Hydrogel armed with Bmp2 mRNA-enriched exosomes enhances bone regeneration

Microenvironment-responsive living hydrogel containing engineered probiotic for treatment of massive bone defects

Self-activating and microenvironment-responsive biomaterials for tissue regeneration would address the escalating need for bone grafting, but remain challenging. The emergence of microbial living therapeutics offers vast potential in regenerative medicine, as genetically engineered probiotics possess efficient stimuli-responsiveness and tunable biological functions. Here, using elevated endogenous nitric oxide (NO) signals as a biological trigger in bone fracture injuries, a Living Responsive Regenerative Medicine (LRRM) strategy for in situ bone defect repair through real-time controlled release of bone morphogenetic protein-2 (BMP2) is proposed. The Escherichia coli Nissle 1917 (EcN) strain, genetically engineered to sense NO signals and correspondingly produce and secrete BMP2, was firstly encapsulated in gelatin methacryloyl (GelMA) microspheres and then embedded in a bulky hyaluronic acid methacryloyl (HAMA) hydrogel to form a living hydrogel device that circumvents immune attack and prevents bacterial leakage. In vivo multiple bone defect models demonstrated the efficacy of the living hydrogel in enhancing the maturation of bone callus, promoting neovascularization, and facilitating full-thickness bone union. Strategic incorporation of engineered probiotics and the bilayer-structured encapsulation system may emerge as an effective and microenvironment-responsive medicine approach for tissue regeneration.

mRNA encoding bone morphogenetic protein-2 facilitated peri-implant bone formation of titanium implants placed in rat femurs

This study evaluated the effectiveness of N1-methylpseudouridine-modified mRNA encoding bone morphogenetic protein-2 (BMP-2 mRNA-LNP) in promoting bone growth and improving titanium implant integration in rat femur bone defects. Sixteen Sprague-Dawley rats (32 femurs) were used, with titanium wires implanted in the femoral defects. The defects were divided into four groups (n = 8): 5 µg BMP-2 mRNA-LNP, 15 µg BMP-2 mRNA-LNP, recombinant BMP-2 (rhBMP-2), and Dulbecco's phosphate-buffered saline (dPBS). Following euthanasia at 3 and 6 weeks, Micro-Computed Tomography (micro-CT) was performed to assess bone volume, trabecular architecture, and bone-to-implant contact. Push-out mechanical testing determined the maximal loading force for implant dislodgment, while elemental analysis using Energy-Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) assessed mineralization on the titanium surfaces. The 15 µg BMP-2 mRNA-LNP group demonstrated significantly enhanced bone volume, trabecular thickness, and bone-to-implant contact compared to the control group (p < 0.05). Additionally, this group showed higher calcium and phosphorus content, indicating superior mineralization. Concomitantly, the mean maximal loading force (N) increased in the BMP-2 mRNA-LNP group, though this increase was not statistically significant. These results suggest that BMP-2 mRNA-LNP offers a promising approach to enhance peri-implant bone formation and bone regeneration. While the 15 µg group showed slightly greater bone formation, most experimental parameters showed no significant differences compared to the 5 µg group, suggesting the lower dose may offer a more cost-effective approach without compromising efficacy.

DNA-based hydrogels for bone regeneration: A promising tool for bone organoids

DNA-based hydrogels stand out for bone regeneration due to their exceptional biocompatibility and programmability. These hydrogels facilitate the formation of spatial bone structures through bulk hydrogel fabricating, microsphere formatting, and 3D printing. Furthermore, the bone microenvironment can be finely tuned by leveraging the degradation products, nanostructure, targeting, and delivery capabilities inherent to DNA-based materials. In this review, we underscore the advantages of DNA-based hydrogels, detailing their composition, gelation techniques, and structure optimization. We then delineate three critical elements in the promotion of bone regeneration using DNA-based hydrogels: (i) osteogenesis driven by phosphate ions, plasmids, and oligodeoxynucleotides (ODNs) that enhance mineralization and promote gene and protein expression; (ii) vascularization facilitated by tetrahedral DNA nanostructures (TDNs) and aptamers, which boosts gene expression and targeted release; (iii) immunomodulation achieved through loaded factors, TDNs, and bound ions that stimulate macrophage polarization and exhibit antibacterial properties. With these advantages and properties, these DNA-based hydrogels can be used to construct bone organoids, providing an innovative tool for disease modeling and therapeutic applications in bone tissue engineering. Finally, we discuss the current challenges and future prospects, emphasizing the potential impacts and applications in regenerative medicine.

Gelatin methacryloyl @MP196/exos hydrogel induced neutrophil apoptosis and macrophage M2 polarization to inhibit periodontal bone loss

OBJECTIVES

Periodontitis is an inflammatory and destructive disease caused by dental plaque, which can result in the immune microenvironment disorders and loss of periodontal support tissue. In order to promote the restoration of local microenvironment stability, a functional biomaterial Gelatin methacryloyl @MP196/exos based on characteristics of disease occurrence is designed.

