Delivery Techniques for Enhancing CAR T Cell Therapy against Solid Tumors

Chimeric antigen receptor (CAR) T cells exhibit promising results for cancer immunotherapy. However, the clinical success is still restricted to certain types of blood cancers, while in solid tumors the clinical activity is modest and potential toxicities remain a concern. There are various barriers that prevent CAR T cells from combating solid tumors. Therefore, distinct strategies have been explored to augment CAR T cell proliferative capacity, persistence, and effector function. Altering the tumor microenvironment, and in particular its physiochemical properties and immunosuppressive milieu, is of great significance to facilitate CAR T cell therapy. In this article, emerging strategies implemented to overcome the barriers of CAR T cell therapy in solid tumors are reviewed. Enhancing infiltration, activation, and persistence of CAR T cells has been addressed in several preclinical models. The future development of this field to promote innovation and clinical translation is also discussed.     

Enzyme-Activated Prodrug-Based Smart Liposomes Specifically Enhance Tumor Hemoperfusion with Efficient Drug Delivery to Pancreatic Cancer Cells and Stellate Cells

Tumor-specific enhanced delivery of chemotherapeutics and modulators to tumor cells and activated pancreatic stellate cells (aPSCs), respectively, represents safer and more effective therapy for pancreatic cancer. Herein, a membrane type 1-matrix metalloproteinase (MT1-MMP)-cleavable spacer is used to assemble low-density cRGDfK onto thermosensitive liposomes loaded with phosphorylated calcipotriol (PCAL) and doxorubicin (DOX), yielding MR-T-PD. The liposome-linked cRGDfK prodrug on MR-T-PD surface is first activated by MT1-MMP, which is selectively expressed on tumor endothelial cells, to release cRGDfK. The free cRGDfK specifically promotes tumor angiogenesis, leading to 3.4-fold higher accumulation and a wider distribution of MR-T-PD in tumors. Furthermore, MR-T-PD rapidly releases PCAL and DOX into the interstitium under heat treatment. The released DOX enters tumor cells to induce apoptosis, whereas the PCAL prodrug is converted to CAL by alkaline phosphatase on the surface of aPSCs; CAL can then enter aPSCs to induce quiescence and promote the antitumor effect of DOX. Finally, by enhancing the exposure of DOX and CAL to tumor cells and aPSCs, respectively, in a tumor-specific manner, MR-T-PD exerts superior efficacy (a 5.9-fold decrease in tumor weight) without causing additional side effects. Overall, this prodrug-based smart liposome system represents a promising paradigm for pancreatic cancer therapy.     

Nanotechnology-Based CAR-T Strategies for Improving Efficacy and Safety of Tumor Immunotherapy

Therapeutic responses to chimeric antigen receptor (CAR) T cell therapy in patients with limited treatment options have been appealing in several clinical trials. However, the efficacy of CAR-T therapy has been challenged by several obstacles when treating patients with solid tumors, such as severe toxicities, restricted access to tumor sites, suboptimal therapeutic persistence, and manufacturing issues. Nanotechnology has the advantages of protecting CAR-T cells from being suppressed by tumor microenvironment (TME) and favorably adapting immune-modulating drugs’ pharmacokinetics by modifying their spatiotemporal release profiles. Loaded with nanoparticles and packed onto CAR-T cells, immune-modulating drugs can be delivered to the tumor site and lymph node more efficiently, stimulating the expansion and activity of CAR-T cells. To protect normal tissues from the nonspecific toxicity of the activated CAR-T cells, formulations are optimized toward tumor targeting delivery of nanotechnology. This review summarizes the nanotechnology strategies to improve the safety and efficacy of CAR-T therapy. In addition, the unsolved problems existing in the clinical application of CAR-T therapy are focused on, where study and exploration by the way of nanotechnology is needed.     

