Cell Surface Engineering Research Articles

Exploring mesenchymal stem cells homing mechanisms and improvement strategies.

Mesenchymal stem cells (MSCs) are multipotent cells with high self-renewal and multilineage differentiation abilities, playing an important role in tissue healing. Recent advancements in stem cell-based technologies have offered new and promising therapeutic options in regenerative medicine. Upon tissue damage, MSCs are immediately mobilized from the bone marrow and move to the injury site via blood circulation. Notably, allogenically transplanted MSCs can also home to the damaged tissue site. Therefore, MSCs hold great therapeutic potential for curing various diseases. However, one major obstacle to this approach is attracting MSCs specifically to the injury site following systemic administration. In this review, we describe the molecular pathways governing the homing mechanism of MSCs and various strategies for improving this process, including targeted stem cell administration, target tissue modification, in vitro priming, cell surface engineering, genetic modifications, and magnetic guidance. These strategies are crucial for directing MSCs precisely to the injury site and, consequently, enhancing their migration and local tissue repair properties. Specifically, our review provides a guide to improving the therapeutic efficacy of clinical applications of MSCs through optimized in vivo administration and homing capacities.

Framework Nucleic Acid-Based Selective Cell Catcher for Endogenous Stem Cell Recruitment.

Cell-surface engineering holds great promise in boosting endogenous stem cell attraction for tissue regeneration. However, challenges such as cellular internalization of ligand and the dynamic nature of cell membranes often complicate ligand-receptor interactions. The aim of this study is to harness the innovative potential of programmable tetrahedral framework nucleic acid (tFNA) to enable precise, tunable ligand-receptor interactions, thereby improving stem cell recruitment efficiency. This approach involves experimental screening and theoretical analysis using dissipative particle dynamics. The results demonstrate that altering the flexibility and topology of ligands on tFNA changes their cellular internalization and membrane binding efficiency. Furthermore, optimizing the distribution of the mesenchymal stem cell (MSC)-binding aptamer 19S (Apt19S) on the tFNA enhances the stem cell capture efficiency. Following successful in vitro MSC capture, Apt19S-modified tFNA is chemically linked to a hyaluronic acid hydrogel, forming an efficient "stem cell catcher" system. Subsequent in vivo experiments demonstrate that this system effectively promotes early stem cell recruitment and accelerates bone regeneration in different bone healing scenarios, including cranial and maxillary defects.

Customizable Glycopolymers as Adjuvants for Cancer Immunotherapy: From Branching Degree Optimization to Cell Surface Engineering.

Engineering dendritic cell (DC) maturation is paramount for robust T-cell responses and immunological memory, critical for cancer immunotherapy. This work unveils a novel strategy using precisely controlled branching in synthetic glycopolymers to optimize DC activation. Using the distinct copolymerization kinetics of 2-(methacrylamido) glucopyranose (MAG) and diethylene glycol dimethacrylate (DEGDMA) in a RAFT polymerization, unique glycopolymers with varying branching degrees are created. These strategically produced gradient branched glycopolymers with sugar moieties on the outer chain potently promote DC maturation. Strikingly, low-branched glycopolymers demonstrate superior activity, both in pure form and when engineered on tumor cell surfaces. Quartz crystal microbalance and theoretical simulations elucidate the crucial role of branching in modulating glycopolymer-DC receptor interactions. Low-branched gradient glycopolymers have shown a notable advantage and are promising adjuvants in DC-based cancer immunotherapy.

2D Nano-Photosensitizer Facilitates Proximity Labeling for Living Cells Surfaceome Deciphering.

Photocatalytic proximity labeling has shown great promise for mapping the spatiotemporal dynamics of surfaceome. Although cell-surface targeting photosensitizers relying on antibodies, lipid molecules, and metabolic labeling have gained effects, the development of simpler and stable methods that avoid complex chemical synthesis and biosynthesis steps is still a huge challenge. Here, the study has introduced 2D nanomaterials with the ability of cell surface engineering to perform the in situ anchoring of photosensitizer on living cell surface. Photosensitizer can be stabilized on nanomaterials by coordination after one-step mixing, resulting in the nano-photosensitizer combining cell surface targeting ability and photosensitivity that allowing surface-specific proximity labeling. Nano-photosensitizer can be dispersed stably in aqueous solution, avoiding the defects of poor water solubility and aggregation of traditional organic photosensitizers. Singlet oxygen is generated locally under light irradiation, enabling spatiotemporally-resolved activating and labeling of cell surface proteome. Further application in the brain metastatic lung cancer has been found effective with numerous quantified differential cell surfaces proteins highly correlated with cancer metastasis and three potential players have been validated via immunoblotting and immunofluorescence, providing important insights for metastasis supported molecular mechanism.

