A Biomimetic Composite Bilayer Dressing Composed of Alginate and Fibroin for Enhancing Full-Thickness Wound Healing

Green Electrospun Poly(vinyl alcohol)/Gelatin-Based Nanofibrous Membrane by Incorporating 45S5 Bioglass Nanoparticles and Urea for Wound Dressing Applications: Characterization and In Vitro and In Vivo Evaluations

This study reports the fabrication and characterization of poly(vinyl alcohol) (PVA) and gelatin (Gel)-based nanofiber membranes cross-linked with citric acid (CA) by a green electrospinning method in which nano 45S5 bioglass (BG) and urea were incorporated. Various combinations of PVA, gelatin, and BG were prepared, and nanofiber membranes with average fiber diameters between 238 and 595 nm were fabricated. Morphological, chemical, and mechanical properties, porosity, swelling, water retention, and water vapor transmission rate of the fabricated membranes were evaluated. PVA:Gel (90:10), 15% CA, and 3% BG were determined as the optimum blend for nanofiber membrane fabrication via electrospinning. The membrane obtained using this blend was further functionalized with 10% w/w polymer urea coating by the electrospray method following the cross-linking. In vitro biocompatibility tests revealed that the fabricated membranes were all biocompatible except for the one that functionalized with urea. In vivo macroscopic and histopathological analysis results of PVA/Gel/BG and PVA/Gel/BG/Urea treated wounds indicated increased collagenization and vascularization and had an anti-inflammatory effect. Furthermore, careful examination of the in vivo macroscopic results of the PVA/Gel/BG/Urea membrane indicated its potential to decrease uneven scar formation. In conclusion, developed PVA/Gel/BG and PVA/Gel/BG/Urea electrospun membranes with multifunctional and biomimetic features may have the potential to be used as beneficial wound dressings.

Recent advances in harnessing biological macromolecules for wound management: A review

Wound dressings (WDs) are an essential component of wound management and serve as an artificial barrier to isolate the injured site from the external environment, thereby helping to prevent exogenous infections and supporting healing. However, maintaining a moist wound environment, providing protection from infection, good biocompatibility, and allowing for gas exchange, remain a challenge in device design. Functional wound dressings (FWDs) prepared from hybrid biological macromolecule-based materials can enhance efficacy of these systems for skin wound management. This review aims to provide an overview of the state-of-the-art FWDs within the field of wound management, with a specific focus on hybrid biomaterials, techniques, and applications developed over the past five years. In addition, we highlight the incorporation of biological macromolecules in WDs, the emergence of smart WDs, and discuss the existing challenges and future prospects for the development of advanced WDs.

Antimicrobial peptide-modified AIE visual composite wound dressing for promoting rapid healing of infected wounds

Wound infection is a major problem faced during wound healing. Therefore, it is necessary to develop wound dressings with excellent antimicrobial properties. Here, a smart response system of PVA-TPE/HA-AMP/SF/ALG wound dressing was prepared by a combination of chemical cross-linking and freeze-drying methods. We grafted AMP onto HA to endow the wound dressing with bacterial resistance and slow release of AMP. At the same time, the system detects bacterial activity in real time for precise antimicrobial activity (through the use of PVA-TPE) and modulates inflammation to reduce bacterial infection (through the use of AMP). In addition, the PVA-TPE/HA-AMP/SF/ALG wound dressing has a good three-dimensional mesh structure, which promotes cell proliferation, enhances collagen deposition and angiogenesis, and thus effectively promotes rapid healing of infected wounds. Moreover, it can induce the expression of inflammatory factors such as VEGF, TNF-α, IFN-γ, IL-4 and TGF-β1 in infected wounds through the Wnt/CAMK/p-PKC signaling pathway, inhibit inflammatory responses, promote wound healing and reduce scar formation. Therefore, the PVA-TPE/HA-AMP/SF/ALG wound dressing smart response system shows great promise in infected wound healing.

