Modulation of Abundance and Location of High-Mobility Group Box 1 in Human Microglia and Macrophages under Oxygen-Glucose Deprivation.

While stroke represents one of the main causes of death worldwide, available effective drug treatment options remain limited to classic thrombolysis with recombinant tissue plasminogen activator (rtPA) for arterial-clot occlusion. Following stroke, multiple pathways become engaged in producing a vicious proinflammatory cycle through the release of damage-associated molecular patterns (DAMPs) such as high-mobility group box 1 (HMGB1) and heat shock protein 70 kDa (HSP72). HMGB1, in particular, can activate proinflammatory cytokine production when acetylated (AcHMGB1), a form that prefers cytosolic localization and extracellular release. This study aimed at determining how HMGB1 and HSP72 are modulated and affected following treatment with the anti-inflammatory compound resveratrol and novel platelet membrane-derived nanocarriers loaded with rtPA (CSM@rtPA) recently developed by our group for ischemic artery recanalization. Under ischemic conditions of oxygen-glucose deprivation (OGD), nuclear abundance of HMGB1 and AcHMGB1 in microglia and macrophages decreased, whereas treatment with CSM@rtPA did not alter nuclear or cytosolic abundance. Resveratrol treatment markedly increased the cytosolic abundance of HSP72 in microglia. Using proximity ligation assays, we determined that HSP72 interacted with HMGB1 and with acetylated HMGB1. The interaction was differentially affected under the OGD conditions. Resveratrol treatment under the OGD further decreased HSP72-HMGB1 interactions, whereas, in contrast, treatment increased HSP72-AcHMGB1 interactions in microglia. This study points out a salient molecular interaction suited for a two-pronged nanotherapeutic intervention in stroke: enhancement of rtPA's thrombolytic activity and modulation of cytosolic interactions between HMGB1 and HSP72 by resveratrol.

The use of a complex tetra-culture alveolar model to study the biological effects induced by gold nanoparticles with different physicochemical properties.

A substantial increase in engineered nanoparticles in consumer products has been observed, heightening human and environmental exposure. Inhalation represents the primary route of human exposure, necessitating a focus on lung toxicity studies. However, to avoid ethical concerns the use of in vitro models is an efficient alternative to in vivo models. This study utilized an in vitro human alveolar barrier model at air-liquid-interface with four cell lines, for evaluating the biological effects of different gold nanoparticles. Exposure to PEGylated gold nanospheres, nanorods, and nanostars did not significantly impact viability after 24 h, yet all AuNPs induced cytotoxicity in the form of membrane integrity impairment. Gold quantification revealed cellular uptake and transport. Transcriptomic analysis identified gene expression changes, particularly related to the enhancement of immune cells. Despite limited impact, distinct effects were observed, emphasizing the influence of nanoparticles physicochemical parameters while demonstrating the model's efficacy in investigating particle biological effects.

Thrombolytic therapy based on lyophilized platelet-derived nanocarriers for ischemic stroke.

BACKGROUND: Intravenous administration of fibrinolytic drugs, such as recombinant tissue plasminogen activator (rtPA) is the standard treatment of acute thrombotic diseases. However, current fibrinolytics exhibit limited clinical efficacy because of their short plasma half-lives and risk of hemorrhagic transformations. Platelet membrane-based nanocarriers have received increasing attention for ischemic stroke therapies, as they have natural thrombus-targeting activity, can prolong half-life of the fibrinolytic therapy, and reduce side effects. In this study we have gone further in developing platelet-derived nanocarriers (defined as cellsomes) to encapsulate and protect rtPA from degradation. Following lyophilization and characterization, their formulation properties, biocompatibility, therapeutic effect, and risk of hemorrhages were later investigated in a thromboembolic model of stroke in mice. RESULTS: Cellsomes of 200 nm size and loaded with rtPA were generated from membrane fragments of human platelets. The lyophilization process did not influence the nanocarrier size distribution, morphology, and colloidal stability conferring particle preservation and long-term storage. Encapsulated rtPA in cellsomes and administered as a single bolus showed to be as effective as a continuous clinical perfusion of free rtPA at equal concentration, without increasing the risk of hemorrhagic transformations or provoking an inflammatory response. CONCLUSIONS: This study provides evidence for the safe and effective use of lyophilized biomimetic platelet-derived nanomedicine for precise thrombolytic treatment of acute ischemic stroke. In addition, this new nanoformulation could simplify the clinical use of rtPA as a single bolus, being easier and less time-consuming in an emergency setting than a treatment perfusion, particularly in stroke patients. We have successfully addressed one of the main barriers to drug application and commercialization, the long-term storage of nanomedicines, overcoming the potential chemical and physical instabilities of nanomedicines when stored in an aqueous buffer.

