Modulating degradation of sodium alginate/bioglass hydrogel for improving tissue infiltration and promoting wound healing

Development of alginate/chitosan hydrogel loaded with obestatin and evaluation of collagen type I, III, VEGF and TGF-β1 gene expression for skin repair in a rat model (in vitro and in vitro study)

BACKGROUND

Skin injuries have long been recognized as a prevalent type of physical injury. As a result, numerous research studies have been performed to discover an effective mechanism for wound healing. Therefore, tissue engineering of skin has developed as a potential solution for traditional methods of treating skin injuries.

METHODS AND MATERIALS

Alginate/Chitosan hydrogel was mixed with 1, 10, 100, and 150 µM Obestatin, and evaluated the morphology, cumulative release, hemocompatibility and cytocompatibility, water absorption, cell viability, weight loss, and antibacterial characteristics of three-dimensional (3D) alginate (Alg) and chitosan (Cs) hydrogels during the process of wound curing. Various concentrations of Obestatin (Obes) were utilized for this purpose. Finally, the hydrogels that were made were tested on a full-thickness dermal wound in a Wistar rat model. The curative effects were determined by analyzing RNA expression and examining tissue stained with Masson's trichrome (MT) and hematoxylin-eosin (H&E).

RESULTS

The biodegradability of this hydrogel was verified using weight loss testing, which demonstrated a reduction of around 90% after a period of 3 days. Furthermore, the MTT assay demonstrated that hydrogels have a beneficial effect on cell proliferation without inducing any harmful effects. Furthermore, the hydrogels produced demonstrated higher wound closure in vivo compared to the wounds treated with gauze (negative control group). Among the hydrogel groups, the chitosan/alginate/obestatin 100 µM group exhibited the apical percentage of wound closure, gene expression, and secondary epithelialization, but in 150 µM concentrations, we saw a lower rate of cell growth and proliferation and increase in hemolysis. In addition, RT-PCR analysis demonstrated that a concentration of 100 µM obestatin resulted in an upregulation in the expression of mRNA for vascular endothelial growth factor (VEGF), collagen type I & type III, and transforming growth factor-beta (TGF-β).

CONCLUSION

The present study suggests that 3D Alg/Cs hydrogels with a concentration of 100 µM obestatin have the potential for clinical application in the treatment of skin injuries.

Propelling Minimally Invasive Tissue Regeneration With Next-Era Injectable Pre-Formed Scaffolds

The growing aging population, with its associated chronic diseases, underscores the urgency for effective tissue regeneration strategies. Biomaterials play a pivotal role in the realm of tissue reconstruction and regeneration, with a distinct shift toward minimally invasive (MI) treatments. This transition, fueled by engineered biomaterials, steers away from invasive surgical procedures to embrace approaches offering reduced trauma, accelerated recovery, and cost-effectiveness. In the realm of MI tissue repair and cargo delivery, various techniques are explored. While in situ polymerization is prominent, it is not without its challenges. This narrative review explores diverse biomaterials, fabrication methods, and biofunctionalization for injectable pre-formed scaffolds, focusing on their unique advantages. The injectable pre-formed scaffolds, exhibiting compressibility, controlled injection, and maintained mechanical integrity, emerge as promising alternative solutions to in situ polymerization challenges. The conclusion of this review emphasizes the importance of interdisciplinary design facilitated by synergizing fields of materials science, advanced 3D biomanufacturing, mechanobiological studies, and innovative approaches for effective MI tissue regeneration.

Bioactive Glass in Tissue Regeneration: Unveiling Recent Advances in Regenerative Strategies and Applications

Bioactive glass (BG) is a class of biocompatible, biodegradable, multifunctional inorganic glass materials, which is successfully used for orthopedic and dental applications, with several products already approved for clinical use. Apart from exhibiting osteogenic properties, BG is also known to be angiogenic and antibacterial. Recently, BG's role in immunomodulation has been gradually revealed. While the therapeutic effect of BG is mostly reported in the context of bone and skin-related regeneration, its application in regenerating other tissues/organs, such as muscle, cartilage, and gastrointestinal tissue, has also been explored recently. The strategies of applying BG have also expanded from powder or cement form to more advanced strategies such as fabrication of composite polymer-BG scaffold, 3D printing of BG-loaded scaffold, and BG-induced extracellular vesicle production. This review presents a concise overview of the recent applications of BG in regenerative medicine. Various regenerative strategies of BG will be first introduced. Next, the applications of BG in regenerating various tissues/organs, such as bone, cartilage, muscle, tendon, skin, and gastrointestinal tissue, will be discussed. Finally, summarizing clinical applications of BG for tissue regeneration will conclude, and outline future challenges and directions for the clinical translation of BG.

Recent Advances in Functional Hydrogel for Repair of Abdominal Wall Defects: A Review

The abdominal wall plays a crucial role in safeguarding the internal organs of the body, serving as an essential protective barrier. Defects in the abdominal wall are common due to surgery, infection, or trauma. Complex defects have limited self-healing capacity and require external intervention. Traditional treatments have drawbacks, and biomaterials have not fully achieved the desired outcomes. Hydrogel has emerged as a promising strategy that is extensively studied and applied in promoting tissue regeneration by filling or repairing damaged tissue due to its unique properties. This review summarizes the five prominent properties and advances in using hydrogels to enhance the healing and repair of abdominal wall defects: (a) good biocompatibility with host tissues that reduces adverse reactions and immune responses while supporting cell adhesion migration proliferation; (b) tunable mechanical properties matching those of the abdominal wall that adapt to normal movement deformations while reducing tissue stress, thereby influencing regulating cell behavior tissue regeneration; (c) drug carriers continuously delivering drugs and bioactive molecules to sites optimizing healing processes enhancing tissue regeneration; (d) promotion of cell interactions by simulating hydrated extracellular matrix environments, providing physical support, space, and cues for cell migration, adhesion, and proliferation; (e) easy manipulation and application in surgical procedures, allowing precise placement and close adhesion to the defective abdominal wall, providing mechanical support. Additionally, the advances of hydrogels for repairing defects in the abdominal wall are also mentioned. Finally, an overview is provided on the current obstacles and constraints faced by hydrogels, along with potential prospects in the repair of abdominal wall defects.

Cell-homing and immunomodulatory composite hydrogels for effective wound healing with neovascularization

Wound healing in cases of excessive inflammation poses a significant challenge due to compromised neovascularization. Here, we propose a multi-functional composite hydrogel engineered to overcome such conditions through recruitment and activation of macrophages with adapted degradation of the hydrogel. The composite hydrogel (G-TSrP) is created by combining gelatin methacryloyl (GelMA) and nanoparticles (TSrP) composed of tannic acid (TA) and Sr2+. These nanoparticles are prepared using a one-step mineralization process assisted by metal-phenolic network formation. G-TSrP exhibits the ability to eliminate reactive oxygen species and direct polarization of macrophages toward M2 phenotype. It has been observed that the liberation of TA and Sr2+ from G-TSrP actively facilitate the recruitment and up-regulation of the expression of extracellular matrix remodeling genes of macrophages, and thereby, coordinate in vivo adapted degradation of the G-TSrP. Most significantly, G-TSrP accelerates angiogenesis despite the TA's inhibitory properties, which are counteracted by the released Sr2+. Moreover, G-TSrP enhances wound closure under inflammation and promotes normal tissue formation with strong vessel growth. Genetic analysis confirms macrophage-mediated wound healing by the composite hydrogel. Collectively, these findings pave the way for the development of biomaterials that promote wound healing by creating regenerative environment.

