Synergy of Polydopamine Nanovaccine and Endostar Alginate Hydrogel for Improving Antitumor Immune Responses Against Colon Tumor.

Background: Tumor immunotherapy, a novel type of therapeutic treatment, has a wide range of applications with potentially prolonged benefits. However, current immunotherapy has a low overall response rate in treating a variety of tumors. Combination of immunotherapy with other therapies can improve the therapeutic response rates. The purpose of this work was to explore the potential of anti-angiogenic treatment in combination with tumor cell lysate loaded polydopamine nanoparticle vaccine as a therapeutic strategy for colon tumor. Methods: We grafted tumor cell lysate onto polydopamine nanoparticles as nano-vaccine (TCLN) and fabricated alginate hydrogel loaded with Endostar (EH), then detected characteristics of EH and TCLN. We also estimated the cytotoxicity of EH/TCLN in vitro. In the tumor-bearing mouse model, we evaluated the antitumor effect of EH/TCLN treatment, and developed the animal survival study. After performing the EH/TCLN treatment, we also analyzed T cells and DCs using flow cytometry, and determined T cell responses and tumor microenvironmental cytokines. At last, we assessed the effect of the EH/TCLN treatment on anti-angiogenesis further. Results: When applied in combination with TCLN in MC-38 tumor-bearing mice, EH/TCLN significantly suppressed tumor growth with more than half of the mice showing tumor regression. In addition, EH/TCLN treatment resulted in noticeable changes in the tumor microenvironment. As compared with the control group, EH/TCLN treatment led to significantly reduced tumor angiogenesis and expression of tumor microenvironment-related cytokines (TMCs), increased proportion of CD8+ T cells in the spleen, lymph node and tumor, elevated activity of cytotoxic T lymphocytes (CTLs) and tumor cell apoptosis. Conclusion: The present study demonstrated that the EH/TCLN treatment effectively created a favorable immune microenvironment for the induction of antitumor immunity and improved antitumor immune responses.

Doxorubicin and CpG loaded liposomal spherical nucleic acid for enhanced Cancer treatment.

Chemotherapeutics that can trigger immunogenic cell death (ICD) and release tumor-specific antigens are effective on treating a variety of cancers. The codelivery of chemotherapeutics with adjuvants is a promising strategy to achieve synergistic therapeutic effect. However, low drug loading and complicated preparation of current delivery systems lead to carrier-associated toxicity and immunogenicity. Herein, we developed a facile approach to construct liposomal spherical nucleic acids (SNA) by the self-assembly of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)-doxorubicin conjugate and DOPE-matrix metalloproteinases-9 (MMP-9) responsive peptide-CpG conjugate (DOPE-MMP-CpG). Liposomal SNAs efficiently co-delivered DOX and CpG into tumors and released the two drugs upon biological stimuli of MMP-9 enzyme in tumor microenvironment (TME) and high concentration of endogenous glutathione in tumor cells. We demonstrated that liposomal SNA enhanced activation of dendritic cells (DCs), promoted expansion of CD8+ and CD4+ T cells in both tumors and spleen, inhibited tumor growth, and extended animal survival. This work provided a simple strategy of delivering chemotherapeutics and adjuvants to tumors with synergistic therapeutic effect and reduced side effect.

Enhanced Antitumor Immune Responses via a Self-Assembled Carrier-Free Nanovaccine.

Nanovaccines have emerged as promising agents for cancer immunotherapy. However, insufficient antitumor immunity caused by inefficient antigen/adjuvant loading and complicated preparation processes are the major obstacles that limit their clinical application. Herein, two adjuvants, monophosphatidyl A (MPLA) and CpG ODN, with antigens were designed into a nanovaccine to overcome the above obstacles. This nanovaccine was constructed with adjuvants (without additional materials) through facile self-assembly, which not only ensured a high loading efficacy and desirable safety but also facilitated clinical translation for convenient fabrication. More importantly, the selected adjuvants could achieve a notable immune response through synergistic activation of Toll-like receptor 4 (TLR4) and TLR9 signaling pathways, and the resulting nanovaccine remarkably inhibited the tumor growth and prolonged the survival of tumor-implanted mice. This nanovaccine system provides an effective strategy to construct vaccines for cancer immunotherapy.

