Spider-Silk-like Fiber Mat-Covered Polypropylene Warp-Knitted Hernia Mesh for Inhibition of Fibrosis under Dynamic Environment.

Hernia surgery is a widely performed procedure, and the use of a polypropylene mesh is considered the standard approach. However, the mesh often leads to complications, including the development of scar tissue that wraps around the mesh and causes it to shrink. Consequently, there is a need to investigate the relationship between the mesh and scar formation as well as to develop a hernia mesh that can prevent fibrosis. In this study, three different commercial polypropylene hernia meshes were examined to explore the connection between the fabric structure and mechanical properties. In vitro dynamic culture was used to investigate the mechanism by which the mechanical properties of the mesh in a dynamic environment affect cell differentiation. Additionally, electrospinning was employed to create polycaprolactone spider-silk-like fiber mats to achieve mechanical energy dissipation in dynamic conditions. These fiber mats were then combined with the preferred hernia mesh. The results demonstrated that the composite mesh could reduce the activation of fibroblast mechanical signaling pathways and inhibit its differentiation into myofibroblasts in dynamic environments.

Cobweb-Inspired Micro/Nanostructured Scaffolds for Soft Tissue Regeneration with Inhibition Effect of Fibrosis under Dynamic Environment.

In soft tissue repair, fibrosis can lead to repair failure and long-term chronic pain in patients. Excessive mechanical stimulation of fibroblasts is one of the causes of fibrosis during abdominal wall regeneration. Inspired by the cobweb, a polycaprolactone beaded fiber is prepared by electrospinning. The cobweb-inspired structure attenuates the mechanical stimulation of cells under a dynamic environment. Nano-protrusions are introduced into the scaffold for further inhibition of fibrosis by self-induced crystallization. A machine is built for in vitro dynamic culture and rat abdominal subcutaneous embedding experiments are performed to verify the inhibiting effect of fibrosis in a dynamic environment in vivo. Results show that the expression of integrin ß1 and α-smooth muscle actin is inhibited by the cobweb-inspired structure under dynamic culture. The results of hematoxylin and eosin and Masson's trichrome indicate that the cobweb-inspired structure has a good inhibitory effect on fibrosis in a dynamic environment in vivo. In general, the cobweb-inspired scaffold with nano-protrusions has a good ability to inhibit fibrosis under both static and dynamic environments. It is believed that the scaffold has promising applications in the field of inhibiting fibrosis caused by mechanical stimulation.

A loofah-inspired scaffold with enhanced mimicking mechanics and tumor cells distribution for in vitro tumor cell culture platform.

Tumor cells cultured in a physiologically related three-dimensional (3D) matrix can replicate many basic characteristics of tumor tissue. Tumor tissues are harder than normal, so when using hydrogels for 3D tumor cell culture, attempts have been made to prepare hydrogel scaffolds that mimic the hardness of tumor tissues without reducing the porosity. In this study, a new 3D loofah-inspired scaffold was developed for prostate cancer cell culture. Since the loofah sponge structure of the spacer fabric, the composite scaffolds had a compression modulus similar to that of natural prostate tumor tissue at a lower hydrogel concentration (0.25% W/V), and also, endowed the scaffold with high porosity (85 ± 2.52%) for mass transfer. The results of in vitro cell experiments showed that the composite scaffold can support tumor cells to form clusters in a short time (3 days). Preliminary chemosensitivity analysis showed that the drug resistance of the composite scaffold was significantly higher than that of two-dimensional (2D) culture and COL scaffold. Therefore, the 3D tumor cell culture scaffold with bionic structures has the potential to be used as a tumor drug screening model.

Hierarchical Nanostructured Electrospun Membrane with Periosteum-Mimic Microenvironment for Enhanced Bone Regeneration.

An ideal periosteum substitute should be able to mimic the periosteum microenvironment that continuously provides growth factors, recruits osteoblasts, and subsequent extracellular matrix (ECM) mineralization to accelerate bone regeneration. Here, a calcium-binding peptide-loaded poly(ε-caprolactone) (PCL) electrospun membrane modified by the shish-kebab structure that can mimic the periosteum microenvironment was developed as a bionic periosteum. The calcium-binding peptide formed by the negatively charged heptaglutamate domain (E7) in the E7-BMP-2 with calcium ion in the tricalcium phosphate sol (TCP sol) through electrostatic chelation not only extended the release cycle of E7-BMP-2 but also promoted the biomineralization of the bionic periosteum. Cell experiments showed that the bionic periosteum could significantly improve the osteogenic differentiation of the rat-bone marrow-derived mesenchymal stem cells (rBMSCs) through both chemical composition and physical structure. The in vivo evaluation of the bionic periosteum confirmed the inherent osteogenesis of this periosteum microenvironment, which could promote the regeneration of vascularized bone tissue. Therefore, the hierarchical nanostructured electrospun membrane with periosteum-mimic microenvironment is a promising periosteum substitute for the treatment of bone defects.

Development of a polycaprolactone/poly(p-dioxanone) bioresorbable stent with mechanically self-reinforced structure for congenital heart disease treatment.