Composite Aerogel Scaffolds Containing Flexible Silica Nanofiber and Tricalcium Phosphate Enable Skin Regeneration

Poor hemostatic ability and less vascularization at the injury site could hinder wound healing as well as adversely affect the quality of life (QOL). An ideal wound dressing should exhibit certain characteristics: (a) good hemostatic ability, (b) rapid wound healing, and (c) skin appendage formation. This necessitates the advent of innovative dressings to facilitate skin regeneration. Therapeutic ions, such as silicon ions (Si4+) and calcium ions (Ca2+), have been shown to assist in wound repair. The Si4+ released from silica (SiO2) can upregulate the expression of proteins, including the vascular endothelial growth factor (VEGF) and alpha smooth muscle actin (α-SMA), which is conducive to vascularization; Ca2+ released from tricalcium phosphate (TCP) can promote the coagulation alongside upregulating the expression of cell migration and cell differentiation related proteins, thereby facilitating the wound repair. The overarching objective of this study was to exploit short SiO2 nanofibers along with the TCP to prepare TCPx@SSF aerogels and assess their wound healing ability. Short SiO2 nanofibers were prepared by electrospinning and blended with varying proportions of TCP to afford TCPx@SSF aerogel scaffolds. The TCPx@SSF aerogels exhibited good cytocompatibility in a subcutaneous implantation model and manifested a rapid hemostatic effect (hemostatic time 75 s) in a liver trauma model in the rabbit. These aerogel scaffolds also promoted skin regeneration and exhibited rapid wound closure, epithelial tissue regeneration, and collagen deposition. Taken together, TCPx@SSF aerogels may be valuable for wound healing.

Biomaterials for immunomodulation in wound healing

The substantial economic impact of non-healing wounds, scarring, and burns stemming from skin injuries is evident, resulting in a financial burden on both patients and the healthcare system. This review paper provides an overview of the skin's vital role in guarding against various environmental challenges as the body's largest protective organ and associated developments in biomaterials for wound healing. We first introduce the composition of skin tissue and the intricate processes of wound healing, with special attention to the crucial role of immunomodulation in both acute and chronic wounds. This highlights how the imbalance in the immune response, particularly in chronic wounds associated with underlying health conditions such as diabetes and immunosuppression, hinders normal healing stages. Then, this review distinguishes between traditional wound-healing strategies that create an optimal microenvironment and recent peptide-based biomaterials that modulate cellular processes and immune responses to facilitate wound closure. Additionally, we highlight the importance of considering the stages of wounds in the healing process. By integrating advanced materials engineering with an in-depth understanding of wound biology, this approach holds promise for reshaping the field of wound management and ultimately offering improved outcomes for patients with acute and chronic wounds.

Cobalt/Bioglass Nanoparticles Enhanced Dermal Regeneration in a 3-Layered Electrospun Scaffold

Purpose

Due to the multilayered structure of the skin tissue, the architecture of its engineered scaffolds needs to be improved. In the present study, 45s5 bioglass nanoparticles were selected to induce fibroblast proliferation and their protein secretion, although cobalt ions were added to increase their potency.

Methods

A 3-layer scaffold was designed as polyurethane (PU) - polycaprolactone (PCL)/ collagen/nanoparticles-PCL/collagen. The scaffolds examined by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), tensile, surface hydrophilicity and weight loss. Biological tests were performed to assess cell survival, adhesion and the pattern of gene expression.

Results

The mechanical assay showed the highest young modulus for the scaffold with the doped nanoparticles and the water contact angle of this scaffold after chemical crosslinking of collagen was reduced to 52.34±7.7°. In both assessments, the values were statistically compared to other groups. The weight loss of the corresponding scaffold was the highest value of 82.35±4.3 % due to the alkaline effect of metal ions and indicated significant relations in contrast to the scaffold with non-doped particles and bare one (P value<0.05). Moreover, better cell expansion, greater cell confluence and a lower degree of toxicity were confirmed. The up-regulation of TGF β1 and VEGF genes introduced this scaffold as a better model for the fibroblasts commitment to a new skin tissue among bare and nondoped scaffold (P value<0.05).

Conclusion

The 3-layered scaffold which is loaded with cobalt ions-bonded bioglass nanoparticles, is a better substrate for the culture of the fibroblasts.

Developing natural polymers for skin wound healing

Natural polymers are complex organic molecules that occur in the natural environment and have not been subjected to artificial synthesis. They are frequently encountered in various creatures, including mammals, plants, and microbes. The aforementioned polymers are commonly derived from renewable sources, possess a notable level of compatibility with living organisms, and have a limited adverse effect on the environment. As a result, they hold considerable significance in the development of sustainable and environmentally friendly goods. In recent times, there has been notable advancement in the investigation of the potential uses of natural polymers in the field of biomedicine, specifically in relation to natural biomaterials that exhibit antibacterial and antioxidant characteristics. This review provides a comprehensive overview of prevalent natural polymers utilized in the biomedical domain throughout the preceding two decades. In this paper, we present a comprehensive examination of the components and typical methods for the preparation of biomaterials based on natural polymers. Furthermore, we summarize the application of natural polymer materials in each stage of skin wound repair. Finally, we present key findings and insights into the limitations of current natural polymers and elucidate the prospects for their future development in this field.

Versatile Bioactive Glass/Zeolitic Imidazolate Framework-8-Based Skin Scaffolds toward High-Performance Wound Healing

Designing a novel biomaterial for wound healing is based on biocompatibility and excellent mechanical strength. In this study, bioactive glass (BG) and zeolitic imidazolate framework-8 (ZIF-8) have been incorporated into poly(ε-caprolactone)/poly(vinyl alcohol) (PCL/PVA) composite skin scaffolds via microfluidic electrospinning. Interestingly, the addition of ZIF-8 further strengthens the BG stability and demonstrates better antibacterial effects. Utilizing the slow release of Zn, Ca, and Si ions, it also significantly promotes growth factor expression and skin regeneration. In addition, it is further demonstrated by in vitro and in vivo studies that the prepared composite skin scaffolds possess excellent biocompatibility, antibacterial capabilities, and mechanical properties. The prepared BG/ZIF-8-loaded scaffold possesses high tensile strength (26 MPa) and excellent antibacterial properties (achieves 89.64 and 78.8% inhibition of E. coli and S. aureus, respectively), and cell viability increased by 51.2%. More importantly, the wound shrinkage of the BG/ZIF-8-loaded scaffold is better than that of an unloaded scaffold, and the shrinkage rates of PCL/PVA@BG/ZIF-8(1 wt %) group is 95% with 2.2 mm granulation growth thickness within 12 days. Thus, the composite skin scaffold loaded with BG/ZIF-8 prepared by microfluidic electrospinning provides a new perspective for accelerating wound healing and is a potential novel therapeutic strategy for efficient wound healing.