Biofabrication of poly(l-lactide-co-ε-caprolactone)/silk fibroin scaffold for the application as superb anti-calcification tissue engineered prosthetic valve.

In this study, electrospun scaffolds were fabricated by blending poly(l-lactide-co-ε-caprolactone) (PLCL) and silk fibroin (SF) with different ratios, and further the feasibility of electrospun PLCL/SF scaffolds were evaluated for application of tissue engineered heart valve (TEHV). Scanning electron microscopy (SEM) results showed that the surface of PLCL/SF electrospun scaffolds was smooth and uniform while the mechanical properties were appropriate as valve prosthesis. In vitro cytocompatibility evaluation results demonstrated that all of the PLCL/SF electrospun scaffolds were cytocompatible and valvular interstitial cells (VICs) cultured on PLCL/SF scaffolds of 80/20 & 70/30 ratios exhibited the best cytocompatibility. The in vitro osteogenic differentiation of VICs including alkaline phosphatase (ALP) activity and quantitative polymerase chain reaction (qPCR) assays indicated that PLCL/SF scaffolds of 80/20 & 90/10 ratios behaved better anti-calcification ability. In the in vivo calcification evaluation model of rat subdermal implantation, PLCL/SF scaffolds of 80/20 & 90/10 ratios presented better anti-calcification ability, which was consistent with the in vitro results. Moreover, PLCL/SF scaffolds of 80/20 & 70/30 ratios showed significantly enhanced cell infiltration and M2 macrophage with higher CD206+/CD68+ ratio. Collectively, our data demonstrated that electrospun scaffolds with the PLCL/SF ratio of 80/20 hold great potential as TEHV materials.

ICG/l-Arginine Encapsulated PLGA Nanoparticle-Thermosensitive Hydrogel Hybrid Delivery System for Cascade Cancer Photodynamic-NO Therapy with Promoted Collagen Depletion in Tumor Tissues.

Photodynamic therapy (PDT) is promising for clinical cancer therapy; however, the efficacy was limited as an individual treatment regimen. Here, an approach synergistically combining PDT and nitric oxide (NO) gas therapy along with destruction of the tumor extracellular matrix (ECM) was presented to eliminate cancer. Specifically, the NO donor l-arginine (l-Arg) and the photosensitizer indocyanine green (ICG) were co-encapsulated in poly(lactic-glycolic acid) (PLGA) nanoparticles and then loaded into the poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL) hydrogel to develop an injectable, thermosensitive dual drug delivery system (PLGA@ICG@l-Arg/Gel). Significantly, reactive oxygen species (ROS) produced by PLGA@ICG@l-Arg/Gel under near-infrared (NIR) light irradiation could not only result in the apoptosis of cancer cells but also oxidize l-Arg to generate NO, which could suppress the proliferation of cancer cells. Moreover, ROS could further oxidize NO to generate peroxynitrite anions (ONOO-). ONOO- could activate matrix metalloproteinases (MMPs), which notably degraded collagen in ECM so as to damage the tumor microenvironment. PLGA@ICG@l-Arg/Gel significantly increased the antitumor efficacy against highly malignant 4T1 tumors in mice. Taken together, PLGA@ICG@l-Arg/Gel is a multifunctional platform that provides a novel strategy for cancer treatment with cascade amplification of the ROS oxidation effect, which holds great potential in clinical translation.

A simple self-adjuvanting biomimetic nanovaccine self-assembled with the conjugate of phospholipids and nucleotides can induce a strong cancer immunotherapeutic effect.

