Multifunctional Immunoliposomes Enhance the Immunotherapeutic Effects of PD-L1 Antibodies against Melanoma by Reprogramming Immunosuppressive Tumor Microenvironment.

The immunosuppressive tumor microenvironment (TME) can significantly limit the immunotherapeutic effects of the PD-L1 antibody (aPDL1) by inhibiting the infiltration of CD8+ cytotoxic T cells (CTLs) into the tumor tissues. However, how to reprogram the immunosuppressive TME and promote the infiltration of CTLs remains a huge challenge for aPDL1 to achieve the maximum benefits. Herein, the authors design a multifunctional immunoliposome that encapsulates the adrenergic receptor blocker carvedilol (CAR) and connects the "don't eat me" signal antibody (aCD47) and aPDL1 in series via a reactive oxygen species (ROS)-sensitive linker on the surface. In ROS-enriched immunosuppressive TME, the multifunctional immunoliposome (CAR@aCD47/aPDL1-SSL) can first release the outer aCD47 to block the "do not eat me" pathway, promote the phagocytosis of tumor cells by phagocytic cells, and activate CTLs. Then, the aPDL1 on the liposome surface is exposed to block the PD-1/PD-L1 signaling pathway, thereby inducing CTLs to kill tumor cells. CAR encapsulated in CAR@aCD47/aPDL1-SSL can block the adrenergic nerves in the tumor tissues and reduce their densities, thereby inhibiting angiogenesis in the tumor tissues and reprogramming the immunosuppressive TME. According to the results, CAR@aCD47/aPDL1-SSL holds an effective way to reprogram the immunosuppressive TME and significantly enhance immunotherapeutic efficiency of aPDL1 against the primary cancer and metastasis.

Multifunctional Immunoliposomes Combining Catalase and PD-L1 Antibodies Overcome Tumor Hypoxia and Enhance Immunotherapeutic Effects Against Melanoma.

BACKGROUND: Immune checkpoint blockades (ICBs) are a promising treatment for cancers such as melanoma by blocking important inhibitory pathways that enable tumor cells to evade immune attack. Programmed death ligand 1 monoclonal antibodies (aPDL1s) can be used as an ICB to significantly enhance the effectiveness of tumor immunotherapy by blocking the PD-1/PD-L1 inhibitory pathway. However, the effectiveness of aPDL1s may be limited by low selectivity in vivo and immunosuppressed tumor microenvironment including hypoxia. PURPOSE: To overcome the limitations, we develop a multifunctional immunoliposome, called CAT@aPDL1-SSL, with catalase (CAT) encapsulated inside to overcome tumor hypoxia and aPDL1s modified on the surface to enhance immunotherapeutic effects against melanoma. METHODS: The multifunctional immunoliposomes (CAT@aPDL1-SSLs) are prepared using the film dispersion/post-insertion method. The efficacy of CAT@aPDL1-SSLs is verified by multiple experiments in vivo and in vitro. RESULTS: The results of this study suggest that the multifunctional immunoliposomes preserve and protect the enzyme activity of CAT and ameliorate tumor hypoxia. Moreover, the enhanced cellular uptake of CAT@aPDL1-SSLs in vitro and their in vivo biodistribution suggest that CAT@aPDL1-SSLs have great targeting ability,resulting in improved delivery and accumulation of immunoliposomes in tumor tissue.Finally, by activating and increasing the infiltration of CD8+ T cells at the tumor site, CAT@aPDL1-SSLs inhibit the growth of tumor and prolong survival time of mice,with low systemic toxicity. CONCLUSION: In conclusion, the multifunctional immunoliposomes developed and proposed in this study are a promising candidate for melanoma immunotherapy, and could potentially be combined with other cancer therapies like radiotherapy and chemotherapy to produce positive outcomes.

In vivo study of doxorubicin-loaded cell-penetrating peptide-modified pH-sensitive liposomes: biocompatibility, bio-distribution, and pharmacodynamics in BALB/c nude mice bearing human breast tumors.

