Isolation of plasma membrane-associated membranes from rat liver

Optimization of Cell Membrane Purification for the Preparation and Characterization of Cell Membrane Liposomes

Cell membrane nanoparticles have attracted increasing interest in nanomedicine because they allow to exploit the complexity of cell membrane interactions for drug delivery. Several methods are used to obtain plasma membrane to generate cell membrane nanoparticles. Here, an optimized method combining nitrogen cavitation in isotonic buffer and sucrose gradient fractionation is presented. The method allows to obtain cell membrane fractions of high purity from both suspension and adherent cells. Comparison with other common methods for membrane extraction, where mechanical lysis using cell homogenizers is performed in isotonic or hypotonic buffers, shows that the optimized procedure yields high purity membrane in a robust and reproducible way. Procedures to mix the purified membrane with synthetic lipids to obtain cell membrane liposomes (CMLs) are presented and indications on how to optimize these steps are provided. CMLs made using crude membrane isolates or the purified membrane fractions show different uptake by cells. The CMLs made with the optimized procedure and liposomes of the same composition but without cell membrane components are thoroughly characterized and compared for their size, zeta potential, bilayer and mechanical properties to confirm membrane protein inclusion in the CMLs. Cell uptake studies confirm that the inclusion of membrane components modifies liposome interactions with cells.

The cell membrane as biofunctional material for accelerated bone repair

The cell (plasma) membrane is enriched with numerous receptors, ligands, enzymes, and phospholipids that play important roles in cell-cell and cell-extracellular matrix interactions governing, for instance, tissue development and repair. We previously showed that plasma membrane nanofragments (PMNFs) act as nucleation sites for bone formation in vivo, and induce in vitro mineralization within 1 day. In this study, we optimized the methods for generating, isolating, and applying PMNFs as a cell-free therapeutic to expedite bone defect repair. The PMNFs were isolated from different mouse cell lines (chondrocytes, osteoblasts, and fibroblasts), pre-conditioned, lyophilized, and subsequently transplanted into 2 mm critical-sized calvarial defects in mice (n = 75). The PMNFs from chondrocytes, following a 3-day pre-incubation, significantly accelerated bone repair within 2 weeks, through a coordinated attraction of macrophages, endothelial cells, and osteoblasts to the healing site. In vitro experiments confirmed that PMNFs enhanced cell adhesion. Comparison of the PMNF efficacy with phosphatidylserine, amorphous calcium phosphate (ACP), and living cells confirmed the unique ability of PMNFs to promote accelerated bone repair. Importantly, PMNFs promoted nearly complete integration of the regenerated bone with native tissue after 6 weeks (% non-integrated bone area = 15.02), contrasting with the partial integration (% non-integrated bone area = 56.10; p < 0.01, Student's test) with transplantation of ACP. Vickers microhardness tests demonstrated that the regenerated bone after 6 weeks (30.10 ± 1.75) exhibited hardness similar to native bone (31.07 ± 2.46). In conclusion, this is the first study to demonstrate that cell membrane can be a promising cell-free material with multifaceted biofunctional properties that promote accelerated bone repair. STATEMENT OF SIGNIFICANCE.

Human glioblastoma-derived cell membrane nanovesicles: a novel, cell-specific strategy for boron neutron capture therapy of brain tumors

Glioblastoma (GBM), one of the deadliest brain tumors, accounts for approximately 50% of all primary malignant CNS tumors, therefore novel, highly effective remedies are urgently needed. Boron neutron capture therapy, which has recently repositioned as a promising strategy to treat high-grade gliomas, requires a conspicuous accumulation of boron atoms in the cancer cells. With the aim of selectively deliver sodium borocaptate (BSH, a 12 B atoms-including molecule already employed in the clinics) to GBM cells, we developed novel cell membrane-derived vesicles (CMVs), overcoming the limits of natural extracellular vesicles as drug carriers, while maintaining their inherent homing abilities that make them preferable to fully synthetic nanocarriers. Purified cell membrane fragments, isolated from patient-derived GBM stem-like cell cultures, were used to prepare nanosized CMVs, which retained some membrane proteins specific of the GBM parent cells and were devoid of potentially detrimental genetic material. In vitro tests evidenced the targeting ability of this novel nanosystem and ruled out any cytotoxicity. The CMVs were successfully loaded with BSH, by following two different procedures, i.e. sonication and electroporation, demonstrating their potential applicability in GBM therapy.

SETD3 is a mechanosensitive enzyme that methylates actin on His73 to regulate mitochondrial dynamics and function

Mitochondria, which act as sensors of metabolic homeostasis and metabolite signaling, form a dynamic intracellular network that continuously changes shape, size and localization to respond to localized cellular energy demands. Mitochondrial dynamics and function depend on interactions with the F-actin cytoskeleton that are poorly understood. Here, we show that SET domain protein 3 (SETD3), a recently described actin histidine methyltransferase, directly methylates actin at histidine-73 and enhances F-actin polymerization on mitochondria. SETD3 is a mechano-sensitive enzyme that is localized on the outer mitochondrial membrane and promotes actin polymerization around mitochondria. SETD3 loss of function leads to diminished F-actin around mitochondria and a decrease in mitochondrial branch length, branch number and mitochondrial movement. Our functional analysis revealed that SETD3 is required for oxidative phosphorylation, and mitochondrial complex I assembly and function. Our data further indicate that SETD3 regulates F-actin formation around mitochondria and is essential for maintaining mitochondrial morphology, movement and function. Finally, we discovered that SETD3 levels are regulated by extracellular matrix (ECM) stiffness and regulate mitochondrial shape in response to changes in ECM stiffness. These findings provide new insight into the mechanism for F-actin polymerization around mitochondria.

Hybrid Cell Membrane-Based Nanoplatforms for Enhanced Immunotherapy against Cancer and Infectious Diseases

Immunotherapy based on nanoplatforms is a promising approach to treat cancer and infectious diseases, and it has achieved considerable progress in clinical practices. Cell membrane-based nanoplatforms endow nanoparticles with versatile characteristics, such as half-life extension, targeting ability, and immune-system regulation. However, monotypic cell membrane usually fails to provoke strong immune response for immunotherapy while maintaining good biosafety. The integration of different cell-membrane types provides a promising approach to construct multifunctional nanoplatforms for improved immunotherapeutic efficacy by enhancing immunogenicity or targeting function, evading immune clearance, or combining with other therapeutic modalities. In this review, the design principles, preparation strategies, and applications of hybrid cell membrane-based nanoplatforms for cancer and infection immunotherapy are first discussed. Furthermore, the challenges and prospects for the potential clinical translation of hybrid cell membrane-based nanoplatforms are discussed.

A Tumor Environment-Activated Photosensitized Biomimetic Nanoplatform for Precise Photodynamic Immunotherapy of Colon Cancer

Aggressive nature of colon cancer and current imprecise therapeutic scenarios simulate the development of precise and effective treatment strategies. To achieve this, a tumor environment-activated photosensitized biomimetic nanoplatform (PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM) is fabricated by encapsulating metal-organic framework loaded with developed photosensitizer PEG2000-SiNcTI-Ph and immunoadjuvant CpG oligodeoxynucleotide within fusion cell membrane expressing programmed death protein 1 (PD-1) and cluster of differentiation 47 (CD47). By stumbling across, systematic evaluation, and deciphering with quantum chemical calculations, a unique attribute of tumor environment (low pH plus high concentrations of adenosine 5'-triphosphate (ATP))-activated photodynamic effect sensitized by long-wavelength photons is validated for PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM, advancing the precision of cancer therapy. Moreover, PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM evades immune surveillance to target CT26 colon tumors in mice mediated by CD47/signal regulatory proteins α (SIRPα) interaction and PD-1/programmed death ligand 1 (PD-L1) interaction, respectively. Tumor environment-activated photodynamic therapy realized by PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM induces immunogenic cell death (ICD) to elicit anti-tumor immune response, which is empowered by enhanced dendritic cells (DC) uptake of CpG and PD-L1 blockade contributed by the nanoplatform. The photodynamic immunotherapy efficiently combats primary and distant CT26 tumors, and additionally generates immune memory to inhibit tumor recurrence and metastasis. The nanoplatform developed here provides insights for the development of precise cancer therapeutic strategies.