Biomimetic nanoparticles have potential applications in many fields due to their favorable properties. Here, we developed a self-adjuvanting biomimetic anti-tumor nanovaccine, which was self-assembled with an amphiphilic conjugate synthesized with the phospholipids of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and hydrophilic Toll-like receptor (TLR9) agonist CpG ODN. The nanovaccine could not only provide effective initial antigen stimulation and sustained long-term antigen supply with a controlled release, but also induce antigen cross-presentation via the MHC-I pathway initiating CD8+ T-cell responses. Moreover, the dense nucleotide shell around the nanovaccine could promote antigen endocytosis via various receptor-mediated pathways into dendritic cells. CpG ODN interacted with TLR9 triggering the cytokine secretion of TNF-α and IL-10, which further boosted the anti-tumor humoral and cellular immune responses, which led to a significant tumor suppressive effect and remarkable survival prolongation. So, this nanovaccine self-assembled with phospholipid-nucleotide amphiphiles can serve as a safe, simple and efficient approach for anti-tumor immunotherapy.

Hybrid spherical nucleotide nanoparticles can enhance the synergistic anti-tumor effect of CTLA-4 and PD-1 blockades.

Combined blockades of CTLA-4 and PD-1 can yield better overall complementary clinical outcomes than individual blockades, but the response rates are still relatively low. To investigate the anti-tumor effects of various combined strategies, we designed various spherical nucleotide nanoparticles (SNPs) loaded with CTLA-4 aptamer (cSNPs), PD-1 siRNA (pSNPs) or both (hybrid SNPs, or hSNPs). The results demonstrated that hSNPs could promote significantly stronger anti-tumor immune responses in a nonredundant fashion than the mixture of pSNPs and cSNPs (pSNPs & cSNPs). We reasoned that this is because all individual immune cells could receive both CTLA-4 and PD-1 blockades when they engulfed hSNPs, but it is much less likely that individual immune cells could receive both CTLA-4 and PD-1 blockades as many of them may not take both pSNPs and cSNPS from pSNPs & cSNPs. Further results revealed that the synergistic immune stimulatory effects of CTLA-4 and PD-1 blockades in the form of hSNPs were at least partly through regulating the immune suppressive function of both Tregs and TIM3+ exhausted-like CD8 T cells and allowing effector T cells to expand. This mechanism is not identical to earlier reported mechanisms of CTLA-4 and PD-1 blockades.

MWCNT-mediated combinatorial photothermal ablation and chemo-immunotherapy strategy for the treatment of melanoma.

Melanoma, the most aggressive skin cancer with a high metastatic index, causes almost 90% of skin cancer mortality. Currently available conservative therapies, including chemotherapy, radiotherapy and immunotherapy, have shown little effect against metastatic melanoma, leading to a very poor prognosis. The present study was aimed at developing a more efficient therapeutic strategy by combining MWCNT mediated photothermal ablation with both chemotherapy and immunotherapy. For this purpose, DOX and CpG were loaded onto MWCNTs via physical adhesion. The diameters of the resultant MWCNT-CpG and MWCNT-DOX were 197.3 ± 5.45 nm and 263.8 ± 7.36 nm, with zeta potentials of -48 ± 4.93 mV and 58 ± 2.42 mV, respectively. Loading with either CpG or DOX significantly enhanced the water dispersibility of the MWCNTs and showed no obvious impact on the physical structure of the MWCNTs. MWCNT loading facilitated the uptake of CpG by bone marrow derived dendritic cells (BMDCs), as well as the maturation of BMDCs. Intratumoral injection of MWCNT-DOX and MWCNT-CpG with subsequent NIR irradiation resulted in a significant delay in tumor progression in melanoma bearing mice, along with an increased number of CD4+ and CD8+ T cells in the spleen, draining lymph nodes and tumor tissues. The regimen promoted TAM shifting from M2 to M1 while decreasing the number of Treg cells in the tumor microenvironment, which probably contributed to the enhanced anti-tumor efficacy of the regimen. Hopefully, the invented strategy might find potential applications for the therapy of melanoma in the future.

Curcumin-crosslinked acellular bovine pericardium for the application of calcification inhibition heart valves.

