Hydroxyapatite nanoparticles drive the potency of Toll-like receptor 9 agonist for amplified innate and adaptive immune response

Dynamic Hybrid Module-Driven NK Cell Stimulation and Release for Tumor Immunotherapy

Natural killer (NK) cells have become a powerful candidate for adoptive tumor immunotherapy, while their therapeutic efficacy in solid tumors remains unsatisfactory. Here, we developed a hybrid module with an injectable hydrogel and hydroxyapatite (HAp) nanobelts for the controlled delivery of NK cells to enhance the therapy of solid tumors. Surface-functionalized HAp nanobelts modified with agonistic antibodies against NKG2D and 4-1BB and cytokines IL-2 and IL-21 support survival and dynamic activation. Thus, the HAp-modified chitosan (CS) thermos-sensitive hydrogel not only improved the retention of NK cells for more than 20 days in vivo but also increased NK cell function by more than one-fold. The unique architecture of this biomaterial complex protects NK cells from the hostile tumor environment and improves antitumor efficacy. The generation of a transient inflammatory niche for NK cells through a biocompatible hydrogel reservoir may be a conversion pathway to prevent cancer recurrence of resectable tumors.

Aspect ratio-dependent dual-regulation of the tumor immune microenvironment against osteosarcoma by hydroxyapatite nanoparticles

Accumulating studies demonstrated that hydroxyapatite nanoparticles (HANPs) showed a selective anti-tumor effect, making them a good candidate for osteosarcoma (OS) treatment. However, the capacity of HANPs with different aspect ratios to regulate tumor immune microenvironment (TIM) was scarcely reported before. To explore it, the three HANPs with aspect ratios from 1.86 to 6.25 were prepared by wet chemical method. After a 24 or 72 h-exposure of OS UMR106 cells or macrophages to the nanoparticles, the tumor cells exhibited immunogenic cell death (ICD) indicated by the increased production of calreticulin (CRT), adenosine triphosphate (ATP) and high mobility group box 1 (HMGB1), and macrophages were activated with the release of pro-inflammatory cytokines. Next, the beneficial crosstalk between tumor cells and macrophages generated in the presence of HANPs for improved anti-tumor immunity activation. In the OS-bearing cognate rat model, HANPs inhibited OS growth, which was positively correlated with CRT and HMGB1 expression, and macrophage polarization in the tumor tissues. Additionally, HANPs promoted CD8+ T cell infiltration into the tumor and systemic dendritic cell maturation. Particularly, HANPs bearing the highest aspect ratio exhibited the strongest immunomodulatory and anti-tumor function. This study suggested the potential of HANPs to be a safe and effective drug-free nanomaterial to control the TIM for OS therapy. STATEMENT OF SIGNIFICANCE: Emerging studies demonstrated that hydroxyapatite nanoparticles (HANPs) inhibited tumor cell proliferation and tumor growth. However, the underlying anti-tumor mechanism still remains unclear, and the capacity of HANPs without any other additive to regulate tumor immune microenvironment (TIM) was scarcely reported before. Herein, we demonstrated that HANPs, in an aspect ratio-dependent manner, showed the potential to delay the growth of osteosarcoma (OS) and to regulate TIM by promoting the invasion of CD8+ T cells and F4/80+ macrophages, and inducing immunogenic cell death (ICD) in tumors. This work revealed the new molecular mechanism for HANPs against OS, and suggested HANPs might be a novel ICD inducer for OS treatment.

