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.

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.

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.

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.

Differences in the Electrochemical Performance of Pt-Based Catalysts Used for Polymer Electrolyte Membrane Fuel Cells in Liquid Half- and Full-Cells.

A substantial amount of research effort has been directed toward the development of Pt-based catalysts with higher performance and durability than conventional polycrystalline Pt nanoparticles to achieve high-power and innovative energy conversion systems. Currently, attention has been paid toward expanding the electrochemically active surface area (ECSA) of catalysts and increase their intrinsic activity in the oxygen reduction reaction (ORR). However, despite innumerable efforts having been carried out to explore this possibility, most of these achievements have focused on the rotating disk electrode (RDE) in half-cells, and relatively few results have been adaptable to membrane electrode assemblies (MEAs) in full-cells, which is the actual operating condition of fuel cells. Thus, it is uncertain whether these advanced catalysts can be used as a substitute in practical fuel cell applications, and an improvement in the catalytic performance in real-life fuel cells is still necessary. Therefore, from a more practical and industrial point of view, the goal of this review is to compare the ORR catalyst performance and durability in half- and full-cells, providing a differentiated approach to the durability concerns in half- and full-cells, and share new perspectives for strategic designs used to induce additional performance in full-cell devices.

Development of Folate-Thioglycolate-Gold Nanoconjugates by Using Citric Acid-PEG Branched Polymer for Inhibition of MCF-7 Cancer Cell Proliferation.

Development of folate (FA)-functionalized gold nanoparticles (AuNPs) has greatly increased in recent years due to their potential in cancer treatment. As surface functionalization of polymer-free AuNPs with thiol groups could result in agglomeration and precipitation, AuNPs should be stabilized with an efficient polymer. In this study, citric acid-PEG branched polymer (CPEG) acted as a reducing as well as stabilizing agent in the synthesis of AuNPs. The thiol group of thioglycolic acid (TGA) attached to CPEG-stabilized AuNPs and interacted with the free carboxylic acid group on the surface of TGA-AuNP nanoconjugates. Stable TGA-AuNP nanoconjugates were obtained only with CPEG-stabilized AuNPs and not with citrate-stabilized AuNPs. The carboxylic acid group on the surface of AuNPs was used to attach FA via an EDC/NHS coupling reaction to obtain FA-TGA-AuNP nanoconjugates. In vitro cytotoxicity studies indicated that FA-TGA-AuNPs were not toxic to normal cells up to a concentration of 200 µg/mL. However, FA-TGA-AuNP nanoconjugates effectively inhibited proliferation of MCF-7 cancer cells at a low concentration of 25 µg/mL after 3 days of incubation. The anticancer activity of FA-TGA-AuNPs was enhanced by incorporating the anticancer drug 5-fluorouracil into the nanoconjugates, which exhibited sustained drug release up to 5 days. Hence, the developed biocompatible FA-TGA-AuNPs could be used for specific killing of breast cancer cells.

Use of 18F-sodium fluoride bone PET for disability evaluation in ankle trauma: a pilot study.

BACKGROUND: There are no objective and accurate rating tools for permanent impairment of traumatized ankles. The purpose of this study is to assess the role of 18F-Sodium fluoride (18F-NaF) positron emission tomography-computed tomography (PET/CT) bone scans in evaluating patients with limited ankle range of motion (ROM) after trauma. METHODS: 18F-NaF PET/CT was performed in 121 patients (75 men, 46 women; mean age: 45.8) who had ROM < 70% of normal after trauma affecting ankles. Metabolic target volume (MTV), the sum of voxels with standardized uptake value (SUV) > 2.5 was automatically obtained from the 3D volume that included the ankle joint. The maximum & mean SUV (SUVmax & SUVmean), and the total lesion activity (TLA) were measured. RESULTS: The median period from injury to performing 18F-NaF PET/CT was 290 days. The causes of injury were as follows: fracture (N = 95), Achilles tendon rupture (N = 12), and ligament injury (N = 12). Hot uptake in the ankle was seen in 113 of 121 patients. The fracture group had higher SUVmax, SUVmean, and TLA values than the non-fracture group. More limited ROM correlated with higher hot-uptake parameters (SUVmax, SUVmean, TLA). In subgroup analysis, the same correlations were present in the fracture, but not in the non-fracture group. CONCLUSIONS: 18F-NaF PET/CT can provide considerable information in impairment evaluations of limited ankle ROM, particularly in fracture around the ankle. Thus, 18F-NaF bone PET/CT may provide an additional option as an objective imaging tool in disability assessment after ankle injury.

