Polymeric biomaterial-inspired cell surface modulation for the development of novel anticancer therapeutics

Phenylboronic acid-functionalized biomaterials for improved cancer immunotherapy via sialic acid targeting

Phenylboronic acid (PBA) is recognized as one of the most promising cancer cell binding modules attributed to its potential to form reversible and dynamic boronic ester covalent bonds. Exploring the advanced chemical versatility of PBA is crucial for developing new anticancer therapeutics. The presence of a specific Lewis acidic boron atom-based functional group and a Π-ring-connected ring has garnered increasing interest in the field of cancer immunotherapy. PBA-derivatized functional biomaterials can form reversible bonds with diols containing cell surface markers and proteins. This review primarily focuses on the following topics: (1) the importance and versatility of PBA, (2) different PBA derivatives with pKa values, (3) specific key features of PBA-mediated biomaterials, and (4) cell surface activity for cancer immunotherapy applications. Specific key features of PBA-mediated materials, including sensing, bioadhesion, and gelation, along with important synthesis strategies, are highlighted. The utilization of PBA-mediated biomaterials for cancer immunotherapy, especially the role of PBA-based nanoparticles and PBA-mediated cell-based therapeutics, is also discussed. Finally, a perspective on future research based on PBA-biomaterials for immunotherapy applications is presented.

Membrane-immobilized gemcitabine for cancer-targetable NK cell surface engineering

Although natural killer (NK) cell-based adoptive cell transfer (ACT) has shown promise in cancer immunotherapy, its efficacy against solid tumors is limited in the immunosuppressive tumor microenvironment (TME). Combinatorial therapies involving chemotherapeutic drugs such as gemcitabine (Gem) and NK cells have been developed to modulate the TME; however, their clinical application is constrained by low drug delivery efficiency and significant off-target toxicity. In this study, we developed cell membrane-immobilized Gem conjugates (i.e., lipid-Gem conjugates), designed to anchor seamlessly onto NK cell surfaces. Our modular-designed ex vivo cell surface engineeringmaterials comprise a lipid anchor for membrane immobilization, poly(ethylene glycol) to inhibit endocytosis, a disulfide bond as cleavable linker by glutathione (GSH) released during cancer cell lysis, and Gem for targeted sensitization. We demonstrated that the intrinsic properties of NK cells, such as proliferation and surface ligand availability, were preserved despite coating with lipid-Gem conjugates. Moreover, delivery of Gem prodrugs by lipid-Gem coated NK (GCNK) cells was shown to enhance antitumor efficacy against pancreatic cancer cells (PANC-1) through the following mechanisms: (1) NK cells recognized and attacked cancer cells, (2) intracellular GSH was leaked out from the lysed cancer cells, enabling cleavage of disulfide bond, (3) released Gem from the GCNK cells delivered to the target cells, (4) Gem upregulated MHC class I-related chain A and B on cancer cells, and (5) thereby activating NK cells led to enhance antitumor efficacy. The simultaneous co-delivery of membrane-immobilized Gem with NK cells could potentially facilitate both immune synapse-mediated cancer recognition and chemotherapeutic effects, offering a promising approach to enhance the anticancer efficacy of conventional ACTs.

Engineered inulin-based hybrid biomaterials for augmented immunomodulatory responses

Modified biopolymers that are based on prebiotics have been found to significantly contribute to immunomodulatory events. In recent years, there has been a growing use of modified biomaterials and polymer-functionalized nanomaterials in the treatment of various tumors by activating immune cells. However, the effectiveness of immune cells against tumors is hindered by several biological barriers, which highlights the importance of harnessing prebiotic-based biopolymers to enhance host defenses against cancer, thus advancing cancer prevention strategies. Inulin, in particular, plays a crucial role in activating immune cells and promoting the secretion of cytokines. Therefore, this mini-review aims to emphasize the importance of inulin in immunomodulatory responses, the development of inulin-based hybrid biopolymers, and the role of inulin in enhancing immunity and modifying cell surfaces. Furthermore, we discuss the various approaches of chemical modification for inulin and their potential use in cancer treatment, particularly in the field of cancer immunotherapy.

