Controlling the Multiscale Network Structure of Fibers To Stimulate Wound Matrix Rebuilding by Fibroblast Differentiation

Otilonium bromide ameliorates pulmonary fibrosis in mice through activating phosphatase PPM1A

Pulmonary fibrosis (PF) is a chronic, progressive and irreversible interstitial lung disease characterized by unremitting pulmonary myofibroblasts activation, extracellular matrix (ECM) deposition and inflammatory recruitment. PF has no curable medication yet. In this study we investigated the molecular pathogenesis and potential therapeutic targets of PF and discovered drug lead compounds for PF therapy. A murine PF model was established in mice by intratracheal instillation of bleomycin (BLM, 5 mg/kg). We showed that the protein level of pulmonary protein phosphatase magnesium-dependent 1A (PPM1A, also known as PP2Cα) was significantly downregulated in PF patients and BLM-induced PF mice. We demonstrated that TRIM47 promoted ubiquitination and decreased PPM1A protein in PF progression. By screening the lab in-house compound library, we discovered otilonium bromide (OB, clinically used for treating irritable bowel syndrome) as a PPM1A enzymatic activator with an EC50 value of 4.23 μM. Treatment with OB (2.5, 5 mg·kg-1·d-1, i.p., for 20 days) significantly ameliorated PF-like pathology in mice. We constructed PF mice with PPM1A-specific knockdown in the lung tissues, and determined that by targeting PPM1A, OB treatment suppressed ECM deposition through TGF-β/SMAD3 pathway in fibroblasts, repressed inflammatory responses through NF-κB/NLRP3 pathway in alveolar epithelial cells, and blunted the crosstalk between inflammation in alveolar epithelial cells and ECM deposition in fibroblasts. Together, our results demonstrate that pulmonary PPM1A activation is a promising therapeutic strategy for PF and highlighted the potential of OB in the treatment of the disease.

Exudate Unidirectional Pump to Promote Glucose Catabolism Triggering Fenton-Like Reaction for Chronic Diabetic Wounds Therapy

The massive accumulation of exudate containing high concentrations of glucose causes wound infection and triggers the release of inflammatory factors, which in turn delays the closure of diabetic wounds. In this study, a Janus membrane is constructed by combining glucose oxidase (GOx) and copper ions (Cu2+) for the treatment of diabetic wounds, which is named as Janus@GOx/Cu2+. It consists of hydrophobic, transitional, and superhydrophilic layers in a three-layer structure with gradient hydrophilicity for self-pumping properties. The Janus@GOx/Cu2+ membrane triggers a series of cascading reactions while pumping out diabetic wound exudates. First, glucose oxidase loaded onto the hydrophilic layer of the Janus@GOx/Cu2+ membrane decomposes glucose into hydrogen peroxide (H2O2) and glucuronic acid, reducing the local glucose level. The generated glucuronic acid neutralizes the local alkaline environment of chronic wounds. Simultaneously, the H2O2 interacts with the Cu2+ contained in the hydrophobic layers of the Janus@GOx/Cu2+ membrane via a Fenton-like reaction, generating hydroxyl radicals with excellent bactericidal properties. Cu2+ promotes angiogenesis and wound healing in diabetic wounds. Under the action of multiple responses, the Janus@GOx/Cu2+ membrane promotes wound healing in diabetic infections.

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 β1 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.

Electrospun Hyaluronan Nanofiber Membrane Immobilizing Aromatic Doxorubicin as Therapeutic and Regenerative Biomaterial

Lesioned tissue requires synchronous control of disease and regeneration progression after surgery. It is necessary to develop therapeutic and regenerative scaffolds. Here, hyaluronic acid (HA) was esterified with benzyl groups to prepare hyaluronic acid derivative (HA-Bn) nanofibers via electrospinning. Electrospun membranes with average fiber diameters of 407.64 ± 124.8 nm (H400), 642.3 ± 228.76 nm (H600), and 841.09 ± 236.86 nm (H800) were obtained by adjusting the spinning parameters. These fibrous membranes had good biocompatibility, among which the H400 group could promote the proliferation and spread of L929 cells. Using the postoperative treatment of malignant skin melanoma as an example, the anticancer drug doxorubicin (DOX) was encapsulated in nanofibers via hybrid electrospinning. The UV spectroscopy of DOX-loaded nanofibers (HA-DOX) revealed that DOX was successfully encapsulated, and there was a π-π interaction between aromatic DOX and HA-Bn. The drug release profile confirmed the sustained release of about 90%, achieved within 7 days. In vitro cell experiments proved that the HA-DOX nanofiber had a considerable inhibitory effect on B16F10 cells. Therefore, the HA-Bn electrospun membrane could facilitate the potential regeneration of injured skin tissues and be incorporated with drugs to achieve therapeutic effects, offering a powerful approach to developing therapeutic and regenerative biomaterial.