In vivo evaluation of drug delivery vectors is essential for clinical translation. In BALB/c nude mice bearing human breast cancer tumors, we investigated the biocompatibility, pharmacokinetics, and pharmacodynamics of doxorubicin (DOX)-loaded novel cell-penetrating peptide (CPP)-modified pH-sensitive liposomes (CPPL) (referred to as CPPL(DOX)) with an optimal CPP density of 4%. In CPPL, a polyethylene glycol (PEG) derivative formed by conjugating PEG with stearate via acid-degradable hydrazone bond (PEG2000-Hz-stearate) was inserted into the surface of liposomes, and CPP was directly attached to liposome surfaces via coupling with stearate to simultaneously achieve long circulation time in blood and improve the selectivity and efficacy of CPP for tumor targeting. Compared to PEGylated liposomes, CPPL enhanced DOX accumulation in tumors up to 1.9-fold (p<0.01) and resulted in more cell apoptosis as a result of DNA disruption as well as a relatively lower tumor growth ratio (T/C%). Histological examination did not show any signs of necrosis or inflammation in normal tissues, but large cell dissolving areas were found in tumors following the treatment of animals with CPPL(DOX). Our findings provide important and detailed information regarding the distribution of CPPL(DOX) in vivo and reveal their abilities of tumor penetration and potential for the treatment of breast cancer.

A dual-mediated liposomal drug delivery system targeting the brain: rational construction, integrity evaluation across the blood-brain barrier, and the transporting mechanism to glioma cells.

As the global population ages, cancer rates increase worldwide, and degenerative diseases of the central nervous system (CNS), brain tumors, and inflammation threaten human health more frequently. We designed a dual-mediated (receptor-mediated and adsorption-mediated) liposome, named transferrin-cell penetrating peptide-sterically stabilized liposome (TF-CPP-SSL), to improve therapy for gliomas through combining molecular recognition of transferrin receptors (TF-Rs) on the blood-brain barrier (BBB) and glioma cells with the internalization and lysosomal escaping ability of CPP. Based on the systematic investigation of structure-activity relations on the cellular level, we constructed TF-CPP-SSL rationally by conjugating TF and CPP moieties to the liposomes via PEG3.4K and PEG2.0K, respectively, and found the optimum densities of TF and CPP were 1.8% and 4%, respectively. These liposomes had the highest targeting efficacy for brain microvascular endothelial cell and C6 cell uptake but avoided capture by normal cells. Fluorescence resonance energy transfer technology and coculture models of BBB and glioma C6 cells indicated that TF-CPP-SSL was transported across the BBB without drug leakage, liposome breakup, or cleavage of ligand. TF-CPP-SSL offered advantages for crossing the BBB and entering into glioma C6 cells. Real-time confocal viewing revealed that TF-CPP-SSL was entrapped in endosomes of glioma C6 cells and then escaped from lysosomes successfully to release the liposomal contents into the cytosol. Entrapped contents, such as doxorubicin, could then enter the nucleus to exert pharmacological effects.

[Biomechanical analysis on healing process of sagittal fracture of the mandibular condyle after rigid fixation].

PURPOSE: To analyze the biomechanical healing process on rigid fixation of sagittal fracture of the mandibular condyle (SFMC), and to provide guidelines for surgical treatment. METHODS: Three-dimensional finite element model (3D-FEAM) of mandible and condyle was established. The right condyle was simulated as SFMC with 0.1 mm space across the condyle length ways. The 3D-FEAM of rigid fixation was established. The biomechanical factors such as stress distribution of condylar surface, displacement around fracture, stress on the plate and stress shielding were calculated during 0, 4, 8 and 12-week after rigid fixation. RESULTS: The maximum equivalent stress of normal condyle was located at the area of middle 1/3 of condylar neck. The maximum equivalent stress at 0-week after fixation was 23 times than that on normal condyle. They were located at the condylar stump and the plate near inferior punctual areas of fracture line. There were little stress on the other areas. The maximum equivalent stress at 4, 8 and 12-week was approximately 6 times than that on normal condyle. They were located at the areas same as the area at 0-week. There were little stress on the other areas at the condyle. The maximum total displacement and maximum total corner were increased 0.57-0.75 mm and 0.01-0.09° respectively during healing process. The maximum equivalent stress at 0-week on the condylar trump was 5-6 times compared with that at 4, 8, and 12-week. The maximum equivalent stress, maximum total displacement and maximum total corner on the fractured fragment were not changed significantly during healing process. The maximum equivalent stress at 0-week on the plate was 7-9 times compared with that at 4, 8, 12-week. CONCLUSIONS: The stress of the condyle and stress shielding of the plate may be the reasons of absorbing and rebuilding on the condyle in healing process of SFMC. The biomechanical parameters increase obviously at 4-week after fixation. Elastic intermaxillary traction is necessary to decrease total displacement and total corner of the condyle, and liquid diet is necessary to decrease equivalent stress within 4 weeks. Rehabilitation training should be used to recover TMJ functions after 4 weeks because the condyle and mandible have the ability to carry out normal functions.