Ex Vivo Peptide Decoration Strategies on Stem Cell Surfaces for Augmenting Endothelium Interaction

Ischemic vascular diseases remain leading causes of disability and death. Although various clinical therapies have been tried, reperfusion injury is a major issue, occurring when blood recirculates at the damaged lesion. As an alternative approach, cell-based therapy has emerged. Mesenchymal stem cells (MSCs) are attractive cellular candidates due to their therapeutic capacities, including differentiation, safety, angiogenesis, and tissue repair. However, low levels of receptors/ligands limit targeted migration of stem cells. Thus, it is important to improve homing efficacy of transplanted MSCs toward damaged endothelium. Among various MSC modulations, ex vivo cell surface engineering could effectively augment homing efficiency by decorating MSC surfaces with alternative receptors/ligands, thereby facilitating intercellular interactions with the endothelium. Especially, exogenous decoration of peptides onto stem cell surfaces could provide appropriate functional signaling moieties to achieve sufficient MSC homing. Based on their protein-like functionalities, high modularity in molecular design, and high specific affinities and multivalency to target receptors, peptides could be representative surface-presentable moieties. Moreover, peptides feature a mild synthetic process, enabling precise control of amino acid composition and sequence. Such ex vivo stem cell surface engineering could be achieved primarily by hydrophobic interactions of the cellular bilayer with peptide-conjugated anchor modules and by covalent conjugation between peptides and available compartments in membranes. To this end, this review provides an overview of currently available peptide-mediated, ex vivo stem cell surface engineering strategies for enhancing MSC homing efficiency by facilitating interactions with endothelial cells. Stem cell surface engineering techniques using peptide-based bioconjugates have the potential to revolutionize current vascular disease treatments while addressing their technical limitations.

Surface Engineering of Natural Killer Cells with CD44-targeting Ligands for Augmented Cancer Immunotherapy

Adoptive immunotherapy utilizing natural killer (NK) cells has demonstrated remarkable efficacy in treating hematologic malignancies. However, its clinical intervention for solid tumors is hindered by the limited expression of tumor-specific antigens. Herein, lipid-PEG conjugated hyaluronic acid (HA) materials (HA-PEG-Lipid) for the simple ex-vivo surface coating of NK cells is developed for 1) lipid-mediated cellular membrane anchoring via hydrophobic interaction and thereby 2) sufficient presentation of the CD44 ligand (i.e., HA) onto NK cells for cancer targeting, without the need for genetic manipulation. Membrane-engineered NK cells can selectively recognize CD44-overexpressing cancer cells through HA-CD44 affinity and subsequently induce in situ activation of NK cells for cancer elimination. Therefore, the surface-engineered NK cells using HA-PEG-Lipid (HANK cells) establish an immune synapse with CD44-overexpressing MIA PaCa-2 pancreatic cancer cells, triggering the "recognition-activation" mechanism, and ultimately eliminating cancer cells. Moreover, in mouse xenograft tumor models, administrated HANK cells demonstrate significant infiltration into solid tumors, resulting in tumor apoptosis/necrosis and effective suppression of tumor progression and metastasis, as compared to NK cells and gemcitabine. Taken together, the HA-PEG-Lipid biomaterials expedite the treatment of solid tumors by facilitating a sequential recognition-activation mechanism of surface-engineered HANK cells, suggesting a promising approach for NK cell-mediated immunotherapy.

Optimized Design of Hyaluronic Acid-Lipid Conjugate Biomaterial for Augmenting CD44 Recognition of Surface-Engineered NK Cells

Triple-negative breast cancer (TNBC) presents treatment challenges due to a lack of detectable surface receptors. Natural killer (NK) cell-based adaptive immunotherapy is a promising treatment because of the characteristic anticancer effects of killing malignant cells directly by secreting cytokines and lytic granules. To maximize the cancer recognition ability of NK cells, biomaterial-mediated ex vivo cell surface engineering has been developed for sufficient cell membrane immobilization of tumor-targeting ligands via hydrophobic anchoring. In this study, we optimized amphiphilic balances of NK cell coating materials composed of CD44-targeting hyaluronic acid (HA)-poly(ethylene glycol) (PEG)-lipid to improve TNBC recognition and the anticancer effect. Changes in the modular design of our material by differentiating hydrophilic PEG length and incorporating lipid amount into HA backbones precisely regulated the amphiphilic nature of HA-PEG-lipid conjugates. The optimized biomaterial demonstrated improved anchoring into NK cell membranes and facilitating the surface presentation level of HA onto NK cell surfaces. This led to enhanced cancer targeting via increasing the formation of immune synapse, thereby augmenting the anticancer capability of NK cells specifically toward CD44-positive TNBC cells. Our approach addresses targeting ability of NK cell to solid tumors with a deficiency of surface tumor-specific antigens while offering a valuable material design strategy using amphiphilic balance in immune cell surface engineering techniques.

