VEGF-Encoding, Gene-Activated Collagen-Based Matrices Promote Blood Vessel Formation and Improved Wound Repair

Genetic and bioactive functionalization of bioinks for 3D bioprinting

3D bioprinting is revolutionizing tissue engineering and regenerative medicine by enabling the precise fabrication of biologically functional constructs. At its core, the success of 3D bioprinting hinges on the development of bioinks, hydrogel-based materials that support cellular viability, proliferation, and differentiation. However, conventional bioinks face limitations in mechanical strength, biological activity, and customization. Recent advancements in genetic engineering have addressed these challenges by enhancing the properties of bioinks through genetic modifications. These innovations allow the integration of stimuli-responsive elements, bioactive molecules, and extracellular matrix (ECM) components, significantly improving the mechanical integrity, biocompatibility, and functional adaptability of bioinks. This review explores the state-of-the-art genetic approaches to bioink development, emphasizing microbial engineering, genetic functionalization, and the encapsulation of growth factors. It highlights the transformative potential of genetically modified bioinks in various applications, including bone and cartilage regeneration, cardiac and liver tissue engineering, neural tissue reconstruction, and vascularization. While these advances hold promise for personalized and adaptive therapeutic solutions, challenges in scalability, reproducibility, and integration with multi-material systems persist. By bridging genetics and bioprinting, this interdisciplinary field paves the way for sophisticated constructs and innovative therapies in tissue engineering and regenerative medicine.

Anisotropic structure of nanofiber hydrogel accelerates diabetic wound healing via triadic synergy of immune-angiogenic-neurogenic microenvironments

Wound healing in chronic diabetic patients remains challenging due to the multiple types of cellular dysfunction and the impairment of multidimensional microenvironments. The physical signals of structural anisotropy offer significant potential for orchestrating multicellular regulation through physical contact and cellular mechanosensing pathways, irrespective of cell type. In this study, we developed a highly oriented anisotropic nanofiber hydrogel designed to provide directional guidance for cellular extension and cytoskeletal organization, thereby achieving pronounced multicellular modulation, including shape-induced polarization of macrophages, morphogenetic maturation of Schwann cells, oriented extracellular matrix (ECM) deposition by fibroblasts, and enhanced vascularization by endothelial cells. Additionally, we incorporated a VEGF-mimicking peptide to further reinforce angiogenesis, a pivotal phase that interlocks with immune regulation, neurogenesis, and tissue regeneration, ultimately contributing to optimized inter-microenvironmental crosstalk. In vivo studies validated that the anisotropic bioactive nanofiber hydrogel effectively accelerated diabetic wound healing by harnessing the triadic synergy of the immune-angiogenic-neurogenic microenvironments. Our findings highlight the promising potential of combining physical and bioactive signals for the modulation of various cell types and the refinement of the multidimensional microenvironment, offering a novel strategy for diabetic wound healing.

A Single H2S-Releasing Nanozyme for Comprehensive Diabetic Wound Healing through Multistep Intervention

Diabetic wound healing presents a significant medical challenge and requires multistep interventions due to comprehensive wound environments, such as hyperglycemia, bacterial infection, and impaired angiogenesis. However, current multistep interventions are complicated and need on-demand sequential release and synergy of multicomponents. Herein, a H2S-releasing cascade nanozyme (FeS@Au), which is composed of ultrasmall gold nanocluster (AuNC) loaded on ferrous sulfide nanoparticle (FeSNP), is developed as a single component to regulate glucose level, eliminate infection, and promote angiogenesis, achieving multistep interventions for comprehensive diabetic wound treatment. The glucose oxidase-like activity of AuNC catalyzes glucose into gluconic acid and H2O2, which not only lowers the local glucose level but also decreases the local pH and increases H2O2 level to boost the peroxidase-like activity of FeSNP to generate abundant hydroxyl radical (reactive oxygen species, ROS), inducing ferroptosis-like death in drug-resistant bacteria. Additionally, FeSNP release H2S in the acidified environment to upregulate hypoxia-inducible factor-1 to enhance vascularization through upregulating the expression of vascular endothelial growth factor (VEGF) and other angiogenesis-related genes, reducing the damage to endothelial cells caused by excessive ROS produced by the nanozyme. In a full-thickness MRSA-infected diabetic rat model, FeS@Au significantly eliminates bacteria, enhances angiogenesis, promotes collagen deposition, and accelerates wound healing. This work presents a single nanozyme with H2S-release for multistep interventions, providing a versatile strategy for healing extensive tissue damage caused by diabetes.