Glutaraldehyde (GA) crosslinked bovine or porcine pericardium tissues exhibit high cell toxicity and calcification in the construction of bioprosthetic valves, which accelerate the failure of valve leaflets and motivate the exploration for alternatives. Polyphenols, including curcumin, procyanidin and quercetin, etc, have showed great calcification inhibition potential in crosslinking collagen and elastin scaffolds. Herein, we developed an innovative phenolic fixing technique by using curcumin as the crosslinking reagent for valvular materials. X-ray photoelectron spectroscopy and Fourier transform infrared spectrometry assessments confirmed the hydrogen bond between curcumin and acellular bovine pericardium. Importantly, the calcification inhibition capability of the curcumin-crosslinked bovine pericardium was proved by the dramatically reduced Ca2+ content in the curcumin-fixed group in in vitro assay, a juvenile rat subcutaneous implants model, as well as an osteogenic differentiation model. In addition, the results showed that the curcumin-fixed bovine pericardium exhibited better performance in the areas of mechanical performance, hemocompatibility and cytocompatibility, in comparison with the GA group and the commercialized product. In summary, we demonstrated that curcumin was a feasible crosslinking reagent to fix acellular bovine pericardium, which showed great potential for biomedical applications, particularly in cardiovascular biomaterials with calcification inhibition capacity.

Epoxy Chitosan-Crosslinked Acellular Bovine Pericardium with Improved Anti-calcification and Biological Properties.

Glutaraldehyde (GA) was conventionally used to crosslink bovine pericardium to prepare bioprosthetic heart valves (BHVs), which usually fail within 10 years because of valve deterioration and calcification. To overcome the high cytotoxicity and severe calcification of GA-crosslinked BHVs, a quaternary ammonium salt of epoxy chitosan (epoxy group-modified 3-chlorine-2-hydroxypropyl trimethyl chitosan, abbreviated as "eHTCC") was developed to modify the acellular bovine pericardium to substitute GA and improve its anti-calcification and biocompatible properties. Mechanical test, enzymatic stability test, blood compatibility assay, and cytocompatibility assay were used to investigate its mechanical property and biocompatibility. The anti-calcification effect of the eHTCC-modified bovine pericardium (eHTCC-BP) was assessed by in vitro assay and rat subcutaneous implantation assay. The results showed that eHTCC-BP could improve the mechanical properties and anti-enzymolysis ability of BP, as well as retain the original three-dimensional structure, compared with the uncrosslinked-BP group. Moreover, the in vivo calcification level of the eHTCC-BP group was much lower than that of the GA-BP group, which was 5.1% (2 weeks), 2.3% (4 weeks), and 0.8% (8 weeks) of the GA-BP group. In summary, this study demonstrated that eHTCC could be a potential crosslinking agent for the extracellular matrix for its favorable crosslinking effects, anti-enzymolysis, anti-calcification, and biocompatibility.

Swim Bladder as a Novel Biomaterial for Cardiovascular Materials with Anti-Calcification Properties.

Calcification is a major cause of cardiovascular materials failure and deterioration, which leads to the restriction of their wide application. To develop new materials with anti-calcification capability is an urgent clinical requirement. Herein, a natural material derived from swim bladders as one promising candidate is introduced, which is prepared by decellularization and glutaraldehyde (GA) crosslinking. Data show that the swim bladder is mainly composed of collagen I, glycosaminoglycan (GAG), and elastin, especially rich in elastin, in accordance with higher elastic modulus in comparison to bovine pericardium. Moreover, the calcification of this material is proved dramatically lower than that of bovine pericardium by in vitro calcification assessments and in vivo assay using a rat subcutaneous implantation model. Meanwhile, good cytocompatibility, hemocompatibility, and enzymatic stability are demonstrated by in vitro assays. Further, a small diameter vascular graft using this material is successfully developed by rolling method and in situ implantation assay using a rat abdominal artery replacement model shows great performances in the aspect of higher patency and lower calcification. Taken together, these superior properties of swim bladder-derived material in anti-calcification, proper mechanical strength and stability, and excellent hemocompatibility and cytocompatibility endow it a great candidate as cardiovascular biomaterials.

