In situ formed scaffold with royal jelly-derived extracellular vesicles for wound healing

Design and characterization of a ROS-responsive antibacterial composite hydrogel for advanced full-thickness wound healing

Full-thickness skin wounds remian a significant and pressing challenge. In this study, we introduce a novel composite hydrogel, CS + GA + Zn-HA. This hydrogel is formulated by incorporating 1 % (1 g/100 mL) of bioactive Zinc-substituted hydroxyapatite nanoparticles (Zn-HA) and 0.2 % (0.2 g/100 mL) of Gallic acid (GA) into chitosan (CS) hydrogels. A 56 % β-glycerophosphate sodium (β-GP) solution serves as the cross-linking agent, and the hydrogel is formed at 37 °C. This composite hydrogel can effectively modulate the wound microenvironment, facilitating comprehensive skin wound healing within two weeks. Physicochemical characterization demonstrates that this hydrogel is thermosensitive, with remarkable swelling behavior, mechanical strength, and drug-delivery performance. In vitro, the GA-incorporated hydrogels possess outstanding reactive oxygen species (ROS) scavenging and antioxidant properties, protecting L929 cells from hydrogen peroxide-induced oxidative damage. The combination of Zn-HA nanoparticles and GA not only augments the functionality of the hydrogel and decreases its degradation rate but also enables the controlled release of curcumin. Moreover, it provides a suitable immune microenvironment in terms of biological effects and significantly boosts the hydrogel's antibacterial ability, as demonstrated by an 89.2 % reduction in E. coli and a 53.6 % reduction in S. aureus. Benefiting from these properties, the CS + GA + Zn-HA composite hydrogel significantly promotes granulation tissue formation, re-epithelialization, angiogenesis, and wound closure in vivo. In conclusion, our research highlights the potential of the CS + GA + Zn-HA hydrogel as a multifunctional scaffold in tissue engineering, providing valuable insights for the design of future wound dressings for diverse wound types.

Molecular Modification of Queen Bee Acid and 10-Hydroxydecanoic Acid with Specific Tripeptides: Rational Design, Organic Synthesis, and Assessment for Prohealing and Antimicrobial Hydrogel Properties

Royal jelly and medical grade honey are traditionally used in treating wounds and infections, although their effectiveness is often variable and insufficient. To overcome their limitations, we created novel amphiphiles by modifying the main reparative and antimicrobial components, queen bee acid (hda) and 10-hydroxyl-decanoic acid (hdaa), through peptide bonding with specific tripeptides. Our molecular design incorporated amphiphile targets as being biocompatible in wound healing, biodegradable, non-toxic, hydrogelable, prohealing, and antimicrobial. The amphiphilic molecules were designed in a hda(hdaa)-aa1-aa2-aa3 structural model with rational selection criteria for each moiety, prepared via Rink/Fmoc-tBu-based solid-phase peptide synthesis, and structurally verified by NMR and LC-MS/MS. We tested several amphiphiles among those containing moieties of hda or hdaa and isoleucine-leucine-aspartate (ILD-amidated) or IL-lysine (ILK-NH2). These tests were conducted to evaluate their prohealing and antimicrobial hydrogel properties. Our observation of their hydrogelation and hydrogel-rheology showed that they can form hydrogels with stable elastic moduli and injectable shear-thinning properties, which are suitable for cell and tissue repair and regeneration. Our disc-diffusion assay demonstrated that hdaa-ILK-NH2 markedly inhibited Staphylococcus aureus. Future research is needed to comprehensively evaluate the prohealing and antimicrobial properties of these novel molecules modified from hda and hdaa with tripeptides.

Sericin coats of silk fibres, a degumming waste or future material?

Silk is a fibrous biopolymer with a recorded history in the textile industries for centuries. This fibre is constituted of two different proteins: fibroin and sericin, of which the latter accounting for approximately 20-30 % of the silk mass. Silk sericin (SSER) was previously considered as a waste by-product in silk fibroin extraction. SSER has recently garnered significant scientific interest due to its extensive biological and pharmacological properties. These include antioxidant effects, biocompatibility, low immunogenicity, controlled biodegradability, and the ability to induce cell proliferation. This review covers studies about various aspects of this emerging material, namely, its general morphology, specific structure, molecular weight, features of different layers, and gene sequences. The impact of different extraction methods and the application of extracted SSER based on molecular weight are discussed. Additionally, the characteristic functional groups in the amino acids of sericin facilitate its applications in regenerative medicine, wound healing, drug delivery, textile, environment, and energy, in various forms like hydrogels, films, scaffolds, and conduits. SSER-based materials offer great potentials for multi-functional applications in the upcoming decades, showcasing adaptability for various functional uses and promising future technological advancements.

