The evaluation of functional small intestinal submucosa for abdominal wall defect repair in a rat model: Potent effect of sequential release of VEGF and TGF-β1 on host integration

SDF-1α/BMP-12 loaded biphasic sustained-release SIS hydrogel/SA microspheres composite for tendon regeneration

Due to the inherent limited regenerative capacity of tendons, rendering countermeasures for tendon injury remains challenging. The pathophysiology of tendon healing is complex and contains three sequential phases including inflammation, proliferation and remodeling. Aiming at the treatment of different stages of tendon injury, in our work, an injectable small intestinal submucosa hydrogel/sodium alginate microspheres (SIS/SA) composite co-encapsulating stromal cell derived factor-1α (SDF-1α) and bone morphogenetic protein-12 (BMP-12) was developed for effective tendon regeneration. BMP-12 was initially embedded into SA microspheres by microfluid method, and then, microspheres were subsequently encapsulated into the SDF-1α loaded SIS hydrogel. The two bioactive molecules were released in a biphasic and controlled manner to facilitate cell recruitment in the early stage and tendon differentiation in the long-time stage, respectively. Meanwhile, with the degradation of hydrogel/microspheres composite, the regeneration process was accelerated through multiple pathways encompassing immune regulation, angiogenesis, and extracellular matrix (ECM) synthesis. The findings of this study present a compelling translational strategy with significant clinical potential for advancing tendon regeneration therapies.

Assembled granular hydrogels loaded with growth factors for enhanced mesenchymal stem cell therapy in abdominal wall defect repair

Abdominal wall defects caused by trauma, congenital rupture, and intra-abdominal infection remain challenging due to the large wound area and complex complications. Herein, an assembled mesenchymal stem cell (MSCs)-laden granular hydrogel (termed assembled GSD@FPs), loaded with basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF), is developed. This hydrogel is constructed through dynamic covalent cross-linking (via borate ester bonds) among dopamine-grafted gelatin methacrylamide (GelMA-DA), phenylborate-modified hyaluronic acid (HA-PBA), and epigallocatechin-3-gallate (EGCG), serving as multifunctional bulk building blocks for cell delivery and abdominal wall repair. The designed assembled granular hydrogels possess good rheological properties, self-healing, injectability, and tissue-adhesion properties. Detailed in vitro cell experiments are conducted, revealing that the GSD@FPs granular hydrogels can effectively promote cell proliferation, cell migration and angiogenesis. Furthermore, in abdominal wall defects, assembled GSD@FPs significantly accelerates the tissue healing process by simultaneously inhibiting the inflammatory response, promoting collagen deposition, and promoting cell proliferation and angiogenesis. Importantly, the assembled GSD@FPs granular hydrogels can also provide mechanical support and increase the thickness of regenerated tissue (1727.8 ± 169.6 μm for the control group, 3204.2 ± 278.5 μm for the assembled GSD@FPs group at 14 d). Eventually, the GSD granular hydrogels biodegraded, facilitating tissue remodeling and generating new muscle tissues. Therefore, this study provides a promising strategy with great potential for application in abdominal wall repair.

ZIF-8 composite nanofibrous membranes loaded with bFGF: a new approach for tendon adhesion prevention and repair

During tendon injury repair, deficiency of basic fibroblast growth factor (bFGF) is a critical factor leading to unsatisfactory repair results. This study aims to prepare bFGF-loaded zeolite imidazole framework-8 (ZIF-8) nanocrystals using a one-pot synthesis method. Subsequently, a bilayer nanofibrous membrane incorporating these drug-loaded nanocrystals was fabricated through electrospinning technology. The potential of this composite nanofibrous membrane to facilitate the continuous release of bFGF at the site of tendon injury was evaluated, with the aim of enhancing the quality of tendon repair. The efficacy of the nanofibrous membrane in promoting tendon differentiation, preventing tendon adhesion, and facilitating tendon repair was assessed through both in vitro and in vivo experiments. At the site of tendon injury, the degradation of ZIF-8 in an acidic microenvironment resulted in the release of bFGF and Zn2+, which contributed to the enhancement of tendon repair. ZIF-8 nanocrystals achieved an encapsulation efficiency of 50.13% ± 1.42%. Following a continuous release period exceeding 40 days, the cumulative in vitro release rate was determined to be 35.02% ± 4.27%. The incorporation of ZIF-8 nanocrystals into a nanofibrous membrane demonstrated the ability to effectively preserve the bioactivity of bFGF while enabling sustained release at the site of tendon injury, thereby facilitating tendon repair. The findings offer novel insights into the treatment of tendon injuries and provide significant theoretical guidance for the tendon repair process.

