Modares Journal of Biotechnology

Abstract According to the novel achievements, nanotopography and steric geometry of the microenvironment around the cells have a drastic role on their fates. Hence, fabrication of biocompatible nanostructures as the scaffolds for the cell culture and in the next step, accurate determination of their physical and geometrical characteristics is widely considered. Despite of broad utilization of Atomic Force Microscopy to investigate topological traits of sophisticated nanopatterns; its capability to characterize electrospun nanofibers has not been studied inquiringly. In the present research, chitosan nanofibers which were successfully electrospun at the optimized conditions were then evaluated using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) respectively. The results suggested that recruitment of both of these techniques have their own advantages and disadvantages. As the first noticeable issue, while the sample preparation and scanning procedure in SEM imaging may disrupt native structure of fibers, probing the sample by AFM doesn't need any pre-imaging treatment. The main application of SEM in analysis of nanofibrillar structures is the rapid survey of nanofibers shape, orientation, diameter and consistency. In the other side, three dimensional imaging by AFM makes it possible to determine whole surface roughness, roughness along fibers and woven tissue thickness. Furthermore, regarding some technical advices, AFM can be used to estimate nanofibers average diameter as well as SEM.

Abstract Stem cell therapy has been introduced as an innovative and promising treatment in Ischemic diseases. Mesenchymal stem cells are considered for cell therapy to some extent due to their immunemodulatory, differentiation potential, feasibility of isolation and proliferation properties. Stem cells, after transplantation, often encounter harsh and hypoxic environment in ischemic tissues, which leads to cell death and decreased therapeutic efficiency. On the other hand, the fate of stem cell viability and differentiation is still an ambiguous issue in cell therapy regenerative medicine. To overcome this problem, Hypoxic/Ischemic preconditioning has been reported as a powerful tool with beneficial effects on cell survival. The reported master regulator in this process is a transcription factor known as HIF-1α. This study aimed to over-express HIF-1α in mesenchymal stem cells along with eGFP by using lenti viral vectors. Bisistronic expression of eGFP and HIF-1α provides the possibilities of tracking the transplanted cells and mimicking the hypoxic conditions for genetically modified stem cells for future animal model studies.