Engineered extracellular vesicles for tissue repair and regeneration

Extracellular vesicles (EVs) are heterogeneous membrane-like vesicles secreted by living cells that are involved in many physiological and pathological processes and act as intermediaries of intercellular communication and molecular transfer. Recent studies have shown that EVs from specific sources regulate tissue repair and regeneration by delivering proteins, lipids, and nucleic acids to target cells as signaling molecules. Nanotechnology breakthroughs have facilitated the development and exploration of engineered EVs for tissue repair. Enhancements through gene editing, surface modification, and content modification have further improved their therapeutic efficacy. This review summarizes the potential of EVs in tissue repair and regeneration, their mechanisms of action, and their research progress in regenerative medicine. This review highlights their design logic through typical examples and explores the development prospects of EVs in tissue repair. The aim of this review is to provide new insights into the design of EVs for tissue repair and regeneration applications, thereby expanding their use in regenerative medicine.

Multifunctional carbomer based ferulic acid hydrogel promotes wound healing in radiation-induced skin injury by inactivating NLRP3 inflammasome

BACKGROUND

Radiation-induced skin injury is a significant adverse reaction to radiotherapy. However, there is a lack of effective prevention and treatment methods for this complication. Ferulic acid (FA) has been identified as an effective anti-radiation agent. Conventional administrations of FA limit the reaching of it on skin. We aimed to develop a novel FA hydrogel to facilitate the use of FA in radiation-induced skin injury.

METHODS

We cross-linked carbomer 940, a commonly used adjuvant, with FA at concentrations of 5%, 10%, and 15%. Sweep source optical coherence tomography system, a novel skin structure evaluation method, was applied to investigate the influence of FA on radiation-induced skin injury. Calcein-AM/PI staining, CCK8 assay, hemolysis test and scratch test were performed to investigate the biocompatibility of FA hydrogel. The reducibility of DPPH and ABTS radicals by FA hydrogel was also performed. HE staining, Masson staining, laser Doppler blood flow monitor, and OCT imaging system are used to evaluate the degree of skin tissue damage. Potential differentially expressed genes were screened via transcriptome analysis.

RESULTS

Good biocompatibility and in vitro antioxidant ability of the FA hydrogels were observed. 10% FA hydrogel presented a better mechanical stability than 5% and 15% FA hydrogel. All three concentrations of FA remarkably promoted the recovery of radiation-induced skin injury by reducing inflammation, oxidative conidiation, skin blood flow, and accelerating skin tissue reconstruction, collagen deposition. FA hydrogel greatly inhibiting the levels of NLRP3, caspase-1, IL-18, pro-IL-1β and IL-1β in vivo and vitro levels through restraining the activation of NLRP3 inflammasome. Transcriptome analysis indicated that FA might regulate wound healing via targeting immune response, inflammatory response, cell migration, angiogenesis, hypoxia response, and cell matrix adhesion.

CONCLUSIONS

These findings suggest that the novel FA hydrogel is a promising therapeutic method for the prevention and treatment of radiation-induced skin injury patients.

Hybrid Cellular Nanovesicles Block PD-L1 Signal and Repolarize M2 Macrophages for Cancer Immunotherapy

The PD1/PD-L1 immune checkpoint blocking is a promising therapy, while immunosuppressive tumor microenvironment (TME) and poor tumor penetration of therapeutic antibodies limit its efficacy. Repolarization of tumor-associated macrophages (TAMs) offers a potential method to ameliorate immunosuppression of TME and further boost T cell antitumor immunity. Herein, hybrid cell membrane biomimetic nanovesicles (hNVs) are developed by fusing M1 macrophage-derived nanovesicles (M1-NVs) and PD1-overexpressed tumor cell-derived nanovesicles (PD1-NVs) to improve cancer immunotherapy. The M1-NVs promote the transformation of M2-like TAMs to M1-like phenotype and further increase the release of pro-inflammatory cytokines, resulting in improved immunosuppressive TME. Concurrently, the PD1-NVs block PD1/PD-L1 pathway, which boosts cancer immunotherapy when combined with M1-NVs. In a breast cancer mouse model, the hNVs efficiently accumulate at the tumor site after intravenous injection and significantly inhibit the tumor growth. Mechanically, the M1 macrophages and CD8+ T lymphocytes in TME increase by twofold after the treatment, indicating effective immune activation. These results suggest the hNVs as a promising strategy to integrate TME improvement with PD1/PD-L1 blockade for cancer immunotherapy.

Expanding the boundaries of silk sericin biomaterials in biomedical applications

Silk sericin (SS) has a long history as a by-product of the textile industry. SS has emerged as a sustainable material for biomedical engineering due to its material properties including water solubility, diverse impact on biological activities including antibacterial and antioxidant properties, and ability to promote cell adhesion and proliferation. This review addresses the origin, structure, properties, extraction, and underlying functions of this protein. An overview of the growing research studies and market evolution is presented, along with highlights of the most common fabrication matrices (hydrogels, bioinks, porous and fibrous scaffolds) and tissue engineering applications. Finally, the future trends with this protein as a multifaceted toolbox for bioengineering are explored, along with the challenges with SS. Overall, the present review can serve as a foundation for the creation of innovative biomaterials utilizing SS as a fundamental building block that hold market potential.

