Primary adipocytes as targetable drug depot to prevent post-surgical cancer recurrence.

Surgery followed by adjuvant chemotherapy or radiation therapy remains the mainstream treatment for breast cancer in the clinic. However, cancer recurrence post surgery is still common. In view of the clinical practice that autologous fat tissue grafting is often used to facilitate breast reconstruction after lumpectomy, here we develop an in vivo targetable adipocyte-based drug depot for the prevention of post-surgical cancer recurrence. We show that primary adipocytes can be metabolically labeled with clickable chemical tags (e.g., azido groups), for subsequent conjugation of dibenzocyclooctyne (DBCO)-bearing cargo via efficient click chemistry. The conjugated cargo can retain well on the adipocyte membrane. By incorporating a cleavable linker between DBCO and cargo, the conjugated cargo can be gradually released from the surface of adipocytes to effect on neighboring cells. In the context of breast cancer surgery, azido-labeled adipocytes grafted to the surgical site can capture circulating DBCO-drugs for improved prevention of 4T1 triple-negative breast cancer (TNBC) recurrence and metastasis. This targetable and refillable adipocyte-based drug depot holds great promise for drug delivery, transplantation, and other applications.

Metabolic tagging of extracellular vesicles and development of enhanced extracellular vesicle based cancer vaccines.

As key mediators of cellular communication, extracellular vesicles (EVs) have been actively explored for diagnostic and therapeutic applications. However, effective methods to functionalize EVs and modulate the interaction between EVs and recipient cells are still lacking. Here we report a facile and universal metabolic tagging technology that can install unique chemical tags (e.g., azido groups) onto EVs. The surface chemical tags enable conjugation of molecules via efficient click chemistry, for the tracking and targeted modulation of EVs. In the context of tumor EV vaccines, we show that the conjugation of toll-like receptor 9 agonists onto EVs enables timely activation of dendritic cells and generation of superior antitumor CD8+ T cell response. These lead to 80% tumor-free survival against E.G7 lymphoma and 33% tumor-free survival against B16F10 melanoma. Our study yields a universal technology to generate chemically tagged EVs from parent cells, modulate EV-cell interactions, and develop potent EV vaccines.

Bio-adhesive Macroporous Hydrogels for In Situ Recruitment and Modulation of Dendritic Cells.

Introduction: Biomaterials that enable in situ recruitment and modulation of immune cells have demonstrated tremendous promise for developing potent cancer immunotherapy such as therapeutic cancer vaccine. One challenge related to biomaterial scaffold-based cancer vaccines is the development of macroporous materials that are biocompatible and stable, enable controlled release of chemokines to actively recruit a large number of dendritic cells (DCs), contain macropores that are large enough to home the recruited DCs, and support the survival and proliferation of DCs. Methods: Bio-adhesive macroporous gelatin hydrogels were synthesized and characterized for mechanical properties, porous structure, and adhesion towards tissues. The recruitment of immune cells including DCs to chemokine-loaded bioadhesive macroporous gels was analyzed. The ability of gels loaded with granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor extracellular vesicles (EVs) to elicit tumor-specific CD8+ T cell responses was also analyzed. Results: Here we develop a bioadhesive macroporous hydrogel that can strongly adhere to tissues, contain macropores that are large enough to home immune cells, are mechanically tough, and enable controlled release of chemokines to recruit and modulate immune cells in situ. The macroporous hydrogel is composed of a double crosslinked network of gelatin and polyacrylic acid, and the macropores are introduced via cryo-polymerization. By incorporating GM-CSF and tumor EVs into the macroporous hydrogel, a high number of DCs can be recruited in situ to process and present EV-encased antigens. These tumor antigen-presenting DCs can then traffic to lymphatic tissues to prime antigen-specific CD8+ T cells. Conclusion: This bioadhesive macroporous hydrogel system provides a new platform for in situ recruitment and modulation of DCs and the development of enhanced immunotherapies including tumor EV vaccines. We also envision the promise of this material system for drug delivery, tissue regeneration, long-term immunosuppression, and many other applications. Supplementary Information: The online version contains supplementary material available at 10.1007/s12195-023-00770-2.

Metabolic glycan labeling immobilizes dendritic cell membrane and enhances antitumor efficacy of dendritic cell vaccine.

