Tailored extracellular matrix-mimetic coating facilitates reendothelialization and tissue healing of cardiac occluders.

Minimally invasive transcatheter interventional therapy utilizing cardiac occluders represents the primary approach for addressing congenital heart defects and left atrial appendage (LAA) thrombosis. However, incomplete endothelialization and delayed tissue healing after occluder implantation collectively compromise clinical efficacy. In this study, we have customized a recombinant humanized collagen type I (rhCol I) and developed an rhCol I-based extracellular matrix (ECM)-mimetic coating. The innovative coating integrates metal-phenolic networks with anticoagulation and anti-inflammatory functions as a weak cross-linker, combining them with specifically engineered rhCol I that exhibits high cell adhesion activity and elicits a low inflammatory response. The amalgamation, driven by multiple forces, effectively serves to functionalize implantable materials, thereby responding positively to the microenvironment following occluder implantation. Experimental findings substantiate the coating's ability to sustain a prolonged anticoagulant effect, enhance the functionality of endothelial cells and cardiomyocyte, and modulate inflammatory responses by polarizing inflammatory cells into an anti-inflammatory phenotype. Notably, occluder implantation in a canine model confirms that the coating expedites reendothelialization process and promotes tissue healing. Collectively, this tailored ECM-mimetic coating presents a promising surface modification strategy for improving the clinical efficacy of cardiac occluders.

Unbiased screening identifies regulators of cell-cell adhesion and treatment options in pemphigus.

Cell-cell junctions, and specifically desmosomes, are crucial for robust intercellular adhesion. Desmosomal function is compromised in the autoimmune blistering skin disease pemphigus vulgaris. We combine whole-genome knockout screening and a promotor screen of the desmosomal gene desmoglein 3 in human keratinocytes to identify novel regulators of intercellular adhesion. Kruppel-like-factor 5 (KLF5) directly binds to the desmoglein 3 regulatory region and promotes adhesion. Reduced levels of KLF5 in patient tissue indicate a role in pemphigus vulgaris. Autoantibody fractions from patients impair intercellular adhesion and reduce KLF5 levels in in vitro and in vivo disease models. These effects were dependent on increased activity of histone deacetylase 3, leading to transcriptional repression of KLF5. Inhibiting histone deacetylase 3 increases KLF5 levels and protects against the deleterious effects of autoantibodies in murine and human pemphigus vulgaris models. Together, KLF5 and histone deacetylase 3 are regulators of desmoglein 3 gene expression and intercellular adhesion and represent potential therapeutic targets in pemphigus vulgaris.

RUNX1 interacts with lncRNA SMANTIS to regulate monocytic cell functions.

Monocytes, the circulating macrophage precursors, contribute to diseases like atherosclerosis and asthma. Long non-coding RNAs (lncRNAs) have been shown to modulate the phenotype and inflammatory capacity of monocytes. We previously discovered the lncRNA SMANTIS, which contributes to cellular phenotype expression by controlling BRG1 in mesenchymal cells. Here, we report that SMANTIS is particularly highly expressed in monocytes and lost during differentiation into macrophages. Moreover, different types of myeloid leukemia presented specific SMANTIS expression patterns. Interaction studies revealed that SMANTIS binds RUNX1, a transcription factor frequently mutated in AML, primarily through its Alu-element on the RUNT domain. RNA-seq after CRISPR/Cas9-mediated deletion of SMANTIS or RUNX1 revealed an association with cell adhesion and both limited the monocyte adhesion to endothelial cells. Mechanistically, SMANTIS KO reduced RUNX1 genomic binding and altered the interaction of RUNX1 with EP300 and CBFB. Collectively, SMANTIS interacts with RUNX1 and attenuates monocyte adhesion, which might limit monocyte vascular egress.

Effect of Silicon Nitride Coating on Titanium Surface: Biocompatibility and Antibacterial Properties.