Hydrogel Loaded with Extracellular Vesicles: An Emerging Strategy for Wound Healing

An increasing number of novel biomaterials have been applied in wound healing therapy. Creating beneficial environments and containing various bioactive molecules, hydrogel- and extracellular vesicle (EV)-based therapies have respectively emerged as effective approaches for wound healing. Moreover, the synergistic combination of these two components demonstrates more favorable outcomes in both chronic and acute wound healing. This review provides a comprehensive discussion and summary of the combined application of EVs and hydrogels to address the intricate scenario of wounds. The wound healing process and related biological mechanisms are outlined in the first section. Subsequently, the utilization of EV-loaded hydrogels during the wound healing process is evaluated and discussed. The moist environment created by hydrogels is conducive to wound tissue regeneration. Additionally, the continuous and controlled release of EVs from various origins could be achieved by hydrogel encapsulation. Finally, recent in vitro and in vivo studies reported on hydrogel dressings loaded with EVs are summarized and challenges and opportunities for the future clinical application of this therapeutic approach are outlined.

Multifunctional hydrogel-based engineered extracellular vesicles delivery for complicated wound healing

The utilization of extracellular vesicles (EVs) in wound healing has been well-documented. However, the direct administration of free EVs via subcutaneous injection at wound sites may result in the rapid dissipation of bioactive components and diminished therapeutic efficacy. Functionalized hydrogels provide effective protection, as well as ensure the sustained release and bioactivity of EVs during the wound healing process, making them an ideal candidate material for delivering EVs. In this review, we introduce the mechanisms by which EVs accelerate wound healing, and then elaborate on the construction strategies for engineered EVs. Subsequently, we discuss the synthesis strategies and application of hydrogels as delivery systems for the sustained release of EVs to enhance complicated wound healing. Furthermore, in the face of complicated wounds, functionalized hydrogels with specific wound microenvironment regulation capabilities, such as antimicrobial, anti-inflammatory, and immune regulation, used for loading engineered EVs, provide potential approaches to addressing these healing challenges. Ultimately, we deliberate on potential future trajectories and outlooks, offering a fresh viewpoint on the advancement of artificial intelligence (AI)-energized materials and 3D bio-printed multifunctional hydrogel-based engineered EVs delivery dressings for biomedical applications.

Exploring the mechanistic role of silk sericin biological and chemical conjugates for effective acute and chronic wound repair and related complications

OBJECTIVE

The current review is designed to elaborate and reveal the underlying mechanism of sericin and its conjugates of drug delivery during wounds and wound-related issues.

SIGNIFICANCE

Wound healing is a combination of different humoral, molecular, and cellular mechanisms. Various natural products exhibit potential in wound healing but among them, sericin, catches much attention of researchers due to its bio-functional properties such as being biodegradable, biocompatible, anti-oxidant, anti-bacterial, photo-protector, anti-inflammatory and moisturizing agent.

METHODS AND RESULTS

Sericin triggers the activity of anti-inflammatory cytokines which decrease cell adhesion and promote epithelial cell formation. Moreover, sericin enhances the anti-oxidant enzymes in the wounded area which scavenge the toxic consequences of reactive species (ROS).

CONCLUSIONS

This article highlights the mechanisms of how topical administration of sericin formulations along with 4-hexylresorcinol,\Chitosan\Ag@MOF-GO, polyvinyl alcohol (PVA), platelet lysate and UV photo cross-linked hydrogel sericin methacrylate which recruits a large number of cytokines on wounded area that stimulate fibroblasts and keratinocyte production as well as collagen deposition that led to early wound contraction. It also reviews the different sericin-based nanoparticles that play a significant role in rapid wound healing.

Injectable Nanocomposite Immune Hydrogel Dressings: Prevention of Tumor Recurrence and Anti-Infection after Melanoma Resection

Complex wound repair due to tumor recurrence and infection following tumor resection presents significant clinical challenges. In this study, a bifunctional nanocomposite immune hydrogel dressing, SerMA-LJC, is developed to address the issues associated with repairing infected damaged tissues and preventing tumor recurrence. Specifically, the immune dressing is composed of methacrylic anhydride-modified sericin (SerMA) and self-assembled nanoparticles (LJC) containing lonidamine (Lon), JQ1, and chlorine e6 (Ce6). In vitro and in vivo experiments demonstrate that the nanocomposite hydrogel dressing can trigger immunogenic cell death (ICD) and has a potent anti-tumor effect. Moreover, this dressing can mitigate the acidic microenvironment of tumor cells and suppress the overexpression of PD-L1 on the tumor cell surface, thereby altering the immunosuppressive tumor microenvironment and augmenting the anti-tumor immune response. Further, the RNA sequencing analysis revealed that the hydrogel dressing significantly impacts pathways associated with positive regulation of immune response, apoptotic process, and other relevant pathways, thus triggering a potent anti-tumor immune response. More importantly, the dressing generates a substantial amount of reactive oxygen species (ROS), which can effectively kill Staphylococcus aureus and promote infectious wound healing. In conclusion, this dual-function nanocomposite immune hydrogel dressing exhibits promise in preventing tumor recurrence and promoting infectious wound healing.