A carboxymethyl chitosan/oxidized hyaluronic acid composite hydrogel dressing loading with stem cell exosome for chronic inflammation wounds healing

Stem cell exosomes (Exo) play an important role in the transformation of macrophages, but the rapid clearance of Exo in vivo limits their therapeutic effects for chronic inflammation wounds healing. Here, stem cell Exo was isolated and introduced to a composite hydrogel including carboxymethyl chitosan (CMCS) and oxidized hyaluronic acid (OHA) through chemical cross-linking, which formed an Exo-loaded (CMCS/OHA/Exo) hydrogel. The CMCS/OHA/Exo hydrogel exhibited a function of Exo sustained release and an Exo protection within 6 days. This CMCS/OHA/Exo hydrogel was much better than CMCS/OHA hydrogel or Exo solution in macrophage cell phagocytosis, proliferation and migration in vitro, especially, played an obviously positive role in the transformation of macrophages compared with the reference groups. For the treatment of the chronic inflammation wounds in vivo, the CMCS/OHA/Exo hydrogel had the best results at wound heal rate and inhibiting the secretion of inflammatory factors, and it was far superior to reference groups in wound re-epithelization and collagen production. CMCS/OHA/Exo hydrogels can promote Exo release based on hydrogel degradation to regulate macrophages transformation and accelerate chronic wound healing. The study offers a method for preparing Exo-loaded hydrogels that effectively promote the transformation of macrophages and accelerate chronic inflammatory wound healing.

Development of a Multifunctional Composite Hydrogel for Enhanced Wound Healing: Hemostasis, Sterilization, and Long-Term Moisturizing Properties

Meeting the diverse requirements of effective wound repair while surpassing the single-function limitations of traditional wound dressings is a significant challenge. In this study, we successfully synthesized an inclusion complex of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and iodine using the saturated aqueous solution method. Additionally, dialdehyde cellulose (DAC) was extracted from fat-free cotton through oxidation. To enhance wound healing, l-glutamine (l-glu) was utilized as a functional molecule, resulting in composite hydrogels with hemostatic, sterilizing, and wound-healing-promoting properties that were achieved by adsorbing the resulting inclusion complex. Through TG and SEM analysis, we confirmed that iodine was effectively accommodated by cyclodextrin and was uniformly attached to the hydrogel. The hydrogel exhibits exceptional long-term moisturizing and bactericidal properties, while also demonstrating excellent swelling, oxygen permeability, hemolytic, and mechanical properties, fully satisfying the requirements of wound treatment. External coagulation tests revealed that the hydrogel can rapidly coagulate 4.5 times its own weight of blood. Moreover, in a full-thickness scald mouse model, the hydrogel effectively promotes wound healing. The development of this multifunctional composite hydrogel presents a novel approach to advance wound dressing research, holding substantial potential for practical applications.

Mechanisms of hydrogel-based microRNA delivery systems and its application strategies in targeting inflammatory diseases

Hydrogels, composed of three-dimensional polymer networks, are excellent delivery carriers and have been extensively employed in the biomedical field. Inflammation acts as a protective mechanism to prevent harmful substances from entering living organisms, but chronic, long-lasting inflammation can cause oxidative stress, which damages tissue and organs and adversely affects patients' quality of life. The aberrant expression of microRNAs (miRNAs) has been found to play a significant part in the etiology and progression of inflammatory diseases, as suggested by growing evidence. Numerous hydrogels that can act as gene carriers for the intracellular delivery of miRNA have been described during ongoing research into innovative hydrogel materials. MiRNA hydrogel delivery systems, which are loaded with exogenous miRNA inhibitors or mimics, enable targeted miRNA intervention in inflammatory diseases and effectively prevent environmental stressors from degrading or inactivating miRNA. In this review, we summarize the classification of miRNA hydrogel delivery systems, the basic strategies and mechanisms for loading miRNAs into hydrogels, highlight the biomedical applications of miRNA hydrogel delivery systems in inflammatory diseases, and share our viewpoints on potential opportunities and challenges in the promising region of miRNA delivery systems. These findings may provide a new theoretical basis for the prevention and treatment of inflammation-related diseases and lay the foundation for clinical translation.

Opportunities for Bioactive Glass in Gastrointestinal Conditions: A Review of Production Methodologies, Morphology, Composition, and Performance

Bioactive glasses (BGs) are widely used in orthopedic and dental applications for their ability to stimulate endogenous bone formation and regeneration. BG applications more recently broadened to include soft tissue conditions, based on their ability to stimulate angiogenesis, soft tissue regeneration, and wound healing. Sol-gel synthesis has helped facilitate this expansion, allowing formulators to tailor the morphological characteristics of the BG matrix. The effectiveness of BGs in skin wound healing is viewed as a gateway for their use as both a therapeutic and drug delivery platform in other soft tissue applications, notably gastrointestinal (GI) applications, which form the focus of this review. Recent changes in international guidelines for GI conditions shifted clinical objectives from symptom management to mucosal wound healing. The additional scrutiny of proton pump inhibitor (PPI) safety, increasing burden of disease, and financial costs associated with gastroesophageal reflux disease (GERD), peptic ulcer disease (PUD), and inflammatory bowel disease (IBD) open new clinical possibilities for BG. This narrative literature review intersects materials engineering, formulation science, and clinical practice, setting it apart from prior literature. Broadly, current evidence for BG applications in GI conditions is sparse and under-developed, which this review directly addresses. It explores and synthesizes evidence that supports the potential use of sol-gel-derived BG for the efficacious treatment of soft tissue applications, with specific reference to GI conditions. An overview with comparative analysis of current BG synthesis techniques and associated challenges is presented, and influences of composition, biologically active ions, and morphological characteristics in soft tissue applications are explored. To contextualize this, sol-gel-derived BGs are proposed as a dual, tailorable therapeutic and drug delivery platform for upper and lower GI conditions. Future directions for this largely untapped area of translational research are also proposed, based on extant literature.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

The effect of oral treatment of royal jelly on the expression of the PDGF-β gene in the skin wound of male mice

AIMS OF THE STUDY

Royal jelly (RJ) is one of the most widely used drugs in traditional medicine. One of its important applications is the repair of skin damage, although the path of its mechanism is still unknown. Platelet-derived growth factor-beta (PDGF-beta) is one of the important factors in wound healing and it has been observed that PDGF-β expression decreases with increasing age. In this study, for the first time, the effect of RJ on skin wounds has been investigated through the expression of PDGF-β and tissue studies.

MATERIALS AND METHODS

25 small laboratory male BALB/c mice were selected randomly and after creating a 5 mm wound on the back of their neck, they were treated with doses of 2.5, 10, and 40 mg/kg body weight, After sampling from the healed wound in 9th day, histopathological studies and the expression of PDGF-β gene were performed by Real-time PCR method.