Mesenchymal Stem Cells Engineered by Multicomponent Coassembled DNA Nanofibers for Enhanced Wound Healing.

A major challenge for stem cell therapies, such as using mesenchymal stem cells to treat skin injuries, is the stable engraftment of exogenous cells and the maintenance of their regenerative capacities in the wound areas. DNA-based self-assembly strategies can be used for artificial and multifunctional cell surface engineering to stabilize and enhance their functions for therapeutic applications. Here, we developed DNA nanofiber-decorated stem cells, in which DNA-based, multivalent fiber-like structures were self-assembled in situ on the cell surfaces. These engineered stem cells have demonstrated robust reactive oxygen species (ROS) scavenging effects, specific adhesion to damaged vascular endothelial cells, and the ability to enhance angiogenesis, which were effective and safe for acute or chronic wound healing in a mouse model with excisional skin injury. This DNA nanostructure-engineered stem cell provides a novel therapeutic platform for the treatment of tissue damage.

Mesenchymal stromal cells surface engineering for efficient hematopoietic reconstitution

Mesenchymal stromal cells (MSCs) are believed to migrate to injury sites, release chemical attractants, and either recruit local stem cells or modulate the immune system positively. Although MSCs are highly desired for their potential to reduce inflammation and promote tissue regeneration, their limited lifespan restricts their applications. This study presents a simple approach for protecting MSCs with epigallocatechin-3-gallate (EGCG) and magnesium (Mg) based metal-organic framework coatings (E-Mg@MSC). The layer strengthens MSCs resistant to harmful stresses and creates a favorable microenvironment for repair by providing Mg to facilitate MSCs' osteogenic differentiation and using EGCG to neutralize excessive reactive oxygen species (ROS). E-Mg@MSC serves as a treatment for hematopoietic injury induced by ionizing radiation (IR). Coated MSCs exhibit sustained secretion of hematopoietic growth factors and precise homing to radiation-sensitive tissues. In vivo studies show substantial enhancement in hematopoietic system recovery and multi-organ protection. Mechanistic investigations suggest that E-Mg@MSC mitigates IR-induced ROS, cell apoptosis, and ferroptosis, contributing to reduced radiation damage. The system represents a versatile and compelling strategy for cell-surface engineering with functional materials to advance MSCs therapy.

Cell Surface Engineering by Phase‐Separated Coacervates for Antibody Display and Targeted Cancer Cell Therapy

AbstractCell therapies such as CAR−T have demonstrated significant clinical successes, driving the investigation of immune cell surface engineering using natural and synthetic materials to enhance their therapeutic performance. However, many of these materials do not fully replicate the dynamic nature of the extracellular matrix (ECM). This study presents a cell surface engineering strategy that utilizes phase‐separated peptide coacervates to decorate the surface of immune cells. We meticulously designed a tripeptide, Fmoc−Lys−Gly−Dopa−OH (KGdelta; Fmoc=fluorenylmethyloxycarbonyl; delta=Dopa, dihydroxyphenylalanine), that forms coacervates in aqueous solution via phase separation. These coacervates, mirroring the phase separation properties of ECM proteins, coat the natural killer (NK) cell surface with the assistance of Fe3+ ions and create an outer layer capable of encapsulating monoclonal antibodies (mAb), such as Trastuzumab. The antibody‐embedded coacervate layer equips the NK cells with the ability to recognize cancer cells and eliminate them through enhanced antibody‐dependent cellular cytotoxicity (ADCC). This work thus presents a unique strategy of cell surface functionalization and demonstrates its use in displaying cancer‐targeting mAb for cancer therapies, highlighting its potential application in the field of cancer therapy.

Cell Surface Engineering by Phase-Separated Coacervates for Antibody Display and Targeted Cancer Cell Therapy.