Erythrocyte membrane-camouflaged DNA-functionalized upconversion nanoparticles for tumor-targeted chemotherapy and immunotherapy

A synergistic combination of treatment with immunogenic cell death (ICD) inducers and immunoadjuvants may be a practical way to boost the anticancer response and successfully induce an immune response. The use of HR@UCNPs/CpG-Apt/DOX, new biomimetic drug delivery nanoparticles generated to combat breast cancer, is reported here as a unique strategy to produce immunogenicity and boost cancer immunotherapy. HR@UCNPs/CpG-Apt/DOX (HR-UCAD) consists of two parts. The core is composed of an immunoadjuvant CpG (a toll-like receptor 9 agonist) fused with a dendritic cell-specific aptamer sequence (CpG-Apt) to decorate upconversion nanoparticles (UCNPs) with the successful intercalation of doxorubicin (DOX) into the consecutive base pairs of Apt-CpG to construct an immune nanodrug UCNPs@CpG-Apt/DOX. The targeting molecule hyaluronic acid (HA) was inserted into a red blood cell membrane (RBCm) to form the shell (HR). HR-UCAD possessed a strong capacity to specifically induce ICD. Following DOX-induced ICD of cancer cells, sufficient exposure to tumor antigens and UCNPs@CpG-Apt (UCA) activated the tumor-specific immune response and reversed the immunosuppressive tumor microenvironment. In addition, HR-UCAD has good biocompatibility and increases the active tumor-targeting effect. Furthermore, HR-UCAD exhibits excellent near-infrared upconversion luminescence emission at 804 nm under irradiation with a 980 nm laser, which has great potential in biomedical imaging. Thus, the RBCm-camouflaged drug delivery system is a promising targeted chemotherapy and immunotherapy nanocomplex that could be used for effective targeted breast cancer treatment.

Sponge-like nano-system suppresses tumor recurrence and metastasis by restraining myeloid-derived suppressor cells-mediated immunosuppression and formation of pre-metastatic niche

Tumor recurrence and metastasis still greatly limit the therapeutic efficiency on the majority of postoperative clinical cases. With the aim to realize more powerful treatment outcomes on postoperative malignant tumors, a sponge-like neutrophil membrane-coated nano-system (NM/PPcDG/D) was fabricated to inhibit tumor recurrence and metastasis by inhibiting the recruitment and functions of myeloid-derived suppressor cell (MDSCs), which reinforced anti-tumor immunity and also suppressed pulmonary metastasis by inhibiting the formation of pre-metastatic niche (PMN). Firstly, PPcDG/D nanoparticles (NPs) were formulated by the self-assembling and crosslinking of synthesized redox-responsive polymer (PPDG) with doxorubicin (DOX) loading in the nanocore (PPcDG/D), followed by coating with activated neutrophils membrane to fabricate biomimetic NM/PPcDG/D. The sponge-like NM/PPcDG/D not only showed obvious natural tropism to postoperative inflammatory site, but also inhibited the recruitment and functions of MDSCs, thus relieved MDSCs-mediated immunosuppression. Additionally, NM/PPcDG/D also suppressed the formation of PMN to inhibit pulmonary metastasis by reducing the recruitment of MDSCs, decreasing the permeability of pulmonary vessels and inhibiting the implantation of circulating tumor cell (CTCs). Eventually, this fabricated NM/PPcDG/D NPs significantly inhibited tumor recurrence and metastasis on postoperative triple negative breast cancer (TNBC) model, presenting a promising therapeutic strategy on postoperative malignant tumors. STATEMENT OF SIGNIFICANCE: Myeloid-derived suppressor cells (MDSCs) play important roles in accelerating tumor recurrence and metastasis by promoting the establishment of immunosuppression in postoperative inflammatory regions and facilitating the formation of pulmonary pre-metastasis niche (PMN). In order to achieve enhanced suppression of recurrence and metastasis, a sponge-like NM/PPcDG/D nano-system was designed and fabricated. This nano-system is also the first attempt to integrate the regulation effects of a nano-sponge and anti-inflammatory agent to achieve enhanced multi-mode manipulation of MDSCs. Ultimately, NM/PPcDG/D powerfully restrained the recurrence and spontaneous metastasis on TNBC model. This article also revealed the particular roles of MDSCs involved in the regulation networks of postoperative recurrence and metastasis, immunosuppression and inflammation.