Assembly of Recombinant Proteins into β-Sheet Fibrillating Peptide-Driven Supramolecular Hydrogels for Enhanced Diabetic Wound Healing

Supramolecular hydrogels offer a noncovalent binding platform that preserves the bioactivity of structural molecules while enhancing their stability, particularly in the context of diabetic wound repair. In this study, we developed protein-peptide-based supramolecular hydrogels by assembling β-sheet fibrillizing peptides (designated Q11) with β-tail fused recombinant proteins. The Q11 peptides have the ability to drive the gradated assembly of N- or C-terminal β-sheet structure (β-tail) fused recombinant proteins. We first investigated the assembly properties of Q11 and assessed its stability under varying pH and temperature conditions by combining Q11 with two β-tail fused fluorescent proteins. The results showed that Q11 enhanced the tolerance of the fluorescent proteins to changes in pH and temperature. Building upon these findings, we designed collagen-like proteins and Sonic Hedgehog-fused recombinant proteins (CLP-Shh) that could be assembled with Q11 to form peptide-protein supramolecular hydrogels. These hydrogels demonstrated the ability to improve cell viability and migration and upregulate key markers of cell growth. Further in vivo studies revealed that the Q11-driven supramolecular hydrogel effectively enhances diabetic wound healing and epidermal regeneration by promoting the expression of epidermal-related proteins and immune factors. This study highlights the potential of supramolecular hydrogels for clinical applications and their promise in the development of biofunctional hydrogels for therapeutic use.

Topography immune-responsive silk films for skin regeneration

Scar formation and chronic refractory wounds pose a significant threat to public health, with abnormal immune regulation as a key characteristic. However, topography, a crucial factor influencing immune responses, has not been adequately considered in the design of wound dressings. In this study, we constructed a hierarchical structure on silk fibroin (SF) films by combining soft lithography and femtosecond laser ablation, without altering the intrinsic properties of SF. The discontinuity in the hierarchical structure induced a transformation in the morphology of macrophage RAW264.7 cells from round to spindle or pancake-like shapes, leading to phenotypic polarization toward M2 or M1. The timely transition from M1 to M2 polarization and the balance between these states promoted fibroblast L929 cells to express mRNA for FN, coll-I, TGF-β1, and α-SMA. The hierarchical structure of SF films facilitates full-thickness wound repair in vivo by regulating inflammation and promoting neovascularization and collagen deposition. Thus, hierarchical topography presents a promising strategy for the design of immunomodulatory wound dressings.

Enhancing diabetic wound healing through anti-bacterial and promoting angiogenesis using dual-functional slow-release microspheres-loaded dermal scaffolds

Bacterial infections and the degeneration of the capillary network comprise the primary factors that contribute to the delayed healing of diabetic wounds. However, treatment modalities that cater to effective diabetic wounds healing in clinical settings are severely lacking. Herein, a dual-functional microsphere carrier was designed, which encapsulates polyhexamethylene biguanide (PHMB) or recombinant human vascular endothelial growth factor (rhVEGF) together. The in vitro release experiments demonstrated that the use of the microspheres ensured the sustained release of the drugs (PHMB or rhVEGF) over a period of 12 days. Additionally, the integration of these controlled-release microspheres into a dermal scaffold (DS-PLGA@PHMB/rhVEGF) imbued both antibacterial and angiogenic functions to the resulting material. Accordingly, the DS-PLGA@PHMB/rhVEGF scaffold exhibited potent antibacterial properties, effectively suppressing bacterial growth and providing a conducive environment for wound healing, thereby addressing the drawbacks associated with the susceptibility of rhVEGF to deactivation in inflammatory conditions. Additionally, the histological analysis revealed that the use of the DS-PLGA@PHMB/rhVEGF scaffold accelerated the process of wound healing by inhibiting inflammatory reactions, stimulating the production of collagen formation, and enhancing angiogenesis. This provides a novel solution for enhancing the antibacterial and vascularization capabilities of artificial dermal scaffolds, providing a beacon of hope for improving diabetic wound healing.

