Nanoparticle-Mediated Blocking of Excessive Inflammation for Prevention of Heart Failure Following Myocardial Infarction.

Severe cardiac damage following myocardial infarction (MI) causes excessive inflammation, which sustains tissue damage and often induces adverse cardiac remodeling toward cardiac function impairment and heart failure. Timely resolution of post-MI inflammation may prevent cardiac remodeling and development of heart failure. Cell therapy approaches for MI are time-consuming and costly, and have shown marginal efficacy in clinical trials. Here, nanoparticles targeting the immune system to attenuate excessive inflammation in infarcted myocardium are presented. Liposomal nanoparticles loaded with MI antigens and rapamycin (L-Ag/R) enable effective induction of tolerogenic dendritic cells presenting the antigens and subsequent induction of antigen-specific regulatory T cells (Tregs). Impressively, intradermal injection of L-Ag/R into acute MI mice attenuates inflammation in the myocardium by inducing Tregs and an inflammatory-to-reparative macrophage polarization, inhibits adverse cardiac remodeling, and improves cardiac function. Nanoparticle-mediated blocking of excessive inflammation in infarcted myocardium may be an effective intervention to prevent the development of post-MI heart failure.

Anti-senescence ion-delivering nanocarrier for recovering therapeutic properties of long-term-cultured human adipose-derived stem cells.

BACKGROUND: Human adipose-derived stem cells (hADSCs) have been used in various fields of tissue engineering because of their promising therapeutic efficacy. However, the stemness of hADSCs cannot be maintained for long durations, and their therapeutic cellular functions, such as paracrine factor secretion decrease during long-term cell culture. To facilitate the use of long-term-cultured hADSCs (L-ADSCs), we designed a novel therapeutic anti-senescence ion-delivering nanocarrier (AIN) that is capable of recovering the therapeutic properties of L-ADSCs. In the present study, we introduced a low-pH-responsive ion nanocarrier capable of delivering transition metal ions that can enhance angiogenic paracrine factor secretion from L-ADSCs. The AINs were delivered to L-ADSCs in an intracellular manner through endocytosis. RESULTS: Low pH conditions within the endosomes induced the release of transition metal ions (Fe) into the L-ADSCs that in turn caused a mild elevation in the levels of reactive oxygen species (ROS). This mild elevation in ROS levels induced a downregulation of senescence-related gene expression and an upregulation of stemness-related gene expression. The angiogenic paracrine factor secretion from L-ADSCs was significantly enhanced, and this was evidenced by the observed therapeutic efficacy in response to treatment of a wound-closing mouse model with conditioned medium obtained from AIN-treated L-ADSCs that was similar to that observed in response to treatment with short-term-cultured adipose-derived stem cells. CONCLUSIONS: This study suggests a novel method and strategy for cell-based tissue regeneration that can overcome the limitations of the low stemness and therapeutic efficacy of stem cells that occurs during long-term cell culture.

Umbilical Cord Mesenchymal Stem Cell-Derived Nanovesicles Potentiate the Bone-Formation Efficacy of Bone Morphogenetic Protein 2.

Recombinant human bone morphogenetic protein 2 (rhBMP-2) is one of the most potent osteogenic factors used to treat bone loss. However, at higher doses, rhBMP-2 does not necessarily increase bone formation but rather increases the incidence of adverse side effects. Here, we investigated whether umbilical cord mesenchymal stem cell (UCMSC)-derived nanovesicles (NVs) further increase the in vivo bone formation at high doses of rhBMP-2. In the presence of UCMSC-derived NVs, proliferation, migration, and tube formation of human umbilical vein endothelial cells were stimulated in vitro. Furthermore, migration and osteogenesis of human bone marrow-derived mesenchymal stem cells were stimulated. To examine the efficacy of UCMSC-derived NVs on in vivo bone formation, collagen sponges soaked with rhBMP-2 and UCMSC-derived NVs were used in athymic nude mice with calvarial defects. At a high rhBMP-2 dosage (500 ng/mL), UCMSC-derived NVs significantly promoted bone formation in calvarial defects; however, the UCMSC-derived NVs alone did not induce in vivo bone formation. Our results indicate that UCMSC-derived NVs can potentiate the bone formation efficacy of rhBMP-2 at a high dosage.