Networked Cluster Formation via Trigonal Lipid Modules for Augmented Ex Vivo NK Cell Priming

Current cytokine-based natural killer (NK) cell priming techniques have exhibited limitations such as the deactivation of biological signaling molecules and subsequent insufficient maturation of the cell population during mass cultivation processes. In this study, we developed an amphiphilic trigonal 1,2-distearoyl-sn-glycero-3-phosphorylethanolamine (DSPE) lipid-polyethylene glycol (PEG) material to assemble NK cell clusters via multiple hydrophobic lipid insertions into cellular membranes. Our lipid conjugate-mediated ex vivo NK cell priming sufficiently augmented the structural modulation of clusters, facilitated diffusional signal exchanges, and finally activated NK cell population with the clusters. Without any inhibition in diffusional signal exchanges and intrinsic proliferative efficacy of NK cells, effectively prime NK cell clusters produced increased interferon-gamma, especially in the early culture periods. In conclusion, the present study demonstrates that our novel lipid conjugates could serve as a promising alternative for future NK cell mass production.

Ex Vivo Surface Decoration of Phenylboronic Acid onto Natural Killer Cells for Sialic Acid-Mediated Versatile Cancer Cell Targeting

Phenylboronic acid (PBA) has been highly acknowledged as a significant cancer recognition moiety in sialic acid-overexpressing cancer cells. In this investigation, lipid-mediated biomaterial integrated PBA molecules onto the surface of natural killer (NK) cells to make a receptor-mediated immune cell therapeutic module. Therefore, a 1,2-distearoyl-sn-glycero-3-phosphorylethanolamine (DSPE) lipid-conjugated di-PEG-PBA (DSPEPEG-di(PEG-PBA) biomaterial was synthesized. The DSPEPEG-di(PEG-PBA) biomaterial exhibited a high affinity for sialic acid (SA), confirmed by fluorescence spectroscopy at pH 6.5 and 7.4. DSPEPEG-di(PEG-PBA) was successfully anchored onto NK cell surfaces (PBA-NK), and this biomaterial maintains intrinsic properties such as viability, ligand availability (FasL & TRAIL), and cytokine secretion response to LPS. The anticancer efficacy of PBA-NK cells was evaluated against 2D cancer cells (MDA-MB-231, HepG2, and HCT-116) and 3D tumor spheroids of MDA-MB-231 cells. PBA-NK cells exhibited greatly enhanced anticancer effects against SA-overexpressing cancer cells. Thus, PBA-NK cells represent a new anticancer strategy for cancer immunotherapy.

Tailoring tumor-recognizable hyaluronic acid-lipid conjugates to enhance anticancer efficacies of surface-engineered natural killer cells

Natural killer (NK) cells have clinical advantages in adoptive cell therapy owing to their inherent anticancer efficacy and their ability to identify and eliminate malignant tumors. However, insufficient cancer-targeting ligands on NK cell surfaces often inhibit their immunotherapeutic performance, especially in immunosuppressive tumor microenvironment. To facilitate tumor recognition and subsequent anticancer function of NK cells, we developed hyaluronic acid (HA, ligands to target CD44 overexpressed onto cancer cells)-poly(ethylene glycol) (PEG, cytoplasmic penetration blocker)-Lipid (molecular anchor for NK cell membrane decoration through hydrophobic interaction) conjugates for biomaterial-mediated ex vivo NK cell surface engineering. Among these major compartments (i.e., Lipid, PEG and HA), optimization of lipid anchors (in terms of chemical structure and intrinsic amphiphilicity) is the most important design parameter to modulate hydrophobic interaction with dynamic NK cell membranes. Here, three different lipid types including 1,2-dimyristoyl-sn-glycero-3-phosphati-dylethanolamine (C14:0), 1,2-distearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE, C18:0), and cholesterol were evaluated to maximize membrane coating efficacy and associated anticancer performance of surface-engineered NK cells (HALipid-NK cells). Our results demonstrated that NK cells coated with HA-PEG-DSPE conjugates exhibited significantly enhanced anticancer efficacies toward MDA-MB-231 breast cancer cells without an off-target effect on human fibroblasts specifically via increased NK cell membrane coating efficacy and prolonged surface duration of HA onto NK cell surfaces, thereby improving HA-CD44 recognition. These results suggest that our HALipid-NK cells with tumor-recognizable HA-PEG-DSPE conjugates could be further utilized in various cancer immunotherapies.

