Engineered mammalian and bacterial extracellular vesicles as promising nanocarriers for targeted therapy

Bioengineered bacterial extracellular vesicles for targeted delivery of an osteoclastogenesis-inhibitory peptide to alleviate osteoporosis

Osteoporosis (OP) is a systemic skeletal disease commonly found in women after 55 years old and men after 65 years old. With the worldwide aging of population, its prevalence rate is increasing rapidly, bringing huge financial burdens to all countries. As a potential alternative to the conventional OP therapeutics with limited efficacies and side effects, a linear peptide FRATtide capable of binding with phosphorylated GSK3β has been discovered by us to inhibit osteoclastogenesis thus reduce bone loss. While its poor proteolytic stability and osteoclast targetability hinder its effective in vivo treatment. As such, bacterial extracellular vesicles secreted by the rationally recombinant probiotics Escherichia coli Nissle 1917 that express pre-osteoclast fusion protein DC-STAMP (BEV-DCS) are engineered and exploited as delivery vehicles. The BEV-DCS not only protect FRAT from enzymatic degradation but also enable its targeted intracellular delivery into pre-osteoclasts. On the ovariectomy mouse model, the FRAT encapsulated BEV-DCS (FRAT@BEV-DCS) exhibit remarkable bone targeting capacity and osteoporosis ameliorating efficacy without any obvious toxicity. These results reveal the great potential of FRAT@BEV-DCS as a novel therapeutic option for the effective and safe OP treatment.

Enhancing immunogenicity and release of in situ-generated tumor vesicles for autologous vaccines

In situ vaccination (ISV) strategies offer an innovative approach to cancer immunotherapy by utilizing drug combinations directly at tumor sites to elicit personalized immune responses. Tumor cell-derived extracellular vesicles (TEVs) in ISV have great potential but face challenges such as low release rates and immunosuppressive proteins like programmed death ligand 1 (PD-L1) and CD47. This study develops a nanoparticle-based ISV strategy (Combo-NPs@shGNE) that enhances TEV release and modulates cargo composition. This approach combines Andrographolide, Icariside II, and shRNA targeting UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE), which accumulates in the tumor region, resulting in the regulation of immunosuppressive pathways and the reduction of sialic acid production. Decreasing the level of sialylation on the membrane through necroptosis and inhibition of sialic acid synthesis decreased the loading of PD-L1 and CD47 on vesicles, while increasing the loading of heat shock protein 70 and high mobility group box 1 on vesicles, and induced the release of highly immunogenic TEVs from the cancer cells, with a 56.44 % release, 9.57 times higher than that of blank nanoparticle-treated cells. In vivo studies demonstrate that Combo-NPs@shGNE enhances TEV yield, tumor growth, reduces metastases, and improves survival in an osteosarcoma mouse model. It promotes dendritic cell maturation, increases CD4+ and CD8+ T cell infiltration, and alters the microenvironment by reducing myeloid-derived suppressor cells and enhancing immunostimulatory factors. Additionally, it transitions tumor-associated macrophages from M2 to an M1 phenotype, thereby augmenting tumor immunity. Overall, Combo-NPs@shGNE offers a promising method for transforming tumors into personalized autologous vaccines, potentially advancing cancer treatment strategies.

Bacterial Extracellular Vesicles: Bridging Pathogen Biology and Therapeutic Innovation

The main role of bacterial extracellular vesicles (BEVs) has been associated with various processes such as intercellular communication and host-pathogen interactions. This comprehensive review explores the multifaceted functions of BEVs across different biological domains, emphasizing their dual nature as contributors to disease and potential vehicles for therapeutic intervention. We examine the intricate interactions of BEVs within bacterial communities and between bacteria and hosts, their involvement in disease development through cargo delivery mechanisms, and their beneficial impact on microbial ecology. The review also highlights BEVs' applications in biomedical field, where they are revolutionizing vaccine development, targeted drug delivery, and cancer therapy. By utilizing the inherent properties of BEVs for controlled drug release, targeted antigen delivery, and immune modulation, they offer a promising frontier in precision medicine. In addition, the diagnostic potential of BEVs is explored through their utility as biomarkers, providing valuable insights into disease states and treatment efficacy. Looking forward, this review underscores the challenges and opportunities in translating BEV research to clinical practice, promoting the need of standardized methods in BEV characterization and scaling up production. The diverse abilities of BEVs, ranging from contributing to pathogen virulence to driving therapeutic innovation, highlight their potential as a cornerstone in the future of biomedical advancements. STATEMENT OF SIGNIFICANCE: Bacterial extracellular vesicles (BEVs) are emerging as pivotal players in both pathogenesis and therapeutic innovation. This review explores their dual nature as agents of disease and as promising biomaterials for biomedical applications, and provides a comprehensive survey on their involvement in disease mechanisms and microbial ecology, and their potential in biomedical applications such as vaccine development, targeted drug delivery, cancer therapy, and diagnosis. It highlights the complex interactions of BEVs within bacterial communities and between bacteria and hosts. This review also addresses current advancements, challenges, and opportunities in translating BEV research into clinical practice. The insights presented here position BEVs as a cornerstone in the future of biomedical advancements, advocating for standardized methods in BEV characterization and scalable production techniques.

Mechanism of selenium-doped black phosphorus nanosheets wrapped with biomimetic tumor cell membrane for prostate cancer immunotherapy

Prostate cancer (PCa) is commonly considered a "cold tumor" due to its immunosuppressive microenvironment. Cold tumors are typically identified by the absence of T-cell infiltration within the tumor, while other immune populations and myeloid cells can be observed in these tumors. To achieve light-heat combined immunotherapy checkpoint inhibitor treatment for castration-resistant prostate cancer, we aimed to transforming "cold tumors" into "hot tumors". We designed and synthesized a two-dimensional material, selenium-doped black phosphorus (BP), to enhance the photothermal conversion efficiency, and formed Se@BPNSs by liquid-phase exfoliation. To address the issue of enhanced permeability and retention effect, and to achieve efficient targeting, we coated the Se@BPNSs with RM-1 cell membrane derived from mouse prostate cancer cells. By injecting a certain dose of Se@BPNSs into the tumor and irradiating with a 808 nm laser, the Se@BPNSs converted light energy into heat to kill tumor cells at high temperatures while releasing antigens captured by dendritic cells. In addition, we combined the immunotherapy checkpoint inhibitor anti-PD1 to enhance the immune response and promote immune cell infiltration. The successful preparation of Se@BPNSs was verified through material characterization, cell-level and animal-level experiments, and the antitumor effect was meanwhile verified, which further provided guidance for prostate cancer treatment by photothermal synergistic immunotherapy.

