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Stem cell based nerve tissue engineering on guided constructs

Yücel, Deniz
Nerve injury is a serious clinical problem that has a direct impact on the quality of life. Nerve tissue engineering (NTE) is one of the most promising methods in human health care to restore the function of damaged neural tissues. The current state of the art involves the construction of a tissue engineered, nano or micropatterned 3-D nerve tube that has fibers or channels in the inside. The scope of this study is to construct a 3-D, biodegradable nerve tube which consists of an aligned, electrospun mat seeded with stem cells that is wrapped in a porous micropatterned film which contains support cells. In two separate approaches human mesenchymal stem cells (MSCs) and mouse neural stem cells (NSCs) were used. In the design with the MSCs, the micropatterned exterior part of the nerve tube contained undifferentiated MSCs as support cells and this was wrapped around the fibers seeded with MSCs which were induced to neural differentiation. In the other case, NSCs differentiated into astrocytes were used as support cells seeded on the micropatterned film and the mat was loaded with undifferentiated NSCs. Differentiation into neural cells and astrocytes were shown with immunocytochemistry and RT-PCR. The neuron-like MSCs and NSCs were shown to express neural marker β-Tubulin III whereas astrocytes expressed glial fibrillary acidic protein (GFAP), an astrocyte marker. RT-PCR showed that early neural markers, nestin and Nurr 1, were expressed at passage 4 by undifferentiated MSCs and by MSCs induced to neural differentiation, while these markers were not expressed in undifferentiated MSCs at passages 2 and 3. The cells aligned along the axis of the micropattern of the film and along the axis of the fiber on the fibrous mat. This behavior was also maintained after construct formation. MTS and confocal microscopy revealed that the cells were viable and homogeneously distributed over the two parts of the scaffold. This indicates that the construct has a potential to be tested in vivo for nerve tissue engineering purposes.