Human Mesenchymal Stromal Cell-Derived Exosomes Promote In Vitro Wound Healing by Modulating the Biological Properties of Skin Keratinocytes and Fibroblasts and Stimulating Angiogenesis

Bone marrow-derived mesenchymal stromal cells (MSCs) are major players in regenerative therapies for wound healing via their paracrine activity, mediated partially by exosomes. Our purpose was to test if MSC-derived exosomes could accelerate wound healing by enhancing the biological properties of the main cell types involved in the key phases of this process. Thus, the effects of exosomes on (i) macrophage activation, (ii) angiogenesis, (iii) keratinocytes and dermal fibroblasts proliferation and migration, and (iv) the capacity of myofibroblasts to regulate the turnover of the extracellular matrix were evaluated. The results showed that, although exosomes did not exhibit anti-inflammatory properties, they stimulated angiogenesis. Exposure of keratinocytes and dermal (myo)fibroblasts to exosomes enhanced their proliferation and migratory capacity. Additionally, exosomes prevented the upregulation of gene expression for type I and III collagen, α-smooth muscle actin, and MMP2 and 14, and they increased MMP13 expression during the fibroblast–myofibroblast transition. The regenerative properties of exosomes were validated using a wound healing skin organotypic model, which exhibited full re-epithelialization upon exosomes exposure. In summary, these data indicate that exosomes enhance the biological properties of keratinocytes, fibroblasts, and endothelial cells, thus providing a reliable therapeutic tool for skin regeneration

Cytocompatibility of PET Films after DC Helium Plasma Treatments and Collagen Immobilization

Films of poly(ethylene terephthalate) have been subject to a direct current helium discharge, the most efficient adsorbtion of collagen on the plasma-treated surfaces being recorded for longer treatment times. All treated samples sustained the adherence and the proliferation of the endothelial cells. Keywords: poly(ethylene terephthalate), helium plasma, protein adsorbtion, endothelial cell The chemical composition and physical surface morphology of polymers are key factors as far as their compatibility with biological systems is concerned Poly(ethylene terephthalate) (PET) is widely used in various forms, such as films, fibers and engineering plastics, for a large variety of applications. PET exhibits good mechanical strength, toughness, fatigue resistance at elevated temperatures and a high crystalline melting temperature. Besides the desirable bulk properties of PET, good interfacial bonding is of great importance for the application of biomaterials. Interface properties, such as chemical bonding and structure, play an important role in the adsorbtion of proteins to polymers Chemical reactions, as well as physical treatments, can be used in order to add chemical groups onto a polymer surface. It is demonstrated Collagen, the most abundant protein in the body, has been widely examined as a potential tissue-engineering scaffold The aim of this study was the evaluation of heliumplasma treatments influence on poly(ethylene terephthalate) (PET) films in order to obtain support surfaces for the immobilization of biologically active molecules and living cells. Even if radio frequency plasma is often used in this types of treatments, in this study one has obtained good results using direct current plasma. The plasma-functionalized PET films were then placed in a collagen-buffer solution and the obtained polymeric supports were used for EA.hy 926 endothelial cell line cultures. Experimental part Materials and methods Plasma treatments The experiments were performed in a direct-current plasma device. The plasma was produced in a glass vessel by a DC discharge sustained between a heated filament cathode and a metal foil negatively biased with respect to the foil. As background gas one used helium at a pressure p = 5Å . 10 -3 mbar. A PET film E (30μm thickness) was immersed into the plasma filling the gas vessel by diffusion, helium being the most efficient of the inert gases for crosslinking the outermost polymeric monolayers. This feature is due to its increased rate of diffusion and the large amount of energy available to transfer to the polymer surface via ion neutralization, Auger de-excitation and Penning ionization in the polymer After plasma treatment, the films were incubated in 3 mg/mL type I collagen/phosphate buffered solution (PBS, pH = 3.4) for 24 h at 24° C. The collagen immobilized films were rinsed with ethanol solution and then with de-ionized water in order to remove the free collagen

Effect of SiC interlayer between Ti6Al4V alloy and hydroxyapatite films

© IMechE 2015.Bioactive coatings are frequently used to improve the osseointegration of the metallic implants used in dentistry or orthopaedics. Among different types of bioactive coatings, hydroxyapatite (Ca10(PO4)6(OH)2) is one of the most extensively used due to its chemical similarities to the components of bones and teeth. In this article, production and characterization of hydroxyapatite films deposited on Ti6Al4V alloy prepared by magnetron sputtering were reported. Besides, SiC was deposited on substrate surface to study the interlayer effect. Obtained coatings were annealed at 600 °C for 30 and 120 min in a mixed atmosphere of N2 + H2O vapours with the heating rate of 12 °C min-1. The effects of SiC interlayer and heat treatment parameters on the structural, mechanical and corrosion properties were investigated. After heat treatment process, the crystalline hydroxyapatite was obtained. Additionally, cell viability tests were performed. The results show that the presence of the SiC interlayer contributes a decrease in surface roughness and improves the mechanical properties and corrosion performance of the hydroxyapatite coatings. Biological properties were not affected by the presence of the SiC interlayer

In Vitro Biocompatibility of Si Alloyed Multi-Principal Element Carbide Coatings.