Electrospun poly(ester-carbonate)/poly(carbonate-urethane) membranes with controlled drug release for potential use in abdominal surgery

Surgical meshes and patches used in abdominal surgery, despite their effectiveness, have a number of disadvantages that may lead to complications. This is due to the properties of the materials used for their construction and the structure of the implant itself. This paper presents an attempt to obtain an implant material, that could be used in surgery, combining the advantages of biodegradable and non-degradable polymers, while eliminating their weaknesses, additionally providing the possibility of using local pharmacotherapy. For this purpose a poly(caprolactone-co-trimethylene carbonate) blend with a 10% addition of poly(ε-caprolactone) (PCLTMC:PCL) was utilized as a biodegradable drug carrier. Using a dual-jet electrospinning method, the blend was interlaced with non-degradable poly(carbonate-urethane) (PCU) nanofibers of varying hydrophilicity, forming semi-fibrous membranes. The primary aim of the research was to obtain control over drugs release kinetics simultaneously maintaining stable mechanical properties of membranes during incubation in vitro. These objectives were achieved through the use of a specific gradient structure design, enriched with a drug-releasing fraction at the surface and PCU in the core. It was observed that the hydrophilicity of membranes influenced the mechanisms and rate of the diffusion of water to the bulk and the drugs along with degradation by-products to the incubation medium. Additionally, the gradient structure enabled control over the permeation of low-molecular-weight model compound from one side of the membrane to the other. The results also demonstrated that the number of fibroblasts adsorbed on the membrane surface depended primarily on its morphology and hydrophilicity, suggesting the potential to achieve favourable integration with tissues. The developed material exhibits significant potential for applications in abdominal surgery.

Prevascularized Hydrogel Enhancing Innervation and Repair of Full-Thickness Volumetric Muscle Loss in Abdominal Wall Defects

Current materials for repairing abdominal peritoneal defects face rapid degradation, infection risk, insufficient vascular ingrowth, slow muscle regeneration, and suboptimal postoperative integration, often causing fibrotic healing and hindering volumetric muscle loss (VML) repair exceeding 30%. To address these issues, photo-cross-linkable gelatin hydrogels are combined with blood vessel-forming cells to reconstruct vascular networks, providing temporary nutrient and gas channels that support cell repair. By developing a polymer-chain propagation time technique, hydrogel properties are optimized, avoiding limitations of conventional light exposure. These gels guide blood-vessel formation in vitro and promote robust microvessel and neural development in vivo. Precise control of light exposure and propagation times balances cross-linking and degradation, fostering blood vessel growth and host motor neuron ingrowth. In 55% VML, these hydrogels enable full-thickness abdominal muscle regeneration, restoring up to 70% of lost muscle while mimicking healthy tissue's strength and structure. Achieving higher degradation rates and a vascular density exceeding 50 vessels/mm-2 is essential for functional muscle repair. These strategies effectively bridge current clinical gaps, advancing regenerative medicine. The ability to fine-tune degradation and stiffness underscores gelatin hydrogels' potential as cell carriers, allowing the reconstruction of temporary vascular and neural channels at injury sites and significantly enhancing muscle tissue regeneration.

Bioactive Peptide-Based Composite Hydrogel for Myocardial Infarction Treatment: ROS Scavenging and Angiogenesis Regulation

After myocardial infarction (MI), the affected area of the myocardium falls into a state of ischemia and hypoxia, and subsequently, cardiomyocytes undergo a series of pathological changes and eventually transform into scar tissue. Therefore, restoring blood perfusion and reducing reactive oxygen species (ROS) are essential to promote the repair process of damaged myocardium. Here, the MMP12 (YWDAW) peptide which has a good antioxidant effect in deep-sea fish muscle, and the KRX (MRPYDANKR) peptide which shows a pro-angiogenesis effect from mammalian endothelial genes, were utilized collaboratively and loaded into an injectable GelMA hydrogel to achieve minimally invasive implantation and long-term retention at the MI site. The incorporation of bioactive peptides builds a stable and efficient system, which in addition to effectively removing ROS and promoting angiogenesis, avoids cell apoptosis and inflammation in the long run, and effectively inhibits the process of myocardial fibrosis. Both in vivo and in vitro experiments have shown that the combination of two short peptides with anti-oxidation and angiogenesis therapy can eventually achieve rapid repair of damaged myocardial tissue. This study fully demonstrated that natural functional peptides have great potential in promoting the repair and regeneration of infarcted hearts. STATEMENT OF SIGNIFICANCE: We have successfully synthesized antioxidant and pro-angiogenic peptides, which were subsequently incorporated into an injectable hydrogel matrix. This bioactive hydrogel system demonstrates dual therapeutic functions, effectively scavenging ROS while promoting angiogenesis, thereby facilitating cardiac tissue repair. Notably, the chemical synthesis approach employed in peptide production establishes a robust foundation for scalable manufacturing and broad biomedical applications, particularly in cardiovascular therapeutics.

