Effects of mesenchymal stromal cells versus serum on tendon healing in a controlled experimental trial in an equine model

Abstract Background Mesenchymal stromal cells (MSC) have shown promising results in the treatment of tendinopathy in equine medicine, making this therapeutic approach seem favorable for translation to human medicine. Having demonstrated that MSC engraft within the tendon lesions after local injection in an equine model, we hypothesized that they would improve tendon healing superior to serum injection alone. Methods Quadrilateral tendon lesions were induced in six horses by mechanical tissue disruption combined with collagenase application 3 weeks before treatment. Adipose-derived MSC suspended in serum or serum alone were then injected intralesionally. Clinical examinations, ultrasound and magnetic resonance imaging were performed over 24 weeks. Tendon biopsies for histological assessment were taken from the hindlimbs 3 weeks after treatment. Horses were sacrificed after 24 weeks and forelimb tendons were subjected to macroscopic and histological examination as well as analysis of musculoskeletal marker expression. Results Tendons injected with MSC showed a transient increase in inflammation and lesion size, as indicated by clinical and imaging parameters between week 3 and 6 (p < 0.05). Thereafter, symptoms decreased in both groups and, except that in MSC-treated tendons, mean lesion signal intensity as seen in T2w magnetic resonance imaging and cellularity as seen in the histology (p < 0.05) were lower, no major differences could be found at week 24. Conclusions These data suggest that MSC have influenced the inflammatory reaction in a way not described in tendinopathy studies before. However, at the endpoint of the current study, 24 weeks after treatment, no distinct improvement was observed in MSC-treated tendons compared to the serum-injected controls. Future studies are necessary to elucidate whether and under which conditions MSC are beneficial for tendon healing before translation into human medicine

Three-dimensional natural convection of fluid with temperature-dependent viscosity within a porous cube having local heater

A numerical simulation is conducted on the convective heat transfer of liquid having variable viscosity in a closed porous 3D enclosure under an influence of isothermal or heat-generating solid body. Two vertical surfaces of the chamber are considered at fixed low temperature while other surfaces are thermally insulated. The local energy source is placed on the lower surface of the chamber. The control equations are written using non-dimensional variables «vector potential functions – vorticity vector – temperature». The finite difference technique of the second order accuracy is used to work out the differential equations. The effect of control parameters including the Rayleigh number, Ostrogradsky number, Darcy number, viscosity variation parameter and time on the liquid flow structure and heat transfer inside the cavity has been studied. The obtained data show that the porous material and variable viscosity working fluid can be considered as good conditions for the heat removal from the heated element in a closed chamber. A comparison of 2D and 3D models for natural convection of fluid having temperature-dependent viscosity in chambers with local heaters of various types has shown the features of different spatial approaches and boundary conditions for heated elements

Transient free convection of variable viscosity liquid in an inclined cube affected by the temperature modulation on a vertical wall

Convective energy transport can be found in various engineering and nature systems. From practical point of view this transport phenomenon within engineering cabinets can be progressed in the presence of temperature modulation. In this research, the transient natural convective heat transference of a temperature-dependent viscosity liquid inside an inclined cube in the presence of time-dependent temperature profile at one vertical bounded surface is investigated. The opposite vertical border is kept at permanent low temperature, whilst other surfaces are thermally insulated. Partial differential equations formulated using dimensionless non-primitive characteristics with appropriate restrictions are worked out by the finite difference technique. Impacts of the domain tilted angle, and wall temperature oscillation frequency on energy transport and flow structures are scrutinized

Effect of third size on natural convection of variable viscosity fluid in a closed parallelepiped

Thermal convection is one of the main mechanisms that are implemented in different cooling systems. Most often this phenomenon occurs in such practical areas as microelectronics, instrumentation and building construction. In this article, the numerical simulation of thermogravitational convection of medium having dependent viscosity inside closed enclosure with isothermal heating/cooling from vertical walls has been conducted. Other borders of the chamber are heat insulated. The control relations have been written employing non-dimensional vector potential functions, vorticity vector and temperature. The finite difference procedures are applied for solving of the considered differential equations. Obtained outcomes have been compared with numerical data for thermal convection within a differentially heated square cabinet. An influence of third coordinate, Rayleigh number and viscosity variation parameter on thermal distribution and flow structures combined with mean Nusselt number has been demonstrated. Obtained outcomes have shown that for the considered 3D problem an evaluation of the mean Nusselt number can be performed by employing 2D data when the aspect ratio is greater than or equal to unity

Lipid droplets as a novel cargo of tunnelling nanotubes in endothelial cells

Intercellular communication is a fundamental process in the development and functioning of multicellular organisms. Recently, an essentially new type of intercellular communication, based on thin membrane channels between cells, has been reported. These structures, termed intercellular or tunnelling nanotubes (TNTs), permit the direct exchange of various components or signals (e.g., ions, proteins, or organelles) between non-adjacent cells at distances over 100 μm. Our studies revealed the presence of tunnelling nanotubes in microvascular endothelial cells (HMEC-1). The TNTs were studied with live cell imaging, environmental scanning electron microscopy (ESEM), and coherent anti-Stokes Raman scattering spectroscopy (CARS). Tunneling nanotubes showed marked persistence: the TNTs could connect cells over long distances (up to 150 μm) for several hours. Several cellular organelles were present in TNTs, such as lysosomes and mitochondria. Moreover, we could identify lipid droplets as a novel type of cargo in the TNTs. Under angiogenic conditions (VEGF treatment) the number of lipid droplets increased significantly. Arachidonic acid application not only increased the number of lipid droplets but also tripled the extent of TNT formation. Taken together, our results provide the first demonstration of lipid droplets as a cargo of TNTs and thereby open a new field in intercellular communication research