Cell therapies such as CAR-T have demonstrated significant clinical successes, driving the investigation of immune cell surface engineering using natural and synthetic materials to enhance their therapeutic performance. However, many of these materials do not fully replicate the dynamic nature of the extracellular matrix (ECM). This study presents a cell surface engineering strategy that utilizes phase-separated peptide coacervates to decorate the surface of immune cells. We meticulously designed a tripeptide, Fmoc-Lys-Gly-Dopa-OH (KGdelta; Fmoc=fluorenylmethyloxycarbonyl; delta=Dopa, dihydroxyphenylalanine), that forms coacervates in aqueous solution via phase separation. These coacervates, mirroring the phase separation properties of ECM proteins, coat the natural killer (NK) cell surface with the assistance of Fe3+ ions and create an outer layer capable of encapsulating monoclonal antibodies (mAb), such as Trastuzumab. The antibody-embedded coacervate layer equips the NK cells with the ability to recognize cancer cells and eliminate them through enhanced antibody-dependent cellular cytotoxicity (ADCC). This work thus presents a unique strategy of cell surface functionalization and demonstrates its use in displaying cancer-targeting mAb for cancer therapies, highlighting its potential application in the field of cancer therapy.

Surface displayed MerR increases mercury accumulation by green microalga Chlamydomonas reinhardtii

Mercury is a highly toxic trace metal that can accumulate in aquatic ecosystems and when resent at high concentrations can pose risks to both aquatic life and humans consuming contaminated fish. This research explores the use of the metalloregulatory protein MerR, known for its high affinity and selectivity toward mercury, in a novel application. Through a cell surface engineering approach, MerR was displayed on cells of green alga Chlamydomonas reinhardtii. A hydroxyproline-rich GP1 protein was used as an anchor to construct the engineered strains GP1-MerR that expresses the fluorescent protein mVenus. The surface engineered GP1-MerR strain led up to five folds higher Hg2+ accumulation compared to the WT strain at concentration range from 10-9 to 10-7 M Hg2+. The binding of Hg2+ via MerR was specific and did not get significantly affected by major freshwater water quality variables such as Ca2+ and dissolved organic matter. The presence of other trace metals (Zn2+, Cu2+, Ni2+, Pb2+, Cd2+) in a same concentration range even resulted in 30–40 % increase in the accumulated Hg. Further, the engineered cells also demonstrated the ability to accumulate Hg2+ from the water extracts of the Hg-contaminated sediment samples. These results demonstrate a novel approach utilizing the cell surface display system in C. reinhardtii for its potential application in bioremediation.

Investigation on Adaptability and Applicability of Polymer-Mediated Cell Surface Engineering by Ligation with Transglutaminase.

Polymer-mediated cell surface engineering can be a powerful tool to modify the cell's biological behavior, but a simple ligation strategy must be identified. This manuscript assessed the use of transglutamination as a versatile and adaptable approach for cell surface engineering in various cellular models relevant to biomedical applications. This enzymatic approach was evaluated for its feasibility and potential for conjugating polymers to diverse cell surfaces and its biological effects. Transglutaminase-mediated ligation was successfully performed at temperatures ranging from 4 to 37 °C in as quickly as 30 min, while maintaining biocompatibility and preserving cell viability. This approach was successfully applied to nine different cell surfaces (including adherent cells and suspension cells) by optimizing the enzyme source (guinea pig liver vs microbial), buffer compositions, and incubation conditions. Finally, polymer-mediated cell surface engineering using transglutaminase exhibited immunocamouflage abilities for endothelial cells, T cells, and red blood cells by preventing the recognition of cell surface proteins by antibodies. Employing transglutaminase in polymer-mediated cell surface engineering is a promising approach to maximize its application in cell therapy and other biomedical applications.

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.

Metal-Induced Energy Transfer (MIET) Imaging of Cell Surface Engineering with Multivalent DNA Nanobrushes.

The spacing between cells has a significant impact on cell-cell interactions, which are critical to the fate and function of both individual cells and multicellular organisms. However, accurately measuring the distance between cell membranes and the variations between different membranes has proven to be a challenging task. In this study, we employ metal-induced energy transfer (MIET) imaging/spectroscopy to determine and track the intermembrane distance and variations with nanometer precision. We have developed a DNA-based molecular adhesive called the DNA nanobrush, which serves as a cellular adhesive for connecting the plasma membranes of different cells. By manipulating the number of base pairs within the DNA nanobrush, we can modify various aspects of membrane-membrane interactions such as adhesive directionality, distance, and forces. We demonstrate that such nanometer-level changes can be detected with MIET imaging/spectroscopy. Moreover, we successfully employed MIET to measure distance variations between a cellular plasma membrane and a model membrane. This experiment not only showcases the effectiveness of MIET as a powerful tool for accurately quantifying membrane-membrane interactions but also validates the potential of DNA nanobrushes as cellular adhesives. This innovative method holds significant implications for advancing the study of multicellular interactions.

