Staff member

Mesenchymal stem cells (MSCs) interact with their surroundings via integrins, which link to the actin cytoskeleton and translate physical cues into biochemical signals through mechanotransduction. N-cadherins enable cell-cell communication and are also linked to the cytoskeleton. This crosstalk between integrins and cadherins modulates MSC mechanotransduction and fate. Here we show the role of this crosstalk in the mechanosensing of viscosity using supported lipid bilayers as substrates of varying viscosity. We functionalize these lipid bilayers with adhesion peptides for integrins (RGD) and N-cadherins (HAVDI), to demonstrate that integrins and cadherins compete for the actin cytoskeleton, leading to an altered MSC mechanosensing response. This response is characterised by a weaker integrin adhesion to the environment when cadherin ligation occurs. We model this competition via a modified molecular clutch model, which drives the integrin/cadherin crosstalk in response to surface viscosity, ultimately controlling MSC lineage commitment. The crosstalk between cell-cell and cell-matrix adhesions regulates stem cell fate. Here, the authors reveal a critical role for matrix viscosity in controlling this crosstalk, which they explain via a modified molecular clutch model.

JTD Keywords: Actin cytoskeleton, Adhesion, Animals, Arginyl-glycyl-aspartic acid, Cadherins, Cell adhesion, Cell communication, Fibronectin, Force transmission, Humans, Hydrogel, Integrins, Lipid bilayers, Matrix, Mechanotransduction, Mechanotransduction, cellular, Mesenchymal stem cells, Mobility, Oligopeptides, Osteogenic differentiation, Substrate stiffness, Vinculin, Viscosity

Local cancer treatment by in situ injections of thermo-responsive hydrogels (HG) offers several advantages over conventional systemic anti-cancer treatments. In this work, a biodegradable and multicompartmental HG composed of N-isopropylacrylamide, cellulose, citric acid, and ceric ammonium nitrate was developed for the controlled release of hydrophilic (doxorubicin) and hydrophobic (niclosamide) drugs. The formulation presented ideal properties regarding thermo-responsiveness, rheological behavior, drug release profile, biocompatibility, and biological activity in colon and ovarian cancer cells. Cellulose was found to retard drugs release rate, being only 4 % of doxorubicin and 30 % of niclosamide released after 1 week. This low release was sufficient to cause cell death in both cell lines. Moreover, HG demonstrated a proper injectability, in situ prevalence, and safety profile in vivo. Overall, the HG properties, together with its natural and eco-friendly composition, create a safe and efficient platform for the local treatment of non-resectable tumors or tumors requiring pre-surgical adjuvant therapy.

JTD Keywords: biodegradable, cellulose, controlled-release formulation, drug delivery systems, hydrogel, thermo-responsiveness, Ammonium-nitrate, Biodegradable, Cancer treatment, Cellulose, Controlled-release formulation, Delivery, Drug delivery systems, Hydrogel, Reduce, Thermo-responsiveness

Lysosomal storage disorders are currently treated by enzyme replacement therapy (ERT) through the direct administration of the unprotected recombinant protein to the patients. Herein we present an ionically cross-linked polyelectrolyte complex (PEC) composed of trimethyl chitosan (TMC) and α-galactosidase A (GLA), the defective enzyme in Fabry disease, with the capability of directly targeting endothelial cells by incorporating peptide ligands containing the RGD sequence. We assessed the physicochemical properties, cytotoxicity, and hemocompatibility of RGD-targeted and untargeted PECs, the uptake by endothelial cells and the intracellular activity of PECs in cell culture models of Fabry disease. Moreover, we also explored the effect of different freeze-drying procedures in the overall activity of the PECs. Our results indicate that the use of integrin-binding RGD moiety within the PEC increases their uptake and the efficacy of the GLA enzyme, while the freeze-drying allows the activity of the therapeutic protein to remain intact. Overall, these results highlight the potential of TMC-based PECs as a highly versatile and feasible drug delivery system for improving the ERT of lysosomal storage disorders.