Electrospun meshes for abdominal wall hernia repair: Potential and challenges

Surgical meshes are widely used in abdominal wall hernia repairs. However, consensus on mesh treatment remains elusive due to varying repair outcomes, especially with the introduction of new meshes, posing a substantial challenge for surgeons. Addressing these issues requires communicating the features of emerging candidates with a focus on clinical considerations. Electrospinning is a versatile technique for producing meshes with biomechanical architectures that closely mimic the extracellular matrix and enable incorporation of bioactive and therapeutic agents into the interconnective porous network, providing a favorable milieu for tissue integration and remodeling. Although this promising technique has drawn considerable interest in mesh fabrication and functionalization, currently developed electrospun meshes have limitations in meeting clinical requirements for hernia repair. This review summarizes the advantages and limitations of meshes prepared through electrospinning based on biomechanical, biocompatible, and bioactive properties/functions, offering interdisciplinary insights into challenges and future directions toward clinical mesh-aided hernia repair. STATEMENT OF SIGNIFICANCE: Consensus for hernia treatments using surgical meshes remains elusive based on varying repair outcomes, presenting significant challenges for researchers and surgeons. Differences in understanding mesh between specialists, particularly regarding material characteristics and clinical requirements, contribute to this issue. Electrospinning has been increasingly applied in mesh preparation through various approaches and strategies, aiming to improve abdominal wall hernia by restoring mechanical, morphological and functional integrity. However, there is no comprehensive overview of these emerging meshes regarding their features, functions, and clinical potentials, emphasizing the necessity of interdisciplinary discussions on this topic that build upon recent developments in electrospun mesh and provide insights from clinically practical prospectives.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

Bioactive peptides and proteins for tissue repair: microenvironment modulation, rational delivery, and clinical potential

Bioactive peptides and proteins (BAPPs) are promising therapeutic agents for tissue repair with considerable advantages, including multifunctionality, specificity, biocompatibility, and biodegradability. However, the high complexity of tissue microenvironments and their inherent deficiencies such as short half-live and susceptibility to enzymatic degradation, adversely affect their therapeutic efficacy and clinical applications. Investigating the fundamental mechanisms by which BAPPs modulate the microenvironment and developing rational delivery strategies are essential for optimizing their administration in distinct tissue repairs and facilitating clinical translation. This review initially focuses on the mechanisms through which BAPPs influence the microenvironment for tissue repair via reactive oxygen species, blood and lymphatic vessels, immune cells, and repair cells. Then, a variety of delivery platforms, including scaffolds and hydrogels, electrospun fibers, surface coatings, assisted particles, nanotubes, two-dimensional nanomaterials, and nanoparticles engineered cells, are summarized to incorporate BAPPs for effective tissue repair, modification strategies aimed at enhancing loading efficiencies and release kinetics are also reviewed. Additionally, the delivery of BAPPs can be precisely regulated by endogenous stimuli (glucose, reactive oxygen species, enzymes, pH) or exogenous stimuli (ultrasound, heat, light, magnetic field, and electric field) to achieve on-demand release tailored for specific tissue repair needs. Furthermore, this review focuses on the clinical potential of BAPPs in facilitating tissue repair across various types, including bone, cartilage, intervertebral discs, muscle, tendons, periodontal tissues, skin, myocardium, nervous system (encompassing brain, spinal cord, and peripheral nerve), endometrium, as well as ear and ocular tissue. Finally, current challenges and prospects are discussed.

Relationship between immune cell traits, circulating inflammatory cytokines, and the risk of incisional hernia after gastric surgery

PURPOSE

The systemic and local inflammatory response in patients after surgical operation is closely related to the quality of the wound healing. Low-quality wound healing and defects in the suture technique lead to the occurrence of incisional hernia (IH). However, the causal relationship between human circulating inflammatory cytokines, immune cell traits, and the risk of IH remains unclear.

METHODS

We used summary data from genome-wide association studies to assess the causal relationship between 91 types of circulating inflammatory factors, 731 types of circulating immune cell traits, and the risk of IH. The outcome dataset was obtained from FinnGen, including 6,336 patients with IH and 232,612 controls. We performed Mendelian Randomization (MR) analysis to identify their causal relationship and immune cell phenotypes upstream of inflammatory factors. Inverse variance weighting is considered to be the main analysis method.