In recent years, with the advent of a super-aged society, lifelong dental care has gained increasing emphasis, and implant therapy for patients with an edentulous jaw has become a significant option. However, for implant therapy to be suitable for elderly patients with reduced regenerative and immunological capabilities, higher osteoconductive and antimicrobial properties are required on the implant surfaces. Silicon nitride, a non-oxide ceramic known for its excellent mechanical properties and biocompatibility, has demonstrated high potential for inducing hard tissue differentiation and exhibiting antibacterial properties. In this study, silicon nitride was deposited on pure titanium metal surfaces and evaluated for its biocompatibility and antibacterial properties. The findings indicate that silicon nitride improves the hydrophilicity of the material surface, enhancing the initial adhesion of rat bone marrow cells and promoting hard tissue differentiation. Additionally, the antibacterial properties were assessed using Staphylococcus aureus, revealing that the silicon nitride-coated surfaces exhibited significant antibacterial activity. Importantly, no cytotoxicity was observed, suggesting that silicon nitride-coated titanium could serve as a novel implant material.

Endothelial Cell-Derived Soluble CD200 Determines the Ability of Immune Cells to Cross the Blood-Brain Barrier.

The infiltration of immune cells into the central nervous system mediates the development of autoimmune neuroinflammatory diseases. We previously showed that the loss of either Fabp5 or calnexin causes resistance to the induction of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of multiple sclerosis (MS). Here we show that brain endothelial cells lacking either Fabp5 or calnexin have an increased abundance of cell surface CD200 and soluble CD200 (sCD200) as well as decreased T-cell adhesion. In a tissue culture model of the blood-brain barrier, antagonizing the interaction of CD200 and sCD200 with T-cell CD200 receptor (CD200R1) via anti-CD200 blocking antibodies or the RNAi-mediated inhibition of CD200 production by endothelial cells increased T-cell adhesion and transmigration across monolayers of endothelial cells. Our findings demonstrate that sCD200 produced by brain endothelial cells regulates immune cell trafficking through the blood-brain barrier and is primarily responsible for preventing activated T-cells from entering the brain.

A Pro-Inflammatory Stimulus versus Extensive Passaging of DITNC1 Astrocyte Cultures as Models to Study Astrogliosis.

Astrogliosis is a process by which astrocytes, when exposed to inflammation, exhibit hypertrophy, motility, and elevated expression of reactivity markers such as Glial Fibrillar Acidic Protein, Vimentin, and Connexin43. Since 1999, our laboratory in Chile has been studying molecular signaling pathways associated with "gliosis" and has reported that reactive astrocytes upregulate Syndecan 4 and αVß3 Integrin, which are receptors for the neuronal glycoprotein Thy-1. Thy-1 engagement stimulates adhesion and migration of reactive astrocytes and induces neurons to retract neurites, thus hindering neuronal network repair. Reportedly, we have used DITNC1 astrocytes and neuron-like CAD cells to study signaling mechanisms activated by the Syndecan 4-αVß3 Integrin/Thy-1 interaction. Importantly, the sole overexpression of ß3 Integrin in non-reactive astrocytes turns them into reactive cells. In vitro, extensive passaging is a simile for "aging", and aged fibroblasts have shown ß3 Integrin upregulation. However, it is not known if astrocytes upregulate ß3 Integrin after successive cell passages. Here, we hypothesized that astrocytes undergoing long-term passaging increase ß3 Integrin expression levels and behave as reactive astrocytes without needing pro-inflammatory stimuli. We used DITNC1 cells with different passage numbers to study reactivity markers using immunoblots, immunofluorescence, and astrocyte adhesion/migration assays. We also evaluated ß3 Integrin levels by immunoblot and flow cytometry, as well as the neurotoxic effects of reactive astrocytes. Serial cell passaging mimicked the effects of inflammatory stimuli, inducing astrocyte reactivity. Indeed, in response to Thy-1, ß3 Integrin levels, as well as cell adhesion and migration, gradually increased with multiple passages. Importantly, these long-lived astrocytes expressed and secreted factors that inhibited neurite outgrowth and caused neuronal death, just like reactive astrocytes in culture. Therefore, we describe two DITNC1 cell types: a non-reactive type that can be activated with Tumor Necrosis Factor (TNF) and another one that exhibits reactive astrocyte features even in the absence of TNF treatment. Our results emphasize the importance of passage numbers in cell behavior. Likewise, we compare the pro-inflammatory stimulus versus long-term in-plate passaging of cell cultures and introduce them as astrocyte models to study the reactivity process.

Barrier Membrane with Janus Function and Structure for Guided Bone Regeneration.