Fusogenic Cell-Derived nanocarriers for cytosolic delivery of cargo inside living cells.

A surface-engineered cell-derived nanocarrier was developed for efficient cytosolic delivery of encapsulated biologically active molecules inside living cells. Thus, a combination of aromatic-labeled and cationic lipids, instrumental in providing fusogenic properties, was intercalated into the biomimetic shell of self-assembled nanocarriers formed from cell membrane extracts. The nanocarriers were loaded, as a proof of concept, with either bisbenzimide molecules, a fluorescently labeled dextran polymer, the bicyclic heptapeptide phalloidin, fluorescently labeled polystyrene nanoparticles or a ribonucleoprotein complex (Cas9/sgRNA). The demonstrated nanocarriers fusogenic behavior relies on the fusogen-like properties imparted by the intercalated exogenous lipids, which allows for circumventing lysosomal storage, thereby leading to efficient delivery into the cytosolic milieu where cargo regains function.

Variations in Biodistribution and Acute Response of Differently Shaped Titania Nanoparticles in Healthy Rodents.

Titanium dioxide nanoparticles (TiO2 NPs) are one of the main sources of the nanoparticulate matter exposure to humans. Although several studies have demonstrated their potential toxic effects, the real nature of the correlation between NP properties and their interaction with biological targets is still far from being fully elucidated. Here, engineered TiO2 NPs with various geometries (bipyramids, plates, and rods) have been prepared, characterized and intravenously administered in healthy mice. Parameters such as biodistribution, accumulation, and toxicity have been assessed in the lungs and liver. Our data show that the organ accumulation of TiO2 NPs, measured by ICP-MS, is quite low, and this is only partially and transiently affected by the NP geometries. The long-lasting permanence is exclusively restricted to the lungs. Here, bipyramids and plates show a higher accumulation, and interestingly, rod-shaped NPs are the most toxic, leading to histopathological pulmonary alterations. In addition, they are also able to induce a transient increase in serum markers related to hepatocellular injury. These results indicate that rods, more than bipyramidal and spherical geometries, lead to a stronger and more severe biological effect. Overall, small physico-chemical differences can dramatically modify both accumulation and safety.

Nanoparticle-based immunotherapeutics: From the properties of nanocores to the differential effects of administration routes.

The engagement with the immune system is one of the main cornerstones in the development of nanotechnologies for therapy and diagnostics. Recent advances have made possible the tuning of features like size, shape and biomolecular modifications that influence such interactions, however, the capabilities for immune modulation of nanoparticles are still not well defined and exploited. This review focuses on recent advances made in preclinical research for the application of nanoparticles to modulate immune responses, and the main features making them relevant for such applications. We review and discuss newest evidence in the field, which include in vivo experiments with an extensive physicochemical characterization as well as detailed study of the induced immune response. We emphasize the need of incorporating knowledge about immune response development and regulation in the design and application of nanoparticles, including the effect by parameters such as the administration route and the differential interactions with immune subsets.

Nanosized metal-organic frameworks as unique platforms for bioapplications.

Metal-organic frameworks (MOFs) are extremely versatile materials, which serve to create platforms with exceptional porosity and specific reactivities. The production of MOFs at the nanoscale (NMOFs) offers the possibility of creating innovative materials for bioapplications as long as they maintain the properties of their larger counterparts. Due to their inherent chemical versatility, synthetic methods to produce them at the nanoscale can be combined with inorganic nanoparticles (NPs) to create nanocomposites (NCs) with one-of-a-kind features. These systems can be remotely controlled and can catalyze abiotic reactions in living cells, which have the potential to stimulate further research on these nanocomposites as tools for advanced therapies.

Biomimetic cell-derived nanocarriers in cancer research.