RESULTS

Among the identified cytokines, TNF-related activation-induced cytokine levels were associated with a lower risk of IH (OR: 0.89; 95% CI: 0.82-0.96; P = 0.003). In contrast, interleukin-5 levels were associated with an increased risk of IH (OR: 1.18; 95% CI: 1.06-1.31; P = 0.003). Additionally, a significant causal relationship was found between four immune cell traits and the risk of IH (P < 0.01). Through two-step MR analysis, we determined that interleukin-5 levels mediate the causal relationship between the relative count of CD25hi % CD4 + in Treg cells and the higher risk of IH.

CONCLUSION

This study found a causal relationship between specific inflammatory cytokines, immune cell traits, and risk of IH. These results can help surgeons predict the risk of IH and take preventive measures.

Advances and impact of human amniotic membrane and human amniotic-based materials in wound healing application

Wound healing is a complicated process, especially when surgical, traumatic, burn, or pathological injury occurs, which requires different kinds of dressing covers including hydrogels, hydrocolloids, alginates foams and films for treatment. The human amniotic membrane (hAM) is a biodegradable extracellular matrix with unique and tailorable physicochemical and biological properties, generated by the membrane itself or other cells that are located on the membrane surface. It is noted as a promising aid for wound healing and tissue regeneration due to the release of growth factors and cytokines, and its antibacterial and immunosuppressive properties. Moreover, hAM has optimal physical, biological, and mechanical properties, which makes it a much better option as a regenerative skin treatment than existing alternative materials. In addition, this layer has a structure with different layers and cells with different functions, which act as a regenerative geometry and reservoir of bioactive substances and cells for wound healing. In the present work, the structural and biological features of hAM are introduced as well as the application of this layer in different forms of composites to enhance wound healing. Future studies are recommended to detect possible further functionalization to enhance the hAM effectiveness on wound healing.

Establishment and evaluation of rat models of parastomal hernia

PURPOSE

Parastomal hernia poses a challenging problem in the field of hernia surgery. The high incidence and recurrence rates of parastomal hernia necessitate surgeons to enhance surgical techniques and repair materials. This study aimed to develop a rat model of parastomal hernia by inducing various types of defects on the abdominal wall with colostomy. This established method has potential for future studies on parastomal hernia.

METHODS

In this study, 32 male rats were included and randomly divided into four groups: the oblique abdominis excision (OE), oblique abdominis dissection (OD), rectus abdominis excision (RE), and rectus abdominis dissection (RD) groups. In each group, colostomy was performed and an abdominal wall defect was induced. The rats were observed for 28 days following surgery. The survival rate, body weight, parastomal hernia model scores, abdominal wall adhesion and inflammation, and collagen level in the hernial sac were compared.

RESULTS

No significant differences in survival rate and weight were observed among the four groups. The parastomal hernia model scores in the RE and RD groups were significantly higher than those in the OE and OD groups. The ratio of collagen I/III in the RE and RD groups was significantly lower than that in the OE and OD groups. Adhesion and inflammation levels were lower in the RE group than in the RD group.

CONCLUSION

Based on a comprehensive comparison of the findings, RE with colostomy emerged as the optimal approach for establishing parastomal hernia models in rats.

Ibuprofen-loaded bilayer electrospun mesh modulates host response toward promoting full-thickness abdominal wall defect repair

Pro-inflammatory response impairs the constructive repair of abdominal wall defects after mesh implantation. Electrospinning-aid functionalization has the potential to improve the highly orchestrated response by attenuating the over-activation of foreign body reactions. Herein, we combined poly(L-lactic acid-co-caprolactone) (PLLA-CL) with gelatin proportionally via electrospinning, with Ibuprofen (IBU) incorporation to fabricate a bilayer mesh for the repair improvement. The PLLA-CL/gelatin/IBU (PGI) mesh was characterized in vitro and implanted into the rat model with a full-thickness defect for a comprehensive evaluation in comparison to the PLLA-CL/gelatin (PG) and off-the-shelf small intestinal submucosa (SIS) meshes. The bilayer PGI mesh presented a sustained release of IBU over 21 days with degradation in vitro and developed less-intensive intraperitoneal adhesion along with a histologically weaker inflammatory response than the PG mesh after 28 days. It elicited an M2 macrophage-dominant foreign body reaction within the process, leading to a pro-remodeling response similar to the biological SIS mesh, which was superior to the PG mesh. The PGI mesh provided preponderant mechanical supports over the SIS mesh and the native abdominal wall with similar compliance. Collectively, the newly developed mesh advances the intraperitoneal applicability of electrospun meshes by guiding a pro-remodeling response and offers a feasible functionalization approach upon immunomodulation.