Spermidine Exerts Protective Effects in Random-Pattern Skin Flap Survival in Rats: Possible Involvement of Inflammatory Cytokines, Nitric Oxide, and VEGF

BACKGROUND

Distal necrosis and inflammation are two of the most common health consequences of random-pattern skin flaps survival (SFS). Anti-inflammatory effects of spermidine have been identified in various studies. On the other hand, considering the involvement of the nitric oxide molecule in the spermidine mode of action and also its role in skin tissue function, we analyzed the possible effects of spermidine on the SFS and also, potential involvement of nitrergic pathway and inflammatory cytokine in these phenomena.

METHODS

Each rat was pretreated with either a vehicle (control) or various doses of spermidine (0.5, 1, 3, 5, 10 and 30 mg/kg) and then was executed a random-pattern skin flap paradigm. Also, spermidine at the dose of 5 mg/kg was selected and one group rats received spermidine 20 min prior to surgery and one additional dose 1 day after operation. Then, 7 days after operations, interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon-gamma (IFN-γ), and nitrite levels were inquired in the tissue samples by ELIZA kit. Vascular endothelial growth factor expression was assessed by DAPI staining and fluorescent microscopes. The concentrations of three polyamines, including spermidine, spermine, and cadaverine, were analyzed using HPLC.

RESULTS

Pretreatment with spermidine 5 mg/kg improved SFS considerably in microscopic skin H&E staining analysis and decreased the percentage of necrotic area. Moreover, spermidine exerted promising anti-inflammatory effects via the modulation of nitric oxide and reducing inflammatory cytokines.

CONCLUSIONS

Spermidine could improve skin flaps survival, probably through the nitrergic system and inflammation pathways. This preclinical study provides level III evidence for the potential therapeutic effects of spermidine on SFS in rats, based on the analysis of animal models. Further studies are needed to confirm these findings in clinical settings.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Canonical WNT/β-catenin signaling upregulates aerobic glycolysis in diverse cancer types

Despite many efforts, a comprehensive understanding and clarification of the intricate connections within cancer cell metabolism remain elusive. This might pertain to intracellular dynamics and the complex interplay between cancer cells, and cells with the tumor stroma. Almost a century ago, Otto Warburg found that cancer cells exhibit a glycolytic phenotype, which continues to be a subject of thorough investigation. Past and ongoing investigations have demonstrated intricate mechanisms by which tumors modulate their functionality by utilizing extracellular glucose as a substrate, thereby sustaining the essential proliferation of cancer cells. This concept of "aerobic glycolysis," where cancer cells (even in the presence of enough oxygen) metabolize glucose to produce lactate plays a critical role in cancer progression and is regulated by various signaling pathways. Recent research has revealed that the canonical wingless-related integrated site (WNT) pathway promotes aerobic glycolysis, directly and indirectly, thereby influencing cancer development and progression. The present review seeks to gather knowledge about how the WNT/β-catenin pathway influences aerobic glycolysis, referring to relevant studies in different types of cancer. Furthermore, we propose the concept of impeding the glycolytic phenotype of tumors by employing specific inhibitors that target WNT/β-catenin signaling.