Neutrophil-derived nanovesicles deliver IL-37 to mitigate renal ischemia-reperfusion injury via endothelial cell targeting

Renal ischemia-reperfusion injury (IRI) is one of the most important causes of acute kidney injury (AKI). Interleukin (IL)-37 has been suggested as a novel anti-inflammatory factor for the treatment of IRI, but its application is still limited by its low stability and delivery efficiency. In this study, we reported a novel engineered method to efficiently and easily prepare neutrophil membrane-derived vesicles (N-MVs), which could be utilized as a promising vehicle to deliver IL-37 and avoid the potential side effects of neutrophil-derived natural extracellular vesicles. N-MVs could enhance the stability of IL-37 and targetedly deliver IL-37 to damaged endothelial cells of IRI kidneys via P-selectin glycoprotein ligand-1 (PSGL-1). In vitro and in vivo evidence revealed that N-MVs encapsulated with IL-37 (N-MV@IL-37) could inhibit endothelial cell apoptosis, promote endothelial cell proliferation and angiogenesis, and decrease inflammatory factor production and leukocyte infiltration, thereby ameliorating renal IRI. Our study establishes a promising delivery vehicle for the treatment of renal IRI and other endothelial damage-related diseases.

Application and advances of biomimetic membrane materials in central nervous system disorders

Central nervous system (CNS) diseases encompass spinal cord injuries, brain tumors, neurodegenerative diseases, and ischemic strokes. Recently, there has been a growing global recognition of CNS disorders as a leading cause of disability and death in humans and the second most common cause of death worldwide. The global burdens and treatment challenges posed by CNS disorders are particularly significant in the context of a rapidly expanding global population and aging demographics. The blood-brain barrier (BBB) presents a challenge for effective drug delivery in CNS disorders, as conventional drugs often have limited penetration into the brain. Advances in biomimetic membrane nanomaterials technology have shown promise in enhancing drug delivery for various CNS disorders, leveraging properties such as natural biological surfaces, high biocompatibility and biosafety. This review discusses recent developments in biomimetic membrane materials, summarizes the types and preparation methods of these materials, analyzes their applications in treating CNS injuries, and provides insights into the future prospects and limitations of biomimetic membrane materials.

A chemical proteomics approach for global mapping of functional lysines on cell surface of living cell

Cell surface proteins are responsible for many crucial physiological roles, and they are also the major category of drug targets as the majority of therapeutics target membrane proteins on the surface of cells to alter cellular signaling. Despite its great significance, ligand discovery against membrane proteins has posed a great challenge mainly due to the special property of their natural habitat. Here, we design a new chemical proteomic probe OPA-S-S-alkyne that can efficiently and selectively target the lysines exposed on the cell surface and develop a chemical proteomics strategy for global analysis of surface functionality (GASF) in living cells. In total, we quantified 2639 cell surface lysines in Hela cell and several hundred residues with high reactivity were discovered, which represents the largest dataset of surface functional lysine sites to date. We discovered and validated that hyper-reactive lysine residues K382 on tyrosine kinase-like orphan receptor 2 (ROR2) and K285 on Endoglin (ENG/CD105) are at the protein interaction interface in co-crystal structures of protein complexes, emphasizing the broad potential functional consequences of cell surface lysines and GASF strategy is highly desirable for discovering new active and ligandable sites that can be functionally interrogated for drug discovery.

Chondrocyte membrane-coated nanoparticles promote drug retention and halt cartilage damage in rat and canine osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive degeneration of articular cartilage. A challenge in the development of disease-modifying drugs is effective delivery to chondrocytes. The unique structure of the joint promotes rapid clearance of drugs through synovial fluid, and the dense and avascular cartilage extracellular matrix (ECM) limits drug penetration. Here, we show that poly(lactide-co-glycolic acid) nanoparticles coated in chondrocyte membranes (CM-NPs) were preferentially taken up by rat chondrocytes ex vivo compared with uncoated nanoparticles. Internalization of the CM-NPs was mediated primarily by E-cadherin, clathrin-mediated endocytosis, and micropinocytosis. These CM-NPs adhered to the cartilage ECM in rat knee joints in vivo and penetrated deeply into the cartilage matrix with a residence time of more than 34 days. Simulated synovial fluid clearance studies showed that CM-NPs loaded with a Wnt pathway inhibitor, adavivint (CM-NPs-Ada), delayed the catabolic metabolism of rat and human chondrocytes and cartilage explants under inflammatory conditions. In a surgical model of rat OA, drug-loaded CM-NPs effectively restored gait, attenuated periarticular bone remodeling, and provided chondroprotection against cartilage degeneration. OA progression was also mitigated by CM-NPs-Ada in a canine model of anterior cruciate ligament transection. These results demonstrate the feasibility of using chondrocyte membrane-coated nanoparticles to improve the pharmacokinetics and efficacy of anti-OA drugs.

Inflammation-Driven Nanohitchhiker Enhances Postoperative Immunotherapy by Alleviating Prostaglandin E2-Mediated Immunosuppression

Inflammation contributes to the immunosuppressive microenvironment and leads to the recurrence of surgically resected tumors. The COX-2/PGE2 axis is considered a key player in shaping the immunosuppression microenvironment. However, targeted modulation of the postoperative tumor microenvironment is challenging. To specifically curb the inflammation and alleviate immunosuppression, here, we developed a PGE2 inhibitor celecoxib (CXB)-loaded bionic nanoparticle (CP@CM) coated with activated murine vascular endothelial cell (C166 cells) membrane to target postoperative melanoma and inhibit its recurrence. CP@CM adhered to inflammatory white blood cells (WBCs) through the adhesion molecules, including ICAM-1, VCAM-1, E-selectin, and P-selection, expressed on the surface of C166 cells. Leveraging the natural tropism of the WBC to the inflammatory postoperative tumor site, CP@CM efficiently targeted postoperative tumors. In melanoma postoperative recurrence models, CXB significantly reduced PGE2 secretion and the recruitment of immunosuppressive cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Treg) by inhibiting the activity of COX-2. This was followed by an increase in the infiltration of CD8+ T cells and CD4+ T cells in tumor tissues. Additionally, the immune responses were further enhanced by combining a PD-L1 monoclonal antibody. Ultimately, this immunotherapeutic strategy reversed the tumor immunosuppressive microenvironment and inhibited tumor recurrence, demonstrating a promising potential for postoperative immunotherapy for melanoma.

Dual siRNA-Loaded Cell Membrane Functionalized Matrix Facilitates Bone Regeneration with Angiogenesis and Neurogenesis

Vascularization and innervation play irreplaceable roles in bone regeneration and bone defect repair. However, the reconstruction of blood vessels and neural networks is often neglected in material design. This study aims to design a genetically functionalized matrix (GFM) and enable it to regulate angiogenesis and neurogenesis to accelerate the process of bone defect repair. The dual small interfering RNA (siRNA)-polyvinylimide (PEI) (siRP) complexes that locally knocked down soluble vascular endothelial growth factor receptor 1 (sFlt-1) and p75 neurotrophic factor receptor (p75NTR ) are prepared. The hybrid cell membrane (MM) loaded siRP is synthesized as siRNA@MMs to coat on polylactone (PCL) electrospun fibers for mimicking the natural bone matrix. The results indicates that siRNA@MMs could regulate the expression of vascular-related and neuro-related cytokines secreted by mesenchymal stem cells (MSCs). GFMs promote the expression of osteogenic differentiation through paracrine function in vitro. GFMs attenuates inflammation and promotes osseointegration by regulating the coupling of vascularization and innervation in vivo. This study uses the natural hybrid cell membrane to carry genetic material and assist in the vascularization and innervation function of two siRNA. The results present the significance of neuro-vascularized organoid bone and may provide a promising choice for the design of bone tissue engineering scaffold.

Microfluidics-Prepared Ultra-small Biomimetic Nanovesicles for Brain Tumor Targeting

Blood-brain-barrier (BBB) serves as a fatal guard of the central nervous system as well as a formidable obstacle for the treatment of brain diseases such as brain tumors. Cell membrane-derived nanomedicines are promising drug carriers to achieve BBB-penetrating and brain lesion targeting. However, the challenge of precise size control of such nanomedicines has severely limited their therapeutic effect and clinical application in brain diseases. To address this problem, this work develops a microfluidic mixing platform that enables the fabrication of cell membrane-derived nanovesicles with precise controllability and tunability in particle size and component. Sub-100 nm macrophage plasma membrane-derived vesicles as small as 51 nm (nanoscale macrophage vesicles, NMVs), with a narrow size distribution (polydispersity index, PDI: 0.27) and a high drug loading rate (up to 89% for indocyanine green-loaded NMVs, NMVs@ICG (ICG is indocyanine green)), are achieved through a one-step process. Compared to beyond-100 nm macrophage cell membrane vesicles (general macrophage vesicles, GMVs) prepared via the traditional methods, the new NMVs exhibits rapid (within 1 h post-injection) and enhanced orthotopic glioma targeting (up to 78% enhancement), with no extra surface modification. This work demonstrates the great potential of such real-nanoscale cell membrane-derived nanomedicines in targeted brain tumor theranostics.