METHODS

Transmission electron microscopy, nanosight particle tracking analysis and western blot analysis were applied to prove the presence of exos in GelMA@MP196/exos. The swelling and degradation rates of GelMA@MP196/exos were evaluated. Cell proliferation, antibacterial ability and cellular uptake and intracellular internalization of exos were assessed in the study. Efferocytosis and M2 polarization of macrophages was estimated and the effects of GelMA@MP196/exos were proved in vivo.

RESULTS

GelMA@MP196/exos upregulated the expression of genes and proteins related to neutrophil apoptosis and promoted neutrophil apoptosis, macrophage M2 polarization, and efferocytosis. Furthermore, GelMA@MP196/exos exhibited significant antibacterial activity against Streptococcus gordonii, Fusobacterium nucleatum, and Porphyromonas gingivalis. GelMA@MP196/exos alleviated periodontitis and reduced alveolar bone loss in vivo in rat models.

CONCLUSIONS

GelMA@MP196/exos can serve as a potential strategy for the treatment of periodontitis.

CLINICAL SIGNIFICANCE

The main aim of periodontal therapy is to remove dental plaque and eliminate inflammation. However, some patients with low plaque scores and insufficient neutrophil clearance, resulting in poor responsiveness to periodontal therapy. Under the circumstances, local Application of drug that regulate the immune microenvironment had significance in controlling the progression of inflammation.

Osteogenesis Differentiation and Molecular Mechanism Study of a Si and Mg Dual-Ion System Based on mRNA Transcriptomic Sequencing Analysis

Both silicon (Si) and magnesium (Mg) ions play essential roles in bone health. However, the precise mechanisms by which these two ions enhance osteogenic differentiation remain to be fully elucidated. Herein, a Si-Mg dual-ion system was designed to investigate the effects of Si and Mg ions on the cytological behavior of mouse bone marrow mesenchymal stem cells (mBMSCs). The molecular mechanism of the Si-Mg dual-ion system regulating osteogenic differentiation of mBMSCs was investigated by transcriptome sequencing technology. In the single-ion system, the Si group with concentrations of 1.5 and 0.75 mM exhibited good combined effects (cell proliferation, alkaline phosphatase (ALP) activity, and osteogenic differentiation gene expression (Runx2, OPN, and Col-I)) of mBMSCs. The Mg group with concentrations of 5 and 2.5 mM showed better combined effects (cell proliferation, ALP activity, and osteogenic differentiation gene expression) of mBMSCs. In the dual-ion system, the silicon (0.75 mM)-magnesium (2.5 mM) experimental group significantly enhanced the proliferation, ALP activity, and osteogenesis-related gene expression (Runx2, OPN, and Col-I) of mBMSCs. The analysis of transcriptome sequencing results showed that Mg ions had a certain pro-stem cell osteogenic differentiation regulatory effect. Si ions had a stronger regulation on osteogenic differentiation than the Mg ions. The regulation of osteogenic differentiation by Si-Mg dual ions was synergistically enhanced compared to that of a single ion. In addition, the transforming growth factor beta (TGF-β) signaling pathway and mitogen-activated protein kinase (MAPK) signaling pathway were involved in mediating the pro-stem cell osteogenic differentiation by Si-Mg dual ions. This study sheds light on investigating the molecular mechanism of dual-ion regulation of the osteogenic differentiation of mBMSCs and enriches the theory of ion-regulating osteogenic differentiation.

Hydrogels empowered mesenchymal stem cells and the derived exosomes for regenerative medicine in age-related musculoskeletal diseases

As the population ages, musculoskeletal diseases (MSK) have emerged as a significant burden for individuals, healthcare systems, and social care systems. Recently, regenerative medicine has exhibited vast potential in age-related MSK, with mesenchymal stromal cells (MSCs) and their derived exosomes (Exos) therapies showing distinct advantages. However, these therapies face several limitations, including issues related to ensuring stability and effective distribution within the body. Hydrogels, acting as an ideal carrier, can enhance the therapeutic effects and application range of MSCs and Exos derived from MSCs (MSC-Exos). Therefore, this review comprehensively summarizes the application progress of MSCs and MSC-Exos combined with hydrogels in age-related MSK disease research. It aims to provide a detailed perspective, showcasing the functional enhancement of MSCs and MSC-Exos when incorporated into hydrogels. Additionally, this review explores their potential and challenges in treating age-related MSK diseases, offering references for future research directions and potential innovative strategies.