Covalent recruitment of polymers and nanoparticles onto glycan-engineered cells enhances gene delivery during short exposure.

Non-viral gene delivery with cationic polymers/nanoparticles relies on iterative optimization of the carrier to achieve delivery. Here we demonstrate, instead, that precision engineering of cell surfaces to covalently capture a polyplex accelerates gene delivery within just 10 min of exposure. Azides were installed into cell-surface sialic acids, which enabled the rapid and selective recruitment of cyclooctyne-functional polyplexes, leading to increased delivery of fluorescent cargo, and also increased plasmid expression and siRNA knockdown. Covalent delivery enhancement was also shown for a polymer-coated nanoparticle delivery system. This validates using cellular metabolic engineering (or other synthetic biology) tools to overcome payload delivery challenges.

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.

Molecular recognition and proteoglycan mimic arrangement: modulating cisplatin toxicity.

We have demonstrated that cisplatin (CP), an anticancer drug, showed a preference for binding the sulfated-L-iduronic acid (S-L-IdoA) unit over the sulfated-D-glucuronic acid unit of heparan sulfate. The multivalency of S-L-IdoA, such as in the proteoglycan mimic, resulted in distinct modes of cell-surface engineering in normal and cancer cells, with these disparities having a significant impact on CP-mediated toxicity.

Display of Polyvalent Hybrid Antibodies on the Cell Surface for Enhanced Cell Recognition.

Cell surface engineering with exogeneous receptors holds great promise for various applications. However, current biological methods face problems with safety, antigen escape, and receptor stoichiometry. The purpose of this study is to develop a biochemical method for displaying polyvalent antibodies (PAbs) on the cell surface. The PAbs are synthesized through the self-assembly of DNA-Ab conjugates under physiological conditions without the involvement of any factors harsh to cells. The data show that PAb-functionalized cells can recognize target cells much more effectively than monovalent controls. Moreover, dual Ab incorporation into the same PAb with a defined stoichiometric ratio leads to the formation of a polyvalent hybrid Ab (DPAb). DPAb-functionalized cells can effectively recognize target cell models with antigen escape, which cannot be achieved by PAbs with one type of Ab. Therefore, this work presents a novel biochemical method for Ab display on the cell surface for enhanced cell recognition.

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.Graphical

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.

Site-selected in situ polymerization for living cell surface engineering

The construction of polymer-based mimicry on cell surface to manipulate cell behaviors and functions offers promising prospects in the field of biotechnology and cell therapy. However, precise control of polymer grafting sites is essential to successful implementation of biomimicry and functional modulation, which has been overlooked by most current research. Herein, we report a biological site-selected, in situ controlled radical polymerization platform for living cell surface engineering. The method utilizes metabolic labeling techniques to confine the growth sites of polymers and designs a Fenton-RAFT polymerization technique with cytocompatibility. Polymers grown at different sites (glycans, proteins, lipids) have different membrane retention time and exhibit differential effects on the recognition behaviors of cellular glycans. Of particular importance is the achievement of in situ copolymerization of glycomonomers on the outermost natural glycan sites of cell membrane, building a biomimetic glycocalyx with distinct recognition properties.

Cell Surface Engineering Tools for Programming Living Assemblies.

Breakthroughs in precision cell surface engineering tools are supporting the rapid development of programmable living assemblies with valuable features for tackling complex biological problems. Herein, the authors overview the most recent technological advances in chemically- and biologically-driven toolboxes for engineering mammalian cell surfaces and triggering their assembly into living architectures. A particular focus is given to surface engineering technologies for enabling biomimetic cell-cell social interactions and multicellular cell-sorting events. Further advancements in cell surface modification technologies may expand the currently available bioengineering toolset and unlock a new generation of personalized cell therapeutics with clinically relevant biofunctionalities. The combination of state-of-the-art cell surface modifications with advanced biofabrication technologies is envisioned to contribute toward generating living materials with increasing tissue/organ-mimetic bioactivities and therapeutic potential.