Cell membrane-based nanomaterials for therapeutics of neurodegenerative diseases

Central nervous system (CNS) diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), glioblastoma (GBM), and peripheral nerve injury have been documented as incurable diseases, which lead to serious impacts on human health especially prevalent in the aging population worldwide. Most of the treatment strategies fail due to low efficacy, toxicity, and poor brain penetration. Recently, advancements in nanotechnology have helped alleviate the challenges associated with the application of cell membrane-based nanomaterials against CNS diseases. In the following review, the existing types of cell membrane-based nanomaterials systems which have improved therapeutic efficacy for CNS diseases would be described. A summary of recent progress in the incorporation of nanomaterials in cell membrane-based production, separation, and analysis will be provided. Addition to, challenges relate to large-scale manufacturing of cell membrane-based nanomaterials and future clinical trial of such platforms will be discussed.

Neural cell membrane-coated DNA nanogels as a potential target-specific drug delivery tool for the central nervous system

A major bottleneck in drug/gene delivery to enhance tissue regeneration after injuries is to achieve targeted delivery to the cells of interest. Unfortunately, we have not been able to attain effective targeted drug delivery in tissues due to the lack of efficient delivery platforms. Since specific cell-cell interactions exist to impart the unique structure and functionality of tissues and organs, we hypothesize that such specific cellular interactions may also be harnessed for drug delivery applications in the form of cell membrane coatings. Here, we employed neural cell-derived membrane coating technique on DNA nanogels to improve target specificity. The efficacy of neural cell membrane-coated DNA nanogels (NCM-nanogels) was demonstrated by using four types of cell membranes derived from the central nervous system (CNS), namely, astrocytes, microglia, cortical neurons, and oligodendrocyte progenitor cells (OPCs). A successful coating of NCMs over DNA nanogels was confirmed by dynamic light scattering, zeta potential measurements and transmission electron microscopy. Subsequently, an overall improvement in cellular uptake of NCM-nanogels over uncoated DNA nanogels (p < 0.005) was seen. Additionally, we observed a selective uptake of OPC membrane-coated DNA nanogels (NCM-O mem) by oligodendrocytes over other cell types both in vitro and in vivo. Our quantitative polymerase chain reaction (qPCR) results also showed selective and effective gene knockdown capacity of NCM-O mem for OPC transfection. The findings in this work may be beneficial for future drug delivery applications targeted at the CNS.

Neutrophil membrane-based nanotherapeutics: Propitious paradigm shift in the management of cancer

Cancer is the leading cause of death across the globe, with 19.3 million new cancer cases and 10 million deaths in the year 2020. Conventional treatment modalities have numerous pitfalls, such as off-site cytotoxicity and poor bioavailability. Nanocarriers (NCs) have been explored to deliver various therapeutic moieties such as chemotherapeutic agents and photothermal agents, etc. However, several limitations, such as rapid clearance by the reticuloendothelial system, poor extravasation into the tumor microenvironment, and low systemic half-life are roadblocks to successful clinical translation. To circumvent the pitfalls of currently available treatment modalities, neutrophil membrane (NM)-based nanotherapeutics have emerged as a promising platform for cancer management. Their versatile features such as natural tumor tropism, tumor-specific accumulation, and prevention from rapid clearance owing to their autologous nature make them an effective anticancer NCs. In this manuscript, we have discussed various methods for isolation, coating and characterization of NM. We have discussed the role of NM-coated nanotherapeutics as neoadjuvant and adjuvant in different treatment modalities, such as chemotherapy, photothermal and photodynamic therapies with rationales behind their inclusion. Clinical hurdles faced during the bench-to-bedside translation with possible solutions have been discussed. We believe that in the upcoming years, NM-coated nanotherapeutics will open a new horizon in cancer management.

Endoplasmic Reticulum Isolation: An Optimized Approach into Cells and Mouse Liver Fractionation

The subfractionation of the endoplasmic reticulum (ER) is a widely used technique in cell biology. However, current protocols present limitations such as low yield, the use of large number of dishes, and contamination with other organelles. Here, we describe an improved method for ER subfractionation that solves other reported methods' main limitations of being time consuming and requiring less starting material. Our protocol involves a combination of different centrifugations and special buffer incubations as well as a fine-tuned method for homogenization followed by western blotting to confirm the purity of the fractions. This protocol contains a method to extract clean ER samples from cells using only five (150 mm) dishes instead of over 50 plates needed in other protocols. In addition, in this article we not only propose a new cell fractionation approach but also an optimized method to isolate pure ER fractions from one mouse liver instead of three, which are commonly used in other protocols. The protocols described here are optimized for time efficiency and designed for seamless execution in any laboratory, eliminating the need for special/patented reagents. Key features • Subcellular fractionation from cells and mouse liver. • Uses only five dishes (150 mm) or one mouse liver to extract highly enriched endoplasmic reticulum without mitochondrial-associated membrane contamination. • These protocols require the use of ultracentrifuges, dounce homogenizers, and/or Teflon Potter Elvehjem. As a result, highly enriched/clean samples are obtained. Graphical overview.

Apoptotic Neutrophil Membrane-Camouflaged Liposomes for Dually Targeting Synovial Macrophages and Fibroblasts to Attenuate Osteoarthritis

No current pharmacological approach is capable of simultaneously inhibiting the symptomatology and structural progression of osteoarthritis. M1 macrophages and activated synovial fibroblasts (SFs) mutually contribute to the propagation of joint pain and cartilage destruction in osteoarthritis. Here, we report the engineering of an apoptotic neutrophil membrane-camouflaged liposome (termed "NM@Lip") for precise delivery of triamcinolone acetonide (TA) by dually targeting M1 macrophages and activated SFs in osteoarthritic joints. NM@Lip has a high cellular uptake in M1 macrophages and activated SFs. Furthermore, TA-loaded NM@Lip (TA-NM@Lip) effectively repolarizes M1 macrophages to the M2 phenotype and transforms pathological SFs to the deactivated phenotype by inhibiting the PI3K/Akt pathway. NM@Lip retains in the joint for up to 28 days and selectively distributes into M1 macrophages and activated SFs in synovium with low distribution in cartilage. TA-NM@Lip decreases the levels of pro-inflammatory cytokines, chemokines, and cartilage-degrading enzymes in osteoarthritic joints. In a rodent model of osteoarthritis-related pain, a single intra-articular TA-NM@Lip injection attenuates synovitis effectively and achieves complete pain relief with long-lasting effects. In a rodent model of osteoarthritis-related joint degeneration, repeated intra-articular TA-NM@Lip injections induce no obvious cartilage damage and effectively attenuate cartilage degeneration. Taken together, TA-NM@Lip represents a promising nanotherapeutic approach for osteoarthritis therapy.

Cell membrane-based nanomaterials for theranostics of central nervous system diseases

Central nervous system (CNS) diseases have been widely acknowledged as one of the major healthy concerns globally, which lead to serious impacts on human health. There will be about 135 million CNS diseases cases worldwide by mid-century, and CNS diseases will become the second leading cause of death after the cardiovascular disease by 2040. Most CNS diseases lack of effective diagnostic and therapeutic strategies with one of the reasons that the biological barrier extremely hampers the delivery of theranostic agents. In recent years, nanotechnology-based drug delivery is a quite promising way for CNS diseases due to excellent properties. Among them, cell membrane-based nanomaterials with natural bio-surface, high biocompatibility and biosafety, are of great significance in both the diagnosis and treatment of different CNS diseases. In this review, the state of art of the fabrication of cell membranes-based nanomaterials is introduced. The characteristics of different CNS diseases, and the application of cell membranes-based nanomaterials in the theranostics are summarized. In addition, the future prospects and limitations of cell membrane nanotechnology are anticipated. Through summarizing the state of art of the fabrication, giving examples of CNS diseases, and highlighting the applications in theranostics, the current review provides designing methods and ideas for subsequent cell membrane nanomaterials.

The plasma membrane of focal adhesions has a high content of cholesterol and phosphatidylcholine with saturated acyl chains

Cellular functions, such as differentiation and migration, are regulated by the extracellular microenvironment, including the extracellular matrix (ECM). Cells adhere to ECM through focal adhesions (FAs) and sense the surrounding microenvironments. Although FA proteins have been actively investigated, little is known about the lipids in the plasma membrane at FAs. In this study, we examine the lipid composition at FAs with imaging and biochemical approaches. Using the cholesterol-specific probe D4 with total internal reflection fluorescence microscopy and super-resolution microscopy, we show an enrichment of cholesterol at FAs simultaneously with FA assembly. Furthermore, we establish a method to isolate the lipid from FA-rich fractions, and biochemical quantification of the lipids reveals that there is a higher content of cholesterol and phosphatidylcholine with saturated fatty acid chains in the lipids of the FA-rich fraction than in either the plasma membrane fraction or the whole-cell membrane. These results demonstrate that plasma membrane at FAs has a locally distinct lipid composition compared to the bulk plasma membrane.