Leveraging engineered yeast small extracellular vesicles serve as multifunctional platforms for effectively loading methyl salicylate through the "esterase-responsive active loading" strategy

Small extracellular vesicles (sEVs) are a promising vehicle for drug delivery because of their good biocompatibility and nontoxicity. The drug loading and encapsulation efficiencies of them are not satisfactory. This is especially the case when drugs are loaded by co-incubation. In this situation, as the difference in drug concentration between the inside and outside of the membrane of ordinary sEVs decreases, the drugs cannot diffuse efficiently into the inside of the vesicles. As a result, the drug loading efficiency is low. In this study, engineered yeast-derived small extracellular vesicles derived from Pichia pastoris X33 (XPP-sEVs) engineered with carboxylesterase 1 (CES1) were constructed using the "esterase-responsive active loading" method, which is based on the concept of prodrug design and guided by the strategy of immobilized enzymes, to improve the loading efficiency of methyl salicylate (MS) to about twice as much. This was achieved by engineering the CES1-contained small extracellular vesicles to catalyze the esterase hydrolysis reaction of MS to establish a continuous MS transmembrane concentration gradient for efficient loading of the active drugs, including methyl salicylate and its hydrolyzed active product salicylic acid. The results showed that the enzyme activity of the CES1-sEVs group finally reached 7.88 ± 0.43 U/mL, and the drug loading efficiency was about doubled. The results of drug release from the engineered extracellular vesicles showed that the release of the drug reached equilibrium around 100 min-2 h, during which there was no sudden release of the MS, and the final amount of the drug released could be increased by 12.34 % compared with the emulsion dosage form of the MS. Overall, the CES1-sEVs prepared in this study significantly improved the drug-loading efficiency of MS without affecting the anti-inflammatory activity of MS. The MS-CES1-sEVs prepared in this study are non-toxic and have a bright application prospect in the treatment of skin inflammation.

[Lipidomics analysis of glycine-induced bacterial outer membrane vesicles]

Outer membrane vesicles (OMVs) are nanoparticles with double-phospholipid membrane structures that are secreted by gram-negative bacteria and carry a variety of bioactive substances from parental bacterial cells; consequently, OMVs serve as disease markers. Moreover, bacterial OMVs are potential anticancer- and antibacterial-drug carriers. While the addition of glycine during bacterial culturing promotes the secretion of bacterial OMVs, glycine-induced differences in the lipid compositions of such OMVs have not yet been reported. In this study, the key plasma membrane components of bacterial OMVs before and after glycine induction were analyzed using lipidomics. Bacterial OMVs were captured from bacterial-culture supernatants using an amphiphilic dendritic polymeric supramolecular probe. Two sets of enriched bacterial OMVs were characterized and their enrichment efficiencies determined, after which the numbers and purities of the OMVs within the samples were determined using a nanofluidic assay. Lipids were extracted using the methyl tert-butyl ether lipid-extraction method when consistent numbers were recorded. The lipid compositions of the bacterial OMVs before and after glycine induction were analyzed using an ultra-performance liquid chromatography-ion mobility spectrometry-quadrupole time-of-flight mass spectrometer (UPLC-IMS-QTOF-MS) and MS-DIAL software. Differential lipid species in the key plasma membranes of the bacterial OMVs following glycine induction were recorded along with their corresponding amounts. Detection was accomplished in positive-ion scanning mode using an ACQUITY UPLC BEH C18 column following UPLC-MS injection, and MSE mass-spectrometry data-acquisition mode. The lipid components in the two groups were determined by combining mass-spectrometric and software-analysis data, which revealed that the addition of glycine to the E. coli Nissle 1917 culture led to two-to-three-times higher concentrations of OMVs than observed for the untreated group under the same culturing and enrichment conditions. Particle numbers measured for the same volume revealed one-order-of-magnitude more bacterial OMVs after induction than before, with the treated group exhibiting slightly larger particles (on average); however, these particles were better dispersed and less likely to aggregate. The identified lipid components were categorized to determine the amount of each lipid type. Differentially expressed lipids were subsequently screened according to experimental conditions; significantly different expression levels were observed following glycine induction, with 820 lipids identified among the 10165 components detected. The lipid classes were ranked in order of quantity as: glycerolipids (GL), fatty acids (FA), sphingolipids (SP), glycerophospholipids (GP), saccharolipids (SL), and sterol lipids (ST), among which 463 GL lipid fractions (56.4% of all characterized lipids) were recorded. The ST lipid fraction contained the fewest members (10) and qualitative lipids were determined to make up 1.2% of the total. The addition of glycine to the E. coli culture was found to induce significant changes in the surface and internal lipid composition of the E. coli OMVs, with significantly more ceramide (Cer) and lysophosphatidyl choline (LPC), and significantly less bis(monoacylglycerol)phosphate (BMP) expressed. Partial triglyceride (TG) and sphingomyelin (SM) were irregularly expressed following glycine treatment, with equal amounts of up- and down-regulated lipids observed. This study provides a reference for subsequent in-depth studies into the lipid compositions of OMVs and their use as novel drug-delivery carriers. The expression of TGs and SM showed irregular changes, which is worthy of the next step of in-depth exploration of its regulatory mechanism, and the present study provides a certain reference for the subsequent in-depth study of the lipid composition of OMV and its use in the study of novel drug delivery carriers.

Advancements in the application of ablative therapy and its combination with immunotherapy in anti-cancer therapy

Cancer is a significant health issue impacting humans. Currently, systemic therapies such as chemotherapy have significantly increased the life expectancy of cancer patients. However, some patients are unable to endure systemic treatment due to its significant adverse effects, leading to an increased focus on local therapies including radiation and ablation therapy. Ablation therapy is a precise, low-toxicity, and minimally invasive localized therapy that is increasingly acknowledged by clinicians and cancer patients. Many cancer patients have benefited from it, with some achieving full recovery. Currently, numerous studies have shown that ablation therapy is effective due to its ability to kill cancer cells efficiently and activate the body's anti-cancer immunity. It can also convert "cold cancers" into "hot cancers" and enhance the effectiveness of immunotherapy when used in combination. In this article, we categorize ablation therapy into thermal ablation, cryoablation, photodynamic therapy (PDT), irreversible electroporation (IRE), etc. Thermal ablation is further divided into Radiofrequency ablation (RFA), microwave ablation (WMA), high-frequency focused ultrasound (HIFU), photothermal therapy (PTT), magnetic heat therapy (MHT), etc. We systematically review the most recent advancements in these ablation therapies that are either currently used in clinic or are anticipated to be used in clinic. Then, we also review the latest development of various ablative therapies combined with immunotherapy, and its future development. CLINICAL RELEVANCE STATEMENT: Ablation therapy, an invasive localized treatment, offers an alternative to systemic therapies for cancer patients who cannot tolerate their adverse effects. Its ability to kill cancer cells efficiently and activate anti-cancer immunity. This article reviews recent advancements in ablation therapies, including thermal, cryoablation, PDT, and IRE, and their potential clinical applications, both standalone and in combination with immunotherapy.