RESULTS

The findings of the present study showed that royal jelly caused a significant increase in PDGF-β (10.99 times) compared to the healthy group. Also, royal jelly increased the formation of covering tissue or epithelium, the synthesis of collagen, the presence of inflammatory cells, and the formation of new blood vessels.

CONCLUSION

The oral treatment of royal jelly is probably effective in skin wound healing by changing the expression of PDGF-β.

Bioinspired Collagen/Hyaluronic Acid/Fibrin-Based Hydrogels for Soft Tissue Engineering: Design, Synthesis, and In Vitro Characterization

A major challenge for future drug development comprises finding alternative models for drug screening. The use of animal models in research is highly controversial, with an ongoing debate on their ethical acceptability. Also, animal models are often poorly predictive of therapeutic outcomes due to the differences between animal and human physiological environments. In this study, we aimed to develop a biomimetic hydrogel that replicates the composition of skin for potential use in in vitro modeling within tissue engineering. The hydrogel was fabricated through the crosslinking of collagen type I, hyaluronic acid, four-arm PEG succinimidyl glutarate (4S-StarPEG), and fibrinogen. Various ratios of these components were systematically optimized to achieve a well-interconnected porosity and desirable rheological properties. To evaluate the hydrogel's cytocompatibility, fibroblasts were embedded within the matrix. The resulting hydrogel exhibited promising properties as a scaffold, also facilitating the growth of and proliferation of the cells. This biomimetic hydrogel holds great potential for tissue engineering applications, particularly in skin regeneration and cancer research. The study used melanoma spheroids fabricated using the 96-round bottom well plate method as a potential application. The results demonstrate that the developed hydrogels allowed the maintenance of spheroid integrity and viability, meaning it has a promising use as a three-dimensional in vitro model of melanoma for both tissue engineering and drug screening applications.

An injectable bioactive dressing based on platelet-rich plasma and nanoclay: Sustained release of deferoxamine to accelerate chronic wound healing

Delayed diabetic wound healing has placed an enormous burden on society. The key factors limiting wound healing include unresolved inflammation and impaired angiogenesis. Platelet-rich plasma (PRP) gel, a popular biomaterial in the field of regeneration, has limited applications due to its non-injectable properties and rapid release and degradation of growth factors. Here, we prepared an injectable hydrogel (DPLG) based on PRP and laponite by a simple one-step mixing method. Taking advantages of the non-covalent interactions, DPLG could overcome the limitations of PRP gels, which is injectable to fill irregular injures and could serve as a local drug reservoir to achieve the sustained release of growth factors in PRP and deferoxamine (an angiogenesis promoter). DPLG has an excellent ability in accelerating wound healing by promoting macrophage polarization and angiogenesis in a full-thickness skin defect model in type I diabetic rats and normal rats. Taken together, this study may provide the ingenious and simple bioactive wound dressing with a superior ability to promote wound healing.

Bioinspired poly(aspartic acid) based hydrogel with ROS scavenging ability as mEGF carrier for wound repairing applications

Poly(amino acid) based self-healing hydrogels have important application in biomedications. In this research, the catechol pendant groups were imported to poly(aspartic acid) based self-healing hydrogel to improved skin adhesion and ROS scavenging performance. The poly(succinimide) (PSI) was reacted with 3,4-dihydroxyphenylalanine (DA) and then hydraziolyzed to import catechol group and hydrazide group respectively, which are responsible for mussel inspired tissue adhesion and dynamic coupling reactivity. The dopamine modified poly(aspartic hydrazide) (PDAH) was reacted with PEO90 dialdehyde (PEO90 DA) to prepare hydrogels, and the resultant hydrogel showed good biocompatibility both in vitro and in vivo. The skin adhesion strength of the mussel inspired hydrogel increased notably with enhanced radical scavenging efficiency fit for in vivo wound repairing applications. The PDAH/PEO90 DA hydrogel also showed sustained albumin release profile and the in vivo wound repairing experiment proved the mouse Epidermal Growth Factor (mEGF) loaded hydrogel as wound dressing material accelerated the wound repairing rate.

Double-network hydrogel enhanced by SS31-loaded mesoporous polydopamine nanoparticles: Symphonic collaboration of near-infrared photothermal antibacterial effect and mitochondrial maintenance for full-thickness wound healing in diabetes mellitus

Diabetic wound healing has become a serious healthcare challenge. The high-glucose environment leads to persistent bacterial infection and mitochondrial dysfunction, resulting in chronic inflammation, abnormal vascular function, and tissue necrosis. To solve these issues, we developed a double-network hydrogel, constructed with pluronic F127 diacrylate (F127DA) and hyaluronic acid methacrylate (HAMA), and enhanced by SS31-loaded mesoporous polydopamine nanoparticles (MPDA NPs). As components, SS31, a mitochondria-targeted peptide, maintains mitochondrial function, reduces mitochondrial reactive oxygen species (ROS) and thus regulates macrophage polarization, as well as promoting cell proliferation and migration, while MPDA NPs not only scavenge ROS and exert an anti-bacterial effect by photothermal treatment under near-infrared light irradiation, but also control release of SS31 in response to ROS. This F127DA/HAMA-MPDA@SS31 (FH-M@S) hydrogel has characteristics of adhesion, superior biocompatibility and mechanical properties which can adapt to irregular wounds at different body sites and provide sustained release of MPDA@SS31 (M@S) NPs. In addition, in a diabetic rat full thickness skin defect model, the FH-M@S hydrogel promoted macrophage M2 polarization, collagen deposition, neovascularization and wound healing. Therefore, the FH-M@S hydrogel exhibits promising therapeutic potential for skin regeneration.

Polysaccharide-based hydrogel promotes skin wound repair and research progress on its repair mechanism

Polysaccharides, being a natural, active, and biodegradable polymer, have garnered significant attention due to their exceptional properties. These properties make them ideal for creating multifunctional hydrogels that can be used as wound dressings for skin injuries. Polysaccharide hydrogel has the ability to both simulate the natural extracellular matrix, promote cell proliferation, and provide a suitable environment for wound healing while protecting it from bacterial invasion. Polysaccharide hydrogels offer a promising solution for repairing damaged skin. This review provides an overview of the mechanisms involved in skin damage repair and emphasizes the potential of polysaccharide hydrogels in this regard. For different skin injuries, polysaccharide hydrogels can play a role in promoting wound healing. However, we still need to conduct more research on polysaccharide hydrogels to provide more possibilities for skin damage repair.

Formulation and Characterization of a Novel Oxidized Alginate-Gelatin-Silk Fibroin Bioink with the Aim of Skin Regeneration

Background

In the present study, a novel bioink was suggested based on the oxidized alginate (OAlg), gelatin (GL), and silk fibroin (SF) hydrogels.

Methods

The composition of the bioink was optimized by the rheological and printability measurements, and the extrusion-based 3D bioprinting process was performed by applying the optimum OAlg-based bioink.