Disruption of ER ion homeostasis maintained by an ER anion channel CLCC1 contributes to ALS-like pathologies

Although anion channel activities have been demonstrated in sarcoplasmic reticulum/endoplasmic reticulum (SR/ER), their molecular identities and functions remain unclear. Here, we link rare variants of Chloride Channel CLIC Like 1 (CLCC1) to amyotrophic lateral sclerosis (ALS)-like pathologies. We demonstrate that CLCC1 is a pore-forming component of an ER anion channel and that ALS-associated mutations impair channel conductance. CLCC1 forms homomultimers and its channel activity is inhibited by luminal Ca2+ but facilitated by phosphatidylinositol 4,5-bisphosphate (PIP2). We identified conserved residues D25 and D181 in CLCC1 N-terminus responsible for Ca2+ binding and luminal Ca2+-mediated inhibition on channel open probability and K298 in CLCC1 intraluminal loop as the critical PIP2-sensing residue. CLCC1 maintains steady-state [Cl-]ER and [K+]ER and ER morphology and regulates ER Ca2+ homeostasis, including internal Ca2+ release and steady-state [Ca2+]ER. ALS-associated mutant forms of CLCC1 increase steady-state [Cl-]ER and impair ER Ca2+ homeostasis, and animals with the ALS-associated mutations are sensitized to stress challenge-induced protein misfolding. Phenotypic comparisons of multiple Clcc1 loss-of-function alleles, including ALS-associated mutations, reveal a CLCC1 dosage dependence in the severity of disease phenotypes in vivo. Similar to CLCC1 rare variations dominant in ALS, 10% of K298A heterozygous mice developed ALS-like symptoms, pointing to a mechanism of channelopathy dominant-negatively induced by a loss-of-function mutation. Conditional knockout of Clcc1 cell-autonomously causes motor neuron loss and ER stress, misfolded protein accumulation, and characteristic ALS pathologies in the spinal cord. Thus, our findings support that disruption of ER ion homeostasis maintained by CLCC1 contributes to ALS-like pathologies.

Splice variants of mitofusin 2 shape the endoplasmic reticulum and tether it to mitochondria

In eukaryotic cells, different organelles interact at membrane contact sites stabilized by tethers. Mitochondrial mitofusin 2 (MFN2) acts as a membrane tether that interacts with an unknown partner on the endoplasmic reticulum (ER). In this work, we identified the MFN2 splice variant ERMIT2 as the ER tethering partner of MFN2. Splicing of MFN2 produced ERMIT2 and ERMIN2, two ER-specific variants. ERMIN2 regulated ER morphology, whereas ERMIT2 localized at the ER-mitochondria interface and interacted with mitochondrial mitofusins to tether ER and mitochondria. This tethering allowed efficient mitochondrial calcium ion uptake and phospholipid transfer. Expression of ERMIT2 ameliorated the ER stress, inflammation, and fibrosis typical of liver-specific Mfn2 knockout mice. Thus, ER-specific MFN2 variants display entirely extramitochondrial MFN2 functions involved in interorganellar tethering and liver metabolic activities.

Multi-Site Attack, Neutrophil Membrane-Camouflaged Nanomedicine with High Drug Loading for Enhanced Cancer Therapy and Metastasis Inhibition

Background

Advanced breast cancer is a highly metastatic tumor with high mortality. Simultaneous elimination of primary tumor and inhibition of neutrophil-circulation tumor cells (CTCs) cluster formation are urgent issues for cancer therapy. Unfortunately, the drug delivery efficiency to tumors and anti-metastasis efficacy of nanomedicine are far from satisfactory.

Methods

To address these problems, we designed a multi-site attack, neutrophil membrane-camouflaged nanoplatform encapsulating hypoxia-responsive dimeric prodrug hQ-MMAE₂ (hQNM-PLGA) for enhanced cancer and anti-metastasis therapy.

Results

Encouraged by the natural tendency of neutrophils to inflammatory tumor sites, hQNM-PLGA nanoparticles (NPs) could target delivery of drug to tumor, and the acute hypoxic environment of advanced 4T1 breast tumor promoted hQ-MMAE₂ degradation to release MMAE, thus eliminating the primary tumor cells to achieve remarkable anticancer efficacy. Alternatively, NM-PLGA NPs inherited the similar adhesion proteins of neutrophils so that NPs could compete with neutrophils to interrupt the formation of neutrophil-CTC clusters, leading to a reduction in extravasation of CTCs and inhibition of tumor metastasis. The in vivo results further revealed that hQNM-PLGA NPs possessed a perfect safety and ability to inhibit tumor growth and spontaneous lung metastasis.

Conclusion

This study demonstrates the multi-site attack strategy provides a prospective avenue with the potential to improve anticancer and anti-metastasis therapeutic efficacy.

Liver-expressed antimicrobial peptide 2 elevation contributes to age-associated cognitive decline

Elderly individuals frequently report cognitive decline, while various studies indicate hippocampal functional declines with advancing age. Hippocampal function is influenced by ghrelin through hippocampus-expressed growth hormone secretagogue receptor (GHSR). Liver-expressed antimicrobial peptide 2 (LEAP2) is an endogenous GHSR antagonist that attenuates ghrelin signaling. Here, we measured plasma ghrelin and LEAP2 levels in a cohort of cognitively normal individuals older than 60 and found that LEAP2 increased with age while ghrelin (also referred to in literature as "acyl-ghrelin") marginally declined. In this cohort, plasma LEAP2/ghrelin molar ratios were inversely associated with Mini-Mental State Examination scores. Studies in mice showed an age-dependent inverse relationship between plasma LEAP2/ghrelin molar ratio and hippocampal lesions. In aged mice, restoration of the LEAP2/ghrelin balance to youth-associated levels with lentiviral shRNA Leap2 downregulation improved cognitive performance and mitigated various age-related hippocampal deficiencies such as CA1 region synaptic loss, declines in neurogenesis, and neuroinflammation. Our data collectively suggest that LEAP2/ghrelin molar ratio elevation may adversely affect hippocampal function and, consequently, cognitive performance; thus, it may serve as a biomarker of age-related cognitive decline. Moreover, targeting LEAP2 and ghrelin in a manner that lowers the plasma LEAP2/ghrelin molar ratio could benefit cognitive performance in elderly individuals for rejuvenation of memory.

Phytochemicals and Cancer Treatment: Cell-Derived and Biomimetic Vesicles as Promising Carriers

The majority of anticancer agents currently used derive from natural sources: plants, frequently the ones employed in traditional medicines, are an abundant source of mono- and diterpenes, polyphenols, and alkaloids that exert antitumor activity through diverse mechanisms. Unfortunately, many of these molecules are affected by poor pharmacokinetics and limited specificity, shortcomings that may be overcome by incorporating them into nanovehicles. Cell-derived nanovesicles have recently risen to prominence, due to their biocompatibility, low immunogenicity and, above all, targeting properties. However, due to difficult scalability, the industrial production of biologically-derived vesicles and consequent application in clinics is difficult. As an efficient alternative, bioinspired vesicles deriving from the hybridization of cell-derived and artificial membranes have been conceived, revealing high flexibility and appropriate drug delivery ability. In this review, the most recent advances in the application of these vesicles to the targeted delivery of anticancer actives obtained from plants are presented, with specific focus on vehicle manufacture and characterization, and effectiveness evaluation performed through in vitro and in vivo assays. The emerging overall outlook appears promising in terms of efficient drug loading and selective targeting of tumor cells, suggesting further engrossing developments in the future.

A caveolin-1 dependent glucose-6-phosphatase trafficking contributes to hepatic glucose production

OBJECTIVE

Deregulation of hepatic glucose production is a key driver in the pathogenesis of diabetes, but its short-term regulation is incompletely deciphered. According to textbooks, glucose is produced in the endoplasmic reticulum by glucose-6-phosphatase (G6Pase) and then exported in the blood by the glucose transporter GLUT2. However, in the absence of GLUT2, glucose can be produced by a cholesterol-dependent vesicular pathway, which remains to be deciphered. Interestingly, a similar mechanism relying on vesicle trafficking controls short-term G6Pase activity. We thus investigated whether Caveolin-1 (Cav1), a master regulator of cholesterol trafficking, might be the mechanistic link between glucose production by G6Pase in the ER and glucose export through a vesicular pathway.

METHODS

Glucose production from fasted mice lacking Cav1, GLUT2 or both proteins was measured in vitro in primary culture of hepatocytes and in vivo by pyruvate tolerance tests. The cellular localization of Cav1 and the catalytic unit of glucose-6-phosphatase (G6PC1) were studied by western blotting from purified membranes, immunofluorescence on primary hepatocytes and fixed liver sections and by in vivo imaging of chimeric constructs overexpressed in cell lines. G6PC1 trafficking to the plasma membrane was inhibited by a broad inhibitor of vesicular pathways or by an anchoring system retaining G6PC1 specifically to the ER membrane.

