Multi-antitumor therapy and synchronous imaging monitoring based on exosome

Engineering extracellular vesicles for diagnosis and therapy

Extracellular vesicle (EV)-based therapeutics have gained substantial interest in the areas of drug delivery, immunotherapy, and regenerative medicine. However, the clinical translation of EVs has been slowed due to limited yields and functional heterogeneity, as well as inadequate targeting. Engineering EVs to modify their inherent function and endow them with additional functions has the potential to advance the clinical translation of EV applications. Bio-orthogonal click chemistry is an engineering approach that modifies EVs in a controlled, specific, and targeted way without compromising their intrinsic structure. Here, we provide an overview of bio-orthogonal labeling approaches involved in EV engineering. We also present the isolation methods of bio-orthogonally labeled vesicles using magnetic beads, microfluidics, and microarray chip technologies. We highlight the in vivo applications of bio-orthogonal labeling EVs for diagnosis and therapy, especially the exciting potential of bio-orthogonal glycometabolic engineered EVs for targeted therapies.

Physicochemical characterization and potential cancer therapy applications of hydrogel beads loaded with doxorubicin and GaOOH nanoparticles

A new type of hybrid polymer particles capable of carrying the cytostatic drug doxorubicin and labeled with a gallium compound was prepared. These microparticles consist of a core and a hydrogel shell, which serves as the structural matrix. The shell can be employed to immobilize gallium oxide hydroxide (GaOOH) nanoparticles and the drug, resulting in hybrid beads with sizes of approximately 3.81 ± 0.09 μm. The microparticles exhibit the ability to incorporate a remarkably large amount of doxorubicin, approximately 0.96 mg per 1 mg of the polymeric carrier. Additionally, GaOOH nanoparticles can be deposited within the hydrogel layer at an amount of 0.64 mg per 1 mg of the carrier. These nanoparticles, resembling rice grains with an average size of 593 nm by 155 nm, are located on the surface of the polymer carrier. In vitro studies on breast and colon cancer cell lines revealed a pronounced cytotoxic effect of the hybrid polymer particles loaded with doxorubicin, indicating their potential for cancer therapies. Furthermore, investigations on doping the hybrid particles with the Ga-68 radioisotope demonstrated their potential application in positron emission tomography (PET) imaging. The proposed structures present a promising theranostic platform, where particles could be employed in anticancer therapies while monitoring their accumulation in the body using PET.

Recent advances to address challenges in extracellular vesicle-based applications for lung cancer

Lung cancer, highly prevalent and the leading cause of cancer-related death globally, persists as a significant challenge due to the lack of definitive tumor markers for early diagnosis and personalized therapeutic interventions. Recently, extracellular vesicles (EVs), functioning as natural carriers for intercellular communication, have received increasing attention due to their ability to traverse biological barriers and deliver diverse biological cargoes, including cytosolic proteins, cell surface proteins, microRNA, lncRNA, circRNA, DNA, and lipids. EVs are increasingly recognized as a valuable resource for non-invasive liquid biopsy, as well as drug delivery platforms, and anticancer vaccines for precision medicine in lung cancer. Herein, given the diagnostic and therapeutic potential of tumor-associated EVs for lung cancer, we discuss this topic from a translational standpoint. We delve into the specific roles that EVs play in lung cancer carcinogenesis and offer a particular perspective on how advanced engineering technologies can overcome the current challenges and expedite and/or enhance the translation of EVs from laboratory research to clinical settings.

Application of capsaicin and calcium phosphate-loaded MOF system for tumor therapy involving calcium overload

Calcium overload therapy refers to the condition of intracellular Ca2+ overload, which causes mitochondrial damage and leads to the uncontrolled release of apoptotic factors into the cytoplasm through the open mitochondrial permeability pore. Based on this, it is playing an increasingly important role in the field of oncology due to its good efficacy and small side effects. However, the regulation of calcium homeostasis by cancer cells themselves, insufficient calcium ions (Ca2+) in tumor sites and low efficiency of calcium entering tumor have limited its efficacy, resulting in unsatisfactory therapeutic effect. Therefore, a novel CAP/BSA@TCP-ZIF-8 nanoparticle drug carrier system was constructed that can provide Ca2+ from exogenous sources for pH-controlled degradation and drug release at the same time. Both in vivo and in vitro experiments have proved that the nanomaterial can activate TRPV1 channels and provide exogenous Ca2+ to cause Ca2+ overload and apoptosis, thus achieving anti-tumor effects.