Dendritic cell (DC) vaccine was among the first FDA-approved cancer immunotherapies, but has been limited by the modest cytotoxic T lymphocyte (CTL) response and therapeutic efficacy. Here we report a facile metabolic labeling approach that enables targeted modulation of adoptively transferred DCs for developing enhanced DC vaccines. We show that metabolic glycan labeling can reduce the membrane mobility of DCs, which activates DCs and improves the antigen presentation and subsequent T cell priming property of DCs. Metabolic glycan labeling itself can enhance the antitumor efficacy of DC vaccines. In addition, the cell-surface chemical tags (e.g., azido groups) introduced via metabolic glycan labeling also enable in vivo conjugation of cytokines onto adoptively transferred DCs, which further enhances CTL response and antitumor efficacy. Our DC labeling and targeting technology provides a strategy to improve the therapeutic efficacy of DC vaccines, with minimal interference upon the clinical manufacturing process.

A smart coating with integrated physical antimicrobial and strain-mapping functionalities for orthopedic implants.

The prevalence of orthopedic implants is increasing with an aging population. These patients are vulnerable to risks from periprosthetic infections and instrument failures. Here, we present a dual-functional smart polymer foil coating compatible with commercial orthopedic implants to address both septic and aseptic failures. Its outer surface features optimum bioinspired mechano-bactericidal nanostructures, capable of killing a wide spectrum of attached pathogens through a physical process to reduce the risk of bacterial infection, without directly releasing any chemicals or harming mammalian cells. On its inner surface in contact with the implant, an array of strain gauges with multiplexing transistors, built on single-crystalline silicon nanomembranes, is incorporated to map the strain experienced by the implant with high sensitivity and spatial resolution, providing information about bone-implant biomechanics for early diagnosis to minimize the probability of catastrophic instrument failures. Their multimodal functionalities, performance, biocompatibility, and stability are authenticated in sheep posterolateral fusion model and rodent implant infection model.

T cell-responsive macroporous hydrogels for in situ T cell expansion and enhanced antitumor efficacy.

Adoptive T cell therapy has demonstrated great promise for treating cancer and other diseases. While extensive effort has been made to improve ex vivo expansion of T cells, strategies for maintaining the proliferation and function of T cells post adoptive transfer are still lacking. Here we report an injectable T cell-responsive macroporous hydrogel that enables in situ activation and expansion of T cells. The macroporous gel is composed of a polymeric network with dispersed macropores (∼150 µm) that are large enough to home T cells. In the presence of T cells that can gradually disrupt the gel network surrounding the macropores, activation cues can be gradually released for in situ activation and expansion of T cells. This T cell-responsive macroporous gel enables expansion of effector T cells in vivo, is stable over weeks upon subcutaneous injection, and results in enhanced CD8+ T cell response and antitumor efficacy. We further show that the T cell-responsive macroporous gel could achieve comparable antitumor efficacy to conventional T cell therapy with a much lower cell dose. This injectable, T cell-responsive macroporous gel provides a platform for in vivo expansion of engineered T cells in a controlled manner, for timely and effective treatment of diseases.

Targeted delivery of liposomal chemoimmunotherapy for cancer treatment.

Chemoimmunotherapy that utilizes the immunomodulatory effect of chemotherapeutics has shown great promise for treating poorly immunogenic solid tumors. However, there remains a significant room for improving the synergy between chemotherapy and immunotherapy, including the efficient, concurrent delivery of chemotherapeutics and immunomodulators into tumors. Here, we report the use of metabolic glycan labeling to facilitate cancer-targeted delivery of liposomal chemoimmunotherapy. 4T1 triple-negative breast cancer cells can be metabolically labeled with azido groups for subsequently targeted conjugation of dibenzocycoloctyne (DBCO)-bearing liposomes loaded with doxorubicin and imiquimod (R837) adjuvant via efficient click chemistry. The encased doxorubicin can induce the immunogenic death of cancer cells and upregulate the expression of CD47 and calreticulin on the surface of cancer cells, while R837 can activate dendritic cells for enhanced processing and presentation of tumor antigens. Targeted delivery of liposomes encapsulating doxorubicin and R837 to 4T1 tumors, enabled by metabolic glycan labeling and click chemistry, showed the promise to reshape the immunosuppressive tumor microenvironment of solid tumors. This cancer-targetable liposomal chemoimmunotherapy could provide a new approach to improving conventional chemotherapy.

In Situ Dendritic Cell Recruitment and T Cell Activation for Cancer Immunotherapy.

Cancer immunotherapy has shifted the paradigm for cancer treatment in the past decade, but new immunotherapies enabling the effective treatment of solid tumors are still greatly demanded. Here we report a pore-forming hydrogel-based immunotherapy that enables simultaneous recruitment of dendritic cells and in situ activation of T cells, for reshaping the immunosuppressive tumor microenvironment and amplifying cytotoxic T lymphocyte response. The injectable pore-forming hydrogel composed of porogen-dispersed alginate network can form a macroporous structure upon injection into mice, and enables controlled release of granulocyte-macrophage colony-stimulating factor (GM-CSF), a chemoattractant for recruiting dendritic cells, and epacadostat, an inhibitor of indoleamine 2, 3-dioxygenase for activating T cells. We show that gels loaded with GM-CSF and epacadostat, after peritumoral injection, can recruit massive dendritic cells in situ and activate effector T cells in the tumor tissues, resulting in enhanced frequency and activation status of dendritic cells, reduced numbers of regulatory T (Treg) cells, and increased CD8+/Treg ratios in the tumor microenvironment. This hydrogel-based immunotherapy holds great promise for treating poorly-immunogenic solid tumors.