Repair mechanisms of bone system tissues based on comprehensive perspective of multi-omics

Bone disorders affect more than half of the adult population worldwide who may have a poor quality of life and physical independence worldwide. Multi-omic techniques are increasingly adopted and applied to determine the molecular mechanisms of bone tissue repair, providing perspective towards personalized medical intervention. Data from genomics, epigenomics, transcriptomics, proteomics, glycomics, and lipidomics were combined to elucidate dynamic processes in bone repair. In this narrative review, the key role of genetic and epigenetic factors in regulating injured cellular responses is highlighted, and changes in RNA and protein expression during the healing phase, as well as glucolipid metabolism adaptation, are described in detail how the repair process is affected. In a word, the integration of multi-omic techniques in this review not only benefits the comprehensive identification of new biomarkers, but also facilitates the development of personalized treatment strategies of bone disorders to revolutionize regenerative medicine.

Advancements in GelMA bioactive hydrogels: Strategies for infection control and bone tissue regeneration

Infectious bone defects present a significant clinical challenge, characterized by infection, inflammation, and subsequent bone tissue destruction. Traditional treatments, including antibiotic therapy, surgical debridement, and bone grafting, often fail to address these defects effectively. However, recent advancements in biomaterials research have introduced innovative solutions for managing infectious bone defects. GelMA, a three-dimensional network of hydrophilic polymers that can absorb and retain substantial amounts of water, has attracted considerable attention in the fields of materials science and biomedical engineering. Its distinctive properties, such as biocompatibility, responsiveness to stimuli, and customisable mechanical characteristics make GelMA an exemplary scaffold material for bone tissue engineering. This review aims to thoroughly explore the current literature on antibacterial and osteogenic strategies using GelMA hydrogels for the restoration of infected bones. It discusses their fabrication methods, biocompatibility, antibacterial effectiveness, and bioactivity. We conclude by discussing the existing challenges and future research directions in this field, with the hope of inspiring further innovations in the synthesis, modification, and application of GelMA-based hydrogels for infection control and bone tissue regeneration.

Nanodrug-Engineered Exosomes Achieve a Jointly Dual-Pathway Inhibition on Cuproptosis

Cuproptosis, caused by an intracellular overload of copper (Cu) ions and overexpression of ferredoxin 1 (FDX1), is identified for its regulatory role in the skin wound healing process. This study verifies the presence of cuproptosis in skin wound beds and reactive oxygen species-induced cells model. To address the two pathways leading to cell cuproptosis, a nanodrug-engineered exosomes is proposed. A Cu-chelator (Clioquinol, CQ) polydopamine (PDA)-modified stem cell exosome loaded with siRNA-FDX1, named EXOsiFDX1-PDA@CQ, is designed to efficiently inhibit the two cuproptosis pathways. The functionalized exosomes are loaded into an injectable hydrogel and applied to treat diabetic wounds in mice and acute skin wounds in pigs. The local and controlled release of EXOsiFDX1-PDA@CQ ensures the retention of the therapeutic agent at wound beds, effectively promoting wound healing. The strategy of engineered exosomes with functional nanoparticles (NPs) proposed in this study offers an efficient and scalable new approach for regulating cuproptosis.

Innovative Nanomedicine Delivery: Targeting Tumor Microenvironment to Defeat Drug Resistance

Nanodrug delivery systems have revolutionized tumor therapy like never before. By overcoming the complexity of the tumor microenvironment (TME) and bypassing drug resistance mechanisms, nanotechnology has shown great potential to improve drug efficacy and reduce toxic side effects. This review examines the impact of the TME on drug resistance and recent advances in nanomedicine delivery systems to overcome this challenge. Characteristics of the TME such as hypoxia, acidity, and high interstitial pressure significantly reduce the effectiveness of chemotherapy and radiotherapy, leading to increased drug resistance in tumor cells. Then, this review summarizes innovative nanocarrier designs for these microenvironmental features, including hypoxia-sensitive nanoparticles, pH-responsive carriers, and multifunctional nanosystems that enable targeted drug release and improved drug penetration and accumulation in tumors. By combining nanotechnology with therapeutic strategies, this review offers a novel perspective by focusing on the innovative design of nanocarriers that interact with the TME, a dimension often overlooked in similar reviews. We highlight the dual role of these nanocarriers in therapeutic delivery and TME modulation, emphasize their potential to overcome drug resistance, and look at future research directions.

Nanoparticle-Mediated Gene Delivery for Bone Tissue Engineering

Critical-sized bone defects represent an urgent clinical problem, necessitating innovative treatment approaches. Gene-activated grafts for bone tissue engineering have emerged as a promising solution. However, traditional gene delivery methods are constrained by limited osteogenic efficacy and safety concerns. Recently, organic and inorganic nanoparticle (NP) vectors have attracted significant attention in bone tissue engineering for their safe, stable, and controllable gene delivery. Targeted gene delivery guided by insights into bone healing mechanisms, coupled with the multifunctional design of NPs, is crucial for enhancing therapeutic outcomes. Here, the theoretical foundations underlying NP-mediated gene therapy for enhancing bone healing across different histological stages are elucidated. Furthermore, the distinct attributes of functionalized NP vectors are discussed, and cutting-edge strategies aimed at optimizing gene delivery efficiency throughout the therapeutic process are highlighted. Additionally, the review addresses the unresolved challenges and prospects of this technology. This review may contribute to the continued development and clinical application of NP-mediated gene delivery for treating critical-sized bone defects.