Acidity-activatable dynamic hybrid nanoplatforms derived from extracellular vesicles of M1 macrophages enhance cancer immunotherapy through synergistic triple immunotherapy

Immunotherapy exhibits considerable promise for sustained tumor reduction. However, current cancer immunotherapy methods elicit limited responses due to the inadequate immunogenicity exhibited by cancer cells. This obstacle may be addressed using nanoplatforms that can activate synergistic therapies (photodynamic therapy and ferroptosis) in response to the acidic pH of the tumor microenvironment. We previously developed an amphiphilic photosensitizer, SR780, which displays satisfactory photodynamic effects. This photosensitizer is inactivated when bound to Fe3+ (SR780Fe) but is activated upon release in mildly acidic conditions. In this study, M1 macrophage-derived extracellular vesicles (EVs) were fused with REV and SR780Fe-loaded liposomes (REV@SR780Fe@Lip) to form REV@SR780Fe@LEV hybrid nanovesicles. Further modification with the RS17 peptide for tumor targeting enabled a combination of photodynamic therapy, ferroptosis, and cGAS-STING pathway activation, resulting in enhanced antitumor efficacy through a synergistic effect. Upon laser irradiation, REV@SR780Fe@LEV-RS17 demonstrated antitumor effects in 4T1 breast cancer models, including the inhibition of lung and liver metastasis, as well as prevention of tumor recurrence.

Tumor-derived nanovesicles enhance cancer synergistic chemo-immunotherapy by promoting cGAS/STING pathway activation and immunogenetic cell death

AIMS

Checkpoint blockade immunotherapy is a promising therapeutic modality that has revolutionized cancer treatment; however, the therapy is only effective on a fraction of patients due to the tumor environment. In tumor immunotherapy, the cGAS-STING pathway is a crucial intracellular immune response pathway. Therefore, this study aimed to develop an immunotherapy strategy based on the cGAS-STING pathway.

MATERIALS AND METHODS

The physicochemical properties of the nanoparticles EM@REV@DOX were characterized by TEM, DLS, and WB. Subcutaneous LLC xenograft tumors were used to determine the biodistribution, antitumor efficacy, and immune response. Blood samples and tissues of interest were harvested for hematological analysis and H&E staining.

SIGNIFICANCE

Overall, our designed nanovesicles provide a new perspective on tumor immunotherapy by ICD and cGAS-STING pathway, promoting DCs maturation, macrophage polarization, and activating T cells, offering a meaningful strategy for accelerating the clinical development of immunotherapy.

KEY FINDINGS

EM@REV@DOX accumulated in the tumor site through EPR and homing targeting effect to release REV and DOX, resulting in DNA damage and finally activating the cGAS-STING pathway, thereby promoting DCs maturation, macrophage polarization, and activating T cells. Additionally, EM@REV@DOX increased the production of pro-inflammatory cytokines (e.g., TNF-α and IFN-β). As a result, EM@REV@DOX was effective in treating tumor-bearing mice and prolonged their lifespans. When combined with αPD-L1, EM@REV@DOX significantly inhibited distant tumor growth, extended the survival of mice, and prevented long-term postoperative tumor metastasis, exhibiting great potential in antitumor immunotherapy.

