Ionizing radiation augments glioma tropism of mesenchymal stem cells

OBJECTIVEMesenchymal stem cells (MSCs) have been shown to localize to gliomas after intravascular delivery. Because these cells home to areas of tissue injury, the authors hypothesized that the administration of ionizing radiation (IR) to tumor would enhance the tropism of MSCs to gliomas. Additionally, they sought to identify which radiation-induced factors might attract MSCs.METHODSTo assess the effect of IR on MSC migration in vitro, transwell assays using conditioned medium (CM) from an irradiated commercially available glioma cell line (U87) and from irradiated patient-derived glioma stem-like cells (GSCs; GSC7-2 and GSC11) were employed. For in vivo testing, green fluorescent protein (GFP)-labeled MSCs were injected into the carotid artery of nude mice harboring orthotopic U87, GSC7-2, or GSC17 xenografts that were treated with either 0 or 10 Gy of IR, and brain sections were quantitatively analyzed by immunofluorescence for GFP-positive cells. These GSCs were used because GSC7-2 is a weak attractor of MSCs at baseline, whereas GSC17 is a strong attractor. To determine the factors implicated in IR-induced tropism, CM from irradiated GSC7-2 and from GSC11 was assayed with a cytokine array and quantitative ELISA.RESULTSTranswell migration assays revealed statistically significant enhanced MSC migration to CM from irradiated U87, GSC7-2, and GSC11 compared with nonirradiated controls and in a dose-dependent manner. After their intravascular delivery into nude mice harboring orthotopic gliomas, MSCs engrafted more successfully in irradiated U87 (p = 0.036), compared with nonirradiated controls. IR also significantly increased the tropism of MSCs to GSC7-2 xenografts (p = 0.043), which are known to attract MSCs only poorly at baseline (weak-attractor GSCs). Ionizing radiation also increased the engraftment of MSCs in strong-attractor GSC17 xenografts, but these increases did not reach statistical significance. The chemokine CCL2 was released by GSC7-2 and GSC11 after irradiation in a dose-dependent manner and mediated in vitro transwell migration of MSCs. Immunohistochemistry revealed increased CCL2 in irradiated GSC7-2 gliomas near the site of MSC engraftment.CONCLUSIONSAdministering IR to gliomas enhances MSC localization, particularly in GSCs that attract MSCs poorly at baseline. The chemokine CCL2 appears to play a crucial role in the IR-induced tropism of MSCs to gliomas.

On Lr-regularity of global attractors generated by strong solutions of reaction-diffusion equations

In this paper we prove that the global attractor generated by strong solutions of a reaction-diffusion equation without uniqueness of the Cauchy problem is bounded in suitable Lr-spaces. In order to obtain this result we prove first that the concepts of weak and mild solutions are equivalent under an appropriate assumption.Also, when the nonlinear term of the equation satisfies a supercritical growth condition the existence of a weak attractor is established.

Dynamical Behaviors of Stochastic Hopfield Neural Networks with Reaction-Diffusion Terms

Dynamical behaviors of stochastic Hopfield neural network with delays and reaction-diffusion terms are investigated. By employing Lyapunov method, Poincare inequality and linear matrix inequality, some novel criteria on ultimate boundedness, weak attractor and asymptotic stability are obtained. The criteria are independent of the magnitude of the delays, and dependent on the diffusion effects and the derivative of the delays. Finally, a numerical example is given to illustrate the correctness and effectiveness of our theoretical results.

Dynamical Behaviors of Stochastic Reaction-Diffusion Cohen-Grossberg Neural Networks with Delays

This paper investigates dynamical behaviors of stochastic Cohen-Grossberg neural network with delays and reaction diffusion. By employing Lyapunov method, Poincaré inequality and matrix technique, some sufficient criteria on ultimate boundedness, weak attractor, and asymptotic stability are obtained. Finally, a numerical example is given to illustrate the correctness and effectiveness of our theoretical results.