A double crosslinking adhesion mechanism for developing tough hydrogel adhesives.

Tough hydrogel adhesives that consist of a robust gel network and can strongly adhere to wet tissues have shown great promise as the next generation of bioadhesives. While a variety of chemistries can be utilized to construct the tough gel network, the covalent conjugation methods for tissue adhesion are still limited. Here we report, for the first time, the use of side product-free amine-thiolactone chemistry which initiates a double crosslinking adhesion mechanism to develop tough gel adhesives. Thiolactone groups can conjugate with tissue-surface amines via a ring-opening reaction. The resultant thiol end groups can be further crosslinked into disulfide linkages, enabling the formation of a robust and stable adhesion layer. The thiolactone-bearing tough hydrogel composed of methacrylate-modified gelatin, acrylic acid, and thiolacone acrylamide exhibited good biocompatibility and mechanical properties, and strong adhesion to various types of engineering solids and tissues. We also demonstrated its ability to function as a tissue sealant and drug depot. The novel adhesion mechanism will diversify future design of bioadhesives for hemostasis, drug delivery, tissue repair, and other applications. STATEMENT OF SIGNIFICANCE: Tough hydrogel adhesives with excellent tissue-adhesive and mechanical properties have demonstrated tremendous promise for hemostasis, tissue repair, and drug delivery applications. However, the covalent chemistry for tissue adhesion has been limited, which narrows the choice of materials for the design of bioadhesives and may pose a safety concern. Here, for the first time, we report the use of side product-free amine-thiolactone chemistry, which involves a double crosslinking adhesion mechanism, for developing tough hydrogel adhesives. We demonstrate that thiolactone-bearing tough hydrogels exhibit favorable biocompatibility and mechanical properties, and superior adhesion to both engineering solids and tissues. Our new adhesion technology will greatly facilitate future development of advanced bioadhesives for numerous biomedical applications.

Recyclable cell-surface chemical tags for repetitive cancer targeting.

Metabolic glycan labeling provides a facile yet powerful tool to install chemical tags to the cell membrane via metabolic glycoengineering processes of unnatural sugars. These cell-surface chemical tags can then mediate targeted conjugation of therapeutic agents via efficient chemistries, which has been extensively explored for cancer-targeted treatment. However, the commonly used in vivo chemistries such as azide-cyclooctyne and tetrazine-cyclooctene chemistries only allow for one-time use of cell-surface chemical tags, posing a challenge for long-term, continuous cell targeting. Here we show that cell-surface ketone groups can be recycled back to the cell membrane after covalent conjugation with hydrazide-bearing molecules, enabling repetitive targeting of hydrazide-bearing agents. Upon conjugation to ketone-labeled cancer cells via a pH-responsive hydrazone linkage, Alexa Fluor 488-hydrazide became internalized and entered endosomes/lysosomes where ketone-sugars can be released and recycled. The recycled ketone groups could then mediate targeted conjugation of Alexa Fluor 647-hydrazide. We also showed that doxorubicin-hydrazide can be targeted to ketone-labeled cancer cells for enhanced cancer cell killing. This study validates the recyclability of cell-surface chemical tags for repetitive targeting of cancer cells with the use of a reversible chemistry, which will greatly facilitate future development of potent cancer-targeted therapies based on metabolic glycan labeling.

A Sensor Array for the Nanomolar Detection of Azo Dyes in Water.

Azo dyes are ubiquitous pollutants that contaminate water supplies and threaten human, biota, and ecosystem health. Their detection and discrimination are a considerable challenge owing to the numerous structural, chemical, and optical similarities between dyes, complexity of the wastewater in which they are found, and low environmental concentrations. Here, we demonstrate that the inner filter effect (IFE), in combination with conjugated polymer array-based sensing, offers a rapid approach for the quantitative profiling of these pollutants. The array was constructed using three anionic conjugated polyelectrolytes whose varying spectroscopic properties led to distinct IFE patterns in the presence of various dyes. These unique fluorescence response patterns were identified and processed using linear discriminant analysis (LDA), enabling the individual identification of 12 closely related azo dyes. To demonstrate the potential for utility in the environment, the array was used to differentiate between these dyes at nanomolar concentrations in water.