Biofabrication of engineered blood vessels for biomedical applications

To successfully engineer large-sized tissues, establishing vascular structures is essential for providing oxygen, nutrients, growth factors and cells to prevent necrosis at the core of the tissue. The diameter scale of the biofabricated vasculatures should range from 100 to 1,000 µm to support the mm-size tissue while being controllably aligned and spaced within the diffusion limit of oxygen. In this review, insights regarding biofabrication considerations and techniques for engineered blood vessels will be presented. Initially, polymers of natural and synthetic origins can be selected, modified, and combined with each other to support maturation of vascular tissue while also being biocompatible. After they are shaped into scaffold structures by different fabrication techniques, surface properties such as physical topography, stiffness, and surface chemistry play a major role in the endothelialization process after transplantation. Furthermore, biological cues such as growth factors (GFs) and endothelial cells (ECs) can be incorporated into the fabricated structures. As variously reported, fabrication techniques, especially 3D printing by extrusion and 3D printing by photopolymerization, allow the construction of vessels at a high resolution with diameters in the desired range. Strategies to fabricate of stable tubular structures with defined channels will also be discussed. This paper provides an overview of the many advances in blood vessel engineering and combinations of different fabrication techniques up to the present time.

Designed modular protein hydrogels for biofabrication

Designing proteins that fold and assemble over different length scales provides a way to tailor the mechanical properties and biological performance of hydrogels. In this study, we designed modular proteins that self-assemble into fibrillar networks and, as a result, form hydrogel materials with novel properties. We incorporated distinct functionalities by connecting separate self-assembling (A block) and cell-binding (B block) domains into single macromolecules. The number of self-assembling domains affects the rigidity of the fibers and the final storage modulus G' of the materials. The mechanical properties of the hydrogels could be tuned over a broad range (G' = 0.1 - 10 kPa), making them suitable for the cultivation and differentiation of multiple cell types, including cortical neurons and human mesenchymal stem cells. Moreover, we confirmed the bioavailability of cell attachment domains in the hydrogels that can be further tailored for specific cell types or other biological applications. Finally, we demonstrate the versatility of the designed proteins for application in biofabrication as 3D scaffolds that support cell growth and guide their function. STATEMENT OF SIGNIFICANCE: Designed proteins that enable the decoupling of biophysical and biochemical properties within the final material could enable modular biomaterial engineering. In this context, we present a designed modular protein platform that integrates self-assembling domains (A blocks) and cell-binding domains (B blocks) within a single biopolymer. The linking of assembly domains and cell-binding domains this way provided independent tuning of mechanical properties and inclusion of biofunctional domains. We demonstrate the use of this platform for biofabrication, including neural cell culture and 3D printing of scaffolds for mesenchymal stem cell culture and differentiation. Overall, this work highlights how informed design of biopolymer sequences can enable the modular design of protein-based hydrogels with independently tunable biophysical and biochemical properties.

Thermodynamically stable ionic liquid microemulsions pioneer pathways for topical delivery and peptide application

Copper peptides (GHK-Cu) are a powerful hair growth promoter with minimal side effects when compared with minoxidil and finasteride; however, challenges in delivering GHK-Cu topically limits their non-invasive applications. Using theoretical calculations and pseudo-ternary phase diagrams, we designed and constructed a thermodynamically stable ionic liquid (IL)-based microemulsion (IL-M), which integrates the high drug solubility of ILs and high skin permeability of microemulsions, thus improving the local delivery of copper peptides by approximately three-fold while retaining their biological function. Experiments in mice validated the effectiveness of our proposed IL-M system. Furthermore, the exact effects of the IL-M system on the expression of growth factors, such as vascular endothelial growth factor, were revealed, and it was found that microemulsion increased the activation of the Wnt/β-catenin signaling pathway, which includes factors involved in hair growth regulation. Overall, the safe and non-invasive IL microemulsion system developed in this study has great potential for the clinical treatment of hair loss.