A novel multifunctional chitosan-gelatin/carboxymethyl cellulose-alginate bilayer hydrogel containing human placenta extract for accelerating full-thickness wound healing

The replication of skin's dermal and epidermal morphology within a full-thickness wound using a bi-layer hydrogel to cater to their distinct needs is a compelling pursuit. Moreover, human placenta extract (HPE), containing a diverse array of bioactive agents, has proven to be effective in promoting the wound healing process and enhancing epidermal keratinocytes. This study presents a multifunctional bi-layer hydrogel incorporating HPE for accelerating full-thickness wound healing through sustained HPE release, inhibition of bacteria invasion, and promotion of cell proliferation. The upper layer of the scaffold, known as the dressing layer, is composed of carboxymethyl cellulose and sodium alginate, serving as a supportive layer for cell proliferation. The under layer, referred to as the regenerative layer, is composed of chitosan and gelatin, providing an extracellular matrix-like, porous, moist, and antibacterial environment for cell growth. The scaffold was optimized to replicate the morphology of the dermal and epidermal layers, with suitable fibroblast infiltration and a pore size of approximately 283μm. Furthermore, the degradation rate of the samples matched the wound healing rate and persisted throughout this period. The sustained HPE release rate, facilitated by the degradation rate, was optimized to reach ~98% after 28 days, covering the entire healing period. The samples demonstrated robust antibacterial capabilities, with bacterial inhibition zone diameters of and 2.63±0.12cm for S. aureus and E. coli, respectively. The biocompatibility of the samples remained at approximately 68.33±4.5% after 21 days of fibroblast cell culture. The in vivo experiment indicated that the HPE@Bilayer hydrogel promotes the formation of new blood vessels and fibroblasts during the early stages of healing, leading to the appropriate formation of granulation tissue and a wound contraction rate of (79.31±3.1)%. Additionally, it resulted in the formation of a thick epidermal layer (keratinization) that effectively covered all the impaired areas, achieving a wound contraction rate of 95.83±6.3% at the late stage of wound healing. Furthermore, immunohistochemistry staining for CD31 and TGF-β revealed that the HPE@Bilayer group had 22 blood vessels/field and 34%-66% immunoactive cells, respectively, after 14 days of healing. However, by day 21, angiogenesis and TGF-β expression had declined, demonstrating that the wounds had been successfully treated with minimal scarring.

Fabrication, characterization and potential application of biodegradable polydopamine-modified scaffolds based on natural macromolecules

Sodium alginate (SA)-based implantable scaffolds with slow-release drugs have become increasingly important in the fields of biomedical and tissue engineering. However, high-molecular-weight SA is difficult to remove from the body due to the lack of SA-degrading enzymes. The very slow degradation properties of SA-based scaffolds limit their applications. Herein, we designed a series of biodegradable oxidized SA (OSA)-based scaffolds through amide bonds, imine bonds and hydrogen bridges between OSA and silk fibroin (SF). SF/OSA-0.4 with a blend ratio of 4/1 was chosen for further polydopamine (PDA) surface modification studies through the optimization of those parameters such as different OSA oxidation degrees, and blend ratios. PDA modified SF/OSA-0.4 (Dopa/SF/OSA-0.4) showed the excellent stability, better stretchable properties, a uniform interconnective porous structure, high thermal stability, a low hemolysis ratio and cytotoxicity. In vitro degradation experiments showed that the degradation rate of SF/OSA was significantly higher than that of SF/SA, but the degradation slowed again after PDA modification. Interestingly, the degradation of Dopa/SF/OSA-0.4 in vivo was significantly faster than that in vitro. Dopa/SF/OSA-0.4 was also more conducive to new tissue growth and collagen bundle formation. Moreover, Dopa/SF/OSA-0.4 improved the absorbability of RhB (model drug) and reduced the sudden release of RhB during the sustained release.