Lipid Nanovesicles in Cancer Treatment: Improving Targeting and Stability of Antisense Oligonucleotides

Cancer remains a leading cause of mortality worldwide, accounting for approximately 10 million deaths annually. Standard treatments, including surgery, radiotherapy, and chemotherapy, often result in damage to healthy cells and severe toxic side effects. In recent years, antisense technology therapeutics, which interfere with RNA translation through complementary base pairing, have emerged as promising approaches for cancer treatment. Despite the availability of various antisense oligonucleotide (ASO) drugs on the market, challenges such as poor active targeting and susceptibility to clearance by circulating enzymes remain. Compared with other delivery systems, lipid nanovesicle (LNV) delivery systems offer a potential solution that uniquely enhances ASO targeting and stability. Studies have shown that LNVs can increase the accumulation of ASOs in tumor sites several-fold, significantly reducing systemic toxic reactions and demonstrating increased therapeutic efficiency in preclinical models. Additionally, LNVs can protect ASOs from enzymatic degradation within the body, extending their half-life and thus enhancing their therapeutic effects. This paper provides a comprehensive review of recent examples and applications of LNV delivery of ASOs in cancer treatment, highlighting their unique functions and outcomes. Furthermore, this paper discusses the key challenges and potential impacts of this innovative approach to cancer therapy.

Bifidobacterium longum NSP001-derived extracellular vesicles ameliorate ulcerative colitis by modulating T cell responses in gut microbiota-(in)dependent manners

Recent studies have shown that intestinal commensal bacteria-derived vesicles may have potential effects in alleviating ulcerative colitis (UC). Although Bifidobacterium longum is widely used to prevent colitis, the potential role of B. longum-derived extracellular vesicles has yet to be explored. Here, we extracted B. longum NSP001-derived extracellular vesicles (NEVs) and investigated the regulatory roles of NEVs in colitis. Our results demonstrated that NEVs alleviate UC by improving intestinal barrier, modulating immune cell differentiation, and promoting the production of SCFAs. NEVs' improvement of inflammation in pseudo-germ-free mice implies that the anti-inflammatory effect of NEVs does not exclusively depend on the regulation of gut microbiota. In conclusion, we suggest that B. longum NSP001 improves UC through the secretion of NEVs. In addition, the study emphasizes the critical role of NEVs in maintaining host immune homeostasis via suppressing STAT3 pathway, thereby highlighting their potential as a novel postbiotic to alleviate UC.

An Injectable Hydrogel Bioimplant Loaded with Engineered Exosomes and Triple Anti-Tuberculosis Drugs with Potential for Treating Bone and Joint Tuberculosis

Purpose

Treatment for bone and joint tuberculosis (BJTB) is challenging due to its refractory and recurrent nature. This study aimed to develop a bioimplantable scaffold with osteoinductive and antituberculosis characteristics to treat BJTB.

Methods

This scaffold is built on oxidized hyaluronic acid and carboxymethyl chitosan hydrogel mixed with hydroxyapatite as a bone tissue engineered material. In order to make the scaffold have the biological activity of promoting tissue repair, the engineered exosomes (Exoeng) were added innovatively. In addition, drug-loaded liposomes equipped with an aldehyde group on the surface are cross-linked with the amine group of the hydrogel skeleton to participate in the Schiff base reaction.

Results

The designed scaffold has characteristics of self-healing and injectability exhibit excellent anti-tuberculosis and promoting bone repair activities. Exoeng strongly stimulates cellular angiogenesis and osteogenic differentiation. The liposomes coated in hydrogel can release three kinds of anti-tuberculosis drugs smoothly and slowly, achieving a long term anti-tuberculosis.

Conclusion

The composite bio-scaffold shows good tissue repair and long-term anti-tuberculosis abilities, which expected to provide a viable treatment plan for bone-related BJTB.

Opportunities and challenges of bacterial extracellular vesicles in regenerative medicine

Extracellular vesicles (EVs) are membrane-bound vesicles that are shed or secreted from the cell membrane and enveloped by a lipid bilayer. They possess stability, low immunogenicity, and non-cytotoxicity, exhibiting extensive prospects in regenerative medicine (RM). However, natural EVs pose challenges, such as insufficient targeting capabilities, potential biosafety concerns, and limited acquisition pathways. Although engineered EVs demonstrate excellent therapeutic efficacy, challenges such as low production yield and the complexity of engineering modifications constrain their further clinical applications. Bacteria have advantages such as rapid proliferation, diverse gene editing methods, mature cultivation techniques, and relatively easy preparation of bacterial EVs (BEVs), which can be used to effectively address the challenges currently encountered in the field of EVs. This review provides a description of the biogenesis and pathophysiological functions of BEVs, and strategies for optimizing BEVs preparation to attain efficiency and safety are discussed. An analysis of natural characteristics of BEVs is also conducted to explore how to leverage their advantages or mitigate their limitations, thereby overcoming constraints on the application of BEVs in RM. In summary, engineered BEVs possess characteristics such as high production yield, excellent stability, and high drug-delivering capabilities, laying the foundation for their application in RM.

Engineering Autologous Cell-Derived Exosomes to Boost Melanoma-Targeted Radio-Immunotherapy by Cascade cGAS-STING Pathway Activation

Radio-immunotherapy has offered emerging opportunities to treat invasive melanoma due to its immunostimulatory performances to activate antitumor immune responses. However, the immunosuppressive microenvironment and insufficient response rate significantly limit the practical efficacy. This study presents an autologous cell-derived exosomes (Exo)-engineered nanoagonist (MnExo@cGAMP) containing with metalloimmunotherapeutic agent (Mn2+ ions) and nucleotidyltransferase (2',3'-cGAMP, a STING agonist) for boosting melanoma-targeted radio-immunotherapy by cascade cGAS-STING pathway activation. The MnExo@cGAMP can efficiently accumulate in tumor cells due to the autologous targeting performance. Once internalized by tumor cells, the released Mn2+ ions will enhance stimulator of interferon gene (STING) binding and sensitize cyclic GMP-AMP (cGAS) to radiotherapy-induced double-straned DNA (dsNDA), resulting in amplification of cGAS-STING pathway activation together with X-ray irradiation. Meanwhile, loaded 2',3'-cGAMP can directly augment pathway activity acting as a secondary messenger. These cascade activations of cGAS-STING pathway trigger the overexpression of type I interferon, promote dendritic cells (DCs) maturation, antigen presentation, and increase CD8+ T cell activation, resulting effective radio-immunotherapeutic outcome by overcoming immune-suppression in melanoma. This study demonstrates a targeted therapeutic modality involving metalloimmunotherapy and agonist for efficient melanoma radio-immunotherapy by cascade cGAS-STING pathway activation.