Nanoparticles have now long demonstrated capabilities that make them attractive to use in biology and medicine. Some of them, such as lipid nanoparticles (SARS-CoV-2 vaccines) or metallic nanoparticles (contrast agents) are already approved for their use in the clinic. However, considering the constantly growing body of different formulations and the huge research around nanomaterials the number of candidates reaching clinical trials or being commercialized is minimal. The reasons behind being related to the "synthetic" and "foreign" character of their surface. Typically, nanomaterials aiming to develop a function or deliver a cargo locally, fail by showing strong off-target accumulation and generation of adverse responses, which is connected to their strong recognition by immune phagocytes primarily. Therefore, rendering in negligible numbers of nanoparticles developing their intended function. While a wide range of coatings has been applied to avoid certain interactions with the surrounding milieu, the issues remained. Taking advantage of the natural cell membranes, in an approach that resembles a cell transfer, the use of cell-derived surfaces has risen as an alternative to artificial coatings or encapsulation methods. Biomimetic technologies are based on the use of isolated natural components to provide autologous properties to the nanoparticle or cargo being encapsulated, thus, improving their therapeutic behavior. The main goal is to replicate the (bio)-physical properties and functionalities of the source cell and tissue, not only providing a stealthy character to the core but also taking advantage of homotypic properties, that could prove relevant for targeted strategies. Such biomimetic formulations have the potential to overcome the main issues of approaches to provide specific features and identities synthetically. In this review, we provide insight into the challenges of nano-biointerfaces for drug delivery; and the main applications of biomimetic materials derived from specific cell types, focusing on the unique strengths of the fabrication of novel nanotherapeutics in cancer therapy.

Pathways Related to NLRP3 Inflammasome Activation Induced by Gold Nanorods.

The widespread and increasing use of engineered nanomaterials (ENM) increases the risk of human exposure, generating concern that ENM may provoke adverse health effects. In this respect, their physicochemical characteristics are critical. The immune system may respond to ENM through inflammatory reactions. The NLRP3 inflammasome responds to a wide range of ENM, and its activation is associated with various inflammatory diseases. Recently, anisotropic ENM have become of increasing interest, but knowledge of their effects on the immune system is still limited. The objective of the study was to compare the effects of gold ENM of different shapes on NLRP3 inflammasome activation and related signalling pathways. Differentiated THP-1 cells (wildtype, ASC- or NLRP3-deficient), were exposed to PEGylated gold nanorods, nanostars, and nanospheres, and, thus, also different surface chemistries, to assess NLRP3 inflammasome activation. Next, the exposed cells were subjected to gene expression analysis. Nanorods, but not nanostars or nanospheres, showed NLRP3 inflammasome activation. ASC- or NLRP3-deficient cells did not show this effect. Gene Set Enrichment Analysis revealed that gold nanorod-induced NLRP3 inflammasome activation was accompanied by downregulated sterol/cholesterol biosynthesis, oxidative phosphorylation, and purinergic receptor signalling. At the level of individual genes, downregulation of Paraoxonase-2, a protein that controls oxidative stress, was most notable. In conclusion, the shape and surface chemistry of gold nanoparticles determine NLRP3 inflammasome activation. Future studies should include particle uptake and intracellular localization.

High-yield halide-assisted synthesis of metal-organic framework UiO-based nanocarriers.

The synthesis of nanosized metal-organic frameworks (NMOFs) is requisite for their application as injectable drug delivery systems (DDSs) and other biorelevant purposes. Herein, we have critically examined the role of different synthetic parameters leading to the production of UiO-66 crystals smaller than 100 nm. Of note, we demonstrate the co-modulator role conferred by halide ions, not only to produce NMOFs with precise morphology and size, but also to significantly improve the reaction yield. The resulting NMOFs are highly crystalline and exhibit sustained colloidal stability in different biologically relevant media. As a proof of concept, these NMOFs were loaded with Rhodamine 6G (R6G), which remained trapped in most common biologically relevant media. When incubated with living mammalian cells, the R6G-loaded NMOFs were efficiently internalized and did not impair cell viability even at relatively high doses.

Sonosensitive capsules for brain thrombolysis increase ischemic damage in a stroke model.