Surface-Bioengineered Extracellular Vesicles Seeking Molecular Biotargets in Lung Cancer Cells

Personalized medicine is a new approach to modern oncology. Here, to facilitate the application of extracellular vesicles (EVs) derived from lung cancer cells as potent advanced therapy medicinal products in lung cancer, the EV membrane was functionalized with a specific ligand for targeting purposes. In this role, the most effective heptapeptide in binding to lung cancer cells (PTHTRWA) was used. The functionalization process of EV surface was performed through the C- or N-terminal end of the heptapeptide. To prove the activity of the EVs functionalized with PTHTRWA, both a model of lipid membrane mimicking normal and cancerous cell membranes as well as human adenocarcinomic alveolar basal epithelial cells (A549) and human normal bronchial epithelial cells (BEAS-2B) have been exposed to these bioconstructs. Magnetic resonance imaging (MRI) showed that the as-bioengineered PTHTRWA-EVs loaded with superparamagnetic iron oxide nanoparticle (SPIO) cargos reach the growing tumor when dosed intravenously in NUDE Balb/c mice bearing A549 cancer. Molecular dynamics (MD) in silico studies elucidated a high affinity of the synthesized peptide to the α5β1 integrin. Preclinical safety assays did not evidence any cytotoxic or genotoxic effects of the PTHTRWA-bioengineered EVs.

Extracellular Vesicles as Next-Generation Diagnostics and Advanced Therapy Medicinal Products

Extracellular vesicles (EVs) hold great promise for clinical application as new diagnostic and therapeutic modalities. This paper describes major GMP-based upstream and downstream manufacturing processes for EV large-scale production, also focusing on post-processing technologies such as surface bioengineering and uploading studies to yield novel EV-based diagnostics and advanced therapy medicinal products. This paper also focuses on the quality, safety, and efficacy issues of the bioengineered EV drug candidates before first-in-human studies. Because clinical trials involving extracellular vesicles are on the global rise, this paper encompasses different clinical studies registered on clinical-trial register platforms, with varying levels of advancement, highlighting the growing interest in EV-related clinical programs. Navigating the regulatory affairs of EVs poses real challenges, and obtaining marketing authorization for EV-based medicines remains complex due to the lack of specific regulatory guidelines for such novel products. This paper discusses the state-of-the-art regulatory knowledge to date on EV-based diagnostics and medicinal products, highlighting further research and global regulatory needs for the safe and reliable implementation of bioengineered EVs as diagnostic and therapeutic tools in clinical settings. Post-marketing pharmacovigilance for EV-based medicinal products is also presented, mainly addressing such topics as risk assessment and risk management.

Cell Membrane Hybrid Lipid Nanovesicles Enhance Innate Immunity for Synergistic Immunotherapy by Promoting Immunogenic Cell Death and cGAS Activation

Immunotherapy shows great therapeutic potential for long-term protection against tumor relapse and metastasis. Innate immune sensors, such as cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING), dissolve DNA and induce type I interferon. Through activation of the cGAS/STING pathway, chemotherapy drugs and reversine (REV) may provide synergetic anti-tumor effects. Here, we prepared drug-loaded cell membrane hybrid lipid nanovesicles (LEVs) (designated LEV@DOX@REV) by fusion of cell membranes, phospholipids, doxorubicin (DOX), and REV, to realize accurate delivery to tumors and chemo-immunotherapy. The cell membranes of LEVs confer "homing" abilities. DOX can induce immunogenic cell death as a result of its specific immunomodulatory effects, which promotes the maturation of immune cells and improves the microenvironment of the immune system. REV is proven to efficiently activate cGAS/STING signaling, thereby enhancing the immune system. The antitumor efficacy of LEV@DOX@REV was evaluated in a 4T1 subcutaneous tumor xenograft model, a distant metastatic tumor model, and a liver metastatic tumor model. LEV@DOX@REV facilitated the infiltration of cytotoxic T lymphocytes within tumors, increased the secretion of proinflammatory cytokines, and modified the tumor microenvironment. In conclusion, LEV@DOX@REV displayed favorable antitumor effects and extended the survival of tumor-bearing mice. We therefore successfully developed nanoparticles capable of enhancing immune activation that have potential therapeutic applications for cancer immunotherapy.