JTD Keywords: Enzyme replacement therapy, Fabry disease, Lysosomal delivery, Nanomedicine, Polyelectrolyte complexes, Trimethyl chitosan, α-galactosidase A

Pulmonary delivery of drugs for both local and systemic action has gained new attention over the last decades. In this work, different amphiphilic polymers (Soluplus®, Pluronic® F68, Pluronic® F108 and Pluronic® F127) were used to produce lyophilized formulations for inhalation of insulin. Development of stimuli-responsive, namely glucose-sensitive, formulations was also attempted with the addition of phenylboronic acid (PBA). Despite influencing the in vitro release of insulin from micelles, PBA did not confer glucose-sensitive properties to formulations. Lyophilized powders with aerodynamic diameter (<. 6. μm) compatible with good deposition in the lungs did not present significant in vitro toxicity for respiratory cell lines. Additionally, some formulations, in particular Pluronic® F127-based formulations, enhanced the permeation of insulin through pulmonary epithelial models and underwent minimal internalization by macrophages in vitro. Overall, formulations based on polymeric micelles presenting promising characteristics were developed for the delivery of insulin by inhalation. From the Clinical Editor: The ability to deliver other systemic drugs via inhalation has received renewed interests in the clinical setting. This is especially true for drugs which usually require injections for delivery, like insulin. In this article, the authors investigated their previously developed amphiphilic polymers for inhalation of insulin in an in vitro model. The results should provide basis for future in vivo studies.

JTD Keywords: Cytotoxicity, Inhalation, Permeability, Phagocytosis, Polymeric micelles, Protein delivery

Abstract Nanocomposite powders composed by polymeric micelles as vehicles for delivery proteins were developed in this work, using insulin as model protein. Results showed that size and polydispersity of micelles were dependent on the amphiphilic polymer used, being all lower than 300 nm, while all the formulations displayed spherical shape and surface charge close to neutrality. Percentages of association efficiency and loading capacity up to 94.15 ± 3.92 and 8.56 ± 0.36, respectively, were obtained. X-ray photoelectron spectroscopy (XPS) measurements confirmed that insulin was partially present at the hydrophilic shell of the micelles. Lyophilization did not significantly change the physical characteristics of micelles, further providing easily dispersion when in contact to aqueous medium. The native-like conformation of insulin was maintained at high percentages (around 80%) after lyophilization as indicated by Fourier transform infrared spectroscopy (FTIR) and far-UV circular dichroism (CD). Moreover, Raman spectroscopy did not evidenced significant interactions among the formulation components. The formulations shown to be physically stable upon storage up to 6 months both at room-temperature (20 C) and fridge (4 C), with only a slight loss (maximum of 15%) of the secondary structure of the protein. Among the polymers tested, Pluronic® F127 produced the carrier formulations more promising for delivery of proteins.

JTD Keywords: Amphiphilic polymers, Insulin, Lyophilization, Polymeric micelles, Stability

Nanopharmaceutics composed of a carrier and a protein have the potential to improve the activity of therapeutical proteins. Therapy for lysosomal diseases is limited by the lack of effective protein delivery systems that allow the controlled release of specific proteins to the lysosomes. Here we address this problem by developing functional polyelectrolyte-based nanoparticles able to promote acidic pH-triggered release of the loaded protein. Trimethyl chitosan (TMC) was synthesized and allowed to form polyelectrolyte complexes (PECs) with the lysosomal enzyme α-GAL through self-assembly and ionotropic gelation, with average particle size <200 nm, polydispersity index (PDI) <0.2, ζ potential of 20 mV, and a protein loading efficiency close to 65%. These polyelectrolyte nanoparticles were stable and active under physiological conditions and able to release the enzyme at acidic pH, as demonstrated by in situ atomic force microscopy (AFM). These nanoparticles were further functionalized with Atto 647N for single-particle characterization and tracking their cellular uptake and fate using high-resolution fluorescence microscopy. In contrast with their precursor, TMC, PECs were efficiently internalized by human endothelial cells and mostly accumulated in lysosomal compartments. The superior physicochemical characteristics of the TMC/α-GAL PECs together with their excellent cellular uptake properties indicate their enormous potential as advanced protein delivery systems for the treatment of lysosomal storage diseases.

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