Guided bone regeneration (GBR) technology has been demonstrated to be an effective method for reconstructing bone defects. A membrane is used to cover the bone defect to stop soft tissue from growing into it. The biosurface design of the barrier membrane is key to the technology. In this work, an asymmetric functional gradient Janus membrane was designed to address the bidirectional environment of the bone and soft tissue during bone reconstruction. The Janus membrane was simply and efficiently prepared by the multilayer self-assembly technique, and it was divided into the polycaprolactone isolation layer (PCL layer, GBR-A) and the nanohydroxyapatite/polycaprolactone/polyethylene glycol osteogenic layer (HAn/PCL/PEG layer, GBR-B). The morphology, composition, roughness, hydrophilicity, biocompatibility, cell attachment, and osteogenic mineralization ability of the double surfaces of the Janus membrane were systematically evaluated. The GBR-A layer was smooth, dense, and hydrophobic, which could inhibit cell adhesion and resist soft tissue invasion. The GBR-B layer was rough, porous, hydrophilic, and bioactive, promoting cell adhesion, proliferation, matrix mineralization, and expression of alkaline phosphatase and RUNX2. In vitro and in vivo results showed that the membrane could bind tightly to bone, maintain long-term space stability, and significantly promote new bone formation. Moreover, the membrane could fix the bone filling material in the defect for a better healing effect. This work presents a straightforward and viable methodology for the fabrication of GBR membranes with Janus-based bioactive surfaces. This work may provide insights for the design of biomaterial surfaces and treatment of bone defects.

Nanomechanical mapping of PLA hydroxyapatite composite scaffolds links surface homogeneity to stem cell differentiation.

Polymer composite scaffolds hold promise in bone tissue engineering due to their biocompatibility, mechanical properties, and reproducibility. Among these materials, polylactic acid (PLA), a biodegradable plastics has gained attention for its processability characteristics. However, a deeper understanding of how PLA scaffold surface properties influence cell behavior is enssential for advancing its applications. In this study, 3D-printed PLA scaffolds containing hydroxyapatite (HA) were analyzed using atomic force microscopy and nanomechanical mapping. The addition of HA significantly increased key surface properties compared to unmodified PLA scaffols. Notably, the HA-modified scaffold demonstrated Gaussian distribution of stiffness and adhesive forces, in contrast to the bimodal properties observed in the unmodified PLA scaffolds. Human adipose-derived mesenchymal stem cell (hADMSC) seeded on the 3D-printed PLA scaffolds blended with 10% HA (P10) exhibited strong attachment. After four weeks, osteogenic differentiation of hADMSCs was detected, with calcium deposition reaching 6.76% ± 0.12. These results suggest that specific ranges of stiffness and adhesive forces of the composite scaffold can support cell attachement, and mineralization. The study highlights that tailoring suface properties of composite scaffolds is crucial for modulating cellular interactions, thus advancing the development of effective bone replacement materials.

A dystroglycan-laminin-integrin axis coordinates cell shape remodeling in the developing Drosophila retina.

Cell shape remodeling is a principal driver of epithelial tissue morphogenesis. While progress continues to be made in our understanding of the pathways that control the apical (top) geometry of epithelial cells, we know comparatively little about those that control cell basal (bottom) geometry. To examine this, we used the Drosophila ommatidium, which is the basic visual unit of the compound eye. The ommatidium is shaped as a hexagonal prism, and generating this 3D structure requires ommatidial cells to adopt specific apical and basal polygonal geometries. Using this model system, we find that generating cell type-specific basal geometries starts with patterning of the basal extracellular matrix, whereby Laminin accumulates at discrete locations across the basal surface of the retina. We find the Dystroglycan receptor complex (DGC) is required for this patterning by promoting localized Laminin accumulation at the basal surface of cells. Moreover, our results reveal that localized accumulation of Laminin and the DGC are required for directing Integrin adhesion. This induces cell basal geometry remodeling by anchoring the basal surface of cells to the extracellular matrix at specific, Laminin-rich locations. We propose that patterning of a basal extracellular matrix by generating discrete Laminin domains can direct Integrin adhesion to induce cell shape remodeling in epithelial morphogenesis.

Nerve growth factor promote VCAM-1-dependent monocyte adhesion and M2 polarization in osteosarcoma microenvironment: Implications for larotrectinib therapy.