A cell-penetrating peptide-assisted nanovaccine promotes antigen cross-presentation and anti-tumor immune response.

Exogenous antigens processed in the cytosol and subsequently cross-presented on major histocompatibility complex class I (MHC-I) molecules activate cytotoxic CD8+ lymphocytes (CTL), which are crucial in cancer immunotherapy. Here, we reported a nanovaccine, which was produced by encapsulating OVA (ovalbumin, a model antigen) chemically modified with MPGΔNLS (MPGΔNLS-OVA conjugate) into poly(lactide-co-glycolide) acid (PLGA) nanoparticles. We hypothesized that after the uptake of the nanovaccine into immune cells, MPGΔNLS, a cell-penetrating peptide (CPP), would assist the escape of the antigens from lysosomes into the cytosol, increase the amount of antigens processed in the cytosol and subsequently enhance antigen cross-presentation via MHC-I molecules to elicit cytotoxic CD8+ T cell responses. The results of the in vitro experiments demonstrated that the MPGΔNLS-OVA-loaded PLGA NPs not only elevated the release of OVA into the cytosol of dendritic cells (BMDCs), but also promoted the maturation and activation of BMDCs. It was also observed in mice vaccinated with MPGΔNLS-OVA-loaded PLGA NPs that the MPGΔNLS modification could stimulate the expansion of OVA-specific T-cells, generation of OVA-specific IgG antibodies and proliferation of OVA-specific memory T cells. Moreover, the treatment of E·G7-OVA tumor-bearing mice with MPGΔNLS-OVA-loaded PLGA NPs resulted in significantly suppressed tumor growth and prolonged survival periods of the mice compared to the treatment with unmodified OVA-PLGA NPs or free OVA. In summary, cell-penetrating peptides linked with antigens encapsulated in nanovaccines can spatiotemporally affect the intracellular localization of antigens, promote antigen cross-presentation and stimulate antigen-specific immune responses, especially CTL responses. Therefore, the CPP modification on antigens is an innovative approach to enhance the efficacy of nanovaccines for cancer immunotherapy.

A Dual-Model Imaging Theragnostic System Based on Mesoporous Silica Nanoparticles for Enhanced Cancer Phototherapy.

Mesoporous silica nanoparticles (MSNs) show great promise to be exploited as versatile multifunctional nanocarriers for effective cancer diagnosis and treatment. In this work, perfluorohexane (PFH)-encapsulated MSNs with indocyanine green (ICG)-polydopamine (PDA) layer and poly(ethylene glycol)-folic acid coating (designated as MSNs-PFH@PDA-ICG-PEG-FA) are successfully fabricated to achieve tumor ultrasonic (US)/near-infrared fluorescence (NIRF) imaging as well as photothermal therapy (PTT)/photodynamic therapy (PDT). MSNs-PFH@PDA-ICG-PEG-FA exhibits good monodispersity with high ICG loading, significantly enhances ICG photostability, and greatly improves cellular uptake. Upon single 808 nm NIR irradiation, the nanocarrier not only efficiently generates hyperthermia to realize PTT, but also produces reactive oxygen species (ROS) for effective PDT. Meanwhile, NIR irradiation can trigger PFH to undergo vaporization and provide a super-resolution US image. Thus, the PTT/PDT combination therapy can be dually guided by PFH-induced US imaging and ICG-induced NIRF imaging. In vivo antitumor studies demonstrate that PTT/PDT from MSNs-PFH@PDA-ICG-PEG-FA significantly inhibits tumor growth and achieves a cure rate of 60% (three out of five mice are completely cured). Hence, the multifunctional MSNs appear to be a promising theragnostic nanoplatform for multimodal cancer imaging and therapy.

Polydopamine nanoparticles carrying tumor cell lysate as a potential vaccine for colorectal cancer immunotherapy.