Results

The results demonstrated that the viscosity of bioink was continuously decreased by increasing the SF/GL ratio, and the bioink displayed a maximum achievable printability (92 ± 2%) at 2% (w/v) of SF and 4% (w/v) of GL. Moreover, the cellular behavior of the scaffolds investigated by MTT assay and live/dead staining confirmed the biocompatibility of the prepared bioink.

Conclusion

The bioprinted OAlg-GL-SF scaffold could have the potential for using in skin tissue engineering applications, which needs further exploration.

3D hypoxia-mimicking and anti-synechia hydrogel enabling promoted neovascularization for renal injury repair and regeneration

In-situ renal tissue engineering is promising yet challenging for renal injury repair and regeneration due to the highly vascularized structure of renal tissue and complex high-oxidative stress and ischemic microenvironment. Herein, a novel biocompatible 3D porous hydrogel (DFO-gel) with sustained release capacity of hypoxia mimicking micromolecule drug deferoxamine (DFO) was developed for in-situ renal injury repair. In vitro and in vivo experimental results demonstrated that the developed DFO-gels can exert the synchronous benefit of scavenging excess reactive oxygen species (ROS) regulating inflammatory microenvironment and promoting angiogenesis for effective renal injury repair by up-regulating hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). The in-situ neogenesis of neonatal glomerular- and tubular-like structures in the implanted areas in the partially nephrectomized rats also suggested the potential for promoting renal injury repair and regeneration. This multifunctional hydrogel can not only exhibit the sustained release and promoted bio-uptake capacity for DFO, but also improve the renal injured microenvironment by alleviating oxidative and inflammatory stress, accelerating neovascularization, and promoting efficient anti-synechia. We believe this work offers a promising strategy for renal injury repair and regeneration.

Reinforcement of Hydrogels with a 3D-Printed Polycaprolactone (PCL) Structure Enhances Cell Numbers and Cartilage ECM Production under Compression

Hydrogels show promise in cartilage tissue engineering (CTE) by supporting chondrocytes and maintaining their phenotype and extracellular matrix (ECM) production. Under prolonged mechanical forces, however, hydrogels can be structurally unstable, leading to cell and ECM loss. Furthermore, long periods of mechanical loading might alter the production of cartilage ECM molecules, including glycosaminoglycans (GAGs) and collagen type 2 (Col2), specifically with the negative effect of stimulating fibrocartilage, typified by collagen type 1 (Col1) secretion. Reinforcing hydrogels with 3D-printed Polycaprolactone (PCL) structures offer a solution to enhance the structural integrity and mechanical response of impregnated chondrocytes. This study aimed to assess the impact of compression duration and PCL reinforcement on the performance of chondrocytes impregnated with hydrogel. Results showed that shorter loading periods did not significantly affect cell numbers and ECM production in 3D-bioprinted hydrogels, but longer periods tended to reduce cell numbers and ECM compared to unloaded conditions. PCL reinforcement enhanced cell numbers under mechanical compression compared to unreinforced hydrogels. However, the reinforced constructs seemed to produce more fibrocartilage-like, Col1-positive ECM. These findings suggest that reinforced hydrogel constructs hold potential for in vivo cartilage regeneration and defect treatment by retaining higher cell numbers and ECM content. To further enhance hyaline cartilage ECM formation, future studies should focus on adjusting the mechanical properties of reinforced constructs and exploring mechanotransduction pathways.

Applied Compressive Strain Governs Hyaline-like Cartilage versus Fibrocartilage-like ECM Produced within Hydrogel Constructs

The goal of cartilage tissue engineering (CTE) is to regenerate new hyaline cartilage in joints and treat osteoarthritis (OA) using cell-impregnated hydrogel constructs. However, the production of an extracellular matrix (ECM) made of fibrocartilage is a potential outcome within hydrogel constructs when in vivo. Unfortunately, this fibrocartilage ECM has inferior biological and mechanical properties when compared to native hyaline cartilage. It was hypothesized that compressive forces stimulate fibrocartilage development by increasing production of collagen type 1 (Col1), an ECM protein found in fibrocartilage. To test the hypothesis, 3-dimensional (3D)-bioprinted hydrogel constructs were fabricated from alginate hydrogel impregnated with ATDC5 cells (a chondrogenic cell line). A bioreactor was used to simulate different in vivo joint movements by varying the magnitude of compressive strains and compare them with a control group that was not loaded. Chondrogenic differentiation of the cells in loaded and unloaded conditions was confirmed by deposition of cartilage specific molecules including glycosaminoglycans (GAGs) and collagen type 2 (Col2). By performing biochemical assays, the production of GAGs and total collagen was also confirmed, and their contents were quantitated in unloaded and loaded conditions. Furthermore, Col1 vs. Col2 depositions were assessed at different compressive strains, and hyaline-like cartilage vs. fibrocartilage-like ECM production was analyzed to investigate how applied compressive strain affects the type of cartilage formed. These assessments showed that fibrocartilage-like ECM production tended to reduce with increasing compressive strain, though its production peaked at a higher compressive strain. According to these results, the magnitude of applied compressive strain governs the production of hyaline-like cartilage vs. fibrocartilage-like ECM and a high compressive strain stimulates fibrocartilage-like ECM formation rather than hyaline cartilage, which needs to be addressed by CTE approaches.

A review on the synthesis and development of alginate hydrogels for wound therapy

Convenient and low-cost dressings can reduce the difficulty of wound treatment. Alginate gel dressings have the advantages of low cost and safe usage, and they have obvious potential for development in biomedical materials. Alginate gel dressings are currently a research area of great interest owing to their versatility, intelligent, and their application attempts in treating complex wounds. We present a detailed summary of the preparation of alginate hydrogels and a study of their performance improvement. Herein, we summarize the various applications of alginate hydrogels. The research focuses in this area mainly include designing multifunctional dressings for the treatment of various wounds and fabricating specialized dressings to assist physicians in the treatment of complex wounds (TOC). This review gives an outlook for future directions in the field of alginate hydrogel dressings. We hope to attract more research interest and studies in alginate hydrogel dressings, thus contributing to the creation of low-cost and highly effective wound treatment materials.

Zwitterionic Polysaccharide-Based Hydrogel Dressing as a Stem Cell Carrier to Accelerate Burn Wound Healing

Stem cell therapy integrated with hydrogels has shown promising potential in wound healing. However, the existing hydrogels usually cannot reach the desired therapeutic efficacy for burn wounds due to the inadaptability to wound shape and weak anti-infection ability. Moreover, it is difficult to improve the environment for the survival and function of stem cells under complicated wound microenvironments. In this study, an injectable and self-healing hydrogel (DSC), comprising sulfobetaine-derived dextran and carboxymethyl chitosan, is fabricated through a Schiff-base reaction. Meanwhile, the DSC hydrogel shows high nonfouling properties, including resistance to bacteria and nonspecific proteins; moreover, the prepared hydrogel can provide a biomimetic microenvironment for cell proliferation whilst maintaining the stemness of adipose-derived stem cells (ADSCs) regardless of complex microenvironments. In burnt murine animal models, the ADSCs-laden hydrogel can significantly accelerate wound healing rate and scarless skin tissue regeneration through multiple pathways. Specifically, the ADSCs-laden DSC hydrogel can avoid immune system recognition and activation and thus reduce the inflammatory response. Moreover, the ADSCs-laden DSC hydrogel can promote collagen deposition, angiogenesis, and enhance macrophage M2 polarization in the wound area. In summary, sulfobetaine-derived polysaccharide hydrogel can serve as a versatile platform for stem cell delivery to promote burn wound healing.