Osteosarcoma is the most prevalent form of primary malignant bone tumor, primarily affecting children and adolescents. The nerve growth factors (NGF) referred to as neurotrophins have been associated with cancer-induced bone pain; however, the role of NGF in osteosarcoma has yet to be elucidated. In osteosarcoma samples from the Genomic Data Commons data portal, we detected higher levels of NGF and M2 macrophage markers, but not M1 macrophage markers. In cellular experiments, NGF-stimulated osteosarcoma conditional medium was shown to facilitate macrophage polarization from the M0 to the M2 phenotype. NGF also enhanced VCAM-1-dependent monocyte adhesion within the osteosarcoma microenvironment by down-regulating miR-513c-5p levels through the FAK and c-Src cascades. In in vivo xenograft models, the overexpression of NGF was shown to enhance tumor growth, while the oral administration of the TrK inhibitor larotrectinib markedly antagonized NGF-promoted M2 macrophage expression and tumor progression. These results suggest that larotrectinib could potentially be used as a therapeutic agent aimed at mitigating NGF-mediated osteosarcoma progression.

Key role of activated platelets in the enhanced adhesion of circulating leucocyte-platelet aggregates to the dysfunctional endothelium in early-stage COPD.

Background: Chronic obstructive pulmonary disease (COPD), usually caused by long-term tobacco smoking, is independently associated with systemic inflammation. However, little is known about the systemic inflammatory status of patients with early-stage COPD (classified as GOLD 1) and long-term smokers with normal lung function (LF). Here, we characterised the early changes in the associated inflammatory state in patients with GOLD 1 and in long-term smokers with normal LF. Methods: Fresh blood samples from 27 patients with GOLD 1, 27 long-term smokers and 14 non-smokers were analysed. Results: Ex vivo blood analysis revealed greater leucocyte-platelet adhesion to TNFα-stimulated pulmonary endothelium in patients with GOLD 1 than in smokers and non-smokers. In addition, platelet reactivity (platelet count and activation, and fibrinogen levels) and the frequency of leucocyte-platelet aggregates were higher in the GOLD 1 group than in the other groups. Some of these findings correlated with the severity of lung dysfunction, while platelet hyperactivity correlated positively with leucocyte-platelet adhesion. The GOLD 1 group also had a higher Th17/Treg ratio and higher circulating levels of IL-17C and C-reactive protein than the other groups. However, long-term smokers also had higher leucocyte counts and activation, and higher plasma levels of TNFα and IL-6 than non-smokers. Conclusion: Our data suggest that the altered inflammatory parameters in long-term smokers may represent early biomarkers of COPD. Accordingly, peripheral immune monitoring based on the above parameters may be useful to prevent disease progression in long-term smokers with normal LF and early COPD.

A flexible loop in the paxillin LIM3 domain mediates its direct binding to integrin ß subunits.

Integrins are fundamental for cell adhesion and the formation of focal adhesions (FA). Accordingly, these receptors guide embryonic development, tissue maintenance, and haemostasis but are also involved in cancer invasion and metastasis. A detailed understanding of the molecular interactions that drive integrin activation, FA assembly, and downstream signalling cascades is critical. Here, we reveal a direct association of paxillin, a marker protein of FA sites, with the cytoplasmic tails of the integrin ß1 and ß3 subunits. The binding interface resides in paxillin's LIM3 domain, where based on the NMR structure and functional analyses, a flexible, 7-amino acid loop engages the unstructured part of the integrin cytoplasmic tail. Genetic manipulation of the involved residues in either paxillin or integrin ß3 compromises cell adhesion and motility of murine fibroblasts. This direct interaction between paxillin and the integrin cytoplasmic domain identifies an alternative, kindlin-independent mode of integrin outside-in signalling particularly important for integrin ß3 function.

Influence of metal oxides on biocompatibility of additively manufactured NiTi.