A simple polydopamine-based platform for engineering extracellular vesicles with brain-targeting peptide and imaging probes to improve stroke outcome

Extracellular vesicles (EVs) have shown great potential for treating various diseases. Translating EVs-based therapy from bench to bedside remains challenging due to inefficient delivery of EVs to the injured area and lack of techniques to visualize the entire targeting process. Here we developed a dopamine surface functionalization platform that facilitates easy and simultaneous conjugation of targeting peptide and multi-mode imaging probes to the surface of EVs. Utilizing this platform we concurrently modified M2 microglia-derived EVs (M2-EVs) with neuronal targeting peptide rabies virus glycoprotein peptide 29 (RVG29) and multi-modal imaging tracers, resulting in the targeted delivery of M2-EVs to stroke mice brain and enabled the dynamic visualization of the targeting process from whole-body to cellular levels. We determined that intra-arterial injection achieved the highest efficiency of targeted delivery of engineered EVs to the stroke mice brain, improved therapeutic efficacy by reducing neuronal apoptosis. Mechanistically, EVs miRNA array revealed that a number of anti-apoptosis related miRNAs were significantly up-regulated, including miR-221-3p and miR-423-3p, both exerted anti-apoptotic effects through p38/ERK signalling pathways in stroke. Overall, this platform provides a facile and powerful tool for multifunctional engineering of EVs for multiscale therapeutic evaluation and enhancement of EV-based therapy, with valuable prospects for clinical translation.

Extracellular vesicles of Lactiplantibacillus plantarum PCM 2675 and Lacticaseibacillus rhamnosus PCM 489: an introductory characteristic

Aim: Extracellular vesicles (EVs) are involved in intercellular and interkingdom communication in the complex communities that constitute the niche-specific microbiome of the colonized host. Therefore, studying the structure and content of EVs produced by resident bacteria is crucial to understanding their functionality and impact on the host and other microorganisms. Methods: Bacterial EVs were isolated by differential centrifugation, their size and concentration were measured by transmission electron microscopy and nanoparticle tracking analysis, and the cargo proteins were identified by liquid chromatography coupled to tandem mass spectrometry. The cytotoxicity of bacterial EVs was tested using the human epithelial cell line A549 and an in vivo model of Galleria mellonella larvae. Results: The isolation and preliminary characteristics of EVs from two strains of lactic acid bacteria - Lactiplantibacillus plantarum PCM 2675 and Lacticaseibacillus rhamnosus PCM 489 - were presented, confirming the production of vesicular structures with sizes in the range of 50-170 nm for L. plantarum and 80-250 nm for L. rhamnosus. In addition, various proteins were identified within EVs cargo, with distinct locations of origin, including membrane, cytoplasmic and extracellular proteins, and with diverse functions, including enzymes with confirmed proteolytic activity. Furthermore, bacterial EVs did not show statistically significant cytotoxicity to the host under the tested conditions. Conclusions: A better understanding of the composition and functionality of bacterial EVs may contribute to their future effective use in supporting human health.

Organoids and organoid extracellular vesicles-based disease treatment strategies

Organoids are "mini-organs" that self-organize and differentiate from stem cells under in vitro 3D culture conditions, mimicking the spatial structure and function of tissues in vivo. Extracellular vesicles (EVs) are nanoscale phospholipid bilayer vesicles secreted by living cells, rich in bioactive molecules, with excellent biocompatibility and low immunogenicity. Compared to EVs, organoid-derived EVs (OEVs) exhibit higher yield and enhanced biological functions. Organoids possess stem cell characteristics, and OEVs are capable of delivering active substances, making both highly promising for medical applications. In this review, we provide an overview of the fundamental biological principles of organoids and OEVs, and discuss their current applications in disease treatment. We then focus on the differences between OEVs and traditional EVs. Subsequently, we present methods for the engineering modification of OEVs. Finally, we critically summarize the advantages and challenges of organoids and OEVs. In conclusion, we believe that a deeper understanding of organoids and OEVs will provide innovative solutions to complex diseases.

Utilization of Probiotic-Derived Extracellular Vesicles as Postbiotics and Their Role in Mental Health Therapeutics

As consumers become more interested in healthier lifestyles, the global functional food market is expanding. Probiotics have gained attention because of their numerous health benefits to the host and may even treat various pathological conditions. Probiotics interact with host cells, and particularly, probiotics-derived extracellular vesicles (PEVs) are key factors in the health benefits of probiotics. Additionally, extracellular vesicles are nano-scaled lipid-bilayer particles that carry various biological molecules, indicating potential as new postbiotics that can provide the same health benefits as probiotics while complementing the side effects associated with probiotics. The importance of mental health care is becoming increasingly prominent considering societal conditions, such as the recent aging population and the coronavirus disease 2019 pandemic. However, the response to mental health issues among modern individuals is insufficient, and there is a need for the development of new personalized treatments to overcome the limitations of current mental health therapies. PEVs have various physiological functions, including mediating cellular communication in the central nervous system, which indicates associations among mental disorders. Therefore, we focused on the beneficial effects of PEVs on the brain and mental health. Recent research has shown that PEVs can adjust the expression of brain-derived neurotrophic factors in vitro and in vivo, demonstrating antidepressant and cognitive function improvement effects. This suggests that PEVs have potential as therapeutic agents for improving mental health and treating brain disorders. Based on this, we review these findings and present the beneficial effects of PEVs on mental health and the challenges that need to be addressed.