Double-Layer Asymmetric Porous Mesh with Dynamic Mechanical Support Properties Enables Efficient Single-Stage Repair of Contaminated Abdominal Wall Defect

Contamination tolerance and long-term mechanical support are the two critical properties of meshes for contaminated abdominal wall defect repair. However, biological meshes with excellent pollution tolerance fail to provide bio-adaptive long-term mechanical support due to their rapid degradation. Here, a novel double-layer asymmetric porous mesh (SIS/PVA-EXO) is designed by simple and efficient in situ freeze-thaw of sticky polyvinyl alcohol (PVA) solution on the loosely porous surface of small intestinal submucosal decellularized matrix (SIS), which can successfully repair the contaminated abdominal wall defect with bio-adaptive dynamic mechanical support through only single-stage surgery. The exosome-loaded degradable loosely porous SIS layer accelerates the tissue healing; meanwhile, the exosome-loaded densely porous PVA layer can maintain long-term mechanical support without any abdominal adhesion. In addition, the tensile strength and strain at break of SIS/PVA-EXO mesh change gradually from 0.37 MPa and 210% to 0.10 MPa and 385% with the degradation of SIS layer. This unique performance can dynamically adapt to the variable mechanical demands during different periods of contaminated abdominal wall reconstruction. As a result, this SIS/PVA-EXO mesh shows an attractive prospect in the treatment of contaminated abdominal wall defect without recurrence by integrating local immune regulation, tissue remodeling, and dynamic mechanical supporting.

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.

Reconstruction of the human nipple-areolar complex: a tissue engineering approach

Introduction: Nipple-areolar complex (NAC) reconstruction after breast cancer surgery is challenging and does not always provide optimal long-term esthetic results. Therefore, generating a NAC using tissue engineering techniques, such as a decellularization-recellularization process, is an alternative option to recreate a specific 3D NAC morphological unit, which is then covered with an in vitro regenerated epidermis and, thereafter, skin-grafted on the reconstructed breast. Materials and methods: Human NACs were harvested from cadaveric donors and decellularized using sequential detergent baths. Cellular clearance and extracellular matrix (ECM) preservation were analyzed by histology, as well as by DNA, ECM proteins, growth factors, and residual sodium dodecyl sulfate (SDS) quantification. In vivo biocompatibility was evaluated 30 days after the subcutaneous implantation of native and decellularized human NACs in rats. In vitro scaffold cytocompatibility was assessed by static seeding of human fibroblasts on their hypodermal side for 7 days, while human keratinocytes were seeded on the scaffold epidermal side for 10 days by using the reconstructed human epidermis (RHE) technique to investigate the regeneration of a new epidermis. Results: The decellularized NAC showed a preserved 3D morphology and appeared white. After decellularization, a DNA reduction of 98.3% and the absence of nuclear and HLA staining in histological sections confirmed complete cellular clearance. The ECM architecture and main ECM proteins were preserved, associated with the detection and decrease in growth factors, while a very low amount of residual SDS was detected after decellularization. The decellularized scaffolds were in vivo biocompatible, fully revascularized, and did not induce the production of rat anti-human antibodies after 30 days of subcutaneous implantation. Scaffold in vitro cytocompatibility was confirmed by the increasing proliferation of seeded human fibroblasts during 7 days of culture, associated with a high number of living cells and a similar viability compared to the control cells after 7 days of static culture. Moreover, the RHE technique allowed us to recreate a keratinized pluristratified epithelium after 10 days of culture. Conclusion: Tissue engineering allowed us to create an acellular and biocompatible NAC with a preserved morphology, microarchitecture, and matrix proteins while maintaining their cell growth potential and ability to regenerate the skin epidermis. Thus, tissue engineering could provide a novel alternative to personalized and natural NAC reconstruction.

A novel electrospun polylactic acid silkworm fibroin mesh for abdominal wall hernia repair

Objective

Abdominal wall hernias are common abdominal diseases, and effective hernia repair is challenging. In clinical practice, synthetic meshes are widely applied for repairing abdominal wall hernias. However, postoperative complications, such as inflammation and adhesion, are prevalent. Although biological meshes can solve this problem to a certain extent, they face the problems of heterogeneity, rapid degradation rate, ordinary mechanical properties, and high-cost. Here, a novel electrospinning mesh composed of polylactic acid and silk fibroin (PLA-SF) for repairing abdominal wall hernias was manufactured with good physical properties, biocompatibility and low production cost.

Materials and methods

FTIR and EDS were used to demonstrate that the PLA-SF mesh was successfully synthesized. The physicochemical properties of PLA-SF were detected by swelling experiments and in vitro degradation experiments. The water contact angle reflected the hydrophilicity, and the stress‒strain curve reflected the mechanical properties. A rat abdominal wall hernia model was established to observe degradation, adhesion, and inflammation in vivo. In vitro cell mesh culture experiments were used to detect cytocompatibility and search for affected biochemical pathways.