RESULTS

Hepatocyte glucose production is reduced at the step catalyzed by G6Pase in the absence of Cav1. In the absence of both GLUT2 and Cav1, gluconeogenesis is nearly abolished, indicating that these pathways can be considered as the two major pathways of de novo glucose production. Mechanistically, Cav1 colocalizes but does not interact with G6PC1 and controls its localization in the Golgi complex and at the plasma membrane. The localization of G6PC1 at the plasma membrane is correlated to glucose production. Accordingly, retaining G6PC1 in the ER reduces glucose production by hepatic cells.

CONCLUSIONS

Our data evidence a pathway of glucose production that relies on Cav1-dependent trafficking of G6PC1 to the plasma membrane. This reveals a new cellular regulation of G6Pase activity that contributes to hepatic glucose production and glucose homeostasis.

Macrophage membrane-biomimetic adhesive polycaprolactone nanocamptothecin for improving cancer-targeting efficiency and impairing metastasis

The recent remarkable success and safety of mRNA lipid nanoparticle technology for producing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has stimulated intensive efforts to expand nanoparticle strategies to treat various diseases. Numerous synthetic nanoparticles have been developed for pharmaceutical delivery and cancer treatment. However, only a limited number of nanotherapies have enter clinical trials or are clinically approved. Systemically administered nanotherapies are likely to be sequestered by host mononuclear phagocyte system (MPS), resulting in suboptimal pharmacokinetics and insufficient drug concentrations in tumors. Bioinspired drug-delivery formulations have emerged as an alternative approach to evade the MPS and show potential to improve drug therapeutic efficacy. Here we developed a biodegradable polymer-conjugated camptothecin prodrug encapsulated in the plasma membrane of lipopolysaccharide-stimulated macrophages. Polymer conjugation revived the parent camptothecin agent (e.g., 7-ethyl-10-hydroxy-camptothecin), enabling lipid nanoparticle encapsulation. Furthermore, macrophage membrane cloaking transformed the nonadhesive lipid nanoparticles into bioadhesive nanocamptothecin, increasing the cellular uptake and tumor-tropic effects of this biomimetic therapy. When tested in a preclinical murine model of breast cancer, macrophage-camouflaged nanocamptothecin exhibited a higher level of tumor accumulation than uncoated nanoparticles. Furthermore, intravenous administration of the therapy effectively suppressed tumor growth and the metastatic burden without causing systematic toxicity. Our study describes a combinatorial strategy that uses polymeric prodrug design and cell membrane cloaking to achieve therapeutics with high efficacy and low toxicity. This approach might also be generally applicable to formulate other therapeutic candidates that are not compatible or miscible with biomimetic delivery carriers.

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Macrophage membrane-biomimetic platform was exploited for nanodelivery of polycaprolactone nanocamptothecin.

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Macrophage-camouflaged nanocamptothecin exhibited tumor-tropic effects and increased tumor cell adhesion.

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The nanotherapy effectively suppressed primary tumor growth and the metastatic burden in vivo.

Spectrin-beta 2 facilitates the selective accumulation of GABAA receptors at somatodendritic synapses

Fast synaptic inhibition is dependent on targeting specific GABA_AR subtypes to dendritic and axon initial segment (AIS) synapses. Synaptic GABA_ARs are typically assembled from α1-3, β and γ subunits. Here, we isolate distinct GABA_ARs from the brain and interrogate their composition using quantitative proteomics. We show that α2-containing receptors co-assemble with α1 subunits, whereas α1 receptors can form GABA_ARs with α1 as the sole α subunit. We demonstrate that α1 and α2 subunit-containing receptors co-purify with distinct spectrin isoforms; cytoskeletal proteins that link transmembrane proteins to the cytoskeleton. β2-spectrin was preferentially associated with α1-containing GABA_ARs at dendritic synapses, while β4-spectrin was associated with α2-containing GABA_ARs at AIS synapses. Ablating β2-spectrin expression reduced dendritic and AIS synapses containing α1 but increased the number of synapses containing α2, which altered phasic inhibition. Thus, we demonstrate a role for spectrins in the synapse-specific targeting of GABA_ARs, determining the efficacy of fast neuronal inhibition.

Cpt1c Downregulation Causes Plasma Membrane Remodelling and Anthracycline Resistance in Breast Cancer

Breast cancer (BC) is the most common malignancy in women worldwide. While the main systemic treatment option is anthracycline-containing chemotherapy, chemoresistance continues to be an obstacle to patient survival. Carnitine palmitoyltransferase 1C (CPT1C) has been described as a poor-prognosis marker for several tumour types, as it favours tumour growth and hinders cells from entering senescence. At the molecular level, CPT1C has been associated with lipid metabolism regulation and important lipidome changes. Since plasma membrane (PM) rigidity has been associated with reduced drug uptake, we explored whether CPT1C expression could be involved in PM remodelling and drug chemoresistance. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) lipid analysis of PM-enriched fractions of MDA-MB-231 BC cells showed that CPT1C silencing increased PM phospholipid saturation, suggesting a rise in PM rigidity. Moreover, CPT1C silencing increased cell survival against doxorubicin (DOX) treatment in different BC cells due to reduced drug uptake. These findings, further complemented by ROC plotter analysis correlating lower CPT1C expression with a lower pathological complete response to anthracyclines in patients with more aggressive types of BC, suggest CPT1C as a novel predictive biomarker for BC chemotherapy.

Elevated Ghrelin Promotes Hippocampal Ghrelin Receptor Defects in Humanized Amyloid-β Knockin Mice During Aging

BACKGROUND

Emerging evidence has revealed that dysregulation of the hormone ghrelin and its receptor, growth hormone secretagogue receptor (GHSR), contributes to the pathogenesis of Alzheimer's disease (AD). Specifically, defective GHSR function and resultant hippocampal ghrelin resistance are linked to hippocampal synaptic injury in AD paradigms. Also, AD patients exhibit elevated ghrelin activation. However, the detailed molecular mechanisms of hippocampal GHSR dysfunction and the relevance of ghrelin elevation to hippocampal ghrelin resistance in AD-relevant pathological settings are not fully understood.

OBJECTIVE

In the current study, we employed a recently established mouse line of AD risk [humanized amyloid beta knockin (hAβ KI mice), also referred to as a mouse model of late-onset AD in previous literature] to further define the role of ghrelin system dysregulation in the development of AD.

METHODS

We employed multidisciplinary techniques to determine the change of plasma ghrelin and the functional status of GHSR in hAβ KI mice as well as primary neuron cultures.

RESULTS

We observed concurrent plasma ghrelin elevation and hippocampal GHSR desensitization with disease progression. Further examination excluded the possibility that ghrelin elevation is a compensatory change in response to GHSR dysfunction. In contrast, further in vitro and in vivo results show that agonist-mediated overstimulation potentiates GHSR desensitization through enhanced GHSR internalization.

CONCLUSIONS

These findings suggest that circulating ghrelin elevation is a pathological event underlying hippocampal GHSR dysfunction, culminating in hippocampal ghrelin resistance and resultant synaptic injury in late-onset AD-related settings.

An Innovative PTD-IVT-mRNA Delivery Platform for CAR Immunotherapy of ErbB(+) Solid Tumor Neoplastic Cells

Chimeric antigen receptor (CAR) immunotherapy includes the genetic modification of immune cells to carry such a receptor and, thus, recognize cancer cell surface antigens. Viral transfection is currently the preferred method, but it carries the risk of off-target mutagenicity. Other transfection platforms have thus been proposed, such the in vitro transcribed (IVT)-mRNAs. In this study, we exploited our innovative, patented delivery platform to produce protein transduction domain (PTD)-IVT-mRNAs for the expression of CAR on NK-92 cells. CAR T1E-engineered NK-92 cells, harboring the sequence of T1E single-chain fragment variant (scFv) to recognize the ErbB receptor, bearing either CD28 or 4-1BB as co-stimulatory signaling domains, were prepared and assessed for their effectiveness in two different ErbB(+) cancer cell lines. Our results showed that the PTD-IVT-mRNA of CAR was safely transduced and expressed into NK-92 cells. CAR T1E-engineered NK-92 cells provoked high levels of cell death (25-33%) as effector cells against both HSC-3 (oral squamous carcinoma) and MCF-7 (breast metastatic adenocarcinoma) human cells in the co-incubation assays. In conclusion, the application of our novel PTD-IVT-mRNA delivery platform to NK-92 cells gave promising results towards future CAR immunotherapy approaches.