Photocrosslinkable Sericin Hydrogel Injected into the Anterior Chamber of Mice with Chronic Ocular Hypertension Efficacy, Medication Sensitivity, and Material Safety

(1) Background: A rise in intraocular pressure (IOP) and decreased retinal ganglion cells are frequent indicators of effective modeling of chronic ocular hypertension in mice. In this study, the sensitivity of the mouse model to pharmaceutical therapy to reduce intraocular tension was assessed, the model's safety was confirmed using a cytotoxicity test, and the success rate of the mouse model of ocular hypertension was assessed by assessing alterations in IOP and neurons in the ganglion cell layer. (2) Methods: A mouse model of chronic ocular hypertension was produced in this study by employing photocrosslinkable sericin hydrogel injection and LED lamp irradiation. The eyes of 25 C57BL/6 male mice were subjected to 405 nm UV light from the front for 2 min after being injected with 5 μL of sericin hydrogel in the anterior chamber of the left eye. IOP in the mice was measured daily, and IOP rises greater than 5 mmHg were considered intraocular hypertension. When the IOP was lowered, the intervention was repeated once, but the interval between treatments was at least 2 weeks. The right eyes were not treated with anything as a normal control group. Mice eyeballs were stained with HE, Ni-type, and immunofluorescence to assess the model's efficacy. Two common drugs (tafluprost eye drops and timolol eye drops) were provided for one week after four weeks of stable IOP, and IOP changes were assessed to determine the drug sensitivity of the mouse model of chronic ocular hypertension. Furthermore, CellTiter 96® AQueous One Solution Cell Proliferation Assay (MTS) was utilized to investigate the safety of the ocular hypertension model by evaluating the deleterious effects of photocrosslinkable sericin hydrogel on cells. (3) Results: Before injection, the basal IOP was (9.42 ± 1.28) mmHg (1 kPa = 7.5 mmHg) in the experimental group and (9.08 ± 1.21) in the control group. After injection, cataract occurred in one eye, corneal edema in one eye, endophthalmitis in one eye, iris incarceration in one eye, and eyeball atrophy in one eye. Five mice with complications were excluded from the experiment, and twenty mice were left. Four weeks after injection, the IOP of the experimental group was maintained at (19.7 ± 4.52) mmHg, and that of the control group was maintained at (9.92 ± 1.55) mmHg, and the difference between the two groups was statistically significant (p < 0.05). Before the intervention, the IOP in the experimental group was (21.7 ± 3.31) mmHg in the high IOP control group, (20.33 ± 2.00) mmHg in the tafluprost eye drops group, and (20.67 ± 3.12) mmHg in the timolol maleate eye drops group. The IOP after the intervention was (23.2 ± 1.03) mmHg, (12.7 ± 2.11) mmHg, and (10.4 ± 1.43) mmHg, respectively. Before and after the intervention, there were no significant differences in the high-IOP control group (p > 0.05), there were statistically significant differences in the timolol eye drops group (p < 0.05), and there were statistically significant differences in the tafluprost eye drops group (p < 0.05). One week after drug withdrawal, there was no significant difference in IOP among the three groups (p > 0.05). In the high-IOP group, the protein (sericin hydrogel) showed a short strips or fragmented structure in the anterior chamber, accompanied by a large number of macrophages and a small number of plasma cells. The shape of the chamber angle was normal in the blank control group. The number of retinal ganglion cells decreased significantly 8 weeks after injection of sericin hydrogel into the anterior chamber, and the difference was statistically significant compared with the blank control group (p < 0.05). After the cells were treated with photocrosslinkable sericin hydrogel, there was no significant difference in the data of the CellTiter 96® assay kit of MTS compared with the blank control group (p > 0.05). (4) Conclusions: A mouse model of chronic intraocular hypertension can be established successfully by injecting sericin in the anterior chamber and irradiating with ultraviolet light. The model can simulate the structural and functional changes of glaucoma and can effectively reduce IOP after the action of most antihypertensive drugs, and it is highly sensitive to drugs. Sericin has no obvious toxic effect on cells and has high safety.