Targeted Delivery of Mesenchymal Stem Cell-Derived Nanovesicles for Spinal Cord Injury Treatment.

Due to the safety issues and poor engraftment of mesenchymal stem cell (MSC) implantation, MSC-derived exosomes have been spotlighted as an alternative therapy for spinal cord injury (SCI). However, insufficient productivity of exosomes limits their therapeutic potential for clinical application. Moreover, low targeting ability of unmodified exosomes is a critical obstacle for their further applications as a therapeutic agent. In the present study, we fabricated macrophage membrane-fused exosome-mimetic nanovesicles (MF-NVs) from macrophage membrane-fused umbilical cord blood-derived MSCs (MF-MSCs) and confirmed their therapeutic potential in a clinically relevant mouse SCI model (controlled mechanical compression injury model). MF-NVs contained larger quantity of ischemic region-targeting molecules compared to normal MSC-derived nanovesicles (N-NVs). The targeting molecules in MF-NVs, which were derived from macrophage membranes, increased the accumulation of MF-NVs in the injured spinal cord after the in vivo systemic injection. Increased accumulation of MF-NVs attenuated apoptosis and inflammation, prevented axonal loss, enhanced blood vessel formation, decreased fibrosis, and consequently, improved spinal cord function. Synthetically, we developed targeting efficiency-potentiated exosome-mimetic nanovesicles and present their possibility of clinical application for SCI.

Therapeutic Efficacy-Potentiated and Diseased Organ-Targeting Nanovesicles Derived from Mesenchymal Stem Cells for Spinal Cord Injury Treatment.

Human mesenchymal stem cell (hMSC)-derived exosomes have been spotlighted as a promising therapeutic agent for cell-free regenerative medicine. However, poor organ-targeting ability and insufficient therapeutic efficacy of systemically injected hMSC-exosomes were identified as critical limitations for their further applications. Therefore, in this study we fabricated iron oxide nanoparticle (IONP)-incorporated exosome-mimetic nanovesicles (NV-IONP) from IONP-treated hMSCs and evaluated their therapeutic efficacy in a clinically relevant model for spinal cord injury. Compared to exosome-mimetic nanovesicles (NV) prepared from untreated hMSCs, NV-IONP not only contained IONPs which act as a magnet-guided navigation tool but also carried greater amounts of therapeutic growth factors that can be delivered to the target cells. The increased amounts of therapeutic growth factors inside NV-IONP were attributed to IONPs that are slowly ionized to iron ions which activate the JNK and c-Jun signaling cascades in hMSCs. In vivo systemic injection of NV-IONP with magnetic guidance significantly increased the amount of NV-IONP accumulating in the injured spinal cord. Accumulated NV-IONP enhanced blood vessel formation, attenuated inflammation and apoptosis in the injured spinal cord, and consequently improved spinal cord function. Taken together, these findings highlight the development of therapeutic efficacy-potentiated extracellular nanovesicles and demonstrate their feasibility for repairing injured spinal cord.

A Disposable Photovoltaic Patch Controlling Cellular Microenvironment for Wound Healing.

Electrical stimulation (ES) is known to affect the wound healing process by modulating skin cell behaviors. However, the conventional clinical devices that can generate ES for promoting wound healing require patient hospitalization due to large-scale of the extracorporeal devices. Herein, we introduce a disposable photovoltaic patch that can be applied to skin wound sites to control cellular microenvironment for promoting wound healing by generating ES. In vitro experiment results show that exogenous ES could enhance cell migration, proliferation, expression of extracellular matrix proteins, and myoblast differentiation of fibroblasts which are critical for wound healing. Our disposable photovoltaic patches were attached to the back of skin wound induced mice. Our patch successfully provided ES, generated by photovoltaic energy harvested from the organic solar cell under visible light illumination. In vivo experiment results show that the patch promoted cutaneous wound healing via enhanced host-inductive cell proliferation, cytokine secretion, and protein synthesis which is critical for wound healing process. Unlike the current treatments for wound healing that engage passive healing processes and often are unsuccessful, our wearable photovoltaic patch can stimulate regenerative activities of endogenous cells and actively contribute to the wound healing processes.