Hollow Copper Sulfide Photothermal Nanodelivery Platform Boosts Angiogenesis of Diabetic Wound by Scavenging Reactive Oxygen Species

Sharply rising oxidative stress and ineffectual angiogenesis have imposed restrictions on diabetic wound healing. Here, a photothermal-responsive nanodelivery platform (HHC) was prepared by peroxidase (CAT)-loaded hollow copper sulfide dispersed in photocurable methacrylamide hyaluronan. The HHC could scavenge reactive oxygen species (ROS) and promote angiogenesis by photothermally driven CAT and Cu2+ release. Under near-infrared light irradiation, the HHC presented safe photothermal performance (<43 °C), efficient bacteriostatic ability against E. coli and S. aureus. It could rapidly release CAT into the external environment for decomposing H2O2 and oxygen generation to alleviate oxidative stress while promoting fibroblast migration and VEGF protein expression of endothelial cells by reducing intracellular ROS levels. The nanodelivery platform presented satisfactory therapeutic effects on murine diabetic wound healing by modulating tissue inflammation, promoting collagen deposition and increasing vascularization in the neodermis. This HHC provided a viable strategy for diabetic wound dressing design.

Gene-Activated Materials in Regenerative Dentistry: Narrative Review of Technology and Study Results

Treatment of a wide variety of defects in the oral and maxillofacial regions requires the use of innovative approaches to achieve best outcomes. One of the promising directions is the use of gene-activated materials (GAMs) that represent a combination of tissue engineering and gene therapy. This approach implies that biocompatible materials will be enriched with gene-carrying vectors and implanted into the defect site resulting in transfection of the recipient's cells and secretion of encoded therapeutic protein in situ. GAMs may be presented in various designs depending on the type of material, encoded protein, vector, and way of connecting the vector and the material. Thus, it is possible to choose the most suitable GAM design for the treatment of a particular pathology. The use of plasmids for delivery of therapeutic genes is of particular interest. In the present review, we aimed to delineate the principle of work and various designs of plasmid-based GAMs and to highlight results of experimental and clinical studies devoted to the treatment of periodontitis, jaw bone defects, teeth avulsion, and other pathologies in the oral and maxillofacial regions.

Multiple Bio-Actives Loaded Gellan Gum Microfibers from Microfluidics for Wound Healing

Wound healing, known as a fundamental healthcare issue worldwide, has been attracting great attention from researchers. Here, novel bioactive gellan gum microfibers loaded with antibacterial peptides (ABPs) and vascular endothelial growth factor (VEGF) are proposed for wound healing by using microfluidic spinning. Benefitting from the high controllability of microfluidics, bioactive microfibers with uniform morphologies are obtained. The loaded ABPs are demonstrated to effectively act on bacteria at the wound site, reducing the risk of bacterial infection. Besides, sustained release of VEGF from microfibers helps to accelerate angiogenesis and further promote wound healing. The practical value of woven bioactive microfibers is demonstrated via animal experiments, where the wound healing process is greatly facilitated because of the excellent circulation of air and nutritious substances. Featured with the above properties, it is believed that the novel bioactive gellan gum microfibers would have a remarkable effect in the field of biomedical application, especially in promoting wound healing.

Negative pressure wound therapy (NPWT) is superior to conventional moist dressings in wound bed preparation for diabetic foot ulcers: A randomized controlled trial

OBJECTIVES

To compare the efficacy of negative pressure wound therapy (NPWT) and alginate dressings on wound bed preparation prior to split thickness skin graft (STSG) surgery for patients with chronic diabetic foot ulcers (DFUs).

METHODS

Between September 2022 and March 2023, we completed a randomized controlled trial in Nanjing First Hospital and PLA 454 Hospital. Patients were divided into 2 groups: i) the NPWT group (with vacuum-assisted closure, n=50); ii) the control group (with alginates dressings, n=50). Once DFU wound was filled with healthy granulation tissues, STSG surgery was performed. The time to STSG surgery was regarded as the primary outcome. The survival rates of skin graft, the wound blood perfusion, the wound neutrophil extracellular traps (NETs) formation, and polarization of M1 and M2 macrophages in DFU wounds were regarded ad secondary outcomes.