Lactobacillus rhamnosus GG-derived extracellular vesicles promote wound healing via miR-21-5p-mediated re-epithelization and angiogenesis

Extracellular vesicles (EVs), especially those derived from stem cells, have emerged as a novel treatment for promoting wound healing in regenerative medicine. However, the clinical application of mammalian cells-derived EVs is hindered by their high cost and low yields. Inspired by the ability of EVs to mediate interkingdom communication, we explored the therapeutic potential of EVs released by the probiotic strain Lactobacillus rhamnosus GG (LGG) in skin wound healing and elucidated the underlying mechanism involved. Using full-thickness skin wound-healing mouse models, we found that LGG-EVs accelerated wound healing procedures, including increased re-epithelialization and promoted angiogenesis. Using in vitro experiments, we further demonstrated that LGG-EVs boosted the proliferation and migration capacities of both epithelial and endothelial cells, as well as promoted endothelial tube formation. miRNA profiling analysis revealed that miR-21-5p was highly enriched in LGG-EVs and LGG-EV treatment significantly increased miR-21-5p level in recipient cells. Mechanically, LGG-EVs induced regulatory effects via miR-21-5p mediated metabolic signaling rewiring. Our results suggest that EVs derived from LGG could serve as a promising candidate for accelerating wound healing and possibly for treating chronic and impaired healing conditions.

The siEGFR nanoplexes for the enhanced brain glioma treatment: Endoplasmic reticulum biomimetic strategy to induce homing effect and non-degradable intracellular transport

The epidermal growth factor receptor (EGFR) plays a pivotal role in tumor progression and is an essential therapeutic target for treating malignant gliomas. Small interfering RNA (siRNA) has the potential to selectively degrade EGFR mRNA, yet its clinical utilization is impeded by various challenges, such as inefficient targeting and limited escape from lysosomes. Our research introduces polyethylene glycol (PEG) and endoplasmic reticulum membrane-coated siEGFR nanoplexes (PEhCv/siEGFR NPs) as an innovative approach to brain glioma therapy by overcoming several obstacles: 1) Tumor-derived endoplasmic reticulum membrane modifications provide a homing effect, facilitating targeted accumulation and cellular uptake; 2) Endoplasmic reticulum membrane proteins mediate a non-degradable "endosome-Golgi-endoplasmic reticulum" transport pathway, circumventing lysosomal degradation. These nanoplexes demonstrated significantly enhanced siEGFR gene silencing in both in vitro and in vivo U87 glioma models. The findings of this study pave the way for the advanced design and effective application of nucleic acid-based therapeutic nanocarriers.

Bacterial extracellular vesicles: biotechnological perspective for enhanced productivity

Bacterial extracellular vesicles (BEVs) are non-replicative nanostructures released by Gram-negative and Gram-positive bacteria as a survival mechanism and inter- and intraspecific communication mechanism. Due to BEVs physical, biochemical, and biofunctional characteristics, there is interest in producing and using them in developing new therapeutics, vaccines, or delivery systems. However, BEV release is typically low, limiting their application. Here, we provide a biotechnological perspective to enhance BEV production, highlighting current strategies. The strategies include the production of hypervesiculating strains through gene modification, bacteria culture under stress conditions, and artificial vesicles production. We discussed the effect of these production strategies on BEVs types, morphology, composition, and activity. Furthermore, we summarized general aspects of BEV biogenesis, functional capabilities, and applications, framing their current importance and the need to produce them in abundance. This review will expand the knowledge about the range of strategies associated with BEV bioprocesses to increase their productivity and extend their application possibilities.

Synthetic biology-based bacterial extracellular vesicles displaying BMP-2 and CXCR4 to ameliorate osteoporosis

Osteoporosis (OP) is a systematic bone disease characterized by low bone mass and fragile bone microarchitecture. Conventional treatment for OP has limited efficacy and long-term toxicity. Synthetic biology makes bacterial extracellular vesicle (BEVs)-based therapeutic strategies a promising alternative for the treatment of OP. Here, we constructed a recombinant probiotics Escherichia coli Nissle 1917-pET28a-ClyA-BMP-2-CXCR4 (ECN-pClyA-BMP-2-CXCR4), in which BMP-2 and CXCR4 were overexpressed in fusion with BEVs surface protein ClyA. Subsequently, we isolated engineered BEVs-BMP-2-CXCR4 (BEVs-BC) for OP therapy. The engineered BEVs-BC exhibited great bone targeting in vivo. In addition, BEVs-BC had good biocompatibility and remarkable ability to promote osteogenic differentiation of BMSCs. Finally, the synthetic biology-based BEVs-BC significantly prevented the OP in an ovariectomized (OVX) mouse model. In conclusion, we constructed BEVs-BC with both bone-targeting and bone-forming in one-step using synthetic biology, which provides an effective strategy for OP and has great potential for industrialization.

Current progression in application of extracellular vesicles in central nervous system diseases

Early diagnosis and pharmacological treatment of central nervous system (CNS) diseases has been a long-standing challenge for clinical research due to the presence of the blood-brain barrier. Specific proteins and RNAs in brain-derived extracellular vesicles (EVs) usually reflect the corresponding state of brain disease, and therefore, EVs can be used as diagnostic biomarkers for CNS diseases. In addition, EVs can be engineered and fused to target cells for delivery of cargo, demonstrating the great potential of EVs as a nanocarrier platform. We review the progress of EVs as markers and drug carriers in the diagnosis and treatment of neurological diseases. The main areas include visual imaging, biomarker diagnosis and drug loading therapy for different types of CNS diseases. It is hoped that increased knowledge of EVs will facilitate their clinical translation in CNS diseases.

New Insights into Pharmaceutical Nanocrystals for the Improved Topical Delivery of Therapeutics in Various Skin Disorders

Nanotechnology has provided nanostructure-based delivery of drugs, among which nanocrystals have been investigated and explored for feasible topical drug delivery. Nanocrystals are nano-sized colloidal carriers, considered pure solid particles with a maximum drug load and a very small amount of stabilizer. The size or mean diameter of the nanocrystals is less than 1 μm and has a crystalline character. Prominent synthesis methods include the utilization of microfluidic- driven platforms as well as the milling approach, which is both adaptable and adjustable. Nanocrystals have shown a high capacity for loading drugs, utilization of negligible amounts of excipients, greater chemical stability, lower toxic effects, and ease of scale-up, as well as manufacturing. They have gained interest as drug delivery platforms, and the significantly large surface area of the skin makes it a potential approach for topical therapeutic formulations for different skin disorders including fungal and bacterial infections, psoriasis, wound healing, and skin cancers, etc. This article explores the preparation techniques, applications, and recent patents of nanocrystals for treating various skin conditions.