Local drug delivery challenges and innovations in spinal neurosurgery

The development of novel therapeutics in the field of spinal neurosurgery faces a litany of translational challenges. Achieving precise drug targeting within the confined spaces associated with the spinal cord, canal and vertebra requires the development of next generation delivery systems and devices. These must be capable of overcoming inherent barriers related to drug diffusion, whilst concurrently ensuring optimal drug distribution and retention. In this review, we provide an overview of the most recent advances in the therapeutic management of diseases and disorders affecting the spine, including systems and devices capable of releasing small molecules and biopharmaceuticals that help eliminate pain and restore the mechanical function and stability of the spine. We highlight material-based approaches and minimally invasive techniques that can be employed to provide control over drug release kinetics and improve retention. We also seek to explore how the newest advancements in nanotechnology, biomaterials, additive manufacturing technologies and imaging modalities can be employed in this translational pursuit. Finally, we discuss the landscape of clinical trials and recently approved products aimed at overcoming the complexities associated with drug delivery to the spine.

Hydrogels for Nucleic Acid Drugs Delivery

Nucleic acid drugs are one of the hot spots in the field of biomedicine in recent years, and play a crucial role in the treatment of many diseases. However, its low stability and difficulty in target drug delivery are the bottlenecks restricting its application. Hydrogels are proven to be promising for improving the stability of nucleic acid drugs, reducing the adverse effects of rapid degradation, sudden release, and unnecessary diffusion of nucleic acid drugs. In this review, the strategies of loading nucleic acid drugs in hydrogels are summarized for various biomedical research, and classify the mechanism principles of these strategies, including electrostatic binding, hydrogen bond based binding, hydrophobic binding, covalent bond based binding and indirect binding using various carriers. In addition, this review also describes the release strategies of nucleic acid drugs, including photostimulation-based release, enzyme-responsive release, pH-responsive release, and temperature-responsive release. Finally, the applications and future research directions of hydrogels for delivering nucleic acid drugs in the field of medicine are discussed.

Exosomes to exosome-functionalized scaffolds: a novel approach to stimulate bone regeneration

Bone regeneration is a complex biological process that relies on the orchestrated interplay of various cellular and molecular events. Bone tissue engineering is currently the most promising method for treating bone regeneration. However, the immunogenicity, stable and cell quantity of seed cells limited their application. Recently, exosomes, which are small extracellular vesicles released by cells, have been found to effectively address these problems and better induce bone regeneration. Meanwhile, a growing line of research has shown the cargos of exosomes may provide effective therapeutic and biomarker tools for bone repair, including miRNA, lncRNA, and proteins. Moreover, engineered scaffolds loaded with exosomes can offer a cell-free bone repair strategy, addressing immunogenicity concerns and providing a more stable functional performance. Herein, we provide a comprehensive summary of the role played by scaffolds loaded with exosomes in bone regeneration, drawing on a systematic analysis of relevant literature available on PubMed, Scopus, and Google Scholar database.

Advanced Hybrid Strategies of GelMA Composite Hydrogels in Bone Defect Repair

To date, severe bone defects remain a significant challenge to the quality of life. All clinically used bone grafts have their limitations. Bone tissue engineering offers the promise of novel bone graft substitutes. Various biomaterial scaffolds are fabricated by mimicking the natural bone structure, mechanical properties, and biological properties. Among them, gelatin methacryloyl (GelMA), as a modified natural biomaterial, possesses a controllable chemical network, high cellular stability and viability, good biocompatibility and degradability, and holds the prospect of a wide range of applications. However, because they are hindered by their mechanical properties, degradation rate, and lack of osteogenic activity, GelMA hydrogels need to be combined with other materials to improve the properties of the composites and endow them with the ability for osteogenesis, vascularization, and neurogenesis. In this paper, we systematically review and summarize the research progress of GelMA composite hydrogel scaffolds in the field of bone defect repair, and discuss ways to improve the properties, which will provide ideas for the design and application of bionic bone substitutes.