Radial Sponges Facilitate Wound Healing by Promoting Cell Migration and Angiogenesis

The topographic cues of wound dressings play important roles in regulating cellular behaviors, such as cellular migration and morphology, and are capable of providing a prolonged stimulus for promoting wound healing. However, 3D porous dressings that can guide wound healing from the periphery to the center are poorly studied. Herein, radial sponges with adjustable lamellar spacing and microridge spacing by ice templating are developed to facilitate wound healing. With denser lamellae and microridges, fibroblasts achieve a more orderly arrangement, a larger elongation, and a greater migration rate. Meanwhile, the elongated state enables human umbilical vein endothelial cells to vascularization. The faster healing rate and a higher degree of vascularization based on radial sponges are further demonstrated in full-thickness skin defects in rats. Taken together, radial sponges with the densest lamellae and microridges perform the best in guiding the wound from the periphery to the center of the repair environment. It is believed that the proposed structure here can be combined with various biochemical factors to provide dressings with functions.

Investigation of wound healing efficiency of multifunctional eudragit/soy protein isolate electrospun nanofiber incorporated with ZnO loaded halloysite nanotubes and allantoin

One significant aspect of the current therapeutic agents employed in wound healing involves the engineering of nano polymeric scaffolds to mimic the properties of extracellular matrix (ECM). The present work aimed to prepare and evaluate Eudragit® L100 (EU) nanofibers in combination with soy protein isolate (SPI). Allantoin (Ala) with a 2 wt% was encapsulated as a model drug renowned for its anti-inflammatory and antioxidant agents. Moreover, the synthesized ZnO-halloysite nanotubes (ZHNTs) with different concentrations of 1, 3, and 5 wt% were incorporated into the EU/SPI/Ala nanofiber as a reinforcing filler and a remarkable antibacterial agent. The scanning electron microscope (SEM) analysis showed that by increasing the weight percentage of SPI from 1 % to 2.5 %, the average diameter of nanofibers decreased from 132.3 ± 51.3 nm to 126.7 ± 47.2 nm. It was 223.5 ± 95.6 nm for nanofibers containing 5 wt% ZHNTs (the optimal sample). The evaluation of in vitro release kinetics of Ala for 24 h, showed a burst release during the first 2 h and a sustained release during the subsequent times. Moreover, the structure, crystallinity, and thermal stability of synthesized nanofibers were characterized by Fourier Transform Infrared Spectrometry (FTIR), X-ray diffraction (XRD), and Thermo gravimetric analysis (TGA), respectively. In vitro degradation and mechanical characteristics of these nanofibers were studied. Furthermore, the capability of the nanofibers for cell proliferation was revealed through the MTT test and field emission scanning electron microscopy (FESEM) images of cell attachment. The antimicrobial activity of EU/SPI/Ala/ZHNTs showed that this sample with high ZHNTs content (5 w%t) had the most remarkable antibacterial activity against S. aureus. The results revealed that EU/SPI/Ala/ZHNTs mats could be promising potential wound dressings.

Printing Structurally Anisotropic Biocompatible Fibrillar Hydrogel for Guided Cell Alignment

Many fibrous biological tissues exhibit structural anisotropy due to the alignment of fibers in the extracellular matrix. To study the impact of such anisotropy on cell proliferation, orientation, and mobility, it is important to recapitulate and achieve control over the structure of man-made hydrogel scaffolds for cell culture. Here, we report a chemically crosslinked fibrous hydrogel due to the reaction between aldehyde-modified cellulose nanofibers and gelatin. We explored two ways to induce structural anisotropy in this gel by extruding the hydrogel precursor through two different printheads. The cellulose nanofibers in the hydrogel ink underwent shear-induced alignment during extrusion and retained it in the chemically crosslinked hydrogel. The degree of anisotropy was controlled by the ink composition and extrusion flow rate. The structural anisotropy of the hydrogel extruded through a nozzle affected the orientation of human dermal fibroblasts that were either seeded on the hydrogel surface or encapsulated in the extruded hydrogel. The reported straightforward approach to constructing fibrillar hydrogel scaffolds with structural anisotropy can be used in studies of the biological impact of tissue anisotropy.