Anti-fibrotic and anti-stricture effects of biodegradable biliary stents braided with dexamethasone-impregnated sheath/core structured monofilaments.

Endoscopic biliary stent insertion has been widely used for the treatment of benign biliary stricture (BBS). Thus, the development of stent materials in the perspectives of structure, mechanical properties, and biocompatibility has been also studied. However, conventional metal and plastic stents have several disadvantages, such as repeated procedures to remove or exchange them, dislodgment, restenosis, biocompatibility, and poor mechanical properties. Sustainable effectiveness, attenuation and prevention of fibrosis, and biocompatibility are key factors for the clinical application of stents to BBS treatment. In addition, loading drugs could show synergistic effects with stents' own performance. We developed a dexamethasone-eluting biodegradable stent (DBS) consisting of a sheath/core structure with outstanding mechanical properties and sustained release of dexamethasone, which maintained its functions in a BBS duct over 12 weeks in a swine model. The insertion of our DBS not only expanded BBS areas but also healed secondary ulcers as a result of the attenuation of fibrosis. After 16 weeks from the insertion, BBS areas were totally improved, and the DBS was degraded and thoroughly disappeared without re-intervention for stent removal. Our DBS would be an effective clinical tool for non-vascular diseases. STATEMENT OF SIGNIFICANCE: This study describes the insertion of a drug-eluting biodegradable stent (DBS) into the bile duct. The sheath/core structure of DBS confers substantial durability and a sustained drug release profile. Drug released from the DBS exhibited anti-fibrotic effects without inflammatory responses in both in vitro and in vivo experiments. The DBS maintained its function over 12 weeks after insertion into the common bile duct, expanding benign biliary stricture (BBS) and reducing inflammation to heal secondary ulcers in a swine BBS model. After 16 weeks from the DBS insertion, the DBS thoroughly disappeared without re-intervention for stent removal, resulting in totally improved BBS areas. Our findings not only spotlight the understanding of the sheath/core structure of the biodegradable stent, but also pave the way for the further application for non-vascular diseases.

Silica-Based Advanced Nanoparticles For Treating Ischemic Disease.

Recently, various attempts have been made to apply diverse types of nanoparticles in biotechnology. Silica nanoparticles (SNPs) have been highlighted and studied for their selective accumulation in diseased parts, strong physical and chemical stability, and low cytotoxicity. SNPs, in particular, are very suitable for use in drug delivery and bioimaging, and have been sought as a treatment for ischemic diseases. In addition, mesoporous silica nanoparticles have been confirmed to efficiently deliver various types of drugs owing to their porous structure. Moreover, there have been innovative attempts to treat ischemic diseases using SNPs, which utilize the effects of Si ions on cells to improve cell viability, migration enhancement, and phenotype modulation. Recently, external stimulus-responsive treatments that control the movement of magnetic SNPs using external magnetic fields have been studied. This review addresses several original attempts to treat ischemic diseases using SNPs, including particle synthesis methods, and presents perspectives on future research directions.

Subaqueous 3D stem cell spheroid levitation culture using anti-gravity bioreactor based on sound wave superposition.