Silk Nanofiber Scaffolds with Multiple Angiogenic Cues to Accelerate Wound Regeneration

Niches with multiple physical and chemical cues can influence the fate of cells and tissues in vivo. Simulating the in vivo niche in the design of bioactive materials is a challenge, particularly to tune multiple cues simultaneously in the same system. Here, an assembly strategy was developed to regulate multiple cues in the same scaffold based on the use of two silk nanofiber components that respond differently during the fabrication processes. An aqueous solution containing the two components, amorphous silk nanofibers (ASNFs) and β-sheet-rich silk nanofibers (BSNFs), was sequentially treated with an electrical field and freeze-drying processes where the BSNFs oriented to the electrical field, while the ASNFs formed stable porous structures during the lyophilization process to impact the mechanical properties. Bioactive cargo, such as deferoxamine (DFO), was loaded on the BSNFs to enrich cell responses with the scaffolds. The in vitro results revealed that the loaded DFO and the anisotropic structures with improved mechanical properties resulted in better vascularization than those of the scaffolds without the anisotropic features. The multiple cues in the scaffolds provided angiogenic niches to accelerate wound healing.

Bilayer Silk Fibroin/Sodium Alginate Scaffold Delivered hUC-MSCs to Enhance Skin Scarless Healing and Hair Follicle Regeneration with the IRE1/XBP1 Pathway Inhibition

Efficient local delivery of mesenchymal stem cells (MSCs) is a decisive factor for their application in regeneration processes. Here, we prepared a biomimetic bilayer silk fibroin/sodium alginate (SF/SA) scaffold to deliver human umbilical mesenchymal stem cells (hUC-MSCs) for wound healing. An SA membrane was prepared by the casting method on the upper layer of the scaffold to simulate the dense epidermal structure. On the lower layer, porous materials simulating the loose structure of the dermis were formed by the freeze-drying method. In vitro, the scaffold was proven to have a high-density pore structure, good swelling property, and suitable degradation rate. The hUC-MSCs could survive on the scaffold for up to 14 days and maintain cell stemness for at least 7 days. In vivo, SF/SA scaffolds loaded with hUC-MSCs (M-SF/SA) were applied to full-thickness defect wounds and compared with the local injection of hUC-MSCs. The M-SF/SA group showed excellent therapeutic efficacy, characterized by induction of macrophage polarization, regulation of TGF-β expression and collagen components, and enhancement of vascular regeneration, thereby preventing scar formation and promoting hair follicle regeneration. Furthermore, the expression of endoplasmic reticulum stress markers IRE1, XBP1, and CHOP was inhibited significantly in M-SF/SA treatment. In conclusion, the bilayer SF/SA scaffold is an ideal delivery platform for hUC-MSCs, and the M-SF/SA system could locally promote scarless skin healing and hair follicle regeneration by alleviating the IRE1/XBP1 signal pathway.

Probiotic-Functionalized Silk Fibroin/Sodium Alginate Scaffolds with Endoplasmic Reticulum Stress-Relieving Properties for Promoted Scarless Wound Healing

Bioactive substances such as probiotics are becoming a research hotspot in the field of tissue regeneration due to their excellent regulatory functions. Here, we proposed to load Lactobacillus casei onto a bilayer silk fibroin/sodium alginate (SF/SA) scaffold to endow the scaffold with both antibacterial and regenerative properties. The performance of the scaffold was characterized systemically. The L. casei-loaded scaffolds (L-SF/SA) bring in lactic acid, which has antibacterial and wound healing properties. In vitro, the cell-free supernatant (CFS) of L. casei inhibited the transformation of fibroblasts to myofibroblasts and relieved the endoplasmic reticulum stress (ERS). In vivo, L-SF/SA accelerated the healing of infected wounds in SD rats. The L-SF/SA reduced the bacterial load, induced M2 polarization of macrophages, increased angiogenesis, regulated collagen ratio, and alleviated the ERS, thereby promoting scarless wound healing and increasing hair follicle regeneration. Therefore, probiotic-functionalized silk fibroin/alginate scaffolds showed potential in the infected wound healing.