Development and Application of an Advanced Biomedical Material-Silk Sericin

Sericin, a protein derived from silkworm cocoons, is considered a waste product derived from the silk industry for thousands of years due to a lack of understanding of its properties. However, in recent decades, a range of exciting properties of sericin are studied and uncovered, including cytocompatibility, low-immunogenicity, photo-luminescence, antioxidant properties, as well as cell-function regulating activities. These properties make sericin-based biomaterials promising candidates for biomedical applications. This review summarizes the properties and bioactivities of silk sericin and highlights the latest developments in sericin in tissue engineering and regenerative medicine. Furthermore, the extended application of sericin in developing flexible electronic devices and 3D bioprinting is also discussed. It is believed that sericin-based biomaterials have great potential of being developed into novel tissue engineering products and smart implantable devices for various medical applications toward improving clinical outcomes.

Comparison of the efficacy of royal jelly and melatonin combinations in experimentally induced wounds in geriatric and young mice

BACKGROUND

Wound healing involves the repair of skin and other soft tissues after an injury. Royal jelly, a product of bees, possesses antioxidant, anti-inflammatory, antibacterial, and antiviral properties. Melatonin, a circadian indoleamine, is produced in the pineal gland and other organs. This study explores the effects of melatonin and royal jelly, both individually and combined, on wound healing in geriatric and young mice.

METHODS

The study includes 90 Balb/C mice divided into ten groups to assess the effects of royal jelly and melatonin on wound healing. Royal jelly was applied topically at a concentration of 300 mg/kg. Melatonin was formulated in a vaseline-based pomade at a concentration of 5 mg/kg. The substances were applied either separately or in combination to wounds created on the mice.

RESULTS

Both substances significantly enhanced wound healing at a macroscopic level in both age groups. Melatonin was found to be more effective during the initial wound formation process, whereas royal jelly was more beneficial during the granulation phase. However, significant results at a histopathological level were observed only in geriatric animals.

CONCLUSION

The findings suggest a potential new therapeutic approach to enhance wound healing, particularly in elderly individuals. However, these findings need to be supported through further research and clinical trials.

M1 macrophage-derived exosomes promote intervertebral disc degeneration by enhancing nucleus pulposus cell senescence through LCN2/NF-κB signaling axis

Intervertebral disc degeneration (IVDD) is the primary factor contributing to low back pain (LBP). Unlike elderly patients, many young IVDD patients usually have a history of trauma or long-term abnormal stress, which may lead to local inflammatory reaction causing by immune cells, and ultimately accelerates degeneration. Research has shown the significance of M1-type macrophages in IVDD; nevertheless, the precise mechanism and the route by which it influences the function of nucleus pulposus cell (NPC) remain unknown. Utilizing a rat acupuncture IVDD model and an NPC degeneration model induced by lipopolysaccharide (LPS), we investigated the function of M1 macrophage-derived exosomes (M1-Exos) in IVDD both in vivo and in vitro in this study. We found that M1-Exos enhanced LPS-induced NPC senescence, increased the number of SA-β-gal-positive cells, blocked the cell cycle, and promoted the activation of P21 and P53. M1-Exos derived from supernatant pretreated with the exosome inhibitor GW4869 reversed this result in vivo and in vitro. RNA-seq showed that Lipocalin2 (LCN2) was enriched in M1-Exos and targeted the NF-κB pathway. The quantity of SA-β-gal-positive cells was significantly reduced with the inhibition of LCN2, and the expression of P21 and P53 in NPCs was decreased. The same results were obtained in the acupuncture-induced IVDD model. In addition, inhibition of LCN2 promotes the expression of type II collagen (Col-2) and inhibits the expression of matrix metalloproteinase 13 (MMP13), thereby restoring the equilibrium of metabolism inside the extracellular matrix (ECM) in vitro and in vivo. In addition, the NF-κB pathway is crucial for regulating M1-Exo-mediated NPC senescence. After the addition of M1-Exos to LPS-treated NPCs, p-p65 activity was significantly activated, while si-LCN2 treatment significantly inhibited p-p65 activity. Therefore, this paper demonstrates that M1 macrophage-derived exosomes have the ability to deliver LCN2, which activates the NF-κB signaling pathway, and exacerbates IVDD by accelerating NPC senescence. This may shed new light on the mechanism of IVDD and bring a fresh approach to IVDD therapy.