BACKGROUND: Recently, various studies have revealed that 3D cell spheroids have several advantages over 2D cells in stem cell culture. However, conventional 3D spheroid culture methods have some disadvantages and limitations such as time required for spheroid formation and complexity of the experimental process. Here, we used acoustic levitation as cell culture platform to overcome the limitation of conventional 3D culture methods. METHODS: In our anti-gravity bioreactor, continuous standing sonic waves created pressure field for 3D culture of human mesenchymal stem cells (hMSCs). hMSCs were trapped and aggerated in pressure field and consequently formed spheroids. The structure, viability, gene and protein expression of spheroids formed in the anti-gravity bioreactor were analyzed by electron microscope, immunostaining, polymerase chain reaction, and western blot. We injected hMSC spheroids fabricated by anti-gravity bioreactor into the mouse hindlimb ischemia model. Limb salvage was quantified to evaluate therapeutic efficacy of hMSC spheroids. RESULTS: The acoustic levitation in anti-gravity bioreactor made spheroids faster and more compact compared to the conventional hanging drop method, which resulted in the upregulation of angiogenic paracrine factors of hMSCs, such as vascular endothelial growth factor and angiopoietin 2. Injected hMSCs spheroids cultured in the anti-gravity bioreactor exhibited improved therapeutic efficacy, including the degree of limb salvage, capillary formation, and attenuation of fibrosis and inflammation, for mouse hindlimb ischemia model compared to spheroids formed by the conventional hanging drop method. CONCLUSION: Our stem cell culture system using acoustic levitation will be proposed as a new platform for the future 3D cell culture system.

Metal Ion Releasing Gold Nanoparticles for Improving Therapeutic Efficiency of Tumor Targeted Photothermal Therapy.

BACKGROUND: Owing to the tumor-targeted migration capacity of human mesenchymal stem cells (hMSCs), they have been combined with nanoparticles for photothermal therapy. However, the low viability of hMSCs following transplantation remains a problem. Here, we developed iron (Fe) ion-releasing gold (Au) nanoparticles (IIAuNPs) for advanced tumor-targeted photothermal therapy using hMSCs. METHODS: IIAuNPs were designed to undergo degradation under low pH conditions, such as the endosomal microenvironment, for Fe ion release in hMSCs. After evaluating the properties of IIAuNP, the IIAuNP concentration for treating hMSCs was optimized in terms of cytotoxicity. In vitro cell migration and antiapoptotic factor secretion were observed in hMSCs. Additionally, IIAuNPs-treated hMSCs were intravenously injected into tumor-bearing mice, and enhanced tumor targeting based on improved cell viability and cell migration was evaluated. Three days after the injection, the mice were irradiated with 660 nm laser to confirm the enhanced photothermal effect. RESULTS: In vitro studies revealed that treating hMSCs with an optimum concentration of IIAuNPs enhanced cell migration and anti-apoptotic gene expression through intracellular Fe ion delivery. The viability of hMSCs under hypoxic cell culture conditions that mimic the in vivo microenvironment was also improved when hMSCs were treated with IIAuNPs, compared to hMSCs without IIAuNPs treatment. IIAuNPs-treated hMSCs showed significantly enhanced tumor-targeting efficiency and subsequent photothermal effect compared to hMSCs without IIAuNP treatment. CONCLUSION: Our results suggest that our metal-ion-releasing photothermal nanoparticles may provide a promising platform for future photothermal therapies and related applications.

Local Delivery of Senolytic Drug Inhibits Intervertebral Disc Degeneration and Restores Intervertebral Disc Structure.

Intervertebral disc (IVD) degeneration (IVDD) is a leading cause of chronic low back pain. There is a strong clinical demand for more effective treatments for IVDD as conventional treatments provide only symptomatic relief rather than arresting IVDD progression. This study shows that senolytic therapy with local drug delivery can inhibit IVDD and restore IVD integrity. ABT263, a senolytic drug, is loaded in poly(lactic-co-glycolic acid) nanoparticles (PLGA-ABT) and intradiscally administered into injury-induced IVDD rat models. The single intradiscal injection of PLGA-ABT may enable local delivery of the drug to avascular IVD, prevention of potential systemic toxicity caused by systemic administration of senolytic drug, and morbidity caused by repetitive injections of free drug into the IVD. The strategy results in the selective elimination of senescent cells from the degenerative IVD, reduces expressions of pro-inflammatory cytokines and matrix proteases in the IVD, inhibits progression of IVDD, and even restores the IVD structure. This study demonstrates for the first time that local delivery of senolytic drug can effectively treat senescence-associated IVDD. This approach can be extended to treat other types of senescence-associated degenerative diseases.