Results

The PLA-SF mesh was successfully synthesized and did not swell or degrade over time in vitro. It had a high hydrophilicity and strength. The PLA-SF mesh significantly reduced abdominal inflammation and inhibited adhesion formation in rat models. The in vitro degradation rate of the PLA-SF mesh was slower than that of tissue remodeling. Coculture experiments suggested that the PLA-SF mesh reduced the expression of inflammatory factors secreted by fibroblasts and promoted fibroblast proliferation through the TGF-β1/Smad pathway.

Conclusion

The PLA-SF mesh had excellent physicochemical properties and biocompatibility, promoted hernia repair of the rat abdominal wall, and reduced postoperative inflammation and adhesion. It is a promising mesh and has potential for clinical application.

Hydroxyapatite-Coated Small Intestinal Submucosa Membranes Enhanced Periodontal Tissue Regeneration through Immunomodulation and Osteogenesis via BMP-2/Smad Signaling Pathway

Periodontitis, a chronic infection causing periodontal tissue loss, may be effectively addressed with in situ tissue engineering. Small intestinal submucosa (SIS) offers exceptional biocompatibility and biodegradability but lacks sufficient osteoconductive and osteoinductive properties. This study develops and characterizes SIS coated with hydroxyapatite (SIS-HA) and gelatin methacrylate hydroxyapatite (SIS-Gel-HA) using biomineralization and chemical crosslinking. The impact on periodontal tissue regeneration is assessed by evaluating macrophage immune response and osteogenic differentiation potential of periodontal ligament stem cells (PDLSCs) in vitro and rat periodontal defects in vivo. The jejunum segment, with the highest collagen type I content, is optimal for SIS preparation. SIS retains collagen fiber structure and bioactive factors. Calcium content is 2.21% in SIS-HA and 2.45% in SIS-Gel-HA, with no significant differences in hydrophilicity, physicochemical properties, protein composition, or biocompatibility among SIS, SIS-HA, SIS-Gel, and SIS-Gel-HA. SIS is found to upregulate M2 marker expression, both SIS-HA and SIS-Gel-HA enhance the osteogenic differentiation of PDLSCs through the BMP-2/Smad signaling pathway, and SIS-HA demonstrates superior in vitro osteogenic activity. In vivo, SIS-HA and SIS-Gel-HA yield denser, more mature bones with the highest BMP-2 and Smad expression. SIS-HA and SIS-Gel-HA demonstrate enhanced immunity-osteogenesis coupling, representing a promising periodontal tissue regeneration approach.

Killing two birds with one stone: A therapeutic copper-loaded bio-patch promoted abdominal wall repair via VEGF pathway

Hernia and life-threatening intestinal obstruction often result from abdominal wall injuries, and the regeneration of abdominal wall defects is limited due to the lack of biocompatible, antibacterial and angiogenic scaffolding materials for treating injured tissues. Taking inspiration from the facile preparation of dopamine polymerization and its surface modification technology, in this study, multi-therapeutic copper element was introduced into porcine small intestinal submucosa (SIS) bio-patches through polydopamine (PDA) deposition, in order to regenerate abdominal wall injury. In both in vitro antibacterial assays, cytocompatibility assays and in vivo abdominal wall repair experiments, the SIS/PDA/Cu bio-patches exhibited robust antibacterial efficiency (＞99%), excellent biocompatibility to cells (＞90%), and enhanced neovascularization and improved collagen maturity compared to other commercially available patches (3.0-fold higher than the PP mesh), due to their activation of VEGF pathway. These findings indicated the bio-patch was a promising application for preventing visceral adhesion, bacterial infection, and promoting soft tissue regeneration.

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.

Multifunctional Extracellular Matrix Hydrogel with Self-Healing Properties and Promoting Angiogenesis as an Immunoregulation Platform for Diabetic Wound Healing