BACKGROUND: Ischemic stroke is the most common cerebrovascular disease and is caused by interruption of blood supply to the brain. To date, recombinant tissue plasminogen activator (rtPA) has been the main pharmacological treatment in the acute phase. However, this treatment has some drawbacks, such as a short half-life, low reperfusion rate, risk of hemorrhagic transformations, and neurotoxic effects. To overcome the limitations of rtPA and improve its effectiveness, we recently designed sonosensitive sub-micrometric capsules (SCs) loaded with rtPA with a size of approximately 600 nm, synthesized using the layer-by-layer (LbL) technique, and coated with gelatine for clot targeting. In this study, we evaluated the rtPA release of ultrasound (US)-responsive SCs in healthy mice and the therapeutic effect in a thromboembolic stroke model. RESULTS: In healthy mice, SCs loaded with rtPA 1 mg/kg responded properly to external US exposure, extending the half-life of the drug in the blood stream more than the group treated with free rtPA solution. The gelatine coating also contributed to stabilizing the encapsulation and maintaining the response to US. When the same particles were administered in the stroke model, these SCs appeared to aggregate in the ischemic brain region, probably generating secondary embolisms and limiting the thrombolytic effect of rtPA. Despite the promising results of these thrombolytic particles, at least under the dose and size conditions used in this study, the administration of these capsules represents a risk factor for stroke. CONCLUSIONS: This is the first study to report the aggregation risk of a drug carrier in neurological pathologies such as stroke. Biocompatibility analysis related to the use of nano-and microparticles should be deeply studied to anticipate the limitations and orientate the design of new nanoparticles for translation to humans.

Plasmonic-Assisted Thermocyclizations in Living Cells Using Metal-Organic Framework Based Nanoreactors.

We describe a microporous plasmonic nanoreactor to carry out designed near-infrared (NIR)-driven photothermal cyclizations inside living cells. As a proof of concept, we chose an intramolecular cyclization that is based on the nucleophilic attack of a pyridine onto an electrophilic carbon, a process that requires high activation energies and is typically achieved in bulk solution by heating at ∼90 °C. The core-shell nanoreactor (NR) has been designed to include a gold nanostar core, which is embedded within a metal-organic framework (MOF) based on a polymer-stabilized zeolitic imidazole framework-8 (ZIF-8). Once accumulated inside living cells, the MOF-based cloak of NRs allows an efficient diffusion of reactants into the plasmonic chamber, where they undergo the transformation upon near-IR illumination. The photothermal-driven reaction enables the intracellular generation of cyclic fluorescent products that can be tracked using fluorescence microscopy. The strategy may find different type of applications, such as for the spatio-temporal activation of prodrugs.

Hyperspectral-enhanced dark field analysis of individual and collective photo-responsive gold-copper sulfide nanoparticles.

We used hyperspectral-enhanced dark field microscopy for studying physicochemical changes in biomaterials by tracking their unique spectral signatures along their pathway through different biological environments typically found in any biomedical application. We correlate these spectral signatures with discrete environmental features causing changes in nanoparticles' physicochemical properties. We use this correlation to track the nanoparticles intracellularly and to assess the impact of these changes on their functionality. We focus on one example of a photothermal nanocomposite, i.e., polymer-coated gold/copper sulfide nanoparticles, because their performance depends on their localized surface plasmon peak, which is highly sensitive to environmental changes. We found spectral differences both in the dependence of time and discrete environmental factors, affecting the range of illumination wavelengths that can be used to activate the functionality of these types of nanoparticles. The presence of proteins (protein corona) and the increase in ionic strength induce a spectral broadening towards the NIR region which we associated with nanoparticles' agglomeration. In acidic environments, such as that of the lysosome, a red shift was also observed in addition to a decrease in the scattering intensity probably associated with a destabilization of the proteins and/or the change in the net charge of the polymer around the nanoparticles. We observed a loss of the photo-excitation potential of those nanoparticles exposed to acidic conditions in the <600 nm spectral rage. In a similar manner, ageing induces a transitioning from a broad multipeak spectrum to a distinct shoulder with time (up to 8 months) with the loss of spectral contribution in the 450-600 nm range. Hence, a fresh preparation of nanoparticles before their application would be recommended for an optimal performance. We highlight the impact of ageing and the acidic environment on the responsiveness of this type of plasmonic nanoparticle. Regardless of the spectral differences found, polymer-coated gold/copper sulfide nanoparticles retained their photothermal response as demonstrated in vitro upon two-photon irradiation. This could be ascribed to their robust geometry provided by the polymer coating. These results should be useful to rationally design plasmonic photothermal probes.

Aerogelation of Polymer-Coated Photoluminescent, Plasmonic, and Magnetic Nanoparticles for Biosensing Applications.