Local delivery of a senolytic drug in ischemia and reperfusion-injured heart attenuates cardiac remodeling and restores impaired cardiac function.

Myocardial ischemia-reperfusion (IR) generates stress-induced senescent cells (SISCs) that play an important role in the pathophysiology of adverse cardiac remodeling and heart failure via secretion of pro-inflammatory molecules and matrix-degrading proteases. Thus, removal of senescent cells using a senolytic drug could be a potentially effective treatment. However, clinical studies on cancer treatment with a senolytic drug have revealed that systemic administration of a senolytic drug often causes systemic toxicity. Herein we show for the first time that local delivery of a senolytic drug can effectively treat myocardial IR injury. We found that biodegradable poly(lactic-co-glycolic acid) nanoparticle-based local delivery of a senolytic drug (ABT263-PLGA) successfully eliminated SISCs in the IR-injured rat hearts without systemic toxicity. Consequently, the treatment ameliorated inflammatory responses and attenuated adverse remodeling. Surprisingly, the ABT263-PLGA treatment restored the cardiac function over time, whereas the cardiac function decreased over time in the no treatment group. Mechanistically, the ABT263-PLGA treatment not only markedly reduced the expression of pro-inflammatory molecules and matrix-degrading proteases, but also induced macrophage polarization from the inflammatory phase to the reparative phase via efferocytosis of apoptotic SISCs by macrophages. Therefore, the senolytic strategy with ABT263-PLGA in the early stage of myocardial IR injury may be an effective therapeutic option for myocardial infarction. STATEMENT OF SIGNIFICANCE: This study describes a local injection of senolytic drug-loaded nanoparticles that selectively kills stress-induced senescent cells (SISCs) in infarcted heart. Removal of SISCs decreases inflammatory cytokines and normal cell death. We firstly revealed that further efferocytosis of apoptotic senescent cells by macrophages restores cardiac function after myocardial ischemia-reperfusion injury. Importantly, a local injection of senolytic drug did not exhibit systemic toxicity, but a systemic injection did. Our findings not only spotlight the basic understanding of therapeutic potential of senolysis in infarcted myocardium, but also pave the way for the further application of senolytic drug for non-aging related diseases.

Multilayered Cell Sheets of Cardiac Reprogrammed Cells for the Evaluation of Drug Cytotoxicity.

BACKGROUND: Various cell-culture systems have been used to evaluate drug toxicity in vitro. However, factors that affect cytotoxicity outcomes in drug toxicity evaluation systems remain elusive. In this study, we used multilayered sheets of cardiac-mimetic cells, which were reprogrammed from human fibroblasts, to investigate the effects of the layer number on drug cytotoxicity outcomes. METHODS: Cell sheets of cardiac-mimetic cells were fabricated by reprogramming of human fibroblasts into cardiac-mimetic cells via coculture with cardiac cells and electric stimulation, as previously described. Double-layered cell sheets were prepared by stacking the cell sheets. The mono- and double-layered cell sheets were treated with 5-fluorouracil (5-FU), an anticancer drug, in vitro. Subsequently, apoptosis and lipid peroxidation were analyzed. Furthermore, effects of cardiac-mimetic cell density on cytotoxicity outcomes were evaluated by culturing cells in monolayer at various cell densities. RESULTS: The double-layered cell sheets exhibited lower cytotoxicity in terms of apoptosis and lipid peroxidation than the mono-layered sheets at the same 5-FU dose. In addition, the double-layered cell sheets showed better preservation of mitochondrial function and plasma membrane integrity than the monolayer sheets. The lower cytotoxicity outcomes in the double-layered cell sheets may be due to the higher intercellular interactions, as the cytotoxicity of 5-FU decreased with cell density in monolayer cultures of cardiac-mimetic cells. CONCLUSION: The layer number of cardiac-mimetic cell sheets affects drug cytotoxicity outcomes in drug toxicity tests. The in vitro cellular configuration that more closely mimics the in vivo configuration in the evaluation systems seems to exhibit lower cytotoxicity in response to drug.