RESULTS

Patients in the NPWT group had less time to STSG surgery than the control group. The patients in the NPWT group had prominently increased survival rates of skin graft, increased wound blood perfusion, and decreased NET formation in comparison with the control group. The macrophages in DFU wounds switched from M1 to M2 phenotype in the NPWT group.

CONCLUSION

Negative pressure wound therapy is superior to conventional moist dressings in wound bed preparation prior to STSG surgery for patients with chronic DFUs.

Overexpression of Pasteurella multocida OmpA induces transcriptional changes and its possible implications for the macrophage polarization

Pasteurella multocida (P. multocida) is a highly infectious, zoonotic pathogen. Outer membrane protein A (OmpA) is an important virulence component of the outer membrane of P. multocida. OmpA mediates bacterial biofilm formation, eukaryotic cell infection, and immunomodulation. It is unclear how OmpA affects the host immune response. We estimated the role of OmpA in the pathogenesis of P. multocida by investigating the effect of OmpA on the immune cell transcriptome. Changes in the transcriptome of rat alveolar macrophages (NR8383) upon overexpression of P. multocida OmpA were demonstrated. A model cell line for stable transcription of OmpA was constructed by infecting NR8383 cells with OmpA-expressing lentivirus. RNA was extracted from cells and sequenced on an Illumina HiSeq platform. Key gene analysis of genes in the RNA-seq dataset were performed using various bioinformatics methods, such as gene ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, Gene Set Enrichment Analysis, and Protein-Protein Interaction Analysis. Our findings revealed 1340 differentially expressed genes. Immune-related pathways that were significantly altered in rat alveolar macrophages under the effect of OmpA included focal adhesion, extracellular matrix and vascular endothelial growth factor signaling pathways, antigen processing and presentation, nucleotide oligomerization domain-like receptor and Toll-like receptor signaling pathways, and cytokine-cytokine receptor interaction. The key genes screened were Vegfa, Igf2r, Fabp5, P2rx1, C5ar1, Nedd4l, Gas6, Cxcl1, Pf4, Pdgfb, Thbs1, Col7a1, Vwf, Ccl9, and Arg1. Data of associated pathways and altered gene expression indicated that OmpA might cause the conversion of rat alveolar macrophages to M2-like. The related pathways and key genes can serve as a reference for OmpA of P. multitocida and host interaction mechanism studies.

Anti-inflammatory effect of polydeoxyribonucleotides (PDRN) extracted from red alga (Porphyra sp.) (Ps-PDRN) in RAW 264.7 macrophages stimulated with Escherichia coli lipopolysaccharides: A comparative study with commercial PDRN

Polydeoxyribonucleotide (PDRN) is a DNA-derived drug extracted from the sperm cells of Oncorhynchus mykiss or O. keta. PDRN exhibits wound healing and anti-inflammatory activities by activating adenosine A2A receptor and salvage pathways. However, commercial PDRN products (e.g., Placentex, Rejuvenex, and HiDr) have limitations as they are exclusively extracted O. mykiss and O. keta, which are expensive and can only be used as extraction sources during a specific period when their sperm cells are activated. Therefore, this study aimed to extract PDRN from Porphyra sp. (Ps-PDRN) and investigate whether it has anti-inflammatory activity through a comparative study with commercial product. The results indicated that Ps-PDRN had an anti-inflammatory effect on Escherichia coli lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. It inhibited nitric oxide production and inducible nitric oxygen synthase protein expression by suppressing phosphorylation of p38 and ERK, without cytotoxicity. Furthermore, Ps-PDRN promoted cell proliferation and collagen production in human dermal fibroblast. In conclusion, our study confirms that Ps-PDRN exhibits both anti-inflammatory and cell proliferative effects. These results indicated that Ps-PDRN has the potential as a bioactive drug for tissue engineering.