Royal Jelly: Biological Action and Health Benefits

Royal jelly (RJ) is a highly nutritious natural product with great potential for use in medicine, cosmetics, and as a health-promoting food. This bee product is a mixture of important compounds, such as proteins, vitamins, lipids, minerals, hormones, neurotransmitters, flavonoids, and polyphenols, that underlie the remarkable biological and therapeutic activities of RJ. Various bioactive molecules like 10-hydroxy-2-decenoic acid (10-HDA), antibacterial protein, apisin, the major royal jelly proteins, and specific peptides such as apisimin, royalisin, royalactin, apidaecin, defensin-1, and jelleins are characteristic ingredients of RJ. RJ shows numerous physiological and pharmacological properties, including vasodilatory, hypotensive, antihypercholesterolaemic, antidiabetic, immunomodulatory, anti-inflammatory, antioxidant, anti-aging, neuroprotective, antimicrobial, estrogenic, anti-allergic, anti-osteoporotic, and anti-tumor effects. Moreover, RJ may reduce menopause symptoms and improve the health of the reproductive system, liver, and kidneys, and promote wound healing. This article provides an overview of the molecular mechanisms underlying the beneficial effects of RJ in various diseases, aging, and aging-related complications, with special emphasis on the bioactive components of RJ and their health-promoting properties. The data presented should be an incentive for future clinical studies that hopefully will advance our knowledge about the therapeutic potential of RJ and facilitate the development of novel RJ-based therapeutic opportunities for improving human health and well-being.

Genetically Edited Cascade Nanozymes for Cancer Immunotherapy

Immune checkpoint blockade (ICB) has brought tremendous clinical progress, but its therapeutic outcome can be limited due to insufficient activation of dendritic cells (DCs) and insufficient infiltration of cytotoxic T lymphocytes (CTLs). Evoking immunogenic cell death (ICD) is one promising strategy to promote DC maturation and elicit T-cell immunity, whereas low levels of ICD induction of solid tumors restrict durable antitumor efficacy. Herein, we report a genetically edited cell membrane-coated cascade nanozyme (gCM@MnAu) for enhanced cancer immunotherapy by inducing ICD and activating the stimulator of the interferon genes (STING) pathway. In the tumor microenvironment (TME), the gCM@MnAu initiates a cascade reaction and generates abundant cytotoxic hydroxyl (•OH), resulting in improved chemodynamic therapy (CDT) and boosted ICD activation. In addition, released Mn2+ during the cascade reaction activates the STING pathway and further promotes the DC maturation. More importantly, activated immunogenicity in the TME significantly improves gCM-mediated PD-1/PD-L1 checkpoint blockade therapy by eliciting systemic antitumor responses. In breast cancer subcutaneous and lung metastasis models, the gCM@MnAu showed synergistically enhanced therapeutic effects and significantly prolonged the survival of mice. This work develops a genetically edited nanozyme-based therapeutic strategy to improve DC-mediated cross-priming of T cells against poorly immunogenic solid tumors.

Genetically Engineered Cytomembrane Nanovaccines for Cancer Immunotherapy

Cancer nanovaccines have attracted widespread attention by inducing potent cytotoxic T cell responses to improve immune checkpoint blockade (ICB) therapy, while the lack of co-stimulatory molecules limits their clinical applications. Here, a genetically engineered cancer cytomembrane nanovaccine is reported that simultaneously overexpresses co-stimulatory molecule CD40L and immune checkpoint inhibitor PD1 to elicit robust antitumor immunity for cancer immunotherapy. The CD40L and tumor antigens inherited from cancer cytomembranes effectively stimulate dendritic cell (DC)-mediated immune activation of cytotoxic T cells, while the PD1 on cancer cytomembranes significantly blocks PD1/PD-L1 signaling pathway, synergistically stimulating antitumor immune responses. Benefiting from the targeting ability of cancer cytomembranes, this nanovaccines formula shows an enhanced lymph node trafficking and retention. Compared with original cancer cytomembranes, this genetically engineered nanovaccine induces twofold DC maturation and shows satisfactory precaution efficacy in a breast tumor mouse model. This genetically engineered cytomembrane nanovaccine offers a simple, safe, and robust strategy by incorporating cytomembrane components and co-stimulatory molecules for enhanced cancer immunotherapy.

[Effects of gelatin methacrylate anhydride hydrogel loaded with small extracellular vesicles derived from human umbilical cord mesenchymal stem cells in the treatment of full-thickness skin defect wounds in mice]