Encapsulation of RNA Molecules in BSA Microspheres and Internalization into Trypanosoma Brucei Parasites and Human U2OS Cancer Cells

RNA was encapsulated in bovine serum albumin (BSA) microspheres using a one‐step sonochemical process from an water–oil solvent biphasic system. Confocal microcoscopy and fluorescence‐activated cell sorting indicate that a CY3‐RNA (RNA labeled with red fluorescent indocarbocyanine Cy3 dye) sphere is encapsulated in the BSA outer sphere. The diameter of the sphere depends on the number of nucleotides of the RNA, ranging from 0.63 to 2.74 μm. Total RNA (t‐RNA) was used as a prototype for the future small interfering RNA (siRNA) delivery. A very broad size distribution characterizes the RNA spheres and therefore, among the loaded BSA spheres, there were sufficiently small spheres to be successfully introduced into trypanosoma brucei parasites and human osteosarcoma U2OS cancer cells.     

Hierarchical Spiky Microstraws‐Integrated Microfluidic Device for Efficient Capture and In Situ Manipulation of Cancer Cells

Techniques for capturing circulating tumor cells (CTCs) play an important role in cancer diagnosis. Recently, various 3D micro/nanostructures have been applied for effective CTC detection, yet in situ manipulation of the captured cancer cells on micro/nano‐structural substrates is rarely achieved. In this work, a hierarchical spiky microstraw array (HS‐MSA)‐integrated microfluidic device is demonstrated that possessed dual functions of cancer cell capture and in situ chemical manipulations of the captured cells. The 3D micro/nanostructure of HS‐MSA could capture cancer cells with high efficiency (≈84%) and strong specificity. Based on the HS‐MSA‐integrated microfluidic device, extracellular drug delivery to the captured cancer cells is achieved in situ with excellent spatial, dose, and temporal controls. In addition, a drug‐screening assay on the captured cancer cells is implemented to investigate the cell apoptosis behavior under the microstraw‐mediated delivery of staurosporine (STS). This microfluidic system not only presents tremendous potential for CTCs detection technology, but also opens up new opportunities for high‐throughput drug screening on cancer cells and understanding the cellular activity.     

Harnessing Topology and Stereochemistry of Glycidylamine-Derived Lipid Nanoparticles for in Vivo mRNA Delivery to Immune Cells in Spleen and Their Application for Cancer Vaccination

mRNA lipid nanoparticles (LNPs) have reached an inflection point and are now paving the way for a new wave of precision therapies. The design of nonhepatocyte RNA delivery systems without targeting ligands, however, remains a challenge. It is reported that the development of ligand-free glycidylamine (GA) derivatives containing LNPs (GA-LNPs) that preferentially deliver mRNA to immune cells in the spleen. Notably, it is demonstrated that the stereochemistry of GA-lipids has a significant impact on their self-assembly and in vitro and in vivo RNA delivery efficiency and tropism. This impact is dependent on the monomeric structure of GA and number of stereogenic centers. Furthermore, the nonlinear topology of GA lipid derivatives induced a sevenfold improvement in mRNA delivery efficiency. The top-performing estriol-GA05-30 LNPs elicited strong antitumor activity in a therapeutic and prophylactic cancer model and are well tolerated in mice. These results highlight the significance of the chemistry of ionizable lipids for extrahepatic RNA delivery and indicated a promising direction for the development of next-generation mRNA immunotherapies.     

Interaction of Human Mesenchymal Stem Cells with Soft Nanocomposite Hydrogels Based on Polyethylene Glycol and Dendritic Polyglycerol

Keeping the stemness of human mesenchymal stem cells (hMSCs) and their adipocyte differentiation potential is critical for clinical use. However, these features are lost on traditional substrates. hMSCs have often been studied on stiff materials whereas culturing hMSCs in their native niche increases their potential. Herein, a patterned hydrogel nanocomposite with the stiffness of liver tissues is obtained without any molding process. To investigate hMSCs' mechanoresponse to the material, the RGD spacing units and the stiffness of the hydrogels are dually tuned via the linker length. This work suggests that hMSCs' locomotion is influenced by the nature of the hydrogel layer (bulk or thin film). Contrary to on bulk surfaces, cell traction occurs during cell spreading on thin films. In addition, hMSCs' spreading behavior varies from shorter to longer linker‐based hydrogels, where on both surfaces hMSCs maintains their stemness as well as their adipogenic differentiation potential with a higher number of adipocytes for nanocomposites with a longer polymer linker. Overall, this work addresses the need for a new alternative for hMSCs culture allowing the cells to differentiate exclusively into adipocytes. This material represents a cell‐responsive platform with a tissue‐mimicking architecture given by the mechanical and morphological properties of the hydrogel.     