Treating chronic wounds is a global challenge. In diabetes mellitus cases, long-time and excess inflammatory responses at the injury site may delay the healing of intractable wounds. Macrophage polarization (M1/M2 types) can be closely associated with inflammatory factor generation during wound healing. Quercetin (QCT) is an efficient agent against oxidation and fibrosis that promotes wound healing. It can also inhibit inflammatory responses by regulating M1-to-M2 macrophage polarization. However, its limited solubility, low bioavailability, and hydrophobicity are the main issues restricting its applicability in wound healing. The small intestinal submucosa (SIS) has also been widely studied for treating acute/chronic wounds. It is also being extensively researched as a suitable carrier for tissue regeneration. As an extracellular matrix, SIS can support angiogenesis, cell migration, and proliferation, offering growth factors involved in tissue formation signaling and assisting wound healing. We developed a series of promising biosafe novel diabetic wound repair hydrogel wound dressings with several effects, including self-healing properties, water absorption, and immunomodulatory effects. A full-thickness wound diabetic rat model was constructed for in vivo assessment of QCT@SIS hydrogel, in which hydrogels achieved a markedly increased wound repair rate. Their effect was determined by the promotion of the wound healing process, the thickness of granulation tissue, vascularization, and macrophage polarization during wound healing. At the same time, we injected the hydrogel subcutaneously into healthy rats to perform histological analyses of sections of the heart, spleen, liver, kidney, and lung. We then tested the biochemical index levels in serum to determine the biological safety of the QCT@SIS hydrogel. In this study, the developed SIS showed convergence of biological, mechanical, and wound-healing capabilities. Here, we focused on constructing a self-healing, water-absorbable, immunomodulatory, and biocompatible hydrogel as a synergistic treatment paradigm for diabetic wounds by gelling the SIS and loading QCT for slow drug release.

Tissue-Adhesive Decellularized Extracellular Matrix Patches Reinforced by a Supramolecular Gelator to Repair Abdominal Wall Defects

Implantation of surgical meshes composed of synthetic and biological materials has been applied for abdominal wall defect repair. Despite many efforts, there are no reliable meshes that fully satisfy clinical requirements because of their lack of biodegradability, mechanical strength, and tissue-adhesive properties. Here, we report biodegradable, decellularized extracellular matrix (dECM)-based biological patches to treat abdominal wall defects. By incorporating a water-insoluble supramolecular gelator that forms physical cross-linking networks through intermolecular hydrogen bonding, dECM patches were reinforced to improve mechanical strength. Reinforced dECM patches possessed higher tissue adhesion strength and underwater stability compared with the original dECM because of enhanced interfacial adhesion strength. In vivo experiments using an abdominal wall defect rat model showed that reinforced dECM patches induced collagen deposition and the formation of blood vessels during material degradation, and the accumulation of CD68-positive macrophages was suppressed compared to nonbiodegradable synthetic meshes. Tissue-adhesive and biodegradable dECM patches with improved mechanical strength by a supramolecular gelator have enormous potential for use in the repair of abdominal wall defects.

Silk Fibroin Combined with Electrospinning as a Promising Strategy for Tissue Regeneration

The development of tissue engineering scaffolds is of great significance for the repair and regeneration of damaged tissues and organs. Silk fibroin (SF) is a natural protein polymer with good biocompatibility, biodegradability, excellent physical and mechanical properties and processability, making it an ideal universal tissue engineering scaffold material. Nanofibers prepared by electrospinning have attracted extensive attention in the field of tissue engineering due to their excellent mechanical properties, high specific surface area, and similar morphology as to extracellular matrix (ECM). The combination of silk fibroin and electrospinning is a promising strategy for the preparation of tissue engineering scaffolds. In this review, the research progress of electrospun silk fibroin nanofibers in the regeneration of skin, vascular, bone, neural, tendons, cardiac, periodontal, ocular and other tissues is discussed in detail.

Enhancement of Tendon Repair Using Tendon-Derived Stem Cells in Small Intestinal Submucosa via M2 Macrophage Polarization

(1) Background: Reconstruction of Achilles tendon defects and prevention of postoperative tendon adhesions were two serious clinical problems. In the treatment of Achilles tendon defects, decellularized matrix materials and mesenchymal stem cells (MSCs) were thought to address both problems. (2) Methods: In vitro, cell adhesion, proliferation, and tenogenic differentiation of tendon-derived stem cells (TDSCs) on small intestinal submucosa (SIS) were evaluated. RAW264.7 was induced by culture medium of TDSCs and TDSCs–SIS scaffold groups. A rat Achilles tendon defect model was used to assess effects on tendon regeneration and antiadhesion in vivo. (3) Results: SIS scaffold facilitated cell adhesion and tenogenic differentiation of TDSCs, while SIS hydrogel coating promoted proliferation of TDSCs. The expression of TGF-β and ARG-1 in the TDSCs-SIS scaffold group were higher than that in the TDSCs group on day 3 and 7. In vivo, the tendon regeneration and antiadhesion capacity of the implanted TDSCs–SIS scaffold was significantly enhanced. The expression of CD163 was significantly highest in the TDSCs–SIS scaffold group; meanwhile, the expression of CD68 decreased more significantly in the TDSCs–SIS scaffold group than the other two groups. (4) Conclusion: This study showed that biologically prepared SIS scaffolds synergistically promote tendon regeneration with TDSCs and achieve antiadhesion through M2 polarization of macrophages.