Lightwave-reinforced stem cells with enhanced wound healing efficacy.

Comprehensive research has led to significant preclinical outcomes in modified human adipose-derived mesenchymal stem cells (hADSCs). Photobiomodulation (PBM), a technique to enhance the cellular capacity of stem cells, has attracted considerable attention owing to its effectiveness and safety. Here, we suggest a red organic light-emitting diode (OLED)-based PBM strategy to augment the therapeutic efficacy of hADSCs. In vitro assessments revealed that hADSCs basked in red OLED light exhibited enhanced angiogenesis, cell adhesion, and migration compared to naïve hADSCs. We demonstrated that the enhancement of cellular capacity was due to an increased level of intracellular reactive oxygen species. Furthermore, accelerated healing and regulated inflammatory response was observed in mice transplanted with red light-basked hADSCs. Overall, our findings suggest that OLED-based PBM may be an easily accessible and attractive approach for tissue regeneration that can be applied to various clinical stem cell therapies.

T-Cell-Mimicking Nanoparticles for Cancer Immunotherapy.

Cancer immunotherapies, including adoptive T cell transfer and immune checkpoint blockades, have recently shown considerable success in cancer treatment. Nevertheless, transferred T cells often become exhausted because of the immunosuppressive tumor microenvironment. Immune checkpoint blockades, in contrast, can reinvigorate the exhausted T cells; however, the therapeutic efficacy is modest in 70-80% of patients. To address some of the challenges faced by the current cancer treatments, here T-cell-membrane-coated nanoparticles (TCMNPs) are developed for cancer immunotherapy. Similar to cytotoxic T cells, TCMNPs can be targeted at tumors via T-cell-membrane-originated proteins and kill cancer cells by releasing anticancer molecules and inducing Fas-ligand-mediated apoptosis. Unlike cytotoxic T cells, TCMNPs are resistant to immunosuppressive molecules (e.g., transforming growth factor-ß1 (TGF-ß1)) and programmed death-ligand 1 (PD-L1) of cancer cells by scavenging TGF-ß1 and PD-L1. Indeed, TCMNPs exhibit higher therapeutic efficacy than an immune checkpoint blockade in melanoma treatment. Furthermore, the anti-tumoral actions of TCMNPs are also demonstrated in the treatment of lung cancer in an antigen-nonspecific manner. Taken together, TCMNPs have a potential to improve the current cancer immunotherapy.

Nanovesicles derived from iron oxide nanoparticles-incorporated mesenchymal stem cells for cardiac repair.

Because of poor engraftment and safety concerns regarding mesenchymal stem cell (MSC) therapy, MSC-derived exosomes have emerged as an alternative cell-free therapy for myocardial infarction (MI). However, the diffusion of exosomes out of the infarcted heart following injection and the low productivity limit the potential of clinical applications. Here, we developed exosome-mimetic extracellular nanovesicles (NVs) derived from iron oxide nanoparticles (IONPs)-incorporated MSCs (IONP-MSCs). The retention of injected IONP-MSC-derived NVs (IONP-NVs) within the infarcted heart was markedly augmented by magnetic guidance. Furthermore, IONPs significantly increased the levels of therapeutic molecules in IONP-MSCs and IONP-NVs, which can reduce the concern of low exosome productivity. The injection of IONP-NVs into the infarcted heart and magnetic guidance induced an early shift from the inflammation phase to the reparative phase, reduced apoptosis and fibrosis, and enhanced angiogenesis and cardiac function recovery. This approach can enhance the therapeutic potency of an MSC-derived NV therapy.

Cardiac-mimetic cell-culture system for direct cardiac reprogramming.