Recent progress in bioresorbable stents (BRSs) has provided a promising alternative for treating coronary artery disease. However, there is still lack of BRSs with satisfied compression and degradation performance for pediatric patients with congenital heart disease, leading to suboptimal therapy effects. Here, we developed a mechanically self-reinforced composite bioresorbable stent (cBRS) for congenital heart disease application. The cBRS consisted of poly(p-dioxanone) monofilaments and polycaprolactone/poly(p-dioxanone) core-shell composite yarns. Interlacing points in cBRS structure were partially bonded, offering the cBRS with significantly higher compression force compared to typical braids and remained good compliance. The suitable degradation profile of the cBRS can possibly preserve vascular remodeling and healing process. In addition, the controllable structural organization provides a method to customize the performance of the cBRS by altering the proportion of different components in the braids. The in vivo results suggested the cBRS supported the vessel wall similar to that of metallic stent. In both abdominal aorta and iliac artery of porcine, cBRS was entirely endothelialized within 1 month and maintained target vessels with good patency in the 12-month follow-up. The in vivo degradation profile of the cBRS is consistent with static degradation results in vitro. It is also demonstrated that there is minimal impact of pulsatile pressure of blood flow and variation of radial force on the degradation rate of the cBRS. Moreover, the lumen of cBRS implanted vessels were enlarged after 6 months, and significantly larger than the vessels implanted with metallic stent in 12 months.

Construction and application of textile-based tissue engineering scaffolds: a review.

Tissue engineering (TE) provides a practicable method for tissue and organ repair or substitution. As the most important component of TE, a scaffold plays a critical role in providing a growing environment for cell proliferation and functional differentiation as well as good mechanical support. And the restorative effects are greatly dependent upon the nature of the scaffold including the composition, morphology, structure, and mechanical performance. Medical textiles have been widely employed in the clinic for a long time and are being extensively investigated as TE scaffolds. However, unfortunately, the advantages of textile technology cannot be fully exploited in tissue regeneration due to the ignoring of the diversity of fabric structures. Therefore, this review focuses on textile-based scaffolds, emphasizing the significance of the fabric design and the resultant characteristics of cell behavior and extracellular matrix reconstruction. The structure and mechanical behavior of the fabrics constructed by various textile techniques for different tissue repairs are summarized. Furthermore, the prospect of structural design in the TE scaffold preparation was anticipated, including profiled fibers and some unique and complex textile structures. Hopefully, the readers of this review would appreciate the importance of structural design of the scaffold and the usefulness of textile-based TE scaffolds in tissue regeneration.

Tricalcium Phosphate Sol-Incorporated Poly(ε-caprolactone) Membrane with Improved Mechanical and Osteoinductive Activity as an Artificial Periosteum.

The periosteum plays a very important role in bone remodeling and regeneration due to its excellent osteogenic ability. However, in bone defects, the periosteum is inevitably damaged, has poor self-repair ability, and requires artificial materials as a substitute. This study is aimed to fabricate a highly bioactive poly(ε-caprolactone)/tricalcium phosphate sol (PCL/TCP sol) hybrid membrane as an artificial periosteum covering the surface of the bone defect to enhance bone regeneration. Three kinds of PCL membranes with different TCP contents were prepared and marked as P20T1 (4.8 wt %), P10T1 (9.1 wt %), and P5T1 (16.7 wt %). The physicochemical properties' evaluation confirmed that TCP sol was homogeneously dispersed in the PCL nanofibers. Compared with P5T1, samples P10T1 and P20T1 had enhanced the mechanical properties and a moderately hydrophilic surface (67.3 ± 2.4° for P20T1 and 48.9 ± 4.1° for P10T1). The biomineralization of hybrid membranes was significantly improved compared to the PCL membrane. Moreover, hybrid membranes significantly upregulated the rat bone marrow mesenchymal stem cells' (rBMSCs) response (proliferation and osteogenic differentiation) to them, and P10T1 showed better surface properties (hydrophilicity, bioactivity, and biomineralization) than P20T1. Thus, sample P10T1 with the best properties in this study has great potential as an artificial periosteum to accelerate bone regeneration.

Long-term anticoagulation and selective cells adhesion surface via combination of covalent grafting and layer by layer assembly.

Surface modification by long-term active component is essential for biocompatible polymers-based vascular grafts to prevent thrombus formation and reduce intimal hyperplasia. In this study, a simple approach was developed to immobilize bioactive heparin to the surface of ε-polycaprolactone (PCL) grafts through a two-step strategy combining covalent grafting and layer by layer assembly of polyelectrolytes. The performance of heparinized PCL was evaluated in vitro, including the release behavior of heparin, anticoagulation and different types of cells adhesion characteristic. A sustained-release of heparin was achieved by this immobilization strategy. Surface remaining heparin was up to 1.10 µg cm-2 on the modified PCL after release in vitro for 30 d. Specifically, the heparinized PCL has the long-term ability to prevent adhesion of blood cells and thrombus formation, and significantly inhibit the adhesion of smooth muscle cells. The two-step strategy provides a simple and general route to incorporate heparin on PCL graft surface. The surface heparinized PCL demonstrated in this work can be a useful material platform for biodegradable vascular stent graft.

Nature differences of fulvic acid fractions induced by extracted sequence as explanatory factors for binding characteristics of Cu2.

The isolation of fulvic acid (FA) fractions with relatively homogeneity is a key to reveal the binding mechanisms between FA and heavy metals. In this work, nine FA fractions were obtained using sequential alkali extraction procedure and nature differences of the extracted FA fractions were considered as explanatory factors for binding characteristics of Cu2+. The results indicate that the contents of carboxyl and phenolic groups decrease with increasing extractions along with an opposite trend for the content of nitrogen-containing groups. The fitted results of ligand binding and bi-Langmuir models indicate that the binding sites for Cu2+ were mainly provided by carboxyl and phenolic groups, which explained the higher sorption capacity and binding affinity of earlier extracted FAs due to its higher contents of carboxyl and phenolic groups. Furthermore, the systemic characterization of FA fractions before and after adsorption indicate the nitrogen-containing groups were gradually showing their contribution in binding Cu2+ with increasing extractions. This work is very helpful to insight the environmental effects of natural organic matter and the behavior of heavy metals in natural environment.