Enhancing bone regeneration and immunomodulation via gelatin methacryloyl hydrogel-encapsulated exosomes from osteogenic pre-differentiated mesenchymal stem cells

Mesenchymal stem cell-derived exosomes (MSC-Exos) have emerged as promising candidates for cell-free therapy in tissue regeneration. However, the native osteogenic and angiogenic capacities of MSC-Exos are often insufficient to repair critical-sized bone defects, and the underlying immune mechanisms remain elusive. Furthermore, achieving sustained delivery and stable activity of MSC-Exos at the defect site is essential for optimal therapeutic outcomes. Here, we extracted exosomes from osteogenically pre-differentiated human bone marrow mesenchymal stem cells (hBMSCs) by ultracentrifugation and encapsulated them in gelatin methacryloyl (GelMA) hydrogel to construct a composite scaffold. The resulting exosome-encapsulated hydrogel exhibited excellent mechanical properties and biocompatibility, facilitating sustained delivery of MSC-Exos. Osteogenic pre-differentiation significantly enhanced the osteogenic and angiogenic properties of MSC-Exos, promoting osteogenic differentiation of hBMSCs and angiogenesis of human umbilical vein endothelial cells (HUVECs). Furthermore, MSC-Exos induced polarization of Raw264.7 cells from a pro-inflammatory phenotype to an anti-inflammatory phenotype under simulated inflammatory conditions, thereby creating an immune microenvironment conducive to osteogenesis. RNA sequencing and bioinformatics analysis revealed that MSC-Exos activate the p53 pathway through targeted delivery of internal microRNAs and regulate macrophage polarization by reducing DNA oxidative damage. Our study highlights the potential of osteogenic exosome-encapsulated composite hydrogels for the development of cell-free scaffolds in bone tissue engineering.

Engineering Approaches for Exosome Cargo Loading and Targeted Delivery: Biological versus Chemical Perspectives

Exosomes are nanoscale membrane bound vesicles secreted by almost all types of cells. Their unique attributes, such as minimal immunogenicity and compatibility with biological systems, make them novel carriers for drug delivery. These native exosomes harbor proteins, nucleic acids, small molecule compounds, and fluorogenic agents. Moreover, through a combination of chemical and bioengineering methodologies, exosomes are tailored to transport precise therapeutic payloads to designated cells or tissues. In this review, we summarize the strategies for exosome modification and drug loading modalities in engineered exosomes. In addition, we provide an overview of the advances in the use of engineered exosomes for targeted drug delivery. Lastly, we discuss the merits and limitations of chemically engineered versus bioengineered exosome-mediated target therapies. These insights offer additional options for refining engineered exosomes in pharmaceutical development and hold promise for expediting the successful translation of engineered exosomes from the bench to the bedside.

Extracellular vesicle-functionalized bioactive scaffolds for bone regeneration

The clinical need for effective bone regeneration in compromised conditions continues to drive demand for innovative solutions. Among emerging strategies, extracellular vesicles (EVs) have shown promise as an acellular approach for bone regeneration. However, their efficacy is hindered by rapid sequestration and clearance when administered via bolus injection. To address this challenge, EV-functionalized scaffolds have recently been proposed as an alternative delivery strategy to enhance EV retention and subsequent healing efficacy. This review aims to consolidate recent advancements in the development of EV-functionalized scaffolds for augmenting bone regeneration. It explores various sources of EVs and different strategies for integrating them into biomaterials. Furthermore, the mechanisms underlying their therapeutic effects in bone regeneration are elucidated. Current limitations in clinical translation and perspectives on the design of more efficient EVs for improved therapeutic efficacy are also presented. Overall, this review can provide inspiration for the development of novel EV-assisted grafts with superior bone regeneration potential.

Emerging role of liver-bone axis in osteoporosis

Background

Increasing attention to liver-bone crosstalk has spurred interest in targeted interventions for various forms of osteoporosis. Liver injury induced by different liver diseases can cause an imbalance in bone metabolism, indicating a novel regulatory paradigm between the liver and bone. However, the role of the liver-bone axis in both primary and secondary osteoporosis remains inadequately elucidated. Therefore, exploring the exact regulatory mechanisms of the liver-bone axis may offer innovative clinical approaches for treating diseases associated with the liver and bone.

Methods

Here, we summarize the latest research on the liver-bone axis by searching the PubMed and Web of Science databases and discuss the possible mechanism of the liver-bone axis in different types of osteoporosis. The literature directly reporting the regulatory role of the liver-bone axis in different types of osteoporosis from the PubMed and Web of Science databases has been included in the discussion of this review (including but not limited to the definition of the liver-bone axis, clinical studies, and basic research). In addition, articles discussing changes in bone metabolism caused by different etiologies of liver injury have also been included in the discussion of this review (including but not limited to clinical studies and basic research).

Results

Several endocrine factors (IGF-1, FGF21, hepcidin, vitamin D, osteocalcin, OPN, LCAT, Fetuin-A, PGs, BMP2/9, IL-1/6/17, and TNF-α) and key genes (SIRT2, ABCB4, ALDH2, TFR2, SPTBN1, ZNF687 and SREBP2) might be involved in the regulation of the liver-bone axis. In addition to the classic metabolic pathways involved in inflammation and oxidative stress, iron metabolism, cholesterol metabolism, lipid metabolism and immunometabolism mediated by the liver-bone axis require more research to elucidate the regulatory mechanisms involved in osteoporosis.