Latest on biomaterial-based therapies for topical treatment of psoriasis

Psoriasis is an autoimmune inflammatory disease which is fundamentally different from dermatitis. Its treatments include topical medications and systemic drugs depending on different stages of the disease. However, these commonly used therapies are falling far short of clinical needs due to various drawbacks. More precise therapeutic strategies with minimized side effects and improved compliance are highly demanded. Recently, the rapid development of biomaterial-based therapies has made it possible and promising to attain topical psoriasis treatment. In this review, we briefly describe the significance and challenges of the topical treatment of psoriasis and emphatically overview the latest progress in novel biomaterial-based topical therapies for psoriasis including microneedles, nanoparticles, nanofibers, and hydrogels. Current clinical trials related to each biomaterial are also summarized and discussed.

Mechanotopography-Driven Design of Dispersible Nanofiber-Laden Hydrogel as a 3D Cell Culture Platform for Investigating Tissue Fibrosis

Fibrosis is one of the most frequent occurrences during one's lifetime, identified by various physiological changes including, most notably, excessive deposition of extracellular matrix (ECM). Despite its physiological importance, it is still a significant challenge to conduct a systematic investigation of tissue fibrosis, mainly due to the lack of in vitro 3D tissue model that can accurately portray the characteristic features of fibrotic events. Herein, a hybrid hydrogel system incorporating dispersible nanofibers is developed to emulate highly collagenous deposits formed within a fibrotic tissue leading to altered mechanotopographical properties. Micrometer-length, aqueous-stable nanofibers consisting of crosslinked gelatin network embedded with graphene oxide (GO) or reduced graphene (rGO) are infused into hydrogel, resulting in controllable mechanotopographical properties while maintaining permeability sufficiently enough for various cellular activities. Ultimately, the ability to induce fibrotic behavior of fibroblasts cultured in these mechanotopography-controlled, nanofiber-laden hydrogels is investigated in detail.

Engineering Advanced In Vitro Models of Systemic Sclerosis for Drug Discovery and Development

Systemic sclerosis (SSc) is a complex multisystem disease with the highest case-specific mortality among all autoimmune rheumatic diseases, yet without any available curative therapy. Therefore, the development of novel therapeutic antifibrotic strategies that effectively decrease skin and organ fibrosis is needed. Existing animal models are cost-intensive, laborious and do not recapitulate the full spectrum of the disease and thus commonly fail to predict human efficacy. Advanced in vitro models, which closely mimic critical aspects of the pathology, have emerged as valuable platforms to investigate novel pharmaceutical therapies for the treatment of SSc. This review focuses on recent advancements in the development of SSc in vitro models, sheds light onto biological (e.g., growth factors, cytokines, coculture systems), biochemical (e.g., hypoxia, reactive oxygen species) and biophysical (e.g., stiffness, topography, dimensionality) cues that have been utilized for the in vitro recapitulation of the SSc microenvironment, and highlights future perspectives for effective drug discovery and validation.

From cells-on-a-chip to organs-on-a-chip: scaffolding materials for 3D cell culture in microfluidics

It is an emerging research area to integrate scaffolding materials in microfluidic devices for 3D cell culture (organs-on-a-chip). The technology of organs-on-a-chip holds the potential to obviate the gaps between pre-clinical and clinical studies. As accumulating evidence shows the importance of extracellular matrix in in vitro cell culture, significant efforts have been made to integrate 3D ECM/scaffolding materials in microfluidics. There are two families of materials that are commonly used for this purpose: hydrogels and electrospun fibers. In this review, we briefly discuss the properties of the materials, and focus on the various technologies to obtain the materials (e.g. extraction of collagen from animal tissues) and to include the materials in microfluidic devices. Challenges and potential solutions of the current materials and technologies were also thoroughly discussed. At the end, we provide a perspective on future efforts to make these technologies more translational to broadly benefit pharmaceutical and pathophysiological research.

Microfluidic spinning-induced heterotypic bead-on-string fibers for dual-cargo release and wound healing

The preparation of dual-release pharmaceutical microfibers provides an ideal material for new biomedical applications. We describe a microfluidic spinning method for engineering heterotypic bead-on-string fibers with the ability to carry dual cargos and to deliver on demand. The core of our technology is to combine microfluidic spinning with biomaterial preparation, in which hydrophobic and hydrophilic cargos can be integrated into a bead-on-string microfiber structure. We demonstrate the loading of bovine serum albumin (BSA) in the sodium alginate phase and ibuprofen in the polylactic acid (PLA) phase, respectively. The heterotypic bead-on-string fibers are biocompatible and show hemostatic ability in vivo. These heterotypic bead-on-string fibers are then woven as a skin scaffold and shown to promote wound healing by loading antibacterial and anti-inflammatory cargos.

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.