Epigenetic regulation of pulmonary inflammation

Pulmonary disease such as chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis and pulmonary hypertension are the leading cause of deaths. More importantly, lung diseases are on the rise and environmental factors induced epigenetic modifications are major players on this increased prevalence. It has been reported that dysregulation of genes involved in epigenetic regulation such as the histone deacetylase (HDACs) and histone acetyltransferase (HATs) play important role in lung health and pulmonary disease pathogenesis. Inflammation is an essential component of respiratory diseases. Injury and inflammation trigger release of extracellular vesicles that can act as epigenetic modifiers through transfer of epigenetic regulators such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), proteins and lipids, from one cell to another. The immune dysregulations caused by the cargo contents are important contributors of respiratory disease pathogenesis. N6 methylation of RNA is also emerging to be a critical mechanism of epigenetic alteration and upregulation of immune responses to environmental stressors. Epigenetic changes such as DNA methylation are stable and often long term and cause onset of chronic lung conditions. These epigenetic pathways are also being utilized for therapeutic intervention in several lung conditions.

PEG-modified carbon-based nanoparticles as tumor-targeted drug delivery system reducing doxorubicin-induced cardiotoxicity

Herein, a doxorubicin-loaded carbon-based drug delivery system, denoted as PC-DOX, composed of pH-responsive imine bond was developed for the tumor-targeted treatment. PC-DOX with a uniform particle size around 180 nm was synthesized by coating of as-synthesized hollow carbon-based nanoparticles (NPs) with dialdehyde PEG, which was used as carrier to attach DOX covalently through dynamic covalent bond. The unique structure endowed the advantages of specific tumor targeting and tumor microenvironment (TME) specific drug delivery capacity with PC-DOX. For the one hand, the tumor targeting caused by the enhanced permeability and retention (EPR) effect could significantly improve the tumor cellular uptake. For the other hand, the pH-responsiveness could realize the effective DOX accumulation in tumor tissues, avoiding the unwanted side effect to the normal tissues. As a result, PC-DOX with high DOX loading capacity (70.12%) and excellent biocompatibility, concurrently, presented a significant anti-tumor effect at a low mass concentration (DOX equivalent dose: 20 μg/mL). Another attractive characteristic of PC-DOX was the remarkable protective effect towards DOX-induced cardiotoxicity, which could be clearly observed from in vitro cellular, and animal assays. Compared with free DOX, the cardiomyocyte viability increased by average 30.58%, and the heart function was also significantly improved. This novel drug delivery nanoplatform provides a new method for the future clinical application of DOX in the cancer's therapeutics.

Click Chemistry and Radiochemistry: An Update

The term "click chemistry" describes a class of organic transformations that were developed to make chemical synthesis simpler and easier, in essence allowing chemists to combine molecular subunits as if they were puzzle pieces. Over the last 25 years, the click chemistry toolbox has swelled from the canonical copper-catalyzed azide-alkyne cycloaddition to encompass an array of ligations, including bioorthogonal variants, such as the strain-promoted azide-alkyne cycloaddition and the inverse electron-demand Diels-Alder reaction. Without question, the rise of click chemistry has impacted all areas of chemical and biological science. Yet the unique traits of radiopharmaceutical chemistry have made it particularly fertile ground for this technology. In this update, we seek to provide a comprehensive guide to recent developments at the intersection of click chemistry and radiopharmaceutical chemistry and to illuminate several exciting trends in the field, including the use of emergent click transformations in radiosynthesis, the clinical translation of novel probes synthesized using click chemistry, and the advent of click-based in vivo pretargeting.

Engineered exosomes-based theranostic strategy for tumor metastasis and recurrence

Metastasis-associated processes are the predominant instigator of fatalities linked to cancer, wherein the pivotal role of circulating tumor cells lies in the resurgence of malignant growth. In recent epochs, exosomes, constituents of the extracellular vesicle cohort, have garnered attention within the field of tumor theranostics owing to their inherent attributes encompassing biocompatibility, modifiability, payload capacity, stability, and therapeutic suitability. Nonetheless, the rudimentary functionalities and limited efficacy of unmodified exosomes curtail their prospective utility. In an effort to surmount these shortcomings, intricate methodologies amalgamating nanotechnology with genetic manipulation, chemotherapy, immunotherapy, and optical intervention present themselves as enhanced avenues to surveil and intercede in tumor metastasis and relapse. This review delves into the manifold techniques currently employed to engineer exosomes, with a specific focus on elucidating the interplay between exosomes and the metastatic cascade, alongside the implementation of tailored exosomes in abating tumor metastasis and recurrence. This review not only advances comprehension of the evolving landscape within this domain but also steers the trajectory of forthcoming investigations.