In order to properly satisfy biomedical constraints for cardiovascular applications, additively manufactured NiTi scaffolds required further process and metallurgical engineering. Additively manufactured NiTi materials for cardiovascular use will have to undergo surface finishing in order to minimize negative surface interactions within the artery. In this study, we sought to understand biocompatibility from chemically etched additively manufactured NiTi scaffolds by laser powder bed fusion (LPBF). Although two distinct oxide films were created in the surface etching process (labeled CP-A and CP-B), no qualitative changes in microroughness were seen between the two conditions. CP-A possessed significantly less Ni at the surface (0.19 at. %) than the CP-B group (3.30 at. %), via x-ray photoelectron spectroscopy, alongside a concomitant shift in the O1 s peak presentation alluding to a greater formation of a Ni based oxide in the CP-B group. Our live dead staining revealed significant toxicity and reduced cellular attachment for the CP-B group, in addition to inducing more cell lysis (20.9 ± 5.1%), which was significantly increased when compared to CP-A (P < 0.01). Future practices of manufacturing NiTi scaffolds using LPBF should focus on producing surface films that are not only smooth, but free of cytotoxic Ni based oxides.

Comparative analysis of hydrophobicity and dentin adhesion ability in Candida albicans strains.

OBJECTIVE: Adhesion to dentin is a first step for a successful microbial root canal colonization. Cell hydrophobicity seems to have some influence in the Candida species adhesion to surfaces. To measure cell surface hydrophobicity and to investigate the adherence ability to human dentin among Candida albicans strains isolated from root canal and lingual dorsum via an in vitro study. METHODOLOGY: adhesion was quantified in function of dentin area covered by blastospores and/or hyphae presence detected by epifluorescence microscope. Cell surface hydrophobicity was estimated by assessing the percentage migration of cells from an aqueous phase to a hydrocarbon phase. Contact angles were measured by the sessile drop technique on the dentin surface using a contact angle measurements apparatus. We also examined the correlation between adhesion ability and hydrophobicity. RESULTS: although there was some intra-species variation in cell surface hydrophobicity, most isolates were characterized by moderate hydrophobicity. There was no significant difference in this parameter when the isolation niche was considered. Both root canal and lingual dorsum yeasts were able to adhere to dentin. No association was found between the strains' site of isolation and adhesion. Moreover, cell surface hydrophobicity and adhesion ability were not correlated. CONCLUSION: although hydrophobicity can influence Candida albicans virulence in many ways, this study suggests that this parameter by itself was not a good predictor of adhesion to dentin.

Nanocrystal hydroxyapatite carrying traditional Chinese medicine for osteogenic differentiation.

Developing biomaterials with high osteogenic properties is crucial for achieving rapid bone repair and regeneration. This study focuses on the application of nanocrystal hydroxyapatite (nHAp) as a drug carrier to load Fu Yuan Huo Xue Decoction (FYHXD), a traditional Chinese medicine derived from Angelica sinensis, aiming to achieve improved efficacy in treating bone diseases such as osteoporosis. Through a facile physical adsorption approach, the FTIR result emerges new characteristic absorption peaks in the range of 1200-950 cm-1, proving the successful absorption of FYHXD onto the nHAp with a loading efficiency of 39.76 %. The modified nHAp exhibits a similar shape to the bone-derived hydroxyapatite nanocrystals, and their diameter increases slightly after modification. The drug release assay implies the rapid release of FYHXD in the first 10 h, followed by a continuously slow release within 70 h. The developed nHAp effectively enhances the adhesion, spreading, and proliferation of MC3T3-E1 cells in vitro, and significantly promotes their osteogenic differentiation, as indicated by increased alkaline phosphatase activity. Overall, the biocomposites hold great promise as active ingredients for integration into bone-associated biomaterials, offering the potential to stimulate spontaneous osteogenesis without requiring exogenous osteogenic factors.

Novel collagen gradient membranes with multiphasic structures: Preparation, characterization, and biocompatibility.

Scaffolds with multiphasic structures are considered to be superior for guided tissue regeneration. Two types of tilapia skin collagen gradient membranes (stepped gradient and linear gradient) with multiphasic structures were prepared by controlling the collagen concentrations and the freezing rates. The results revealed that collagen gradient membranes were more capable of guiding tissue regeneration compared to homogeneous membranes. These two gradient membranes featured a dense outer layer and a loose inner layer, with good mechanical properties as indicated by tensile strengths of more than 250 Kpa and porosities exceeding 85 %. Additionally, these membranes also showed good hydrophilicity and water absorption, with an inner layer contact angle of less than 91° and a water absorption ratio greater than 40 times. Furthermore, the multiphasic scaffolds were proved to be biocompatible by the acute toxicity assay, the intradermal irritation test and so on. Gradient membranes could effectively promote the adhesion and proliferation of fibroblasts and osteoblasts, through elevating the TGF-ß/Smad signaling pathway by TGF-ß and Smads, and activating the Wnt/ß-catenin signaling pathway by LRP5 and ß-catenin, similar to homogenous membranes. Therefore, collagen gradient membranes from tilapia skin show important application value in guiding tissue regeneration.