Polydopamine nanoparticles (PDA NPs) were prepared via dopamine self-polymerization; then, tumor cell lysate (TCL) was covalently attached onto the PDA NPs. The TCL loading capacity was 480 µg per mg of PDA NPs, and the resulting TCL@PDA NPs (241.9 nm) had perfect storage stability and negligible cytotoxicity against APCs. Tumor-bearing mice vaccinated with TCL@PDA NPs experienced significant delay in tumor progression due to the sufficient amount of CTLs and M1-type TAM as well as the deficient number of immunosuppression-related cells in the tumor tissues. Furthermore, empty PDA NPs had the ability to modulate DC maturation and delayed the development of tumors by facilitating the production of activated T cells and decreasing the subpopulation of MDSCs within the tumor microenvironment. Overall, these PDA NPs are expected to be a promising candidate for application as antigen delivery carriers because of their facile antigen loading method as well as their simple and rapid preparation process.

Targeted Codelivery of an Antigen and Dual Agonists by Hybrid Nanoparticles for Enhanced Cancer Immunotherapy.

Among approaches of current cancer immunotherapy, a dendritic cell (DC)-targeted vaccine based on nanotechnology could be a promising way to efficiently induce potent immune responses. To enhance DC targeting and vaccine efficiency, we included imiquimod (IMQ), a toll-like receptor 7/8 (TLR 7/8) agonist, and monophosphoryl lipid A (MPLA), a TLR4 agonist, to synthesize lipid-polymer hybrid nanoparticles using PCL-PEG-PCL and DOTAP (IMNPs) as well as DSPE-PEG-mannose (MAN-IMNPS). The spatiotemporal delivery of MPLA (within the outer lipid layer) to extracellular TLR4 and IMQ (in the hydrophobic core of NPs) to intracellular TLR7/8 can activate DCs synergistically to improve vaccine efficacy. Ovalbumin (OVA) as a model antigen was readily absorbed by positively charged DOTAP and showed a quick release in vitro. Our results demonstrated that this novel nanovaccine enhanced cellular uptake, cytokine production, and maturation of DCs. Compared with the quick metabolism of free OVA-agonists, the depot effect of OVA-IMNPs was observed, whereas MAN-OVA-IMNPs promoted trafficking to secondary lymphoid organs. After immunization with a subcutaneous injection, the nanovaccine, especially MAN-OVA-IMNPs, induced more antigen-specific CD8+ T cells, greater lymphocyte activation, stronger cross-presentation, and more generation of memory T cells, antibody, IFN-γ, and granzyme B. Prophylactic vaccination of MAN-OVA-IMNPs significantly delayed tumor development and prolonged the survival in mice. The therapeutic tumor challenge indicated that MAN-OVA-IMNPs prohibited tumor progression more efficiently than other formulations, and the combination with an immune checkpoint blockade further enhanced antitumor effects. Hence, the DC-targeted vaccine codelivery with IMQ and MPLA adjuvants by hybrid cationic nanoparticles in a spatiotemporal manner is a promising multifunctional antigen delivery system in cancer immunotherapy.

Co-delivery of antigen and dual agonists by programmed mannose-targeted cationic lipid-hybrid polymersomes for enhanced vaccination.

Exploiting Toll-like receptor (TLR) agonists or their certain combinations can enhance the immune potency of subunit vaccine. Nevertheless, the design of co-delivery systems which can act in a synergistic and spatio-temporal way to achieve effective and durable specific immune response is still challenging. Here we fabricated mannose-functionalized lipid-hybrid polymersomes (MAN-IMO-PS) for co-delivery of ovalbumin antigen both inside the inner core and outside the lipid layer, TLR7/8 agonist imiquimod within the hydrophobic membrane, TLR4 agonist monophosphoryl lipid A in the lipid layer as programmed nanovaccine to synergistically activate immune responses for improving vaccine efficacy. After efficiently internalized by dendritic cells via mannose targeting and TLR4 ligating, MAN-IMO-PS significantly enhanced cross-presentation and cytokine production. In addition, MAN-IMO-PS showed depot effect at the injection site and enhanced migration to draining lymph nodes. Mice immunized with MAN-IMO-PS elicited greater lymphocyte activation, CD4+ and CD8+ T cell response, effector cytokines secretion, and induced Th-1 biased humoral responses. More importantly, prophylactic vaccination by MAN-IMO-PS significantly delayed tumor occurrence, suppressed tumor growth with prolonged survival, and achieved long-term immune effect. The present study demonstrates a rationally designed nanovaccine for combining antigen, different TLR agonists, and targeting moiety in a programmed manner to induce synergistic antitumor immune response.