Conclusion

During primary and secondary osteoporosis, the liver-bone axis is responsible for liver and bone homeostasis via several hepatokines and osteokines as well as biochemical signaling. Combining multiomics technology and data mining technology could further advance our understanding of the liver-bone axis, providing new clinical strategies for managing liver and bone-related diseases.The translational potential of this article is as follows: Abnormal metabolism in the liver could seriously affect the metabolic imbalance of bone. This review summarizes the indispensable role of several endocrine factors and biochemical signaling pathways involved in the liver-bone axis and emphasizes the important role of liver metabolic homeostasis in the pathogenesis of osteoporosis, which provides novel potential directions for the prevention, diagnosis, and treatment of liver and bone-related diseases.

Bibliometric and visualized analysis of the applications of exosomes based drug delivery

Exosomes, endogenous vesicles secreted by cells, possess unique properties like high biocompatibility, low immunogenicity, targeting ability, long half-life, and blood-brain barrier permeability. They serve as crucial intercellular communication vectors in physiological processes and disease occurrence. Our comprehensive analysis of exosome-based drug delivery research from 2013 to 2023 revealed 2,476 authors from 717 institutions across 33 countries. Keyword clustering identified five research areas: drug delivery, mesenchymal stem cells, cancer immunotherapy, targeting ligands, surface modifications, and macrophages. The combination of exosome drug delivery technology with a proven clinical model enables the precise targeting of tumors with chemotherapy or radiosensitising agents, as well as facilitating gene therapy. This bibliometric analysis aims to characterize the current state and advance the clinical application of exosome-based drug delivery systems.

Harnessing the potential of hydrogels for advanced therapeutic applications: current achievements and future directions

The applications of hydrogels have expanded significantly due to their versatile, highly tunable properties and breakthroughs in biomaterial technologies. In this review, we cover the major achievements and the potential of hydrogels in therapeutic applications, focusing primarily on two areas: emerging cell-based therapies and promising non-cell therapeutic modalities. Within the context of cell therapy, we discuss the capacity of hydrogels to overcome the existing translational challenges faced by mainstream cell therapy paradigms, provide a detailed discussion on the advantages and principal design considerations of hydrogels for boosting the efficacy of cell therapy, as well as list specific examples of their applications in different disease scenarios. We then explore the potential of hydrogels in drug delivery, physical intervention therapies, and other non-cell therapeutic areas (e.g., bioadhesives, artificial tissues, and biosensors), emphasizing their utility beyond mere delivery vehicles. Additionally, we complement our discussion on the latest progress and challenges in the clinical application of hydrogels and outline future research directions, particularly in terms of integration with advanced biomanufacturing technologies. This review aims to present a comprehensive view and critical insights into the design and selection of hydrogels for both cell therapy and non-cell therapies, tailored to meet the therapeutic requirements of diverse diseases and situations.

Unveiling the versatility of gelatin methacryloyl hydrogels: a comprehensive journey into biomedical applications

Gelatin methacryloyl (GelMA) hydrogels have gained significant recognition as versatile biomaterials in the biomedical domain. GelMA hydrogels emulate vital characteristics of the innate extracellular matrix by integrating cell-adhering and matrix metalloproteinase-responsive peptide motifs. These features enable cellular proliferation and spreading within GelMA-based hydrogel scaffolds. Moreover, GelMA displays flexibility in processing, as it experiences crosslinking when exposed to light irradiation, supporting the development of hydrogels with adjustable mechanical characteristics. The drug delivery landscape has been reshaped by GelMA hydrogels, offering a favorable platform for the controlled and sustained release of therapeutic actives. The tunable physicochemical characteristics of GelMA enable precise modulation of the kinetics of drug release, ensuring optimal therapeutic effectiveness. In tissue engineering, GelMA hydrogels perform an essential role in the design of the scaffold, providing a biomimetic environment conducive to cell adhesion, proliferation, and differentiation. Incorporating GelMA in three-dimensional printing further improves its applicability in drug delivery and developing complicated tissue constructs with spatial precision. Wound healing applications showcase GelMA hydrogels as bioactive dressings, fostering a conducive microenvironment for tissue regeneration. The inherent biocompatibility and tunable mechanical characteristics of GelMA provide its efficiency in the closure of wounds and tissue repair. GelMA hydrogels stand at the forefront of biomedical innovation, offering a versatile platform for addressing diverse challenges in drug delivery, tissue engineering, and wound healing. This review provides a comprehensive overview, fostering an in-depth understanding of GelMA hydrogel's potential impact on progressing biomedical sciences.