Macroscopic materials with nanoscopic properties have recently been synthesized by self-assembling defined nanoparticles to form self-supported networks, so-called aerogels. Motivated by the promising properties of this class of materials, the search for versatile routes toward the controlled assembly of presynthesized nanoparticles into such ultralight macroscopic materials has become a great interest. Overcoating procedures of colloidal nanoparticles with polymers offer versatile means to produce aerogels from nanoparticles, regardless of their size, shape, or properties while retaining their original characteristics. Herein, we report on the surface modification and assembly of various building blocks: photoluminescent nanorods, magnetic nanospheres, and plasmonic nanocubes with particle sizes between 5 and 40 nm. The polymer employed for the coating was poly(isobutylene-alt-maleic anhydride) modified with 1-dodecylamine side chains. The amphiphilic character of the polymer facilitates the stability of the nanocrystals in aqueous media. Hydrogels are prepared via triggering the colloidally stable solutions, with aqueous cations acting as linkers between the functional groups of the polymer shell. Upon supercritical drying, the hydrogels are successfully converted into macroscopic aerogels with highly porous, open structure. Due to the noninvasive preparation method, the nanoscopic properties of the building blocks are retained in the monolithic aerogels, leading to the powerful transfer of these properties to the macroscale. The open pore system, the universality of the polymer-coating strategy, and the large accessibility of the network make these gel structures promising biosensing platforms. Functionalizing the polymer shell with biomolecules opens up the possibility to utilize the nanoscopic properties of the building blocks in fluorescent probing, magnetoresistive sensing, and plasmonic-driven thermal sensing.

New Approaches in Nanomedicine for Ischemic Stroke.

Ischemic stroke, caused by the interruption of blood flow to the brain and subsequent neuronal death, represents one of the main causes of disability in developed countries. Therapeutic methods such as recanalization approaches, neuroprotective drugs, or recovery strategies have been widely developed to improve the patient's outcome; however, important limitations such as a narrow therapeutic window, the ability to reach brain targets, or drug side effects constitute some of the main aspects that limit the clinical applicability of the current treatments. Nanotechnology has emerged as a promising tool to overcome many of these drug limitations and improve the efficacy of treatments for neurological diseases such as stroke. The use of nanoparticles as a contrast agent or as drug carriers to a specific target are some of the most common approaches developed in nanomedicine for stroke. Throughout this review, we have summarized our experience of using nanotechnology tools for the study of stroke and the search for novel therapies.

In depth characterisation of the biomolecular coronas of polymer coated inorganic nanoparticles with differential centrifugal sedimentation.

Advances in nanofabrication methods have enabled the tailoring of new strategies towards the controlled production of nanoparticles with attractive applications in healthcare. In many cases, their characterisation remains a big challenge, particularly for small-sized functional nanoparticles of 5 nm diameter or smaller, where current particle sizing techniques struggle to provide the required sensitivity and accuracy. There is a clear need for the development of new reliable characterisation approaches for the physico-chemical characterisation of nanoparticles with significant accuracy, particularly for the analysis of the particles in the presence of complex biological fluids. Herein, we show that the Differential Centrifugal Sedimentation can be utilised as a high-precision tool for the reliable characterisation of functional nanoparticles of different materials. We report a method to correlate the sedimentation shift with the polymer and biomolecule adsorption on the nanoparticle surface, validating the developed core-shell model. We also highlight its limit when measuring nanoparticles of smaller size and the need to use several complementary methods when characterising nanoparticle corona complexes.

Core-Shell Palladium/MOF Platforms as Diffusion-Controlled Nanoreactors in Living Cells and Tissue Models.

Translating the potential of transition metal catalysis to biological and living environments promises to have a profound impact in chemical biology and biomedicine. A major challenge in the field is the creation of metal-based catalysts that remain active over time. Here, we demonstrate that embedding a reactive metallic core within a microporous metal-organic framework-based cloak preserves the catalytic site from passivation and deactivation, while allowing a suitable diffusion of the reactants. Specifically, we report the fabrication of nanoreactors composed of a palladium nanocube core and a nanometric imidazolate framework, which behave as robust, long-lasting nanoreactors capable of removing propargylic groups from phenol-derived pro-fluorophores in biological milieu and inside living cells. These heterogeneous catalysts can be reused within the same cells, promoting the chemical transformation of recurrent batches of reactants. We also report the assembly of tissue-like 3D spheroids containing the nanoreactors and demonstrate that they can perform the reactions in a repeated manner.