Rationale: Cardiovascular diseases often cause substantial heart damage and even heart failure due to the limited regenerative capacity of adult cardiomyocytes. The direct cardiac reprogramming of fibroblasts could be a promising therapeutic option for these patients. Although exogenous transcriptional factors can induce direct cardiac reprogramming, the reprogramming efficiency is too low to be used clinically. Herein, we introduce a cardiac-mimetic cell-culture system that resembles the microenvironment in the heart and provides interactions with cardiomyocytes and electrical cues to the cultured fibroblasts for direct cardiac reprogramming. Methods: Nano-thin and nano-porous membranes and heart like electric stimulus were used in the cardiac-mimetic cell-culture system. The human neonatal dermal fibroblasts containing cardiac transcription factors were plated on the membrane and cultured with the murine cardiomyocyte in the presence of the electric stimulus. The reprogramming efficiency was evaluated by qRT-PCR and immunocytochemistry. Results: Nano-thin and nano-porous membranes in the culture system facilitated interactions between fibroblasts and cardiomyocytes in coculture. The cellular interactions and electric stimulation supplied by the culture system dramatically enhanced the cardiac reprogramming efficiency of cardiac-specific transcriptional factor-transfected fibroblasts. Conclusion: The cardiac-mimetic culture system may serve as an effective tool for producing a feasible number of reprogrammed cardiomyocytes from fibroblasts.

M1 Macrophage-Derived Nanovesicles Potentiate the Anticancer Efficacy of Immune Checkpoint Inhibitors.

Cancer immunotherapy modulates immune cells to induce antitumor immune responses. Tumors employ immune checkpoints to evade immune cell attacks. Immune checkpoint inhibitors such as anti-PD-L1 antibody (aPD-L1), which is being used clinically for cancer treatments, can block immune checkpoints so that the immune system can attack tumors. However, immune checkpoint inhibitor therapy may be hampered by polarization of macrophages within the tumor microenvironment (TME) into M2 tumor-associated macrophages (TAMs), which suppress antitumor immune responses and promote tumor growth by releasing anti-inflammatory cytokines and angiogenic factors. In this study, we used exosome-mimetic nanovesicles derived from M1 macrophages (M1NVs) to repolarize M2 TAMs to M1 macrophages that release pro-inflammatory cytokines and induce antitumor immune responses and investigated whether the macrophage repolarization can potentiate the anticancer efficacy of aPD-L1. M1NV treatment induced successful polarization of M2 macrophages to M1 macrophages in vitro and in vivo. Intravenous injection of M1NVs into tumor-bearing mice suppressed tumor growth. Importantly, injection of a combination of M1NVs and aPD-L1 further reduced the tumor size, compared to the injection of either M1NVs or aPD-L1 alone. Thus, our study indicates that M1NV injection can repolarize M2 TAMs to M1 macrophages and potentiate antitumor efficacy of the checkpoint inhibitor therapy.

Therapeutic angiogenesis using tumor cell-conditioned medium.

Stem cell-conditioned medium (CM), which contains angiogenic factors that are secreted by stem cells, represents a potential therapy for ischemic diseases. Along with stem cells, tumor cells also secrete various angiogenic factors. Here, tumor cells as a cell source of CM for therapeutic angiogenesis was evaluated and the therapeutic efficacy of tumor cell CM in mouse hindlimb ischemia models was demonstrated. CM obtained from a human fibrosarcoma HT1080 cell line culture was compared with CM obtained from a human bone marrow-derived mesenchymal stem cell (MSC) culture. HT1080 CM contained higher concentrations of angiogenic factors compared with MSC CM, which was attributable to the higher cell density that resulted from a much faster growth rate of HT1080 cells compared with MSCs. For use in in vitro and in vivo angiogenesis studies, HT1080 CM was diluted such that HT1080 CM and MSC CM would have the same cell number basis. The two types of CMs induced the same extent of human umbilical vein endothelial cell (HUVEC) proliferation in vitro. The injection of HT1080 CM into mouse ischemic limbs significantly improved capillary density and blood perfusion compared with the injection of fresh medium. Although the therapeutic outcome of HT1080 CM was similar to that of MSC CM, the preparation of CM by tumor cell line culture would be much more efficient due to the faster growth and unlimited life-time of the tumor cell line. These data suggest the potential application of tumor cell CM as a therapeutic modality for angiogenesis and ischemic diseases. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:456-464, 2016.