higher in VDAT than in SDAT, while the collagen I expression and matrix stiffness of SDAT was significantly higher in comparison to VDAT. This result suggested that porcine adipose tissue could serve as a promising candidate for preparing DAT.

Biological Scaffolds for Abdominal Wall Repair: Future in Clinical Application?

Millions of abdominal wall repair procedures are performed each year for primary and incisional hernias both in the European Union and in the United States with extremely high costs. Synthetic meshes approved for augmenting abdominal wall repair provide adequate mechanical support but have significant drawbacks (seroma formation, adhesion to viscera, stiffness of abdominal wall, and infection). Biologic scaffolds (i.e., derived from naturally occurring materials) represent an alternative to synthetic surgical meshes and are less sensitive to infection. Among biologic scaffolds, extracellular matrix scaffolds promote stem/progenitor cell recruitment in models of tissue remodeling and, in the specific application of abdominal wall repair, have enough mechanical strength to support the repair. However, many concerns remain about the use of these scaffolds in the clinic due to their higher cost of production compared with synthetic meshes, despite having the same recurrence rate. The present review aims to highlight the pros and cons of using biologic scaffolds as surgical devices for abdominal wall repair and present possible improvements to widen their use in clinical practice.

Large Hiatal Hernia Repair with Urinary Bladder Matrix Graft Reinforcement and Concomitant Sleeve Gastrectomy

Background:

There is no current consensus on the management of large hiatal hernias concomitant with performance of a sleeve gastrectomy procedure. Proposed solutions have included performing a modified Nissen fundoplication, performing cruroplasty alone, utilizing the Linx device, performing cruroplasty with reinforcement material, and avoiding the sleeve procedure altogether in favor of a bypass procedure in order to minimize gastroesophageal reflux. Urinary bladder matrix (UBM) represents a biologically derived material for use in hiatal hernia repair reinforcement with the potential to improve durability of repair without incurring the risks of other reinforcement materials.

Methods:

This study reports the results of a retrospective chart review of 32 cases of large hiatal hernia repair utilizing both primary crural repair and UBM reinforcement concomitant with laparoscopic sleeve gastrectomy by a single surgeon. Hernia diameter averaged 6 cm (range 4–9 cm). After an average of 1 year followup, 30 patients were assessed for subjective symptoms of gastroesophageal reflux (GERD) using the Gastroesophageal Reflux Disease-Health Related Quality of Life (GERD-HRQL) score. Twenty patients were evaluated with either upper gastrointestinal (GI) series, endoscopy, or both.

Results:

Each repair was successful and completed laparoscopically concomitant with sleeve gastrectomy. Anterior and posterior cruroplasty was performed using interrupted 0-Ethibond suture using the Endostitch device. The UBM graft exhibited favorable handling characteristics placed as a keyhole geometry sutured to the crura with absorbable suture. A careful chart review was undertaken to assess for complications. There have been no reoperations. After a median of 12 months (range, 4–27 months) of followup, an assessment of recurrences or long-term complications was completed. Median GERD-HRQL score was 6, with a range of 0 to 64 (of possible 75), indicating very low-level reflux symptomatology. Follow-up upper GI radiographs or endoscopy were obtained in 20 cases and show intact repairs.

Conclusion:

In this series of 32 cases, laparoscopic cruroplasty with UBM graft reinforcement has been effective and durable at 12 months of followup. This technique may offer one satisfactory solution for large hiatal hernia repair concomitant with laparoscopic sleeve gastrectomy that may achieve a durable repair with low GERD symptoms.

Preparation and properties of cellulose nanocrystals, gelatin, hyaluronic acid composite hydrogel as wound dressing

Gelatin (GA), hyaluronic acid (HA) and cellulose nanocrystals (CNC) are promising materials for skin wound care. In this study the GA-HA-CNC hydrogels were prepared by cross-linking and freeze-drying. The composition and mechanism of GA-HA-CNC hydrogels were confirmed by FTIR. The morphology and pore size were obtained by SEM. We accessed the physical property from rheological results and swelling ratio. NIH-3T3 cells were inoculated into the hydrogels and cultured for different days, then we analyzed the cytotoxicity of the prepared hydrogels by CCK-8 methods and live/dead pictorial diagram using staining kits. FTIR revealed the combination between GA, HA and CNC was attributed to the amide bond and hydrogen bonding. SEM results showed that the drying GA-HA-CNC hydrogels were spongy, with the pore diameter about 80-120 µm. CNC significantly enhanced the property of the hydrogels and play a vital role according to the rheology and swelling results. The cells culture results showed that NIH-3T3 cells can attached to, grow, and proliferate well on the GA-HA-CNC hydrogels. In conclusion, the natural GA-HA-CNC hydrogel has great potential for the skin wound repair.

