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.

Glioblastoma multiforme (GBM) is the most frequently occurring brain cancer. Although the existence of cancer stem cells (CSCs) in GBM has been established, there is little evidence to explain the link between CSCs and chemoresistance. In this study, we developed a dissociated cell system of human GBM cells, A172 and established GBM2 cells, that have shown resistance to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). After exposure to a lethal dose of BCNU, the small population of GBM cancer cells survived and proliferated, as opposed to direct inhibition of the apoptosis and activation of the proliferation signal. Also, these cells contained subpopulations of stem-like cells, expressing CD133, CD117, CD90, CD71, and CD45 cell-surface markers, and had the capacity for multipotency. Moreover, we observed that BCNU-resistant subpopulations derived from GBM cancer cells can be grown to tumors when transplanted into severe combined immunodeficient (SCID) mouse brain. These results demonstrated that BCNU-resistant subpopulations derived from GBM have cancer stem-like cell properties. These findings provide further evidence that CSCs in GBM display chemotherapeutic drug resistance. Hopefully, it will be possible to improve the therapeutic outcome of GBM, leading to better anticancer strategies.

Development of localized inflammatory environments by M1 macrophages in the cardiac infarction region exacerbates heart failure after myocardial infarction (MI). Therefore, the regulation of inflammation by M1 macrophages and their timely polarization toward regenerative M2 macrophages suggest an immunotherapy. Particularly, controlling cellular generation of reactive oxygen species (ROS), which cause M1 differentiation, and developing M2 macrophage phenotypes in macrophages propose a therapeutic approach. Previously, stem or dendritic cells were used in MI for their anti-inflammatory and cardioprotective potentials and showed inflammation modulation and M2 macrophage progression for cardiac repair. However, cell-based therapeutics are limited due to invasive cell isolation, time-consuming cell expansion, labor-intensive and costly ex vivo cell manipulation, and low grafting efficiency. Here, we report that graphene oxide (GO) can serve as an antioxidant and attenuate inflammation and inflammatory polarization of macrophages via reduction in intracellular ROS. In addition, GO functions as a carrier for interleukin-4 plasmid DNA (IL-4 pDNA) that propagates M2 macrophages. We synthesized a macrophage-targeting/polarizing GO complex (MGC) and demonstrated that MGC decreased ROS in immune-stimulated macrophages. Furthermore, DNA-functionalized MGC (MGC/IL-4 pDNA) polarized M1 to M2 macrophages and enhanced the secretion of cardiac repair-favorable cytokines. Accordingly, injection of MGC/IL-4 pDNA into mouse MI models attenuated inflammation, elicited early polarization toward M2 macrophages, mitigated fibrosis, and improved heart function. Taken together, the present study highlights a biological application of GO in timely modulation of the immune environment in MI for cardiac repair. Current therapy using off-the-shelf material GO may overcome the shortcomings of cell therapies for MI.

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.

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.

immune surveillance, cytotoxic immune cells such as T lymphocytes (CTLs) play crucial roles. CTLs can migrate to inflamed tumor sites via interactions with tumor vasculatures through adhesion proteins (e.g., lymphocyte functionassociated antigen 1; LFA-1). [4] Upon T cell receptor (TCR)-mediated recognition of tumor antigens presented on major histocompatibility complex molecules, CTLs can eliminate malignant cells by secreting cytotoxic molecules (e.g., granzyme) and providing the Fas ligand (FasL) signal. [5-8] Infusion of ex vivo expanded tumorreactive CTLs or TCR-engineered T cells (e.g., chimeric antigen receptor cells) has shown impressive clinical outcomes. [9,10] The selection of the appropriate target tumor antigens and proper ex vivo expansion of the T cells are essential for the success of adoptive T cell transfer therapy. [11] However, there are several obstacles in adoptive T cell transfer therapy, including expensive and labor-intensive procedures for ex vivo expansion of T cells, loss of target tumor antigens due to cancer immunoediting, antigens heterogeneity among individual patients, and the immunosuppressive nature of 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-membraneoriginated 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-β1 (TGF-β1)) and programmed death-ligand 1 (PD-L1) of cancer cells by scavenging TGF-β1 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.

Liposomes are clinically used as drug carriers for cancer therapy; however, unwanted leakage of the encapsulated anticancer drug and poor tumor-targeting efficiency of liposomes may generate toxic side effects on healthy cells and lead to failure of tumor eradication. To overcome these limitations, we functionalized liposomes with a photosensitizer (KillerRed, KR)-embedded cancer cell membrane (CCM). A lipid adjuvant was also embedded in the lipocomplex to promote the anticancer immune response. KR proteins were expressed on CCM and did not leak from the lipocomplex. Owing to the homotypic affinity of the CCM for the source cancer cells, the lipocomplex exhibited a 3.3-fold higher cancer-targeting efficiency in vivo than a control liposome. The liposome functionalized with KR-embedded CCM and lipid adjuvant generated cytotoxic reactive oxygen species in photodynamic therapy and effectively induced anticancer immune responses, inhibiting primary tumor growth and lung metastasis in homotypic tumor-bearing mice. Taken together, the lipocomplex technology may improve liposome-based cancer therapy.

Although T‐cell therapy is a remarkable breakthrough in cancer immunotherapy, the therapeutic efficacy is limited for solid tumors. A major cause of the low efficacy is T‐cell exhaustion by immunosuppressive mechanisms of solid tumors, which are mainly mediated by programmed death‐ligand 1 (PD‐L1) and transforming growth factor‐beta (TGF‐β). Herein, T‐cell‐derived nanovesicles (TCNVs) produced by the serial extrusion of cytotoxic T cells through membranes with micro‐/nanosized pores that inhibit T‐cell exhaustion and exhibit antitumoral activity maintained in the immunosuppressive tumor microenvironment (TME) are presented. TCNVs, which have programmed cell death protein 1 and TGF‐β receptor on their surface, block PD‐L1 on cancer cells and scavenge TGF‐β in the immunosuppressive TME, thereby preventing cytotoxic‐T‐cell exhaustion. In addition, TCNVs directly kill cancer cells via granzyme B delivery. TCNVs successfully suppress tumor growth in syngeneic‐solid‐tumor‐bearing mice. Taken together, TCNV offers an effective cancer immunotherapy strategy to overcome the tumor's immunosuppressive mechanisms.