808 nm-activable core@multishell upconverting nanoparticles with enhanced stability for efficient photodynamic therapy.

BACKGROUND: The unique upconversion properties of rare-earth-doped nanoparticles offers exciting opportunities for biomedical applications, in which near-IR remote activation of biological processes is desired, including in vivo bioimaging, optogenetics, and light-based therapies. Tuning of upconversion in purposely designed core-shell nanoparticles gives access to biological windows in biological tissue. In recent years there have been several reports on NIR-excitable upconverting nanoparticles capable of working in biological mixtures and cellular settings. Unfortunately, most of these nanosystems are based on ytterbium's upconversion at 980 nm, concurrent with water's absorption within the first biological window. Thus, methods to produce robust upconverting nanoplatforms that can be efficiently excited with other than 980 nm NIR sources, such as 808 nm and 1064 nm, are required for biomedical applications. RESULTS: Herein, we report a synthetic method to produce aqueous stable upconverting nanoparticles that can be activated with 808 nm excitation sources, thus avoiding unwanted heating processes due to water absorbance at 980 nm. Importantly, these nanoparticles, once transferred to an aqueous environment using an amphiphilic polymer, remain colloidally stable for long periods of time in relevant biological media, while keeping their photoluminescence properties. The selected polymer was covalently modified by click chemistry with two FDA-approved photosensitizers (Rose Bengal and Chlorin e6), which can be efficiently and simultaneously excited by the light emission of our upconverting nanoparticles. Thus, our polymer-functionalization strategy allows producing an 808 nm-activable photodynamic nanoplatform. These upconverting nanocomposites are preferentially stored in acidic lysosomal compartments, which does not negatively affect their performance as photodynamic agents. Upon 808 nm excitation, the production of reactive oxidative species (ROS) and their effect in mitochondrial integrity were demonstrated. CONCLUSIONS: In summary, we have demonstrated the feasibility of using photosensitizer-polymer-modified upconverting nanoplatforms that can be activated by 808 nm light excitation sources for application in photodynamic therapy. Our nanoplatforms remain photoactive after internalization by living cells, allowing for 808 nm-activated ROS generation. The versatility of our polymer-stabilization strategy promises a straightforward access to other derivatizations (for instance, by integrating other photosensitizers or homing ligands), which could synergistically operate as multifunctional photodynamic platforms nanoreactors for in vivo applications.

Plasmonic Cell-Derived Nanocomposites for Light-Controlled Cargo Release inside Living Cells.

Translating the potential of thermoplasmonics to cell-derived nanomaterials offers exciting opportunities to fabricate beyond state-of-art artificial biomimetic nanocomposites that upon illumination perform active tasks such as delivery of cargo in complex, dynamic media such as the cytosol of cells. Cell-derived nanoparticles have shown stunning potential to implement cell-specific functions, such as long blood circulation or targeting capabilities, into advanced drug delivery nanosystems. The biomimicry nanotechnology has now advanced to offer new and exciting opportunities to improve the commonly poor in vivo performance of most current nanomedicines, including evading the immune system and targeting specific tissues such as tumors, the latest remaining among the most wanted breakthroughs in nanomedicine. However, the use of cell-derived nanocomposites as stimulus-controlled drug delivery agents remains virtually unexplored. This study reports the fabrication of a plasmonic cell-derived nanocomposite by integrating near-infrared active gold nanorods in its structure. As a proof of concept, the plasmonic nanomembranes are loaded with cell non-permeant antibodies, which upon near-infrared stimulation can be released from the plasmonic nanomembranes into the cytosol of living cells, without impairing cell viability or the antibodies' function. These results set the stage for the development of photoactive cell-derived nanocarriers, which in addition to cell-specific functions promise straightforward access to spatiotemporal-controlled intracellular delivery of antibodies.

Correction to: Optimizing conditions for labeling of mesenchymal stromal cells (MSCs) with gold nanoparticles: a prerequisite for in vivo tracking of MSCs.

The authors apologized for the unfortunate error in figure during publication of the article and they also explained that some of the solid grey graphs in Fig. 5 are intentionally based on the same data. For 8 different surface makers (CD14, CD73, CD34, CD105, CD19, CD90, CD45, HA-DR) in accordance to the guidelines of the manufacturer a panel of 4 different isotype controls were used, corresponding to 4 different fluorescence channels.