Engineering an Extracellular Matrix Mimic Using Hemoglobin Protein Nanofibrils.

Extracellular matrix (ECM) is essential for tissue development, providing structural support and a microenvironment that is necessary for cells. As tissue engineering advances, there is a growing demand for ECM mimics. Polycaprolactone (PCL) is a commonly used synthetic polymer for ECM mimic materials. However, its biologically inactive surface limits its direct application in tissue engineering. Our study aimed to improve the biocompatibility of PCL by incorporating hemoglobin nanofibrils (HbFs) into PCL using an electrospinning technique. HbFs were formed from bovine hemoglobin (Hb) extracted from industrial byproducts and designed to offer PCL an improved cell adhesion property. The fabricated HbFs@PCL electrospun scaffold exhibits improved fibroblast adherence, proliferation, and deeper fibroblast infiltration into the scaffold compared with the pure PCL scaffold, indicating its potential to be an ECM mimic. This study represents the pioneering utilization of Hb-sourced nanofibrils in the electrospun PCL scaffolds for tissue engineering applications.

Integrating molecular-caged nano-hydroxyapatite into post-crosslinked PVA nanofibers for artificial periosteum.

Artificial periosteum is deemed a novel strategy for inducing endogenous bone regeneration, but ideal periosteum substitutes achieved by orchestrating a biomimetic microenvironment for bone regeneration remain a significant challenge. Here, we design and fabricate a hybridized nanofiber-based artificial periosteum with boosted osteoinduction properties. Via a "molecular cage" biomineralization strategy, nano-hydroxyapatite (nano-HAp) with a controllable size (∼22 nm) and excellent dispersion serves as unique nano-additives for water-soluble polyvinyl-alcohol (PVA)-based artificial periosteum. The PVA/HAp composite is electrospun into nanofibers to replicate the extracellular-matrix-inspired nanostructure for inducing cell adhesion, proliferation, and fate manipulation. A simple post-crosslinking treatment is subsequently applied to further booster its mechanical strength (6.6 MPa) and swelling stability. The optimized sample of C-PVA/HAp (10 wt% nano-HAp) artificial periosteum features excellent biocompatibility and remarkable in vitro mineralization. Cell experiments demonstrate that its effectively boasted cell modulation for enhanced osteogenesis without the aid of growth factors, showing a possible activation of the ERK/MAPK signaling pathway. This work provides an effective strategy for designing novel HAp nano-additives and expands the possibility of biomimetic fabrication for more advanced nanofiber-based artificial periosteum.

Matrix stiffness increases energy efficiency of endothelial cells.

To form blood vessels, endothelial cells rearrange their cytoskeleton, generate traction stresses, migrate, and proliferate, all of which require energy. Despite these energetic costs, stiffening of the extracellular matrix promotes tumor angiogenesis and increases cell contractility. However, the interplay between extracellular matrix, cell contractility, and cellular energetics remains mechanistically unclear. Here, we utilized polyacrylamide substrates with various stiffnesses, a real-time biosensor of ATP, and traction force microscopy to show that endothelial cells exhibit increasing traction forces and energy usage trend as substrate stiffness increases. Inhibition of cytoskeleton reorganization via ROCK inhibition resulted in decreased cellular energy efficiency, and an opposite trend was found when cells were treated with manganese to promote integrin affinity. Altogether, our data reveal a link between matrix stiffness, cell contractility, and cell energetics, suggesting that endothelial cells on stiffer substrates can better convert intracellular energy into cellular traction forces. Given the critical role of cellular metabolism in cell function, our study also suggests that not only energy production but also the efficiency of its use plays a vital role in regulating cell behaviors and may help explain how increased matrix stiffness promotes angiogenesis.

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.