In the current study, we have examined the possibility to improve the biocompatibility of the (TiZrNbTaHf)C through replacement of either Ti or Ta by Si. The coatings were deposited on Si and 316L stainless steel substrates by magnetron sputtering in an Ar+CH4 mixed atmosphere and were examined for elemental composition, chemical bonds, surface topography, surface electrical charge and biocompatible characteristics. The net surface charge was evaluated at nano and macroscopic scale by measuring the electrical potential and work function, respectively. The biocompatible tests comprised determination of cell viability and cell attachment to the coated surface. The deposited coatings had C/(metal+Si) ratios close to unity, while a mixture of metallic carbide, free-carbon and oxidized species formed on the film surface. The coatings' surfaces were smooth and no influence of surface roughness on electrical charge or biocompatibility was found. The biocompatible characteristics correlated well with the electrical potential/work function, suggesting a significant role of surface charge in improving biocompatibility, particularly cell attachment to coating's surface. Replacement of either Ti or Ta by Si in the (TiZrNbTaHf)C coating led to an enhanced surface electrical charge, as well as to superior biocompatible properties, with best results for the (TiZrNbSiHf)C coating

Ti-Nb-Zr system and its surface biofunctionalization for biomedical applications

In the biomedical field, a main challenge is to find a material that can provide all the requirements imposed by biomedical applications, including consisting of biocompatible elements; a low elastic modulus to avoid the stress shield effect in bone fixation; a high wear-corrosion resistance; proper biocompatibility; etc. Presently, metallic materials are the most used in biomedical applications, especially for the dental and orthopedic fields. The most common is the Ti-6Al-4V alloy. However, due to the fact that Al and V can cause mutagenic, cytotoxic, and allergic reactions, the current research has been focused on replacing the Ti-6Al-4V alloy with one consisting only of biocompatible elements. Various systems have been proposed, and in recent years, a novel Ti-Nb-Zr system with different compositions has been developed, as Zr and Nb are known to be more biocompatible than Al and V. Nevertheless, these systems still have low osseointegration and bioactivity, which limits their use for biomedical applications. Based on this, the functionalization of their surfaces by various bioactive coatings was proposed. Also the peptide coatings were proposed for improving their osseoconductivity along with good bioactivity and antibacterial properties. The present chapter reports the general classification and fabrication methods of titanium alloys and their use in medicine as well as experimental details regarding the Ti-Nb-Zr system used for biomedical applications, such as elastic modulus, corrosion resistance, and in vitro biological properties. Attention is then devoted to methods for improving the osseoconductivity and bioactivity of the Ti-Nb-Zr system used for biomedical applications

Mechanical, In Vitro Corrosion Resistance and Biological Compatibility of Cast and Annealed Ti25Nb10Zr Alloy

Compared to other alloys, Ti6Al4V is the most used in medicine. In recent years, concerns regarding the toxicity of Al and V elements found in the composition of Ti6Al4V have drawn the attention of the scientific community, due to the release of Al or V ions after long term exposure to human body fluids which can lead to a negative response of the human host. Based on this, the aim of the paper was to manufacture a Ti25Nb10Zr alloy consisting of biocompatible elements which can replace Ti6Al4V usage in medical applications. In order to prove that this alloy possessed improved properties, the mechanical, wear and corrosion resistance, wettability, and cell viability were performed in comparison with those of the Ti6Al4V alloy. The corrosion behavior of this new alloy in simulated body fluid (SBF) and Hank solutions is superior to that of Ti6Al4V. The cast Ti25Nb10Zr alloy has a good tribological performance in SBF, while annealed Ti25Nb10Zr alloy is better in Hank solution. Cell viability and proliferation assay after five days indicated that Ti25Nb10Zr presented a good viability and proliferation with values of approximately 7% and 10% higher, respectively, than the ones registered for pure Ti. When compared with Ti6Al4V, the obtained results for Ti25Nb10Zr indicated smaller values with 20% in the case of both tests. Overall, it can be concluded that cell proliferation and viability tests indicated that the biocompatibility of the Ti25Nb10Zr alloy is as good as pure Ti and Ti6Al4V alloy

Correlation between the electrical potential, work function and cell viability of the investigated coatings.

<p>Correlation between the electrical potential, work function and cell viability of the investigated coatings.</p

Electrical potential of the (TiZrNbTaHf)C, (SiZrNbTaHf)C and (TiZrNbSiHf)C coatings.

<p>Data show the mean and SD values obtained for each type of coating on two replicates in 5 different areas. Ra roughness measurements were performed by surface profilometer (scanned area: (150 × 150) μm²), and the RMS roughness measurements were performed by AFM microscopy (scanned area: (3 × 3) μm²).</p

AFM surface images of the coated Si samples.

<p>Representative AFM images of the coatings: scanned area: 3 × 3 μm².</p