Fabrication of initial trabecular bone-inspired three-dimensional structure with cell membrane nano fragments

The extracellular matrix of trabecular bone has a large surface exposed to the bone marrow and plays important roles such as hematopoietic stem cell niche formation and maintenance. In vitro reproduction of trabecular bone microenvironment would be valuable not only for developing a functional scaffold for bone marrow tissue engineering but also for understanding its biological functions. Herein, we analyzed and reproduced the initial stages of trabecular bone formation in mouse femur epiphysis. We identified that the trabecular bone formation progressed through the following steps: (i) partial rupture of hypertrophic chondrocytes; (ii) calcospherite formation on cell membrane nano fragments (CNFs) derived from the ruptured cells; and (iii) calcospherite growth and fusion to form the initial three-dimensional (3D) structure of trabecular bones. For reproducing the initial trabecular bone formation in vitro, we collected CNFs from cultured cells and used as nucleation sites for biomimetic calcospherite formation. Strikingly, almost the same 3D structure of the initial trabecular bone could be obtained in vitro by using additional CNFs as a binder to fuse biomimetic calcospherites.

Analyzing the mechanisms that facilitate the subtype-specific assembly of γ-aminobutyric acid type A receptors

Impaired inhibitory signaling underlies the pathophysiology of many neuropsychiatric and neurodevelopmental disorders including autism spectrum disorders and epilepsy. Neuronal inhibition is regulated by synaptic and extrasynaptic γ-aminobutyric acid type A receptors (GABA _A Rs), which mediate phasic and tonic inhibition, respectively. These two GABA _A R subtypes differ in their function, ligand sensitivity, and physiological properties. Importantly, they contain different α subunit isoforms: synaptic GABA _A Rs contain the α1-3 subunits whereas extrasynaptic GABA _A Rs contain the α4-6 subunits. While the subunit composition is critical for the distinct roles of synaptic and extrasynaptic GABA _A R subtypes in inhibition, the molecular mechanism of the subtype-specific assembly has not been elucidated. To address this issue, we purified endogenous α1- and α4-containing GABA _A Rs from adult murine forebrains and examined their subunit composition and interacting proteins using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and quantitative analysis. We found that the α1 and α4 subunits form separate populations of GABA _A Rs and interact with distinct sets of binding proteins. We also discovered that the β3 subunit, which co-purifies with both the α1 and α4 subunits, has different levels of phosphorylation on serines 408 and 409 (S408/9) between the two receptor subtypes. To understand the role S408/9 plays in the assembly of α1- and α4-containing GABA _A Rs, we examined the effects of S408/9A (alanine) knock-in mutation on the subunit composition of the two receptor subtypes using LC-MS/MS and quantitative analysis. We discovered that the S408/9A mutation results in the formation of novel α1α4-containing GABA _A Rs. Moreover, in S408/9A mutants, the plasma membrane expression of the α4 subunit is increased whereas its retention in the endoplasmic reticulum is reduced. These findings suggest that S408/9 play a critical role in determining the subtype-specific assembly of GABA _A Rs, and thus the efficacy of neuronal inhibition.

KLHL3 deficiency in mice ameliorates obesity, insulin resistance, and nonalcoholic fatty liver disease by regulating energy expenditure

Obesity is a growing global epidemic that can cause serious adverse health consequences, including insulin resistance (IR) and nonalcoholic fatty liver disease (NAFLD). Obesity development can be attributed to energy imbalance and metabolic inflexibility. Here, we demonstrated that lack of Kelch-like protein 3 (KLHL3) mitigated the development of obesity, IR, and NAFLD by increasing energy expenditure. KLHL3 mutations in humans cause Gordon’s hypertension syndrome; however, the role of KLHL3 in obesity was previously unknown. We examined differences in obesity-related parameters between control and Klhl3^−/− mice. A significant decrease in body weight concomitant with fat mass loss and improved IR and NAFLD were observed in Klhl3^−/− mice fed a high-fat (HF) diet and aged. KLHL3 deficiency inhibited obesity, IR, and NAFLD by increasing energy expenditure with augmentation of O₂ consumption and CO₂ production. Delivering dominant-negative (DN) Klhl3 using adeno-associated virus into mice, thereby dominantly expressing DN-KLHL3 in the liver, ameliorated diet-induced obesity, IR, and NAFLD. Finally, adenoviral overexpression of DN-KLHL3, but not wild-type KLHL3, in hepatocytes revealed an energetic phenotype with an increase in the oxygen consumption rate. The present findings demonstrate a novel function of KLHL3 mutation in extrarenal tissues, such as the liver, and may provide a therapeutic target against obesity and obesity-related diseases.

Mice that are genetically engineered to lack a protein involved in regulating energy expenditure are protected against the onset of obesity and the related problems of insulin resistance and non-alcoholic fatty liver disease. Jeong-Ki Min, Jong-Gil Park and colleagues at the Korea Research Institute of Bioscience & Biotechnology in South Korea, Daejon, discovered that the beneficial effect of the lack of the protein, called KLHL3, was due to an increase in energy expenditure. Mutations in the gene for KLHL3 are known to cause a variety of metabolic diseases in humans, including a form of high blood pressure called Gordon’s hypertension syndrome, but the protein’s role in human obesity has not been studied. The results suggest that drugs able to regulate the production or activity of KLHL3 might offer a new approach to treating obesity.

LDL Promotes Disorders in β-Cell Cholesterol Metabolism, Implications on Insulin Cellular Communication Mediated by EVs

Dyslipidemia is described as a hallmark of metabolic syndrome, promoting a stage of metabolic inflammation (metainflammation) that could lead to misbalances in energetic metabolism, contributing to insulin resistance, and modifying intracellular cholesterol pathways and the renin-angiotensin system (RAS) in pancreatic islets. Low-density lipoprotein (LDL) hypercholesterolemia could disrupt the tissue communication between Langerhans β-cells and hepatocytes, wherein extracellular vesicles (EVs) are secreted by β-cells, and exposition to LDL can impair these phenomena. β-cells activate compensatory mechanisms to maintain insulin and metabolic homeostasis; therefore, the work aimed to characterize the impact of LDL on β-cell cholesterol metabolism and the implication on insulin secretion, connected with the regulation of cellular communication mediated by EVs on hepatocytes. Our results suggest that β-cells can endocytose LDL, promoting an increase in de novo cholesterol synthesis targets. Notably, LDL treatment increased mRNA levels and insulin secretion; this hyperinsulinism condition was associated with the transcription factor PDX-1. However, a compensatory response that maintains basal levels of intracellular calcium was described, mediated by the overexpression of calcium targets PMCA1/4, SERCA2, and NCX1, together with the upregulation of the unfolded protein response (UPR) through the activation of IRE1 and PERK arms to maintain protein homeostasis. The LDL treatment induced metainflammation by IL-6, NF-κB, and COX-2 overexpression. Furthermore, LDL endocytosis triggered an imbalance of the RAS components. LDL treatment increased the intracellular levels of cholesterol on lipid droplets; the adaptive β-cell response was portrayed by the overexpression of cholesterol transporters ABCA1 and ABCG1. Therefore, lipotoxicity and hyperinsulinism induced by LDL were regulated by the natural compound auraptene, a geranyloxyn coumarin modulator of cholesterol-esterification by ACAT1 enzyme inhibition. EVs isolated from β-cells impaired insulin signaling via mTOR/p70S6Kα in hepatocytes, a phenomenon regulated by auraptene. Our results show that LDL overload plays a novel role in hyperinsulinism, mechanisms associated with a dysregulation of intracellular cholesterol, lipotoxicity, and the adaptive UPR, which may be regulated by coumarin-auraptene; these conditions explain the affectations that occur during the initial stages of insulin resistance.

Neutrophil membrane engineered HucMSC sEVs alleviate cisplatin-induced AKI by enhancing cellular uptake and targeting

Human umbilical cord mesenchymal stem cells-derived small extracellular vesicles (hucMSC-sEVs) have been demonstrated as a therapeutic agent to prevent and treat cisplatin-induced acute kidney injury (AKI). However, hucMSC-sEVs still face many problems and challenges in the repair and treatment of tissue injury, including short circulation time, insufficient targeting, and low therapeutic efficacy. Therefore, we constructed engineered hybrid vesicles fused with nanovesicles derived from human neutrophil membranes and hucMSC-sEVs, named neutrophil membrane engineered hucMSC-sEVs (NEX). NEX significantly enhanced the targeting of hucMSC-sEVs to injured kidney tissues, improved the impaired renal function via reducing pro-inflammatory cytokines expression, promoted the proliferation of renal tissue cells, and inhibited renal cell apoptosis in vivo. In addition, NEX enhanced hucMSC-sEVs uptake by NRK52E cells, but inhibited its uptake by RAW264.7 cells. Moreover, administration of NEX reduced cellular oxidative stress and promoted proliferation of NRK52E cells treated with cisplatin in vitro. In summary, our findings indicate that this design of a universal approach enhances the targeting and therapeutic efficacy of hucMSC-sEVs in kidney tissue regeneration, and provides new evidence promoting its clinical application.