Objective: To investigate the effects of gelatin methacrylate anhydride (GelMA) hydrogel loaded with small extracellular vesicles derived from human umbilical cord mesenchymal stem cells (hUCMSCs-sEVs) in the treatment of full-thickness skin defect wounds in mice. Methods: This study was an experimental study. hUCMSCs-sEVs were extracted by ultracentrifugation, their morphology was observed through transmission electron microscope, and the expression of CD9, CD63, tumor susceptibility gene 101 (TSG101), and calnexin was detected by Western blotting. The human umbilical vein endothelial cells (HUVECs), the 3rd and 4th passages of human epidermal keratinocytes (HEKs) and human dermal fibroblasts (HDFs) were all divided into blank control group (routinely cultured) and hUCMSC-sEV group (cultured with the cell supernatant containing hUCMSCs-sEVs). The cell scratch test was performed and the cell migration rates at 6, 12, and 24 h after scratching were calculated, the cell Transwell assay was performed and the number of migration cells at 12 h after culture was calculated, and the proportion of proliferating cells was detected by 5-acetylidene-2'-deoxyuridine and Hoechst staining at 24 h after culture, with sample numbers being all 3. The simple GelMA hydrogel and the GelMA hydrogel loaded with hUCMSCs-sEVs (hereinafter referred to as hUCMSC-sEV/GelMA hydrogel) were prepared. Then the micromorphology of 2 kinds of hydrogels was observed under scanning electron microscope, the distribution of hUCMSCs-sEVs was observed by laser scanning confocal microscope, and the cumulative release rates of hUCMSCs-sEVs at 0 (immediately), 2, 4, 6, 8, 10, and 12 d after soaking hUCMSC-sEV/GelMA hydrogel in phosphate buffer solution (PBS) were measured and calculated by protein colorimetric quantification (n=3). Twenty-four 6-week-old male C57BL/6J mice were divided into PBS group, hUCMSC-sEV alone group, GelMA hydrogel alone group, and hUCMSC-sEV/GelMA hydrogel group according to the random number table, with 6 mice in each group, and after the full-thickness skin defect wounds on the back of mice in each group were produced, the wounds were performed with PBS injection, hUCMSC-sEV suspenson injection, simple GelMA coverage, and hUCMSC-sEV/GelMA hydrogel coverage, respectively. Wound healing was observed on post injury day (PID) 0 (immediately), 4, 8, and 12, and the wound healing rates on PID 4, 8, and 12 were calculated, and the wound tissue was collected on PID 12 for hematoxylin-eosin staining to observe the structure of new tissue, with sample numbers being both 6. Results: The extracted hUCMSCs-sEVs showed a cup-shaped structure and expressed CD9, CD63, and TSG101, but barely expressed calnexin. At 6, 12, and 24 h after scratching, the migration rates of HEKs (with t values of 25.94, 20.98, and 20.04, respectively), HDFs (with t values of 3.18, 5.68, and 4.28, respectively), and HUVECs (with t values of 4.32, 19.33, and 4.00, respectively) in hUCMSC-sEV group were significantly higher than those in blank control group (P<0.05). At 12 h after culture, the numbers of migrated HEKs, HDFs, and HUVECs in hUCMSC-sEV group were 550±23, 235±9, and 856±35, respectively, which were significantly higher than 188±14, 97±6, and 370±32 in blank control group (with t values of 22.95, 23.13, and 17.84, respectively, P<0.05). At 24 h after culture, the proportions of proliferating cells of HEKs, HDFs, and HUVECs in hUCMSC-sEV group were significantly higher than those in blank control group (with t values of 22.00, 13.82, and 32.32, respectively, P<0.05). The inside of simple GelMA hydrogel showed a loose and porous sponge-like structure, and hUCMSCs-sEVs was not observed in it. The hUCMSC-sEV/GelMA hydrogel had the same sponge-like structure, and hUCMSCs-sEVs were uniformly distributed in clumps. The cumulative release rate curve of hUCMSCs-sEVs from hUCMSC-sEV/GelMA hydrogel tended to plateau at 2 d after soaking, and the cumulative release rate of hUCMSCs-sEVs was (59.2±1.8)% at 12 d after soaking. From PID 0 to 12, the wound areas of mice in the 4 groups gradually decreased. On PID 4, 8, and 12, the wound healing rates of mice in hUCMSC-sEV/GelMA hydrogel group were significantly higher than those in the other 3 groups (P<0.05); the wound healing rates of mice in GelMA hydrogel alone group and hUCMSC-sEV alone group were significantly higher than those in PBS group (P<0.05). On PID 8 and 12, the wound healing rates of mice in hUCMSC-sEV alone group were significantly higher than those in GelMA hydrogel alone group (P<0.05). On PID 12, the wounds of mice in hUCMSC-sEV/GelMA hydrogel group showed the best wound epithelization, loose and orderly arrangement of dermal collagen, and the least number of inflammatory cells, while the dense arrangement of dermal collagen and varying degrees of inflammatory cell infiltration were observed in the wounds of mice in the other 3 groups. Conclusions: hUCMSCs-sEVs can promote the migration and proliferation of HEKs, HDFs, and HUVECs which are related to skin wound healing, and slowly release in GelMA hydrogel. The hUCMSC-sEV/GelMA hydrogel as a wound dressing can significantly improve the healing speed of full-thickness skin defect wounds in mice.

New frontiers in salivary extracellular vesicles: transforming diagnostics, monitoring, and therapeutics in oral and systemic diseases

Salivary extracellular vesicles (EVs) have emerged as key tools for non-invasive diagnostics, playing a crucial role in the early detection and monitoring of diseases. These EVs surpass whole saliva in biomarker detection due to their enhanced stability, which minimizes contamination and enzymatic degradation. The review comprehensively discusses methods for isolating, enriching, quantifying, and characterizing salivary EVs. It highlights their importance as biomarkers in oral diseases like periodontitis and oral cancer, and underscores their potential in monitoring systemic conditions. Furthermore, the review explores the therapeutic possibilities of salivary EVs, particularly in personalized medicine through engineered EVs for targeted drug delivery. The discussion also covers the current challenges and future prospects in the field, emphasizing the potential of salivary EVs in advancing clinical practice and disease management.