Study the Anticancer Properties of Thymol-Loaded PEGylated Bovine Serum Albumin Nanoparticles Conjugated with Folic Acid

Phenolic compounds such as Thymol have an effective role in suppressing cancer, however, their low solubility in aqueous solution has limited their use. This study aimed to prepare Thymol (TY)-loaded bovine serum albumin (BSA) nanoparticles surface-modified with polyethylene glycol (PEG) conjugated with folic acid (FA) and evaluate their inhibitory activity on cancer cells. The TY-BSA-PEG-FA was characterized using DLS, FESEM, and FTIR. The encapsulation efficiency (EE) was evaluated indirectly by using UV absorption. The antioxidant property of nanoparticles was evaluated by 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing ability of plasm (FRAP) methods. The effects of nanoparticles against cancer cells were investigated by MTT, AO/PI, flow cytometry, and real-time qPCR methods. The results showed the spherical morphology of TY-BSA-PEG-FA with an average size of 70.0 nm, a PDI of 0.32, a zeta potential of -11.3 mV, and an EE of 89.0±2.3 %. The cytotoxicity effects of nanoparticles against all cell lines were in a concentration-dependent manner. AGS gastric cancer cells were reported to be the most vulnerable to treatment, while pancreatic cancer cells (PANC-1) and normal skin cells (HFF) would be the most resistant. The SubG1 phase arrest of about 66 % occurred at 85 μg/mL. An increase in apoptotic cells in fluorescent staining, along with decreased expression of Bcl-2 and increased expression of the BAX gene demonstrated the induction of apoptosis in treated cells. The powerful inhibitory effect of nanoparticles in inhibiting ABTS free radicals (IC50 =82 μg/mL) and DPPH free radicals (IC50 =844 μg/mL) and the ability to reduce iron ions indicated the antioxidant effects of TY-BSA-PEG-FA. Based on these results, the synthesized nanoparticles may be suitable for further investigation in the treatment of cancer, notably gastric cancer.

Biomaterial-Mediated Exogenous Facile Coating of Natural Killer Cells for Enhancing Anticancer Efficacy toward Hepatocellular Carcinoma

Natural killer (NK) cells exhibit a good therapeutic efficacy against various malignant cancer cells. However, the therapeutic efficacy of plain NK cells is relatively low due to inadequate selectivity for cancer cells. Therefore, to enhance the targeting selectivity and anticancer efficacy of NK cells, we have rationally designed a biomaterial-mediated ex vivo surface engineering technique for the membrane decoration of cancer recognition ligands onto NK cells. Our designed lipid conjugate biomaterial contains three major functional moieties: (1) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) lipid for cell membrane anchoring, (2) polyethylene glycol for intracellular penetration blocker, and (3) lactobionic acid (LBA) for cancer recognition. The biomaterial was successfully applied to NK cell surfaces (LBA-NK) to enhance recognition and anticancer functionalities, especially toward asialoglycoprotein receptor (ASGPR)-overexpressing hepatocellular carcinoma. Highly efficient and homogeneous NK cell surface editing was achieved with a simple coating process while maintaining intrinsic properties of NK cells. LBA-NK cells showed potential ASGPR-mediated tumor cell binding (through LBA-ASGPR interaction) and thereby significantly augmented anticancer efficacies against HepG2 liver cancer cells. Thus, LBA-NK cells can be a novel engineering strategy for the treatment of liver cancers via facilitated immune synapse interactions in comparison with currently available cell therapies.