Immortalized Mesenchymal Stem Cells: A Safe Cell Source for Cellular or Cell Membrane-Based Treatment of Glioma

Mesenchymal stem cells (MSCs) have emerged as putative therapeutic tools due to their intrinsic tumor tropism, and anti-tumor and immunoregulatory properties. The limited passage and self-differentiation abilities of MSCs in vitro hinder preclinical studies on them. In this study, we focused on the safety of immortalized mesenchymal stem cells (im-MSCs) and, for the first time, studied the feasibility of im-MSCs as candidates for the treatment of glioma. The im-MSCs were constructed by lentiviral transfection of genes. The proliferative capacity of im-MSCs and the proliferative phenotype of MSCs and MSCs co-cultured with glioma cells (U87) were measured using CCK-8 or EdU assays. After long-term culture, karyotyping of im-MSCs was conducted. The tumorigenicity of engineered MSCs was evaluated using soft agar cloning assays. Next, the engineered cells were injected into the brain of female BALB/c nude mice. Finally, the cell membranes of im-MSCs were labeled with DiO or DiR to detect their ability to be taken up by glioma cells and target in situ gliomas using the IVIS system. Engineered cells retained the immunophenotype of MSC; im-MSCs maintained the ability to differentiate into mesenchymal lineages in vitro; and im-MSCs showed stronger proliferative capacity than unengineered MSCs but without colony formation in soft agar, no tumorigenicity in the brain, and normal chromosomes. MSCs or im-MSCs co-cultured with U87 cells showed enhanced proliferation ability, but did not show malignant characteristics in vitro. Immortalized cells continued to express homing molecules. The cell membranes of im-MSCs were taken up by glioma cells and targeted in situ gliomas in vivo, suggesting that im-MSCs and their plasma membranes can be used as natural drug carriers for targeting gliomas, and providing a safe, adequate, quality-controlled, and continuous source for the treatment of gliomas based on whole-cell or cell membrane carriers.

High-fat diet induced alterations in plasma membrane cholesterol content impairs insulin receptor binding and signalling in mouse liver but is ameliorated by atorvastatin

A high-fat diet (HFD) impairs insulin binding and signalling and may contribute to the development of insulin resistance. In addition, in vitro studies have shown that alterations in plasma membrane cholesterol influence ligand binding and downstream signalling for several receptor-tyrosine kinases (RTKs), including the insulin receptor. Using an ex vivo approach, we explored the effects of a HFD on insulin binding and signalling in mouse liver and relate these to observed changes in plasma membrane cholesterol. Mice fed a HFD demonstrated decreased insulin signalling compared to mice fed a normal chow diet (ND), indicated by a 3-fold decrease in insulin binding (P < 0.001) and a similar decrease in insulin receptor phosphorylation (~2.5-fold; P < 0.0001). Interestingly, we also observed a marked decrease in the cholesterol content of liver plasma membranes in the HFD fed mice (P < 0.0001). These effects of the HFD were found to be ameliorated by atorvastatin treatment (P < 0.0001). However, in ND mice, atorvastatin had no influence on membrane cholesterol content or insulin binding and signalling. The influence of membrane cholesterol on insulin binding and signalling was also corroborated in HepG2 cells. To the best of our knowledge, this is the first demonstration of the effects of a HFD and atorvastatin treatment on changes in plasma membrane cholesterol content and the consequent effects on insulin binding and signalling. Collectively, these findings suggest that changes in membrane cholesterol content could be an important underlying reason for the long-known effects of a HFD on the development of insulin resistance.

Site-specific ubiquitination of MLKL targets it to endosomes and targets Listeria and Yersinia to the lysosomes

Phosphorylation of the pseudokinase mixed lineage kinase domain-like protein (MLKL) by the protein kinase RIPK3 targets MLKL to the cell membrane, where it triggers necroptotic cell death. We report that conjugation of K63-linked polyubiquitin chains to distinct lysine residues in the N-terminal HeLo domain of phosphorylated MLKL (facilitated by the ubiquitin ligase ITCH that binds MLKL via a WW domain) targets MLKL instead to endosomes. This results in the release of phosphorylated MLKL within extracellular vesicles. It also prompts enhanced endosomal trafficking of intracellular bacteria such as Listeria monocytogenes and Yersinia enterocolitica to the lysosomes, resulting in decreased bacterial yield. Thus, MLKL can be directed by specific covalent modifications to differing subcellular sites, whence it signals either for cell death or for non-deadly defense mechanisms.

Biohybrid Variable-Stiffness Soft Actuators that Self-Create Bone

Inspired by the dynamic process of initial bone development, in which a soft tissue turns into a solid load-bearing structure, the fabrication, optimization, and characterization of bioinduced variable-stiffness actuators that can morph in various shapes and change their properties from soft to rigid are hereby presented. Bilayer devices are prepared by combining the electromechanically active properties of polypyrrole with the compliant behavior of alginate gels that are uniquely functionalized with cell-derived plasma membrane nanofragments (PMNFs), previously shown to mineralize within 2 days, which promotes the mineralization in the gel layer to achieve the soft to stiff change by growing their own bone. The mineralized actuator shows an evident frozen state compared to the movement before mineralization. Next, patterned devices show programmed directional and fixated morphing. These variable-stiffness devices can wrap around and, after the PMNF-induced mineralization in and on the gel layer, adhere and integrate onto bone tissue. The developed biohybrid variable-stiffness actuators can be used in soft (micro-)robotics and as potential tools for bone repair or bone tissue engineering.

Alcohol-Induced Liver Injury: Down-regulation and Redistribution of Rab3D Results in Atypical Protein Trafficking

Previous work from our laboratories has identified multiple defects in endocytosis, protein trafficking, and secretion, along with altered Golgi function after alcohol administration. Manifestation of alcohol-associated liver disease (ALD) is associated with an aberrant function of several hepatic proteins, including asialoglycoprotein receptor (ASGP-R), their atypical distribution at the plasma membrane (PM), and secretion of their abnormally glycosylated forms into the bloodstream, but trafficking mechanism is unknown. Here we report that a small GTPase, Rab3D, known to be involved in exocytosis, secretion, and vesicle trafficking, shows ethanol (EtOH)-impaired function, which plays an important role in Golgi disorganization. We used multiple approaches and cellular/animal models of ALD, along with Rab3D knockout (KO) mice and human tissue from patients with ALD. We found that Rab3D resides primarily in trans- and cis-faces of Golgi; however, EtOH treatment results in Rab3D redistribution from trans-Golgi to cis-medial-Golgi. Cells lacking Rab3D demonstrate enlargement of Golgi, especially its distal compartments. We identified that Rab3D is required for coat protein I (COPI) vesiculation in Golgi, and conversely, COPI is critical for intra-Golgi distribution of Rab3D. Rab3D/COPI association was altered not only in the liver of patients with ALD but also in the donors consuming alcohol without steatosis. In Rab3D KO mice, hepatocytes experience endoplasmic reticulum (ER) stress, and EtOH administration activates apoptosis. Notably, in these cells, ASGP-R, despite incomplete glycosylation, can still reach cell surface through ER-PM junctions. This mimics the effects seen with EtOH-induced liver injury. Conclusion: We revealed that down-regulation of Rab3D contributes significantly to EtOH-induced Golgi disorganization, and abnormally glycosylated ASGP-R is excreted through ER-PM connections, bypassing canonical (ER→Golgi→PM) anterograde transportation. This suggests that ER-PM sites may be a therapeutic target for ALD.

Loss of function TRPV6 variants are associated with chronic pancreatitis in nonalcoholic early-onset Polish and German patients

PURPOSE

Loss of function variants of the transient receptor potential cation channel, subfamily V, member 6 (TRPV6) have been recently associated with chronic pancreatitis (CP) in Japanese, German and French patients. Here, we investigated the association of TRPV6 variants with CP in independent European cohorts of early-onset CP patients from Poland and Germany.

PATIENTS AND METHODS

We enrolled 152 pediatric CP patients (median age 8.6 yrs) with no history of alcohol/smoking abuse and 472 controls from Poland as well as 157 nonalcoholic young CP patients (median age 20 yrs) and 750 controls from Germany. Coding regions of TRPV6 were screened by Sanger and next generation sequencing. Selected, potentially pathogenic TRPV6 variants were expressed in HEK293T cells and TRPV6 activity was analyzed using ratiometric Ca²⁺ measurements.

RESULTS

Overall, we identified 10 novel (3 nonsense and 7 missenses) TRPV6 variants in CP patients. TRPV6 p.V239SfsX53 nonsense variant and the variants showing significant decrease in intracellular Ca²⁺ concentration in HEK293T cells (p.R174X, p.L576R, p.R342Q), were significantly overrepresented in Polish patients as compared to controls (6/152, 3.9% vs. 0/358, 0%; P = 0,0007). Nonsense TRPV6 variants predicted as loss of function (p.V239SfsX53 and p.R624X) were also significantly overrepresented in German patients (3/157; 2.0% vs 0/750; 0%, P = 0.005).