Progress of regulatory RNA in small extracellular vesicles in colorectal cancer

Colorectal cancer (CRC) is the second most common malignant tumor of the gastrointestinal tract with the second highest mortality rate and the third highest incidence rate. Early diagnosis and treatment are important measures to reduce CRC mortality. Small extracellular vesicles (sEVs) have emerged as key mediators that facilitate communication between tumor cells and various other cells, playing a significant role in the growth, invasion, and metastasis of cancer cells. Regulatory RNAs have been identified as potential biomarkers for early diagnosis and prognosis of CRC, serving as crucial factors in promoting CRC cell proliferation, invasion and metastasis, angiogenesis, drug resistance, and immune cell differentiation. This review provides a comprehensive summary of the vital role of sEVs as biomarkers in CRC diagnosis and their potential application in CRC treatment, highlighting their importance as a promising avenue for further research and clinical translation.

Engineering goat milk-derived extracellular vesicles for multiple bioimaging-guided and photothermal-enhanced therapy of colon cancer

Multimodal image-guided photothermal therapy (PTT) has great application potential in cancer treatment due to its advantages of low side effects and good efficacy. There is an urgent need for PTT nanocarriers with high loading efficiency and modified surfaces. Goat milk-derived extracellular vesicles (GMVs) an ideal PTT nanoplatforms due to their anti-inflammatory ability, tumor retention ability, high yield, and high biosafety. This study used GMVs to design a theranostic nanoprobe for positron emission tomography/computer tomography/near-infrared fluorescence (PET/CT/NIRF) imaging and image-guided PTT for colon cancer. The key genes, important biological processes, and important signaling pathways of indocyanine green (ICG)-mediated PTT and N₃-GMV@ICG-mediated PTT were analyzed. The nanoprobe triggered anti-tumor immune and inflammation responses to enhance PTT. In addition, the nanoprobe could attenuate PTT-induced inflammation benefiting from the anti-inflammatory efficacy of GMVs. Therefore, our findings conceptually advanced the diagnosis and treatment of colon cancer. We believed that the nanoprobe had broad clinical transformation prospects, and GMVs might be ideal nanocarriers for constructing integrated diagnostic and PTT probes.

Extracellular Vesicles in Colorectal Cancer: From Tumor Growth and Metastasis to Biomarkers and Nanomedications

Colorectal cancer (CRC) is a leading public health concern due to its incidence and high mortality rates, highlighting the requirement of an early diagnosis. Evaluation of circulating extracellular vesicles (EVs) might constitute a noninvasive and reliable approach for CRC detection and for patient follow-up because EVs display the molecular features of the cells they originate. EVs are released by almost all cell types and are mainly categorized as exosomes originating from exocytosis of intraluminal vesicles from multivesicular bodies, ectosomes resulting from outward budding of the plasma membrane and apoptotic bodies' ensuing cell shrinkage. These vesicles play a critical role in intercellular communications during physiological and pathological processes. They facilitate CRC progression and premetastatic niche formation, and they enable transfer of chemotherapy resistance to sensitive cells through the local or remote delivery of their lipid, nucleic acid and protein content. On another note, their stability in the bloodstream, their permeation in tissues and their sheltering of packaged material make engineered EVs suitable vectors for efficient delivery of tracers and therapeutic agents for tumor imaging or treatment. Here, we focus on the physiopathological role of EVs in CRCs, their value in the diagnosis and prognosis and ongoing investigations into therapeutic approaches.