Effect of varying the crosslinking degree of a pericardial implant with oligourethane on the repair of a rat full-thickness abdominal wall defect

The stability and bioactivity of biologic implants rely mainly on the control of the crosslinking process of collagen. However, the most common methods have no control on the crosslinking degree producing it excessively. This study outlines the role of crosslinking of collagen-based implants with oligourethane on the host response following reconstruction of a rat full-thickness abdominal wall defect. We decellularized and crosslinked bovine pericardial tissue to achieve two crosslinking degrees. For the decellularized implants, named as non-crosslinked (N-CL), the collagen-amines were 0.42 ± 0.02 mmol/mg. Crosslinking by the oligourethane reduced the primary amine concentration to 0.28 ± 0.01 and 0.19 ± 0.01 mmol/mg; these values were classified as low (∼30%, L-CL) and medium crosslinking (∼50%, M-CL), respectively. By imaging the implants using second harmonic generation microscopy, we observed undulated bundles of collagen fibers organized in multi-directed layers localized in N-CL and L-CL samples. Post-implantation, a negligible change in the organization of collagen fibers in the crosslinked implants was observed, suggesting that the in vivo biodegradation was delayed. An enlargement of the implant area was also observed, without rupture, in all three (N-CL, L-CL, M-CL) materials, whereas adhesion to the omentum, but not to the bowel, was observed. The number of blood vessels after 90-day implantation in N-CL and L-CL was 13 ± 1 and 12 ± 1 per field, respectively, while the number significantly decreased to 2 ± 1 in M-CL. The results suggest that the controlled degree of crosslinking in oligourethane-modified biologic implants can be used as a strategy to balance biodegradation and remodeling in surgical repair of soft tissues.

Silk Fibroin Microparticles with Hollow Mesoporous Silica Nanocarriers Encapsulation for Abdominal Wall Repair

Therapeutic vascularization appears to be an effective way of repairing abdominal wall defects. Attempts to implement this treatment tend to focus on the generation of featured drug carriers with the ability effectively to encapsulate the angiogenesis-stimulating agents and control their release to maintain an appropriate concentration at the injured area. Here, a new type of composite microparticle (CM) composed of silk fibroin (SF) and hollow mesoporous silica nanocarriers (HMSNs) is presented for therapeutic agent delivery. The CMs are generated by drying microfluidic emulsion templates of HMSN-dispersed SF solution. The resultant CMs have a distinctive micro-nanostructure, in which two barriers control the drug release. The encapsulated HMSNs increase the drug-carrying capacity of the CMs, and also form the first barrier via physical absorption. The microfluidic SF microparticles not only provide a shell with excellent monodispersity and biocompatibility but also form the second barrier via efficient encapsulation. Because of these superior properties of the CMs, the loaded drugs can be delivered with a satisfactory activity at the required rate, making them ideal for implementing therapeutic vascularization and repairing abdominal wall defects.

Comparison of in vivo remodeling of urinary bladder matrix and acellular dermal matrix in an ovine model

Aim: Biologically derived surgical graft materials come from a variety of sources with varying mechanical properties. This study aimed to evaluate the host response and mechanical performance of two extracellular matrix devices in a large animal preclinical model. Materials & methods: Bilateral defects were created in the fascia lata of sheep and repaired with either an acellular dermal matrix (ADM) or urinary bladder matrix (UBM). After 1 or 3 months, the repair site was explanted for histological and mechanical analysis. Results & conclusion: Despite pre-implantation mechanical differences, both UBM and ADM demonstrated similar mechanical performance at 3 months. However, UBM was completely remodeled into site-appropriate tissue by 3 months, while ADM showed limited tissue incorporation.