Honokiol@PF127 crosslinked hyaluronate-based hydrogel for promoting wound healing by regulating macrophage polarization

Bacterial infection, oxidative stress and inflammation are the main obstacles in wound healing. Hydrogels with moist and inherent properties are beneficial to wound healing. Here, we fabricated a honokiol-laden micelle-crosslinked hyaluronate-based hydrogel by simply mixing honokiol-laden PF127-CHO micelles, 3,3'-dithiobis(propionohydrazide) grafted hyaluronic acid and silver ions. PF127 could not only effectively load hydrophobic small molecules but also be macromolecular crosslinker for preparing hydrogels. Hyaluronic acid plays an essential role in wound healing processes including regulating macrophage polarization towards M2 phenotype. The chemical dynamic acylhydrazone crosslinking and physical crosslinking among PF127-CHO micelles constructed hydrogel's networks, which endowed hydrogel with excellent self-healing properties. PF-HA-3 hydrogel also exhibited outstanding antioxidant and antibacterial capabilities. In a full-thickness skin defect model, this degradable and biocompatible hydrogel could promote wound healing by remodeling wound tissues, regulating M2 polarization and angiogenesis. In summary, this inherent multifunctional hydrogel will provide a promising strategy for designing bioactive compounds-based wound dressings.

Piezoelectric Bioactive Glasses Composite Promotes Angiogenesis by the Synergistic Effect of Wireless Electrical Stimulation and Active Ions

Insufficient angiogenesis frequently occurs after the implantation of orthopedic materials, which greatly increases the risk of bone defect reconstruction failure. Therefore, the development of bone implant with improved angiogenic properties is of great importance. Mimicking the extracellular matrix clues provides a more direct and effective strategy to modulate angiogenesis. Herein, inspired by the bioelectrical characteristics of the bone microenvironment, a piezoelectric bioactive glasses composite (P-KNN/BG) based on the incorporation of polarized potassium sodium niobate is constructed, which could effectively promote angiogenesis. It is found that P-KNN/BG has exceptional wireless electrical stimulation performance and sustained active ions release. In vitro cell experiments reveal that P-KNN/BG enhances endothelial cell adhesion, migration, and differentiation via activating the eNOS/NO signaling pathway, which might be contributed to cell membrane hyperpolarization induced by wireless electrical stimulation increase the influx of active ions into the cells. In vivo chick chorioallantoic membrane experiment demonstrates that P-KNN/BG shows excellent pro-angiogenic capacity and biocompatibility. This work broadens the current understanding of bioactive materials with bionic electrical properties, which brings new insights into the clinical treatment of bone defect repair.

Thermosensitive Injectable Gradient Hydrogel-Induced Bidirectional Differentiation of BMSCs

Osteochondral defects threaten the quality of life of patients to a great extent. To simulate gradient changes in osteochondral tissue, a gradient-mixing injection device consisting of a controller and injection pumps is design. Bioactive glass (BG) and gellan gum (GG) are used to prepare thermosensitive injectable gradient hydrogels (B_0.5 G, B₁ G) with an upper critical solution temperature (UCST) range of 37.7-40.2 °C using this device for the first time. The mechanical properties of gradient hydrogels are significantly better than those of pure GG hydrogels. The gradients in the composition, structure, and morphology of gradient hydrogels are confirmed via physicochemical characterization. Cytocompatibility tests show that hydrogels, especially B_0.5 G gradient hydrogels, promote the proliferation of bone marrow mesenchymal stem cells (BMSCs). Most importantly, qRT-PCR shows that the different components in B_0.5 G gradient hydrogels simultaneously induce the osteogenic and chondrogenic differentiation of BMSCs. Experimental injection in porcine osteochondral defects indicates that the B_0.5 G gradient hydrogel seamlessly fills irregular osteochondral defects in a less invasive manner by controlling the temperature to avoid cellular and tissue damage arising from crosslinkers or other conditions. These results show that thermosensitive injectable B_0.5 G gradient hydrogels have the potential for less invasive integrated osteochondral repair.

Carboxymethyl chitosan/sodium alginate hydrogels with polydopamine coatings as promising dressings for eliminating biofilm and multidrug-resistant bacteria induced wound healing

Microorganisms induced wound infection and the accompanying excessive inflammatory response is the daunting problems in wound treatment. Due to the lack of corresponding biological functions, traditional wound dressings cannot effectively protect the wound and are prone to induce local infection, excessive inflammation, and vascular damage, resulting in prolonged unhealing. Here, a mussel-inspired strategy was adopted to prepare a multifunctional hydrogel created by H₂O₂/CuSO₄-induced rapid polydopamine (PDA) deposition on carboxymethyl chitosan (CMC)/sodium alginate (Alg) based hydrogel, termed as CAC/PDA/Cu(H₂O₂). The prepared CAC/PDA/Cu(H₂O₂) hydrogel features excellent biocompatibility, adequate mechanical properties, and good degradability. Moreover, the CAC/PDA/Cu(H₂O₂) hydrogel can not only realize antibacterial, and anti-inflammatory effects, but also promote angiogenesis to accelerate wound healing in vitro thanks to the composite PDA/Cu(H₂O₂) coatings. Significantly, CAC/PDA/Cu(H₂O₂) hydrogel illustrates excellent therapeutic effects in Methicillin-resistant Staphylococcus aureus (MRSA) induced-rat infection models, which can efficiently eliminate MRSA, dramatically reduce inflammatory expression, promote angiogenesis, and ultimately shorten the wound healing time. CAC/PDA/Cu(H₂O₂) hydrogel exhibited the best wound healing rate on days 7 (80.63 ± 2.44 %), 11 (92.45 ± 2.26 %), and 14 (97.86 ± 0.66 %). Thus, the multifunctional hydrogel provides a facile and efficient approach to wound management and represents promising potential in the therapy for wound healing.

Renewable marine polysaccharides for microenvironment-responsive wound healing

Marine polysaccharides (MPs) are an eco-friendly and renewable resource with a distinctive set of biological functions and are regarded as biological materials that can be in contact with tissues and body fluids for an extended time and promote tissue or organ regeneration. Skin tissue is easily invaded by the external environment due to its softness and large surface area. However, the body's natural physiological healing process is often too slow or suffers from the incomplete restoration of skin structure and function. Functional wound dressings are crucial for skin tissue engineering. Herein, popular MPs from different sources are summarized systematically. In particular, the structure-effectiveness of MP-based wound dressings and the physiological remodeling process of different wounds are reviewed in detail. Finally, the prospect of MP-based smart wound dressings is stated in conjunction with the wound microenvironment and provides new opportunities for high-value biomedical applications of MPs.