Nonglutaraldehyde Fixation for off the Shelf Decellularized Bovine Pericardium in Anticalcification Cardiac Valve Applications.

In valvular replacement surgery, especially in the construction of bioprosthetic valves with decellularized pericardial xenograft, glutaraldehyde (GA) is routinely utilized as the golden standard reagent to fix bovine or porcine pericardial tissues. However, the apparent defects of GA, including cytotoxicity and calcification, increase the probability of leaflet failure and motivate the exploration for alternatives. Thus, the aim of this study is to develop nonglutaraldehyde combined-cross-linking reagents composed of alginate-EDC/NHS (Alg) or oxidized alginate-EDC/NHS (Alg-CHO) as substitute for GA, which is confirmed to be less toxic and more biocompatible. Evaluations of the fixed acellular bovine pericardial tissues included mechanical performance, thermodynamics/enzymatic/in vivo stability tests, blood compatibility assay, cytocompatibility assay, in vitro anticalcification, and in vivo anticalcification assay by subcutaneous implantation in juvenile Wistar rats. The data revealed that the tissues fixed with the combined cross-linking reagents were superior to GA control and commercially available Sino product in terms of better in vitro hemocompatibility and cytocompatibility, lower calcification levels, better thermodynamics stability, and better regenerative capacity in subcutaneous implants, while the mechanical strength and in vivo stability were comparable. Considering all above performances, it indicated that both Alg and Alg-CHO are appropriate to replace GA as the cross-linkers for biological tissue, particularly as a nonglutaraldehyde fixation for off the shelf decellularized bovine pericardial tissue in the anticalcification cardiac valve applications. Nevertheless, studies on the long-term durability and calcification-resistance capacity in large animal model are further needed.

Polydopamine as the Antigen Delivery Nanocarrier for Enhanced Immune Response in Tumor Immunotherapy.

This study aimed to investigate the efficacy of polydopamine nanoparticles (Pdop-NPs) as a subcutaneous antigen delivery vehicle in antitumor therapy. The nanoparticles were prepared by self-polymerization of dopamine in an aerobic and weak alkaline solution, and the tumor model antigen-ovalbumin (OVA) was grafted onto the nanoparticles to form OVA@Pdop nanoparticles (OVA@Pdop-NPs). The particle size of OVA@Pdop-NPs was 232.8 nm with a zeta potential of -23.4 mV, and the loading capacity of OVA protein was 754 µg mg-1. OVA@Pdop-NPs were essentially noncytotoxic and even demonstrated a slightly viability effect on bone-marrow-derived dendritic cells (BMDCs). As compared to free OVA, OVA@Pdop-NPs exhibited higher cellular uptake and were easier to migrate to lymph nodes in vivo. Both in vitro and in vivo experiments showed that OVA@Pdop-NPs promoted the maturation of DCs with up-regulated expression of major histocompatibility complex (MHC), costimulatory molecules, and cytokines. When used to treat the mice bearing OVA-MC38 colon tumor, OVA@Pdop-NPs could effectively activate OVA-specific cytotoxic CD8+ T cells and induce the production of memory CD4+ and CD8+ T cells and thus led to significantly suppressed tumor growth. All the preliminary data demonstrated the application potential of OVA@Pdop-NPs as a vaccine vector in cancer immunotherapy.