Engineered bacterial extracellular vesicles for central nervous system diseases

The prevalence of central nervous system (CNS) diseases is on the rise as the population ages. The presence of various obstacles, particularly the blood-brain barrier (BBB), poses a challenge for drug delivery to the CNS. An expanding body of study suggests that gut microbiota (GM) plays an important role in CNS diseases. The communication between GM and CNS diseases has received increasing attention. Accumulating evidence indicates that the GM can modulate host signaling pathways to regulate distant organ functions by delivering bioactive substances to host cells via bacterial extracellular vesicles (BEVs). BEVs have emerged as a promising platform for the treatment of CNS diseases due to their nanostructure, ability to penetrate the BBB, as well as their low toxicity, high biocompatibility, ease of modification and large-scale culture. Here, we discuss the biogenesis, internalization mechanism and engineering modification methods of BEVs. We then focus on the use and potential role of BEVs in the treatment of CNS diseases. Finally, we outline the main challenges and future prospects for the application of BEVs in CNS diseases. We hope that the comprehensive understanding of the BEVs-based gut-brain axis will provide new insights into the treatment of CNS diseases.

Human Breast Milk miRNAs: Their Diversity and Potential for Preventive Strategies in Nutritional Therapy

The endogenous miRNAs of breast milk are the products of more than 1000 nonprotein-coding genes, giving rise to mature small regulatory molecules of 19-25 nucleotides. They are incorporated in macromolecular complexes, loaded on Argonaute proteins, sequestrated in exosomes and lipid complexes, or present in exfoliated cells of epithelial, endothelial, or immune origins. Their expression is dependent on the stage of lactation; however, their detection depends on progress in RNA sequencing and the reappraisal of the definition of small RNAs. Some miRNAs from plants are detected in breast milk, opening the possibility of the stimulation of immune cells from the allergy repertoire. Each miRNA harbors a seeding sequence, which targets mRNAs, gene promoters, or long noncoding RNAs. Their activities depend on their bioavailability. Efficient doses of miRNAs are estimated to be roughly 100 molecules in the cytoplasm of target cells from in vitro and in vivo experiments. Each miRNA is included in networks of stimulation/inhibition/sequestration, driving the expression of cellular phenotypes. Three types of stress applied during lactation to manipulate miRNA supply were explored using rodent offspring: a foster mother, a cafeteria diet, and early weaning. This review presents the main mature miRNAs described from current mothers' cohorts and their bioavailability in experimental models as well as studies assessing the potential of miR-26 or miR-320 miRNA families to alter offspring phenotypes.

Role of Legionella pneumophila outer membrane vesicles in host-pathogen interaction

Legionella pneumophila is an opportunistic intracellular pathogen that inhabits artificial water systems and can be transmitted to human hosts by contaminated aerosols. Upon inhalation, it colonizes and grows inside the alveolar macrophages and causes Legionnaires' disease. To effectively control and manage Legionnaires' disease, a deep understanding of the host-pathogen interaction is crucial. Bacterial extracellular vesicles, particularly outer membrane vesicles (OMVs) have emerged as mediators of intercellular communication between bacteria and host cells. These OMVs carry a diverse cargo, including proteins, toxins, virulence factors, and nucleic acids. OMVs play a pivotal role in disease pathogenesis by helping bacteria in colonization, delivering virulence factors into host cells, and modulating host immune responses. This review highlights the role of OMVs in the context of host-pathogen interaction shedding light on the pathogenesis of L. pneumophila. Understanding the functions of OMVs and their cargo provides valuable insights into potential therapeutic targets and interventions for combating Legionnaires' disease.

Bio-Inspired Nanocarriers Derived from Stem Cells and Their Extracellular Vesicles for Targeted Drug Delivery

With their seemingly limitless capacity for self-improvement, stem cells have a wide range of potential uses in the medical field. Stem-cell-secreted extracellular vesicles (EVs), as paracrine components of stem cells, are natural nanoscale particles that transport a variety of biological molecules and facilitate cell-to-cell communication which have been also widely used for targeted drug delivery. These nanocarriers exhibit inherent advantages, such as strong cell or tissue targeting and low immunogenicity, which synthetic nanocarriers lack. However, despite the tremendous therapeutic potential of stem cells and EVs, their further clinical application is still limited by low yield and a lack of standardized isolation and purification protocols. In recent years, inspired by the concept of biomimetics, a new approach to biomimetic nanocarriers for drug delivery has been developed through combining nanotechnology and bioengineering. This article reviews the application of biomimetic nanocarriers derived from stem cells and their EVs in targeted drug delivery and discusses their advantages and challenges in order to stimulate future research.

Opportunities for engineering outer membrane vesicles using synthetic biology approaches

Gram-negative bacteria naturally shed lipid vesicles, which contain complex molecular cargoes, from their outer membrane. These outer membrane vesicles (OMVs) have important biological functions relating to microbial stress responses, microbiome regulation, and host-pathogen interactions. OMVs are also attractive vehicles for delivering drugs, vaccines, and other therapeutic agents because of their ability to interact with host cells and their natural immunogenic properties. OMVs are also set to have a positive impact on other biotechnological and medical applications including diagnostics, bioremediation, and metabolic engineering. We envision that the field of synthetic biology offers a compelling opportunity to further expand and accelerate the foundational research and downstream applications of OMVs in a range of applications including the provision of OMV-based healthcare technologies. In our opinion, we discuss how current and potential future synergies between OMV research and synthetic biology approaches might help to further accelerate OMV research and real-world applications for the benefit of animal and human health.

An interplay between non-coding RNAs and gut microbiota in human health

Humans have a complicated symbiotic relationship with their gut microbiome, which is postulated to impact host health and disease broadly. Epigenetic alterations allow host cells to regulate gene expression without altering the DNA sequence. The gut microbiome, offering environmental hints, can influence responses to stimuli by host cells with modifications on their epigenome and gene expression. Recent increasing data suggest that regulatory non-coding RNAs (miRNAs, circular RNAs, and long lncRNA) may affect host-microbe interactions. These RNAs have been suggested as potential host response biomarkers in microbiome-associated disorders, including diabetes and cancer. This article reviews the current understanding of the interplay between gut microbiota and non-coding RNA, including lncRNA, miRNA, and circular RNA. This can lead to a profound understanding of human disease and influence therapy. Furthermore, microbiome engineering as a mainstream strategy for improving human health has been discussed and confirms the hypothesis about a direct cross-talk between microbiome composition and non-coding RNA.