Alginate/polyvinyl alcohol films for wound healing: Advantages and challenges

The skin is the largest organ in the human body and its physical integrity must be maintained for body homeostasis and to prevent the entry of pathogenic microorganisms. Sodium alginate (SA) and polyvinyl alcohol (PVA) are two polymers widely used in films for wound dressing applications. Furthermore, blends between SA and PVA improve physical, mechanical and biological properties of the final wound healing material when compared to the individual polymers. Different drugs have been incorporated into SA/PVA-based films to improve wound healing activity. It is noteworthy that SA/PVA films can be crosslinked with Ca²⁺ or other agents, which improves physicochemical and biological properties. Thus, SA/PVA associations are promising for the biomedical field, as a potential alternative for wound treatment. This review focuses on the main techniques for obtaining SA/PVA films, their physical-chemical characterization, drug incorporation, and the advantages and challenges of these films for wound healing.

Polysaccharide-based hydrogels: New insights and futuristic prospects in wound healing

Polysaccharides elicit enormous and promising applications due to their extensive obtainability, innocuousness, and biodegradability. Various outstanding features of polysaccharides can be employed to fabricate biomimetic and multifunctional hydrogels as efficient wound dressings. These hydrogels mimic the natural extracellular matrix and also boost the proliferation of cells. Owing to distinctive architectures and abundance of functional groups, polysaccharide-derived hydrogels have exceptional physicochemical properties and unique therapeutic interventions. Hydrogels designed using polysaccharides can effectively safeguard wounds from bacterial attack. This review includes wound physiology and emphasises on numerous polysaccharide-based hydrogels for wound repair applications. Polysaccharide hydrogels for different wound types and diverse therapeutic agents loaded in hydrogels for wound repair with recent patents are portrayed in the current manuscript, debating the potential of fascinating hydrogels for effective wound healing. More research is required to engineer multifaceted advanced polysaccharide hydrogels with tuneable and adjustable properties to attain huge potential in wound healing.

Mesoporous bioglass capsule composite injectable hydrogels with antibacterial and vascularization promotion properties for chronic wound repair

Building an angiogenesis microenvironment and inhibiting wound infection are of great significance for chronic wound repair. In this paper, polydopamine-encapsulated mesoporous bioglass (MBG@PDA) capsules were constructed to realize the integration of angiogenesis and infection inhibition through the formation of a composite hydrogel with modified hyaluronic acid (HAMA) to promote wound healing. The experiments showed that the composite hydrogel had good adhesion and toughness and promoted the migration of fibroblasts to accelerate the epithelialization process. In addition, in the composite hydrogel, MBG@PDA could release Mg²⁺ to promote the proliferation and migration of vascular endothelial cells for angiogenesis. At the same time, MBG@PDA in the composite hydrogel could facilitate the long-term release of drugs to inhibit the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) for reducing the possibility of wound infection. Finally, the results of in vivo experiments showed that a multifunctional dressing could repair wounds more quickly by promoting angiogenesis and reducing the pathological areas. In summary, the construction of these composite hydrogels can provide a repair method in the wound-repair field.

Preparation and properties of nano silica-based bioactive glass/apatite/sodium alginate composite hydrogel

In this paper, given the lack of osteogenic activity of sodium alginate (SA) hydrogel and to simulate the composition of natural bone, ionic-crosslinking NBG/n-HA/SA hydrogel scaffolds were prepared by using nano bioactive glass (NBG) and nano hydroxyapatite (n-HA) with high bioactivity as composite calcium sources and reinforcement phases, and D-gluconic acid δ-lactone (GDL) as the coagulant. The results showed that the mixture of the precursor forming the network had good injectability and plasticity. When the dosage of GDL was 0.75 g, the gelling time of the composite hydrogel could be regulated within 4-8 min, and the hydrogel had high compressive strength (170-220 kPa), as well. When the mass ratio of calcium source to SA was 1:1, the crosslinking network was relatively uniform with a considerable number of large pores around 40 μm in the structure. In the immersion experiment in vitro, it was found that the composite hydrogel could promote the deposition of bone-like apatite on the material's surface. Meanwhile, the cell experiments in vitro verified that the NBG/n-HA/SA composite hydrogel had good cytocompatibility without cytotoxicity. Moreover, the composite hydrogel could enhance the activity of ALP of mouse bone marrow mesenchymal stem cells, and thus, it had good osteogenic activity.

Self-floating capsule of algicidal bacteria Bacillus sp. HL and its performance in the dissolution of Microcystis aeruginosa

Algicidal bacteria is considered as an efficient and environmentally friendly approach to suppress Microcystis aeruginosa (M. aeruginosa). However, algicidal bacteria in natural water is limited during the practical application due to the interference of external factors and the low reuse capability. In this study, a bio-degradation capsule for M. aeruginosa is prepared by bio-compatible sodium alginate (SA) compositing with eco-friendly ethyl cellulose (EC) to improve the property and reuse capability of algicidal bacteria. Bacterial strain HL was well immobilized and the capsule was obtained with 2% of SA, 3% of calcium chloride (CaCl₂) and 3% of EC. It has been proved that capsules immobilizing bacteria HL shows considerable advantage over traditional bio-treatment systems (free-living bacteria) and good reusable performance. A better algicidal rate of 77.67% ± 1.14% at 7th day was obtained with the use of capsule embedding 50 mL of algicidal bacteria, enhanced by 11.05% comparing with same amount of free-living bacteria. Moreover, the algicidal rate of M. aeruginosa still reached 68.57% ± 2.88% after three times repetitive use. The effect of capsules on the fluorescence and antioxidant system of M. aeruginosa indicated that the photosystems were irreversibly damaged and the antioxidant response of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly induced. Overall, capsules prepared in this study can provide a desirable environment for algicidal bacteria HL and ensure algicidal bacteria to in-situ work well in inhibiting booms of algae.

An NIR photothermal-responsive hybrid hydrogel for enhanced wound healing

Moderately regulating vascularization and immune microenvironment of wound site is necessary to achieve scarless wound healing of the skin. Herein, we have prepared an angiogenesis-promoting and scar-preventing band-aid with a core-shell structure, that consists of MXene-loaded nanofibers (MNFs) as the core and dopamine-hyaluronic acid hydrogel (H) as the shell (MNFs@V-H@DA) to encapsulate a growth factor (vascular endothelial growth factor, VEGF, abbreviated as V) and H2S donor (diallyl trisulfide, DATS, abbreviated as DA). The continuous release of DA from this system produced H2S, which would successfully induce macrophages to polarize into M2-lile phenotype, regulating the immune microenvironment and inhibiting an excessive inflammatory response at the wound sites. It is conducive to the proliferation of skin cells, facilitating the wound healing. In addition, an appropriate amount of VEGF can be released from the MXene nanofibrous skeleton by adjusting the time of near-infrared (NIR) light exposure, preventing excessive neovascularization and extracellular matrix deposition at the wound sites. Collectively, this NIR photothermal-responsive band-aid achieved scarless wound healing through gradient-controlled vascularization and a related immune sequential reaction of damaged skin tissue.