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.

Lipid-mediated ex vivo cell surface engineering for augmented cellular functionalities.

Once administrated, intercellular adhesion to recognize and/or arrest target cells is essential for specific treatments, especially for cancer or tumor. However, immune cells administrated into the tumor-microenvironment could lose their intrinsic functionalities such as target recognition ability, resulting in an ineffective cancer immunotherapy. Various manipulation techniques for decorating functional moieties onto cell surface and enhancing target recognition have been developed. A hydrophobic interaction-mediated ex-vivo cell surface engineering using lipid-based biomaterials could be a state-of-the-art engineering technique that could achieve high-efficiency cell surface modification by a single method without disturbance of intrinsic characteristics of cells. In this regard, this review provides design principles for the development of lipid-based biomaterials with a linear structure of lipid, polyethylene glycol, and functional group, strategies for the synthesis process, and their practical applications in biomedical engineering. Especially, we provide new insights into the development of a novel surface coating techniques for natural killer (NK) cells with engineering decoration of cancer targeting moieties on their cell surfaces. Among immune cells, NK cells are interesting cell population for substituting T cells because of their excellent safety and independent anticancer efficacy. Thus, optimal strategies to select cancer-type-specific targeting moieties and present them onto the surface of immune cells (especially, NK cells) using lipid-based biomaterials could provide additional tools to capture cancer cells for developing novel immune cell therapy products. Enhanced anticancer efficacies by surface-engineered NK cells have been demonstrated both in vitro and in vivo. Therefore, it could be speculated that recent progresses in cell surface modification technology via lipid-based biomaterials could strengthen immune surveillance and immune synapses for utilization in a next-generation cancer immunotherapy, beyond currently available genetic engineering tool such as chimeric antigen receptor-mediated immune cell modulation.

Fabrication Parameter-Dependent Physico-Chemical Properties of Thiolated Gelatin/PEGDA Interpenetrating Network Hydrogels.

BACKGROUND: The development of three-dimensional hydrogels using polymeric biomaterials is a key technology for tissue engineering and regenerative medicine. Successful tissue engineering requires the control and identification of the physicochemical properties of hydrogels. METHODS: Interpenetrating network (IPN) hydrogel was developed using thiolated gelatin (GSH) and poly(ethylene glycol) diacrylate (PEGDA), with the aid of ammonium persulfate (APS) and N,N,N,N'-tetramethylethylenediamine (TEMED) as radical initiators. Each component was prepared in the following concentrations, respectively: 2.5 and 5% GSH (LG and HG), 12.5 and 25% PEGDA (LP and HP), 3% APS/1.5% TEMED (LI), and 4% APS/2% TEMED (HI). IPN hydrogel was fabricated by the mixing of GSH, PEGDA, and initiators in 5:4:1 volume ratios, and incubated at 37 °C for 30 min in the following 6 experimental formulations: (1) HG-LP-LI, (2) HG-LP-HI, (3) LG-HP-LI, (4) LG-HP-HI, (5) HG-HP-HI, and (6) HG-HP-LI. Herein, the physico-chemical characteristics of IPN hydrogels, including their morphological structures, hydrolytic degradation properties, mechanical properties, embedded protein release kinetics, and biocompatibility, were investigated. RESULTS: The characteristics of the hydrogel were significantly manipulated by the concentration of the polymer, especially the conversion between HP and LP, rather than the concentration of the initiator, and no hydrogel formulation exhibited any toxicity to fibroblast and HaCaT cells. CONCLUSION: We provide structural-physical relationships of the hydrogels by which means their physical properties could be conveniently controlled through component control, which could be versatilely utilized for various organizational engineering strategies.

Enhanced anticancer efficacy of primed natural killer cells via coacervate-mediated exogenous interleukin-15 delivery.