Flexible Nanosomes (SECosomes) Enable Efficient siRNA Delivery in Cultured Primary Skin Cells and in the Viable Epidermis of Ex Vivo Human Skin

The extent to which nanoscale‐engineered systems cross intact human skin and can exert pharmacological effects in viable epidermis is controversial. This research seeks to develop a new lipid‐based nanosome that enables the effective delivery of siRNA into human skin. The major finding is that an ultraflexible siRNA‐containing nanosome—prepared using DOTAP, cholesterol, sodium cholate, and 30% ethanol—penetrates into the epidermis of freshly excised intact human skin and is able to enter into the keratinocytes. The nanosomes, called surfactant‐ethanol‐cholesterol‐osomes (SECosomes), show excellent size, surface charge, morphology, deformability, transfection efficiency, stability, and skin penetration capacity after complexation with siRNA. Importantly, these nanosomes have ideal characteristics for siRNA encapsulation, in that the siRNA is stable for at least 4 weeks, they enable highly efficient transfection of in vitro cultured cells, and are shown to transport siRNA delivery through intact human skin where changes in the keratinocyte cell state are demonstrated. It is concluded that increasing flexibility in nanosomes greatly enhances their ability to cross the intact human epidermal membrane and to unload their payload into targeted epidermal cells.     

BPD-MA光动力作用对膀胱癌细胞凋亡及bcl-2蛋白表达的影响

目的:研究激光活化BPD-MA光动力诱导肿瘤细胞凋亡及其可能机制。方法:应用流式细胞仪分析BPD-MA光动力作用后细胞凋亡及免疫组化染色检测凋亡相关蛋白bcl-2蛋白表达水平。结果:激光活化BPD-MA光动力实验组人膀胱癌细胞株BIU-87凋亡发生率达26.11±2.59%,与对照组相比,差异非常显著性(P<0.01);光动力作用后膀胱癌细胞线粒体相关调控蛋白bcl-2表达显著低于对照组(P<0.05)。结论:激光活化BPD-MA光动力作用具有诱导人膀胱癌细胞株BIU-87凋亡的生物效应,而线粒体相关调控蛋白bcl-2表达水平的降低可能是激光活化BPD-MA光动力诱导人膀胱癌细胞株BIU-87凋亡的重要机制之一。     

Self‐Assembled Nanoparticles with Dual Effects of Passive Tumor Targeting and Cancer‐Selective Anticancer Effects

Nanoparticular drug delivery systems may help to overcome the limitations of conventional chemotherapy. They have been reported to improve the specificity of distribution, the bioavailability, and the solubility of drugs, as well as the duration of drug efficacy, and helping to overcome multidrug resistance. Although various polymeric nanoparticles have been developed for delivery of anticancer agents, most nanoparticles still focus on solubilizing drugs, improving targeting ability, and reducing side effects. In particular, targeting to the tumor is typically improved through passive or active targeting. Despite great achievements in both strategies, yet to be resolved are issues of toxicity in normal cells and enhancement of tumor‐specificity. A new approach combining the dual strategies of passive tumor targeting and cancer‐selective efficacy is proposed. Recombinant human gelatin conjugated with lipoic acid (rHG‐LA) developed in this study forms nanoparticles spontaneously in aqueous solution and encapsulates alpha‐tocopheryl succinate (α‐TOS), a well‐known cancer‐selective apoptosis‐inducing agent, within a hydrophobic core during the self‐assembly. This study describes the promising applicability of α‐TOS‐loaded rHG‐LA nanoparticles with passive targeting ability and cancer‐specificity.