Inflammation Self-Limiting Electrospun Fibrous Tape via Regional Immunity for Deep Soft Tissue Repair

Overexpression of inflammatory cytokines and chemokines occurs at deep soft tissue injury sites impeding the inflammation self-limiting and impairing the tissue remodeling process. Inspired by the electrostatically extracellular matrix (ECM) binding property of the inflammatory signals, an inflammation self-limiting fibrous tape is designed by covalently modifying the thermosensitive methacrylated gelatin (GelMA) and negatively charged methacrylated heparin (HepMA) hydrogel mixture with proper ratio onto the electrospun fibrous membrane by mild alkali hydrolysis and carboxyl-amino condensation reaction to restore inflammation self-limiting and promote tissue repair via regional immunity regulation. While the GelMA guarantees cell compatibility, the negatively charged HepMA successfully adsorbs the inflammatory cytokines and chemokines by electrostatic interactions and inhibits immune cell migration in vitro. Furthermore, in vivo inflammation self-limiting and regional immunity regulation efficacy is evaluated in a rat abdominal hernia model. Reduced local inflammatory cytokines and chemokines in the early stage and increased angiogenesis and ECM remodeling in the later phase confirm that the tape is an approach to maintain an optimal regional immune activation level after soft tissue injury. Overall, the reported electrospun fibrous tape will find its way into clinical transformation and solve the challenges of deep soft tissue injury.

Inflammation-mediated matrix remodeling of extracellular matrix-mimicking biomaterials in tissue engineering and regenerative medicine

Extracellular matrix (ECM)-mimicking biomaterials are considered effective tissue-engineered scaffolds for regenerative medicine because of their biocompatibility, biodegradability, and bioactivity. ECM-mimicking biomaterials preserve natural microstructures and matrix-related bioactive components and undergo continuous matrix remodeling upon transplantation. The interaction between host immune cells and transplanted ECM-mimicking biomaterials has attracted considerable attention in recent years. Transplantation of biomaterials may initiate injuries and early pro-inflammation reactions characterized by infiltration of neutrophils and M1 macrophages. Pro-inflammation reactions may lead to degradation of the transplanted biomaterial and drive the matrix into a fetal-like state. ECM degradation leads to the release of matrix-related bioactive components that act as signals for cell migration, proliferation, and differentiation. In late stages, pro-inflammatory cells fade away, and anti-inflammatory cells emerge, which involves macrophage polarization to the M2 phenotype and leukocyte activation to T helper 2 (Th2) cells. These anti-inflammatory cells interact with each other to facilitate matrix deposition and tissue reconstruction. Deposited ECM molecules serve as vital components of the mature tissue and influence tissue homeostasis. However, dysregulation of matrix remodeling results in several pathological conditions, such as aggressive inflammation, difficult healing, and non-functional fibrosis. In this review, we summarize the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. STATEMENT OF SIGNIFICANCE: Extracellular matrix (ECM)-mimicking biomaterials are effectively used as scaffolds in tissue engineering and regenerative medicine. However, dysregulation of matrix remodeling can cause various pathological conditions. Here, the review describes the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. We believe that understanding host immune responses to matrix remodeling of transplanted biomaterials is important for directing effective tissue regeneration of ECM-mimicking biomaterials. Considering the close relationship between immune response and matrix remodeling results, we highlight the need for studies of the effects of clinical characteristics on matrix remodeling of transplanted biomaterials.

Regulated Exogenous/Endogenous Inflammation via "Inner-Outer" Medicated Electrospun Fibers for Promoting Tissue Reconstruction

Regenerative medicine aims to provide solutions for structural and functional recovery in conditions where organs suffer from varying degrees of diseases or injuries. However, the exogenous inflammation triggered by implanted biomaterials and endogenous inflammation caused by some disease or tissue destruction has not been solved properly yet. Herein, a functional "inner-outer" medicated core-shell electrospun fibrous membrane is fabricated with RGD surface modification for exogenous inflammation suppression and puerarin loading in the core for long-term endogenous inflammation inhibition through microsol electrospinning technique. The "outer" RGD significantly increases biocompatibility of fibrous membrane through promoting cell viability, adhesion, and proliferation while the "inner" puerarin suppresses inflammatory gene expression via sustained drug release in vitro. Moreover, in a rat abdominal wall hernia model, the functional fibrous membrane successfully reduces exogenous and endogenous inflammation response and promotes wound healing through collagen deposition, smooth muscle formation, and vascularization. In summary, the functional "inner-outer" medicated fibrous membrane holds a great potential for clinical treatment of diseases that needs tissue reconstruction structurally and functionally accompanied by immunoregulation.