Effective exogenous delivery of interleukin (IL)-15 to natural killer (NK) cells with subsequent anticancer efficacy could be a promising immune cell-based cancer immunotherapy. For the protection of encapsulated cargo IL-15 while maintaining its bioactivity under physiological conditions, we utilized a coacervate (Coa) consisting of a cationic methoxy polyethylene glycol-poly(ethylene arginyl aspartate diglyceride) (mPEG-PEAD) polymer, anionic counterpart heparin, and cargo IL-15. mPEGylation into the backbone cation effectively preserved the colloidal stability of Coa in harsh environments and enhanced the protection of cargo IL-15 than normal Coa without mPEGylation. Proliferation and anticancer efficacy of primed NK cells through co-culture with multiple cancer cell lines were enhanced in the mPEG-Coa group due to the maintained bioactivity of cargo IL-15 during the ex vivo expansion of NK cells. These facilitated functions of NK cells were also supported by the increased expression of mRNAs related to anticancer effects of NK cells, including cytotoxic granules, death ligands, anti-apoptotic proteins, and activation receptors. In summary, our Coa-mediated exogenous IL-15 delivery could be an effective ex vivo priming technique for NK cells with sustained immune activation that can effectively facilitate its usage for cancer immunotherapy.

Digital evaluation of axial displacement by implant-abutment connection type: An in vitro study.

PURPOSE: To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS: Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at 10 N·cm, simulating hand tightening, and then at the manufacturers' recommended torque (30 N·cm) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS: Significant differences were observed in axial displacement according to the type of implant-abutment connection (P<.001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P<.05). CONCLUSION: Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

Biomimetic Approach to Stimulate Osteogenesis on Titanium Implant Surfaces Using Fibronectin Derived Oligopeptide.

Our previous studies demonstrated that a recombinant fibronectin (FN)-derived oligopeptide that we named F20 stimulated osteoblast adhesion, proliferation, and differentiation in vitro and in vivo. In the present study, we used a synthetic oligopeptide and investigated the osteogenic potential of F20 coating on titanium discs, to stimulate superior osseointegration for dental implant surface modification. Surface characteristic analysis of titanium was performed by confocal laser scanning microscopy (CLSM) observation. Synthetic F20 was coated onto the machined or SLA titanium discs by an adsorption procedure. ST2 cells were seeded on the titanium discs. We evaluated cell adhesion with SEM and CLSM observation, cell proliferation with picogreen assay, and osteoblast differentiation with real-time PCR, ALP activity assay, immunoblot assay and ALP staining. FITC-labeled F20 coating on the discs was detected by fluorescence, showing good F20 adsorption and different coating patterns according to the surface roughness. In the SEM and CLSM observations, cells were well attached on the machined surface and greater stress fiber formation was seen on discs coated with F20 than on other discs. F20 stimulated cellular proliferation, as well as osteoblast differentiation through the extracellular signalregulated kinase (Erk) signaling pathway. These cellular responses to F20 were slightly better on the machined titanium surface than the SLA surface. These results suggest that F20 promotes osteogenesis through the Erk pathway and is a suitable biomolecule for surface modification of dental implants for improved osseointegration.

The effect of the thread depth on the mechanical properties of the dental implant.

PURPOSE: This study aimed to evaluate the effect of implant thread depth on primary stability in low density bone. MATERIALS AND METHODS: The insertion torque was measured by inserting Ti implants with different thread depths into solid rigid polyurethane blocks (Sawbones) with three different bone densities (0.16 g/cm(3), 0.24 g/cm(3), and 0.32 g/cm(3)). The insertion torque value was evaluated with a surgical engine. The static compressive strength was measured with a universal testing machine (UTM) and the Ti implants were aligned at 30° against the loading direction of the UTM. After the static compressive strength test, the Ti implants were analyzed with a Measurescope. RESULTS: The Ti implants with deeper thread depth showed statistically higher mean insertion torque values (P<.001). Groups A and group B had similar maximum static compressive strengths, as did groups C and D (P>.05). After the static compressive strength, the thread shape of the Ti implants with deeper thread depth did not show any breakage but did show deformation of the implant body and abutment. CONCLUSION: The implants with deeper thread depth had higher mean insertion torque values but not lower compressive strength. The deep threads had a mechanical stability. Implants with deeper thread depth may increase the primary stability in areas of poor quality bone without decreasing mechanical strength.

Nanoscale size effect of magnetic nanocrystals and their utilization for cancer diagnosis via magnetic resonance imaging.

Since the use of magnetic nanocrystals as probes for biomedical system is attractive, it is important to develop optimal synthetic protocols for high-quality magnetic nanocrystals and to have the systematic understanding of their nanoscale properties. Here we present the development of a synthetically controlled magnetic nanocrystal model system that correlates the nanoscale tunabilities in terms of size, magnetism, and induced nuclear spin relaxation processes. This system further led to the development of high-performance nanocrystal-antibody probe systems for the diagnosis of breast cancer cells via magnetic resonance imaging.