CONCLUSIONS

We showed that TRPV6 loss of function variants are associated with elevated CP risk in early-onset Polish and German patients confirming that TRPV6 is a novel CP susceptibility gene.

Cell Membrane-Coated Mimics: A Methodological Approach for Fabrication, Characterization for Therapeutic Applications, and Challenges for Clinical Translation

Cell membrane-coated (CMC) mimics are micro/nanosystems that combine an isolated cell membrane and a template of choice to mimic the functions of a cell. The design exploits its physicochemical and biological properties for therapeutic applications. The mimics demonstrate excellent biological compatibility, enhanced biointerfacing capabilities, physical, chemical, and biological tunability, ability to retain cellular properties, immune escape, prolonged circulation time, and protect the encapsulated drug from degradation and active targeting. These properties and the ease of adapting them for personalized clinical medicine have generated a significant research interest over the past decade. This review presents a detailed overview of the recent advances in the development of cell membrane-coated (CMC) mimics. The primary focus is to collate and discuss components, fabrication methodologies, and the significance of physiochemical and biological characterization techniques for validating a CMC mimic. We present a critical analysis of the two main components of CMC mimics: the template and the cell membrane and mapped their use in therapeutic scenarios. In addition, we have emphasized on the challenges associated with CMC mimics in their clinical translation. Overall, this review is an up to date toolbox that researchers can benefit from while designing and characterizing CMC mimics.

Ligand-modified homologous targeted cancer cell membrane biomimetic nanostructured lipid carriers for glioma therapy

The main treatment measure currently used for glioma treatment is chemotherapy; the biological barrier of solid tumors hinders the deep penetration of nanomedicines and limits anticancer therapy. Furthermore, the poor solubility of many chemotherapeutic drugs limits the efficacy of antitumor drugs. Therefore, improving the solubility of chemotherapeutic agents and drug delivery to tumor tissues through the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB) are major challenges in glioma treatment. Nanostructured lipid carriers (NLCs) have high drug loading capacity, high stability, and high in vivo safety; moreover, they can effectively improve the solubility of insoluble drugs. Therefore, in this study, we used solvent volatilization and ultrasonic melting methods to prepare dihydroartemisinin nanostructured lipid carrier (DHA-NLC). We further used the glioma C6 cancer cell (CC) membrane to encapsulate DHA-NLC owing to the homologous targeting mechanism of the CC membrane; however, the targeting ability of the CC membrane was weak. We accordingly used targeting ligands for modification, and developed a bionanostructured lipid carrier with BBB and BBTB penetration and tumor targeting abilities. The results showed that DHA-loaded NGR/CCNLC (asparagine-glycine-arginine, NGR) was highly targeted, could penetrate the BBB and BBTB, and showed good anti-tumor effects both in vitro and in vivo, which could effectively prolong the survival time of tumor-bearing mice. Thus, the use of DHA-loaded NGR/CCNLC is an effective strategy for glioma treatment and has the potential to treat glioma.

Camouflaged Hybrid Cancer Cell-Platelet Fusion Membrane Nanovesicles Deliver Therapeutic MicroRNAs to Presensitize Triple-Negative Breast Cancer to Doxorubicin

Camouflaged cell-membrane-based nanoparticles have been gaining increasing attention owing to their improved biocompatibility and immunomodulatory properties. Using nanoparticles prepared from the membranes of specific cell types, or fusions derived from different cells membranes, can improve their functional performance in several aspects. Here, we used cell membranes extracted from breast cancer cells and platelets to fabricate a hybrid-membrane vesicle fusion (cancer cell-platelet-fusion-membrane vesicle, CPMV) in which we loaded therapeutic microRNAs (miRNAs) for the treatment of triple-negative breast cancer (TNBC). We used a clinically scalable microfluidic platform for the fusion of cell membranes. The reconstitution process during synthesis allows for efficient loading of miRNAs into CPMVs. We systematically optimized the conditions for preparation of miRNA-loaded CPMVs and demonstrated their property of homing to source cells using in vitro experiments, and by therapeutic evaluation in vivo. In vitro, the CPMVs exhibited significant recognition of their source cells and avoided engulfment by macrophages. After systemic delivery in mice, the CPMVs showed a prolonged circulation time and site-specific accumulation at implanted TNBC-xenografts. The delivered antimiRNAs sensitized TNBCs to doxorubicin, resulting in an improved therapeutic response and survival rate. This strategy has considerable potential for clinical translation to improve personalized therapy for breast cancer and other malignancies.

Cancer Cell Membrane-Coated Nanosuspensions for Enhanced Chemotherapeutic Treatment of Glioma

Effective intracerebral delivery is key for glioma treatment. However, the drug delivery system within the brain is largely limited by its own adverse physical and chemical properties, low targeting efficiency, the blood-brain barrier and the blood-brain tumor barrier. Herein, we developed a simple, safe and efficient biomimetic nanosuspension. The C6 cell membrane (CCM) was utilized to camouflaged the 10-hydroxycamptothecin nanosuspension (HCPT-NS) in order to obtain HCPT-NS/CCM. Through the use of immune escape and homotypic binding of the cancer cell membrane, HCPT-NS/CCM was able to penetrate the blood-brain barrier and target tumors. The HCPT-NS is only comprised of drugs, as well as a small amount of stabilizers that are characterized by a simple preparation method and high drug loading. Similarly, the HCPT-NS/CCM is able to achieve targeted treatment of glioma without any ligand modification, which leads it to be stable and efficient. Cellular uptake and in vivo imaging experiments demonstrated that HCPT-NS/CCM is able to effectively cross the blood-brain barrier and was concentrated at the glioma site due to the natural homing pathway. Our results reveal that the glioma cancer cell membrane is able to promote drug transport into the brain and enter the tumor via a homologous targeting mechanism.

Biomimetic cell membrane-coated DNA nanoparticles for gene delivery to glioblastoma

Gene therapy has been introduced as an alternative to radiation and chemical therapy for glioblastoma. Biomimetic nanoparticles coated with cell membranes (CM) have advantages such as high biocompatibility and prolong half-life. To apply CM coated nanoparticles to gene delivery, the polyethylenimine (PEI25k)/plasmid DNA (pDNA) complexes were coated with CM from C6 rat glioblastoma cells. With the CM covering, the PEI25k/pDNA complexes formed stable nanoparticles with negative surface charge. The PEI25k/pDNA/CM nanoparticles had high colloidal stability and could be stored for approximately 20 days without aggregation. The transfection efficiency of the PEI25k/pDNA/CM nanoparticles was higher than that of the PEI25k/pDNA complex in serum-containing medium. This suggests that serum does not interfere with transfection efficiency of the nanoparticles. Moreover, the PEI25k/pDNA/CM nanoparticles had lower toxicity than the PEI25k/DNA complex in vitro and in vivo. The PEI25k/pDNA/CM nanoparticles prepared with CMs of different types of cells were transfected into cells. The results showed that the PEI25k/pDNA/CM nanoparticles with the C6 CM had the highest transfection efficiency to C6 cells, suggesting the homotypic targeting effect. The therapeutic effects of the nanoparticles were evaluated in intracranial C6 transplanted glioblastoma animal models. The PEI25k/pDNA/CM nanoparticles were prepared with herpes simplex virus thymidine kinase plasmid (pHSVtk) and injected into the tumor locally. The results showed that the PEI25k/pHSVtk/CM nanoparticles induced higher HSVtk expression compared with the PEI25k/pHSVtk complex. Furthermore, tumor size was reduced more efficiently by the PEI25k/pHSVtk/CM nanoparticles than by the PEI25k/pHSVtk complex. Overall results indicate that PEI25k/pDNA/CM nanoparticles are suitable for pDNA delivery to glioblastoma.

Interferon lambda 4 impairs hepatitis C viral antigen presentation and attenuates T cell responses

Genetic variants of the interferon lambda (IFNL) gene locus are strongly associated with spontaneous and IFN treatment-induced clearance of hepatitis C virus (HCV) infections. Individuals with the ancestral IFNL4-dG allele are not able to clear HCV in the acute phase and have more than a 90% probability to develop chronic hepatitis C (CHC). Paradoxically, the IFNL4-dG allele encodes a fully functional IFNλ4 protein with antiviral activity against HCV. Here we describe an effect of IFNλ4 on HCV antigen presentation. Only minor amounts of IFNλ4 are secreted, because the protein is largely retained in the endoplasmic reticulum (ER) where it induces ER stress. Stressed cells are significantly weaker activators of HCV specific CD8⁺ T cells than unstressed cells. This is not due to reduced MHC I surface presentation or extracellular IFNλ4 effects, since T cell responses are restored by exogenous loading of MHC with HCV antigens. Rather, IFNλ4 induced ER stress impairs HCV antigen processing and/or loading onto the MHC I complex. Our results provide a potential explanation for the IFNλ4-HCV paradox.