Hierarchically porous composite microparticles from microfluidics for controllable drug delivery

Abdominal wall defect repair remains a major clinical need, and a particle-based controllable drug delivery system offers a solution to this problem. Here, we present a new type of hierarchically porous microparticles (HPMs) composed of poly(lactic-co-glycolic acid) (PLGA) and hollow mesoporous silica nanoparticles (HMSNs) for the delivery. The HPMs are generated by drying microfluidic emulsion templates of HMSNs-dispersed PLGA solution. The resultant HPMs have tailorable porous structures, that provide a three-hierarchy architecture for the controlled release of actives. The first hierarchy is formed for controlling the drug release via physical absorption as a result of the presence of the HMSNs in the HPMs. The second hierarchy channels with small pores scattered throughout the surface of the HPMs are formed during evaporation of the solvent. The third hierarchy with openings on the surface of the HPMs is formed as a result of the inner droplets leaking out of the double emulsion templates during the PLGA solidification. Thus, by manipulating the flow of solutions during the microfluidic emulsification, the porous structures of HPMs can be easily and precisely adjusted, and the loaded drugs are delivered at the required rate. These features of the HPMs make them ideal for repairing abdominal wall defects.

Retrorectus repair of incisional ventral hernia with urinary bladder matrix reinforcement in a long-term porcine model

Aim: Not all biologically derived materials elicit the same host response when used for reinforcement of ventral hernia repairs. This study aimed to evaluate the remodeling characteristics of the abdominal wall following reinforcement with urinary bladder matrix (UBM) in a large animal preclinical model of ventral hernia repair. Materials & methods: Midline defects in 36 Yucatan minipigs were reinforced with UBM-derived surgical devices using a classic Rives–Stoppa–Wantz approach, and compared with primary repair controls. After 3 or 8 months, the abdominal wall was explanted for histological and mechanical analysis. Results & conclusion: All UBM-derived surgical devices were completely resorbed within 8 months and facilitated deposition of vascularized, biomechanically functional connective tissue in the retrorectus plane, with no evidence of hernia formation.

Extracellular Matrix for Myocardial Repair

Multiple strategies have been investigated to restore functional myocardium following injury or disease including the local administration of cytokines or chemokines, stem/progenitor cell therapy, mechanical circulatory support, pharmacologic use, and the use of inductive biomaterials. The use of xenogeneic biologic scaffolds composed of extracellular matrix (ECM) has been shown to facilitate functional restoration of several tissues and organs including the esophagus, skeletal muscle, skin, and myocardium, among others. The present chapter describes the current understanding of specific components of biologic scaffolds composed of ECM, the mechanisms by which ECM bioscaffolds promote constructive cardiac remodeling after injury, determinants of remodeling outcome, and the versatility of ECM as a potential cardiac therapeutic.

Extracellular Matrix Bioscaffolds for Building Gastrointestinal Tissue

Regenerative medicine is a rapidly advancing field that uses principles of tissue engineering, developmental biology, stem cell biology, immunology, and bioengineering to reconstruct diseased or damaged tissues. Biologic scaffolds composed of extracellular matrix have shown great promise as an inductive substrate to facilitate the constructive remodeling of gastrointestinal (GI) tissue damaged by neoplasia, inflammatory bowel disease, and congenital or acquired defects. The present review summarizes the preparation and use of extracellular matrix scaffolds for bioengineering of the GI tract, identifies significant advances made in regenerative medicine for the reconstruction of functional GI tissue, and describes an emerging therapeutic approach.

Biologic Scaffolds

Biologic scaffold materials composed of allogeneic or xenogeneic extracellular matrix are commonly used for the repair and functional reconstruction of injured and missing tissues. These naturally occurring bioscaffolds are manufactured by the removal of the cellular content from source tissues while preserving the structural and functional molecular units of the remaining extracellular matrix (ECM). The mechanisms by which these bioscaffolds facilitate constructive remodeling and favorable clinical outcomes include release or creation of effector molecules that recruit endogenous stem/progenitor cells to the site of scaffold placement and modulation of the innate immune response, specifically the activation of an anti-inflammatory macrophage phenotype. The methods by which ECM biologic scaffolds are prepared, the current understanding of in vivo scaffold remodeling, and the associated clinical outcomes are discussed in this article.