New insights of engineered extracellular vesicles as promising therapeutic systems

Extracellular vesicles (EVs) are natural biological particles that carry and deliver molecular fingerprints from parental cells to receptor cells, where they take effect. EVs are widely recognized for their role as intercellular communication mediators and high correlation with disease evolution, making them a valuable target in many aspects, especially biomarker profiling and therapeutics. In the past decade, scientists from various disciplines, including biology, physics, chemistry, materials science, electrical engineering, and mechanical engineering, have jointly devoted efforts to advance the study of EVs from fundamental molecular mechanisms to EV-based translational medicine, covering EV marker-based diagnostics and EV-based drug delivery. Diverse interfacial engineering strategies have been developed to facilitate in vitro and in vivo studies of EVs. This special issue, titled "Interfacial Engineering Strategies for EV in vitro and in vivo Studies", focuses on understanding the engineering logic and design rules of EVs in biomedical fields, highlighting their therapeutic potential in combating many diseases. This will provide new insights into the construction of promising diagnostic and therapeutic systems.

Targeted microbubbles combined with low-power focused ultrasound promote the thrombolysis of acute deep vein thrombosis

Introduction: The side effects of conventional therapy for acute deep vein thrombosis (DVT) are severe, with inflammatory reactions playing a pivotal role. It is particularly important to explore new ways of treatment thrombosis by targeting inflammatory factors.

Methods: A targeted microbubble contrast agent was prepared using the biotin-avidin method. The 40 DVT model rabbits were established and divided into four groups according to different treatment regimens. The four coagulation indexes, TNF-α, and D-dimer content of experimental animals were measured before modeling and before and after treatment, and the thrombolysis was assessed by ultrasound imaging. Finally, the results were verified by pathology.

Results and Discussion: Fluorescence microscopy verified the successful preparation of targeted microbubbles. Among the groups, PT, APTT, and TT in Group II-IV were longer than those in Group I (all p < 0.05). FIB and D-dimer content were lower than those in Group I (all p < 0.05), and TNF-α content in Group IV was lower than that in Group I-III (all p < 0.05). Pairwise comparison before modeling and before treatment and after treatment showed that, after treatment, the PT, APTT, and TT in Group II-IV were longer than those before modeling (all p < 0.05). The contents of FIB and D-dimer were lower than those before modeling and before treatment (all p < 0.05). The content of TNF-α decreased significantly only in Group IV, but increased in the other three groups. Targeted microbubbles combined with Low-power focused ultrasound can reduce inflammation, significantly promote thrombolysis, and provide new ideas and methods for the diagnosis and treatment of acute DVT.

Intra-articular nanodrug delivery strategies for treating osteoarthritis

Osteoarthritis (OA) is characterized by progressive cartilage degeneration. Pharmaceutical intervention remains a main treatment approach. However, drug delivery via intra-articular administration (IA) can be restricted by rapid clearance, the dense and highly negatively charged extracellular matrix (ECM) of cartilage, and uneven distribution of diseased chondrocytes. Nanodrug delivery systems, such as liposomes, micelles, and nanoparticles (NPs), have shown great potential to prolong intra-articular residence, penetrate the ECM, and achieve diseased chondrocyte-specific delivery. In this review, we discuss the challenges associated with intra-articular drug delivery in OA and the nanodrug delivery strategies developed to overcome these challenges. It is anticipated that these nanodrug delivery strategies will advance IA of drugs into broader applications in OA treatment.

Selection and identification of a novel ssDNA aptamer targeting human skeletal muscle

Skeletal muscle disorders have posed great threats to health. Selective delivery of drugs and oligonucleotides to skeletal muscle is challenging. Aptamers can improve targeting efficacy. In this study, for the first time, the human skeletal muscle-specific ssDNA aptamers (HSM01, etc.) were selected and identified with Systematic Evolution of Ligands by Exponential Enrichment (SELEX). The HSM01 ssDNA aptamer preferentially interacted with human skeletal muscle cells in vitro. The in vivo study using tree shrews showed that the HSM01 ssDNA aptamer specifically targeted human skeletal muscle cells. Furthermore, the ability of HSM01 ssDNA aptamer to target skeletal muscle cells was not affected by the formation of a disulfide bond with nanoliposomes in vitro or in vivo, suggesting a potential new approach for targeted drug delivery to skeletal muscles via liposomes. Therefore, this newly identified ssDNA aptamer and nanoliposome modification could be used for the treatment of human skeletal muscle diseases.

Exosomes: from biology to immunotherapy in infectious diseases

Exosomes are extracellular vesicles derived from the endosomal compartment, which are released by all kinds of eukaryotic and prokaryotic organisms. These vesicles contain a variety of biomolecules that differ both in quantity and type depending on the origin and cellular state. Exosomes are internalized by recipient cells, delivering their content and thus contributing to cell-cell communication in health and disease. During infections exosomes may exert a dual role, on one hand, they can transmit pathogen-related molecules mediating further infection and damage, and on the other hand, they can protect the host by activating the immune response and reducing pathogen spread. Selective packaging of pathogenic components may mediate these effects. Recently, quantitative analysis of samples by omics technologies has allowed a deep characterization of the proteins, lipids, RNA, and metabolite cargoes of exosomes. Knowledge about the content of these vesicles may facilitate their therapeutic application. Furthermore, as exosomes have been detected in almost all biological fluids, pathogenic or host-derived components can be identified in liquid biopsies, making them suitable for diagnosis and prognosis. This review attempts to organize the recent findings on exosome composition and function during viral, bacterial, fungal, and protozoan infections, and their contribution to host defense or to pathogen spread. Moreover, we summarize the current perspectives and future directions regarding the potential application of exosomes for prophylactic and therapeutic purposes.

Extracellular vesicles derived from host and gut microbiota as promising nanocarriers for targeted therapy in osteoporosis and osteoarthritis

Osteoporosis (OP), a systemic bone disease that causes structural bone loss and bone mass loss, is often associated with fragility fractures. Extracellular vesicles (EVs) generated by mammalian and gut bacteria have recently been identified as important mediators in the intercellular signaling pathway that may play a crucial role in microbiota-host communication. EVs are tiny membrane-bound vesicles, which range in size from 20 to 400 nm. They carry a variety of biologically active substances across intra- and intercellular space. These EVs have developed as a promising research area for the treatment of OP because of their nanosized architecture, enhanced biocompatibility, reduced toxicity, drug loading capacity, ease of customization, and industrialization. This review describes the latest development of EVs derived from mammals and bacteria, including their internalization, isolation, biogenesis, classifications, topologies, and compositions. Additionally, breakthroughs in chemical sciences and the distinctive biological features of bacterial extracellular vesicles (BEVs) allow for the customization of modified BEVs for the therapy of OP. In conclusion, we give a thorough and in-depth summary of the main difficulties and potential future of EVs in the treatment of OP, as well as highlight innovative uses and choices for the treatment of osteoarthritis (OA).