Combinational antitumor strategies of exosomes as drug carriers: Mini review

Cancer therapies have made tremendous progress in the last decade, but monotherapy still has apparent limitations and lacks therapeutic efficacy. Thus, the simultaneous administration of multiple drugs has been widely explored and has shown better outcomes. Exosomes, deriving from almost all living cells, are natural nanocarriers designed to deliver drugs to tumor sites. Therefore, combinational antitumor therapies based on exosomes, such as engineered exosomes and different combinations of chemotherapeutic agents, therapeutic nucleic acids, photosensitizers, immunotherapy and phytochemicals, have considerable prospects and potential for clinical translation. Here, we summarize current strategies of cancer combination therapy in exosomes and propose opportunities and challenges in the future.

Chlorin e6-loaded goat milk-derived extracellular vesicles for Cerenkov luminescence-induced photodynamic therapy

PURPOSE

Photodynamic therapy (PDT) is a promising cancer treatment strategy with rapid progress in preclinical and clinical settings. However, the limitations in penetration of external light and precise delivery of photosensitizers hamper its clinical translation. As such, the internal light source such as Cerenkov luminescence (CL) from decaying radioisotopes offers new opportunities. Herein, we show that goat milk-derived extracellular vesicles (GEV) can act as a carrier to deliver photosensitizer Chlorin e6 (Ce6) and tumor-avid 18F-FDG can activate CL-induced PDT for precision cancer theranostics.

METHODS

GEV was isolated via differential ultracentrifugation of commercial goat milk and photosensitizer Ce6 was loaded by co-incubation to obtain Ce6@GEV. Tumor uptake of Ce6@GEV was examined using confocal microscopy and flow cytometry. To demonstrate the ability of 18F-FDG to activate photodynamic effects against cancer cells, apoptosis rates were measured using flow cytometry, and the production of 1O2 was measured by reactive oxygen species (ROS) monitoring kit. Moreover, we used the IVIS device to detect Cherenkov radiation and Cerenkov radiation energy transfer (CRET). For animal experiments, a small-animal IVIS imaging system was used to visualize the accumulation of the GEV drug delivery system in tumors. PET/CT and CL images of the tumor site were performed at 0.5, 1, and 2 h. For in vivo antitumor therapy, changes of tumor volume, survival time, and body weight in six groups of tumor-bearing mice were monitored. Furthermore, the blood sample and organs of interest (heart, liver, spleen, lungs, kidneys, and tumor) were collected for hematological analysis, immunohistochemistry, and H&E staining.

RESULTS

Confocal microscopy of 4T1 cells incubated with Ce6@GEV for 4 h revealed strong red fluorescence signals in the cytoplasm, which demonstrated that Ce6 loaded in GEV could be efficiently delivered into tumor cells. When Ce6@GEV and 18F-FDG co-existed incubated with 4T1 cells, the cell viability plummeted from more than 88.02 ± 1.30% to 23.79 ± 1.59%, indicating excellent CL-induced PDT effects. In vivo fluorescence images showed a peak tumor/liver ratio of 1.36 ± 0.09 at 24 h after Ce6@GEV injection. For in vivo antitumor therapy, Ce6@GEV + 18F-FDG group had the best tumor inhibition rate (58.02%) compared with the other groups, with the longest survival rate (35 days, 40%). During the whole treatment process, neither blood biochemical analysis nor histological observation revealed vital organ damage, suggesting the biosafety of this treatment strategy.

CONCLUSIONS

The simultaneous accumulation of 18F-FDG and Ce6 in tumor tissues is expected to overcome the deficiency of traditional PDT. This strategy has the potential to extend PDT to a variety of tumors, including metastases, using targeted radiotracers to provide internal excitation of light-responsive therapeutics. We expect that our method will play a critical role in precision treatment of deep solid tumors.

Future in precise surgery: Fluorescence-guided surgery using EVs derived fluorescence contrast agent