Precisely Tuning the Pore-Wall Surface Composition of Bioceramic Scaffolds Facilitates Angiogenesis and Orbital Bone Defect Repair

Orbital bone damage (OBD) may result in severe post-traumatic enophthalmos, craniomaxillofacial deformities, vision loss, and intracranial infections. However, it is still a challenge to fabricate advanced biomaterials that can match the individual anatomical structure and enhance OBD repair in situ. Herein, we aimed to develop a selective surface modification strategy on bioceramic scaffolds and evaluated the effects of inorganic or organic functional coating on angiogenesis and osteogenesis, ectopically and orthotopically in OBD models. It was shown that the low thermal bioactive glass (BG) modification or layer-by-layer assembly of a biomimetic hydrogel (Biogel) could readily integrate into the pore wall of the bioceramic scaffolds. The BG and Biogel modification showed appreciable enhancement in the initial compressive strength (∼30-75%) or structural stability in vivo, respectively. BG modification could enhance by nearly 2-fold the vessel ingrowth, and the osteogenic capacity was also accelerated, accompanied with a mild scaffold biodegradation after 3 months. Meanwhile, the Biogel-modified scaffolds showed enhanced osteogenic differentiation and mineralization through calcium and phosphorus retention. The potential mechanism of the enhanced bone repair was elucidated via vascular and osteogenic cell responses in vitro, and the cell tests indicated that the Biogel and BG functional layers were both beneficial for in vitro osteoblastic differentiation and mineralization on bioceramics. Totally, these findings demonstrated that the bioactive ions or biomolecules could significantly improve the angiogenic and osteogenic capabilities of conventional bioceramics, and the integration of inorganic or organic functional coating in the pore wall is a highly flexible material toolbox that can be tailored directly to improve orbital bone defect repair.

Multiple Coordination-Derived Bioactive Hydrogel with Proangiogenic Hemostatic Capacity for Wound Repair

Bioactive hydrogels with multifunctional properties have shown promising potential in promoting wound repair and skin tissue regeneration. The regulation on different stages of skin wound healing (hemostasis and inflammation) is important for wound repair. Herein, a multiple coordination-derived bioactive hydrogel (SGPA) with anti-inflammatory proangiogenic hemostatic capacity for wound repair is reported. The SGPA is prepared through a facile multiple metal coordination action based on the sodium alginate, metal ions (Gd³⁺ ), and bisphosphate functionalized polycitrate. The SGPA exhibits a large porous structure, good injectability, and self-healing performance, as well as controlled biodegradation. Furthermore, the SGPA has good cytocompatibility and hemocompatibility, and can further promote the migration of endothelial cells. The SGPA hydrogel presents good hemostasis capacity in a liver hemorrhage model in vivo. The full-thickness cutaneous wound model demonstrates that the SGPA hydrogel can effectively accelerate the wound repair through down-regulating the inflammatory factors and stimulating the angiogenesis around the wound beds. This work suggests that the multiple metal-organic coordination may be a good strategy to construct the multifunctional bioactive hydrogel for wound repair.

Synthesis and Characterization of Novel Patchouli Essential Oil Loaded Starch-Based Hydrogel

Starch hydrogels are highly available, biocompatible and biodegradable materials that have promising applications in medical and pharmaceutical industries. However, their applications are very limited due to their poor mechanical properties and fragility. Here, we investigated, for the first time, conventional corn and waxy corn starch-based hydrogels for loading patchouli essential oil. The essential oil extracted by supercritical carbon dioxide with a yield reached 8.37 ± 1.2 wt.% (wet sample) at 80 °C temperature and 10 MPa pressure. Patchouli essential oil exhibited a 23 to 28 mm zone of inhibition against gram-positive and gram-negative bacteria. Waxy starch hydrogels had better properties in term of viscosity, water evaporation stability and the delivery of essential oil than conventional starch hydrogels. The viscosity and spreadability of a 6% waxy starch sample were 15,016 ± 59 cP and 4.02 ± 0.34 g·cm/s, respectively, compared with those of conventional starch hydrogel (13,008 ± 29 cP and 4.59 ± 0.88 g·cm/s). Waxy starch-based hydrogels also provided slower in vitro biodegradation behavior and sustained release of essential oil compared with conventional starch hydrogels. All the samples were biocompatible and non-cytotoxic to fibroblast cells; the addition of patchouli essential oil enhances the proliferation of the cells. The enhanced viscosity, good antibacterial and improved biocompatibility results of prepared hydrogels confirm their suitability for wound healing applications.

Skin-inspired injectable adhesive gelatin/HA biocomposite hydrogel for hemostasis and full-thickness dermal wound healing

An insufficient adhesion to wet surfaces and biased functions for therapeutic efficacy are limitations to the application of gelatin and hyaluronic acid. Herein, we developed a simple double-injection approach to prepare a skin-inspired gelatin/HA-based injectable remoistenable adhesive hydrogel (HI/DA-Gel) through a simultaneous crosslinking and bio-compositing strategy of genipin incorporated with dopamine (DA) grafted gelatin and N-hydroxy succinimide (NHS) merged with hyaluronic acid. The integrative crosslinking and bio-compositing strategy led to the formation of a HI/DA-Gel with a highly skin-bionic interconnected internal double network 3D-structure with elevated surface wettability, thermal-stablity, adhesive and mechanical properties as expected. In vitro/in vivo biostudies showed that HI/DA-Gel enhanced collagen deposition, hemostatic effects and upregulated the production of CD31, showing an effective hemostasis and full-thickness dermal wound healing strategy. This work proposes a novel facile double-injection approach for the design of gelatin/ hyaluronic acid multi-functional injectable bio-composite hydrogels for integrated therapeutic effects.

Coaxially Fabricated Dual-Drug Loading Electrospinning Fibrous Mat with Programmed Releasing Behavior to Boost Vascularized Bone Regeneration

In clinical treatment, the bone regeneration of critical-size defects is desiderated to be solved, and the regeneration of large bone segment defects depends on early vascularization. Therefore, overcoming insufficient vascularization in artificial bone grafts may be a promising strategy for critical-size bone regeneration. Herein, a novel dual-drug programmed releasing electrospinning fibrous mat (EFM) with a deferoxamine (DFO)-loaded shell layer and a dexamethasone (DEX)-loaded core layer is fabricated using coaxial electrospinning technology, considering the temporal sequence of vascularization and bone repair. DFO acts as an angiogenesis promoter and DEX is used as an osteogenesis inducer. The results demonstrate that the early and rapid release of DFO promotes angiogenesis in human umbilical vascular endothelial cells and the sustained release of DEX enhances the osteogenic differentiation of rat bone mesenchymal stem cells. DFO and DEX exert synergetic effects on osteogenic differentiation via the Wnt/β-catenin signaling pathway, and the dual-drug programmed releasing EFM acquired perfect vascularized bone regeneration ability in a rat calvarial defect model. Overall, the study suggests a low-cost strategy to enhance vascularized bone regeneration by adjusting the behavior of angiogenesis and osteogenesis in time dimension.