Advances and Trends of Photoresponsive Hydrogels for Bone Tissue Engineering

The development of static hydrogels as an optimal choice for bone tissue engineering (BTE) remains a difficult challenge primarily due to the intricate nature of bone healing processes, continuous physiological functions, and pathological changes. Hence, there is an urgent need to exploit smart hydrogels with programmable properties that can effectively enhance bone regeneration. Increasing evidence suggests that photoresponsive hydrogels are promising bioscaffolds for BTE due to their advantages such as controlled drug release, cell fate modulation, and the photothermal effect. Here, we review the current advances in photoresponsive hydrogels. The mechanism of photoresponsiveness and its advanced applications in bone repair are also elucidated. Future research would focus on the development of more efficient, safer, and smarter photoresponsive hydrogels for BTE. This review is aimed at offering comprehensive guidance on the trends of photoresponsive hydrogels and shedding light on their potential clinical application in BTE.

Genetically engineered loaded extracellular vesicles for drug delivery

The use of extracellular vesicles (EVs) for drug delivery is being widely explored by scientists from several research fields. To fully exploit their therapeutic potential, multiple methods for loading EVs have been developed. Although exogenous methods have been extensively utilized, in recent years the endogenous method has gained significant attention. This approach, based on parental cell genetic engineering, is suitable for loading large therapeutic biomolecules such as proteins and nucleic acids. We review the most commonly used EV loading methods and emphasize the inherent advantages of the endogenous method over the others. We also examine the most recent advances and applications of this innovative approach to inform on the diverse therapeutic opportunities that lie ahead in the field of EV-based therapies.

Engineered exosomes and composite biomaterials for tissue regeneration

Exosomes, which are small vesicles enclosed by a lipid bilayer and released by many cell types, are widely dispersed and have garnered increased attention in the field of regenerative medicine due to their ability to serve as indicators of diseases and agents with therapeutic potential. Exosomes play a crucial role in mediating intercellular communication through the transfer of many biomolecules, including proteins, lipids, RNA, and other molecular constituents, between cells. The targeted transport of proteins and nucleic acids to specific cells has the potential to enhance or impair specific biological functions. Exosomes have many applications, and they can be used alone or in combination with other therapeutic approaches. The examination of the unique attributes and many functions of these factors has emerged as a prominent field of study in the realm of biomedical research. This manuscript summarizes the origins and properties of exosomes, including their structural, biological, physical, and chemical aspects. This paper offers a complete examination of recent progress in tissue repair and regenerative medicine, emphasizing the possible implications of these methods in forthcoming tissue regeneration attempts.

The role and applications of extracellular vesicles in osteoporosis

Osteoporosis is a widely observed condition characterized by the systemic deterioration of bone mass and microarchitecture, which increases patient susceptibility to fragile fractures. The intricate mechanisms governing bone homeostasis are substantially impacted by extracellular vesicles (EVs), which play crucial roles in both pathological and physiological contexts. EVs derived from various sources exert distinct effects on osteoporosis. Specifically, EVs released by osteoblasts, endothelial cells, myocytes, and mesenchymal stem cells contribute to bone formation due to their unique cargo of proteins, miRNAs, and cytokines. Conversely, EVs secreted by osteoclasts and immune cells promote bone resorption and inhibit bone formation. Furthermore, the use of EVs as therapeutic modalities or biomaterials for diagnosing and managing osteoporosis is promising. Here, we review the current understanding of the impact of EVs on bone homeostasis, including the classification and biogenesis of EVs and the intricate regulatory mechanisms of EVs in osteoporosis. Furthermore, we present an overview of the latest research progress on diagnosing and treating osteoporosis by using EVs. Finally, we discuss the challenges and prospects of translational research on the use of EVs in osteoporosis.

Exosomal non-coding RNAs: Emerging insights into therapeutic potential and mechanisms in bone healing

Exosomes are nano-sized extracellular vesicles (EVs) released by diverse types of cells, which affect the functions of targeted cells by transporting bioactive substances. As the main component of exosomes, non-coding RNA (ncRNA) is demonstrated to impact multiple pathways participating in bone healing. Herein, this review first introduces the biogenesis and secretion of exosomes, and elucidates the role of the main cargo in exosomes, ncRNAs, in mediating intercellular communication. Subsequently, the potential molecular mechanism of exosomes accelerating bone healing is elucidated from the following four aspects: macrophage polarization, vascularization, osteogenesis and osteoclastogenesis. Then, we systematically introduce construction strategies based on modified exosomes in bone regeneration field. Finally, the clinical trials of exosomes for bone healing and the challenges of exosome-based therapies in the biomedical field are briefly introduced, providing solid theoretical frameworks and optimization methods for the clinical application of exosomes in orthopedics.