Microbiota and Extracellular Vesicles in Anti-PD-1/PD-L1 Therapy

Simple Summary

Immune checkpoint inhibitors (ICI) targeting PD-1/PD-L1 have emerged as contemporary treatments for a variety of cancers. However, the efficacy of antibody-based ICIs could be further enhanced. Microbiota have been demonstrated to be among the vital factors governing cancer progression and response to therapy in patients. Bacteria secrete extracellular vesicles carrying bioactive metabolites within their cargo that can cross physiological barriers, selectively accumulate near tumor cells, and alter the tumor microenvironment. Extracellular vesicles, particularly those derived from bacteria, could thus be of promising assistance in refining the treatment outcomes for anti-PD-1/PD-L1 therapy. The potentiality of microbiota-derived extracellular vesicles in improving the currently used treatments and presenting new therapeutic avenues for cancer has been featured in this review.

Abstract

Cancer is a deadly disease worldwide. In light of the requisite of convincing therapeutic methods for cancer, immune checkpoint inhibition methods such as anti-PD-1/PD-L1 therapy appear promising. Human microbiota have been exhibited to regulate susceptibility to cancer as well as the response to anti-PD-1/PD-L1 therapy. However, the probable contribution of bacterial extracellular vesicles (bEVs) in cancer pathophysiology and treatment has not been investigated much. bEVs illustrate the ability to cross physiological barriers, assemble around the tumor cells, and likely modify the tumor microenvironment (EVs). This systematic review emphasizes the correlation between cancer-associated extracellular vesicles, particularly bEVs and the efficacy of anti-PD-1/PD-L1 therapy. The clinical and pharmacological prospective of bEVs in revamping the contemporary treatments for cancer has been further discussed.

Engineered extracellular vesicles as intelligent nanosystems for next-generation nanomedicine

Extracellular vesicles (EVs), as natural carriers of bioactive cargo, have a unique micro/nanostructure, bioactive composition, and characteristic morphology, as well as fascinating physical, chemical and biochemical features, which have shown promising application in the treatment of a wide range of diseases. However, native EVs have limitations such as lack of or inefficient cell targeting, on-demand delivery, and therapeutic feedback. Recently, EVs have been engineered to contain an intelligent core, enabling them to (i) actively target sites of disease, (ii) respond to endogenous and/or exogenous signals, and (iii) provide treatment feedback for optimal function in the host. These advances pave the way for next-generation nanomedicine and offer promise for a revolution in drug delivery. Here, we summarise recent research on intelligent EVs and discuss the use of "intelligent core" based EV systems for the treatment of disease. We provide a critique about the construction and properties of intelligent EVs, and challenges in their commercialization. We compare the therapeutic potential of intelligent EVs to traditional nanomedicine and highlight key advantages for their clinical application. Collectively, this review aims to provide a new insight into the design of next-generation EV-based theranostic platforms for disease treatment.

Bone-Targeted Nanoparticle Drug Delivery System: An Emerging Strategy for Bone-Related Disease

Targeted delivery by either systemic or local targeting of therapeutics to the bone is an attractive treatment for various bone metabolism diseases such as osteoporosis, osteoarthritis, osteosarcoma, osteomyelitis, etc. To overcome the limitations of direct drug delivery, the combination of bone-targeted agents with nanotechnology has the opportunity to provide a more effective therapeutic approach, where engineered nanoparticles cause the drug to accumulate in the bone, thereby improving efficacy and minimizing side effects. Here, we summarize the current advances in systemic or local bone-targeting approaches and nanosystem applications in bone diseases, which may provide new insights into nanocarrier-delivered drugs for the targeted treatment of bone diseases. We envision that novel drug delivery carriers developed based on nanotechnology will be a potential vehicle for the treatment of currently incurable bone diseases and are expected to be translated into clinical applications.

Liposomes: An emerging carrier for targeting Alzheimer's and Parkinson's diseases

The function of the brain can be affected by various factors that include infection, tumor, and stroke. The major disorders reported with altered brain function are Alzheimer's disease (AD), Parkinson's disease (PD), dementia, brain cancer, seizures, mental disorders, and other movement disorders. The major barrier in treating CNS disease is the blood-brain barrier (BBB), which protects the brain from toxic molecules, and the cerebrospinal fluid (CSF) barrier, which separates blood from CSF. Brain endothelial cells and perivascular elements provide an integrated cellular barrier, the BBB, which hamper the invasion of molecules from the blood to the brain. Even though many drugs are available to treat neurological disorders, it fails to reach the desired site with the required concentration. In this purview, liposomes can carry required concentrations of molecules intracellular by diverse routes such as carrier-mediated transport and receptor-mediated transcytosis. Surface modification of liposomes enables them to deliver drugs to various brain cells, including neurons, astrocytes, oligodendrocytes, and microglia. The research studies supported the role of liposomes in delivering drugs across BBB and in reducing the pathogenesis of AD and PD. The liposomes were surface-functionalized with various molecules to reach the cells intricated with the AD or PD pathogenesis. The targeted and sustained delivery of drugs by liposomes is disturbed due to the antibody formation, renal clearance, accelerated blood clearance, and complement activation-related pseudoallergy (CARPA). Hence, this review will focus on the characteristics, surface functionalization, drug loading, and biodistribution of liposomes respective to AD and PD. In addition, the alternative strategies to overcome immunogenicity are discussed briefly.

Characterization and assessment of lung and bone marrow derived endothelial cells and their bone regenerative potential

Angiogenesis is important for successful fracture repair. Aging negatively affects the number and activity of endothelial cells (ECs) and subsequently leads to impaired bone healing. We previously showed that implantation of lung-derived endothelial cells (LECs) improved fracture healing in rats. In this study, we characterized and compared neonatal lung and bone marrow-derived endothelial cells (neonatal LECs and neonatal BMECs) and further asses3sed if implantation of neonatal BMECs could enhance bone healing in both young and aged mice. We assessed neonatal EC tube formation, proliferation, and wound migration ability in vitro in ECs isolated from the bone marrow and lungs of neonatal mice. The in vitro studies demonstrated that both neonatal LECs and neonatal BMECs exhibited EC traits. To test the function of neonatal ECs in vivo, we created a femoral fracture in young and aged mice and implanted a collagen sponge to deliver neonatal BMECs at the fracture site. In the mouse fracture model, endochondral ossification was delayed in aged control mice compared to young controls. Neonatal BMECs significantly improved endochondral bone formation only in aged mice. These data suggest BMECs have potential to enhance aged bone healing. Compared to LECs, BMECs are more feasible for translational cell therapy and clinical applications in bone repair. Future studies are needed to examine the fate and function of BMECs implanted into the fracture sites.