Surgery is the only cure for many solid tumors, but positive resection margins, damage to vital nerves, vessels and organs during surgery, and the range and extent of lymph node dissection are significant concerns which hinder the development of surgery. The emergence of fluorescence-guided surgery (FGS) means a farewell to the era when surgeons relied only on visual and tactile feedback, and it gives surgeons another eye to distinguish tumors from normal tissues for precise resection and helps to find a balance between complete tumor lesions removal and maximal organ function conservation. However, the existing synthetic fluorescence contrast agent has flaws in safety, specificity and biocompatibility to various extents. Extracellular vesicles (EVs) are a group of heterogeneous types of cell-derived membranous structures present in all biological fluids. EVs, especially engineered targeting EVs, play an increasingly important role in drug delivery because of their good biocompatibility, validated safety and targeting ability. Nevertheless, few studies have employed EVs loaded with fluorophores to construct fluorescence contrast agents and used them in FGS. Here, we systematically reviewed the current state of knowledge regarding FGS, fundamental characteristics of EVs, and the development of engineered targeting EVs, and put forward a novel strategy and procedures to produce EVs-based fluorescence contrast agent used in fluorescence-guided surgery.

Modified Bovine Milk Exosomes for Doxorubicin Delivery to Triple-Negative Breast Cancer Cells

Biological nanoparticles, such as exosomes, offer an approach to drug delivery because of their innate ability to transport biomolecules. Exosomes are derived from cells and an integral component of cellular communication. However, the cellular cargo of human exosomes could negatively impact their use as a safe drug carrier. Additionally, exosomes have the intrinsic yet enigmatic, targeting characteristics of complex cellular communication. Hence, harnessing the natural transport abilities of exosomes for drug delivery requires predictably targeting these biological nanoparticles. This manuscript describes the use of two chemical modifications, incorporating a neuropilin receptor agonist peptide (iRGD) and a hypoxia-responsive lipid for targeting and release of an encapsulated drug from bovine milk exosomes to triple-negative breast cancer cells. Triple-negative breast cancer is a very aggressive and deadly form of malignancy with limited treatment options. Incorporation of both the iRGD peptide and hypoxia-responsive lipid into the lipid bilayer of bovine milk exosomes and encapsulation of the anticancer drug, doxorubicin, created the peptide targeted, hypoxia-responsive bovine milk exosomes, iDHRX. Initial studies confirmed the presence of iRGD peptide and the exosomes' ability to target the αvβ3 integrin, overexpressed on triple-negative breast cancer cells' surface. These modified exosomes were stable under normoxic conditions but fragmented in the reducing microenvironment created by 10 mM glutathione. In vitro cellular internalization studies in monolayer and three-dimensional (3D) spheroids of triple-negative breast cancer cells confirmed the cell-killing ability of iDHRX. Cell viability of 50% was reached at 10 μM iDHRX in the 3D spheroid models using four different triple-negative breast cancer cell lines. Overall, the tumor penetrating, hypoxia-responsive exosomes encapsulating doxorubicin would be effective in reducing triple-negative breast cancer cells' survival.

Minimizing adverse effects of Cerenkov radiation induced photodynamic therapy with transformable photosensitizer-loaded nanovesicles

Background

Photodynamic therapy (PDT) is a promising antitumor strategy with fewer adverse effects and higher selectivity than conventional therapies. Recently, a series of reports have suggested that PDT induced by Cerenkov radiation (CR) (CR-PDT) has deeper tissue penetration than traditional PDT; however, the strategy of coupling radionuclides with photosensitizers may cause severe side effects.

Methods

We designed tumor-targeting nanoparticles (¹³¹I-EM@ALA) by loading 5-aminolevulinic acid (ALA) into an ¹³¹I-labeled exosome mimetic (EM) to achieve combined antitumor therapy. In addition to playing a radiotherapeutic role, ¹³¹I served as an internal light source for the Cerenkov radiation (CR).

Results

The drug-loaded nanoparticles effectively targeted tumors as confirmed by confocal imaging, flow cytometry, and small animal fluorescence imaging. In vitro and in vivo experiments demonstrated that ¹³¹I-EM@ALA produced a promising antitumor effect through the synergy of radiotherapy and CR-PDT. The nanoparticles killed tumor cells by inducing DNA damage and activating the lysosome-mitochondrial pathways. No obvious abnormalities in the hematology analyses, blood biochemistry, or histological examinations were observed during the treatment.

Conclusions

We successfully engineered a nanocarrier coloaded with the radionuclide ¹³¹I and a photosensitizer precursor for combined radiotherapy and PDT for the treatment of breast cancer.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01401-0.