Engineered Exosome for Drug Delivery: Recent Development and Clinical Applications

Exosomes are nano-sized membrane vesicles that transfer bioactive molecules between cells and modulate various biological processes under physiological and pathological conditions. By applying bioengineering technologies, exosomes can be modified to express specific markers or carry therapeutic cargo and emerge as novel platforms for the treatment of cancer, neurological, cardiovascular, immune, and infectious diseases. However, there are many challenges and uncertainties in the clinical translation of exosomes. This review aims to provide an overview of the recent advances and challenges in the translation of engineered exosomes, with a special focus on the methods and strategies for loading drugs into exosomes, the pros and cons of different loading methods, and the optimization of exosome production based on the drugs to be encapsulated. Moreover, we also summarize the current clinical applications and prospects of engineered exosomes, as well as the potential risks and limitations that need to be addressed in exosome engineering, including the standardization of exosome preparation and engineering protocols, the quality and quantity of exosomes, the control of drug release, and the immunogenicity and cytotoxicity of exosomes. Overall, engineered exosomes represent an exciting frontier in nanomedicine, but they still face challenges in large-scale production, the maintenance of storage stability, and clinical translation. With continuous advances in this field, exosome-based drug formulation could offer great promise for the targeted treatment of human diseases.

Exosome-based engineering strategies for the diagnosis and treatment of oral and maxillofacial diseases

Oral and maxillofacial diseases are one of the most prevalent diseases in the world, which not only seriously affect the health of patients' oral and maxillofacial tissues, but also bring serious economic and psychological burdens to patients. Therefore, oral and maxillofacial diseases require effective treatment. Traditional treatments have limited effects. In recent years, nature exosomes have attracted increasing attention due to their ability to diagnose and treat diseases. However, the application of nature exosomes is limited due to low yield, high impurities, lack of targeting, and high cost. Engineered exosomes can be endowed with better comprehensive therapeutic properties by modifying exosomes of parent cells or directly modifying exosomes, and biomaterial loading exosomes. Compared with natural exosomes, these engineered exosomes can achieve more effective diagnosis and treatment of oral and maxillary system diseases, and provide reference and guidance for clinical application. This paper reviews the engineering modification methods of exosomes and the application of engineered exosomes in oral and maxillofacial diseases and looks forward to future research directions.

Diabetic and nondiabetic BMSC-derived exosomes affect bone regeneration via regulating miR-17-5p/SMAD7 axis

Diabetic bone disease (DBD) is a complication of diabetes mellitus (DM) and is characterized by impaired osteocyte function and delayed bone remodeling due to high blood glucose levels and sustained release of inflammatory factors. Recent studies show that the regulation of osteoblasts (OBs) by bone marrow stromal cells (BMSCs) is an important mechanism in alleviating DBD and that exosomes are recognized as the key medium. Mesenchymal stem cell-derived exosome (MSC-Exos) therapy is a promising approach to facilitate tissue repair. However, the influence of exosomes from diabetic conditioned BMSCs on OBs and bone regeneration, as well as the underlying mechanism, are still elusive. Here, we used high-glucose medium to mimic diabetic conditions and normal-glucose medium as control to mimic nondiabetic conditions in vitro and found that microRNA-17 (miR-17) was downregulated in diabetic-conditioned BMSC-derived exosomes (HG-Exos), HG-Exo-co-cultured osteoblasts, and the skull of rats with type 2 diabetes mellitus (T2DM). Further experiment concluded that nondiabetic conditioned BMSC-Exos (NG-Exos) promoted the osteogenesis of OBs and bone regeneration of rats with T2DM via upregulation of miR-17. Compare with NG-Exos, HG-Exos impeded osteogenesis of OBs in vitro and bone regeneration of rats in vivo by downregulation of miR-17. Moreover, miR-17 promoted bone regeneration by targeting SMAD7, which was further proved to have a negative effect on osteogenesis. Taken together, nondiabetic BMSC-derived exosomes greatly foster bone regeneration, whereas diabetic BMSC-derived exosomes undermine the promotion effect of MSC-Exos by regulating the miR-17/SMAD7 axis. These findings provide support for the miR-17-5p/SMAD7 axis as a promising therapeutic target to treat DBD.

Bioengineered nanotechnology for nucleic acid delivery

Nucleic acid-based therapy has emerged as a promising therapeutic approach for treating various diseases, such as genetic disorders, cancers, and viral infections. Diverse nucleic acid delivery systems have been reported, and some, including lipid nanoparticles, have exhibited clinical success. In parallel, bioengineered nucleic acid delivery nanocarriers have also gained significant attention due to their flexible functional design and excellent biocompatibility. In this review, we summarize recent advances in bioengineered nucleic acid delivery nanocarriers, focusing on exosomes, cell membrane-derived nanovesicles, protein nanocages, and virus-like particles. We highlight their unique features, advantages for nucleic acid delivery, and biomedical applications. Furthermore, we discuss the challenges that bioengineered nanocarriers face towards clinical translation and the possible avenues for their further development. This review ultimately underlines the potential of bioengineered nanotechnology for the advancement of nucleic acid therapy.