Near-Infrared Fluorescence Probe for Indication of the Pathological Stages of Wound Healing Process and Its Clinical Application

Chronic wound healing is one of the most complicated biological processes in human life, which is also a serious challenge for human health. During the healing process, multiple biological pathways are activated, and various kinds of reactive oxygen species participate in this process. Hydrogen peroxide (H2O2) involves in chronic wounds and its concentration is fluctuated in different pathological stages during the wound healing process. Therefore, H2O2 may be recognized as a powerful biomarker to indicate the wound healing process. However, the pathological roles of H2O2 cannot be fully understood yet. Herein, we proposed a near-infrared fluorescent probe DCM-H2O2 for highly sensitive and rapid detection of H2O2 in living cells and scald and incision wound mice models. DCM-H2O2 exhibited a low detection limit and high specificity with low cytotoxicity for H2O2, which had great potential for its application in vivo. The probe was successfully utilized to monitor the fluctuation of endogenous H2O2 in the proliferation process of human immortalized epidermal (HACAT) cells, which confirmed that H2O2 participated in the cells' proliferation activity through a growth factor signaling pathway. In the scald and incision wound mice models, H2O2 concentration fluctuations at different pathological stages during the wound healing process could be obtained by in vivo fluorescence imaging. Finally, H2O2 concentrations in different stages of human diabetic foot tissues were also confirmed by the proposed probe. We expect that H2O2 could be a sensitive biomarker to indicate the wound healing process.

Engineered Extracellular Vesicles in Wound Healing: Design, Paradigms, and Clinical Application

The severe quality of life and economic burden imposed by non-healing skin wounds, infection risks, and treatment costs are affecting millions of patients worldwide. To mitigate these challenges, scientists are relentlessly seeking effective treatment measures. In recent years, extracellular vesicles (EVs) have emerged as a promising cell-free therapy strategy, attracting extensive attention from researchers. EVs mediate intercellular communication, possessing excellent biocompatibility and stability. These features make EVs a potential tool for treating a plethora of diseases, including those related to wound repair. However, there is a growing focus on the engineering of EVs to overcome inherent limitations such as low production, relatively fixed content, and targeting capabilities of natural EVs. This engineering could improve both the effectiveness and specificity of EVs in wound repair treatments. In light of this, the present review will introduce the latest progress in the design methods and experimental paradigms of engineered EVs applied in wound repair. Furthermore, it will comprehensively analyze the current clinical research status and prospects of engineered EVs within this field.

Bacteria-based drug delivery for treating non-oncological diseases

Bacteria inhabit all over the human body, especially the skin, gastrointestinal tract, respiratory tract, urogenital tract, as well as specific lesion sites, such as wound and tumor. By leveraging their distinctive attributes including rapid proliferation, inherent abilities to colonize various biointerfaces in vivo and produce diverse biomolecules, and the flexibility to be functionalized via genetic engineering or surface modification, bacteria have been widely developed as living therapeutic agents, showing promising potential to make a great impact on the exploration of advanced drug delivery systems. In this review, we present an overview of bacteria-based drug delivery and its applications in treating non-oncological diseases. We systematically summarize the physiological positions where living bacterial therapeutic agents can be delivered to, including the skin, gastrointestinal tract, respiratory tract, and female genital tract. We discuss the success of using bacteria-based drug delivery systems in the treatment of diseases that occur in specific locations, such as skin wound healing/infection, inflammatory bowel disease, respiratory diseases, and vaginitis. We also discuss the advantages as well as the limitations of these living therapeutics and bacteria-based drug delivery, highlighting the key points that need to be considered for further translation. This review article may provide unique insights for designing next-generation bacteria-based therapeutics and developing advanced drug delivery systems.

Recent advances of hydrogels as smart dressings for diabetic wounds

Chronic diabetic wounds have been an urgent clinical problem, and wound dressings play an important role in their management. Due to the design of traditional dressings, it is difficult to achieve adaptive adhesion and on-demand removal of complex diabetic wounds, real-time monitoring of wound status, and dynamic adjustment of drug release behavior according to the wound microenvironment. Smart hydrogels, as smart dressings, can respond to environmental stimuli and achieve more precise local treatment. Here, we review the latest progress of smart hydrogels in wound bandaging, dynamic monitoring, and drug delivery for treatment of diabetic wounds. It is worth noting that we have summarized the most important properties of smart hydrogels for diabetic wound healing. In addition, we discuss the unresolved challenges and future prospects in this field. We hope that this review will contribute to furthering progress on smart hydrogels as improved dressing for diabetic wound healing and practical clinical application.