Date

2013

Author

Dursun, Tuğba

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Permanent loss of neurologic function occurs when the central nervous system (CNS) is injured. Nerve regeneration is extremely limited because of dense scar tissue formation at the lesion site, especially in the spinal cord. For the treatment of this type of injury, different strategies are needed. The emerging approach to solve these problems is to provide a physical support via tubular bridging devices such as “nerve guides”. They are used to bridge the neural gaps in the treatment of spinal cord injury, and therefore, the design of its inner architecture is very important to provide desired guidance. To test this, the effectiveness of the aligned and random media within tubular nerve guides were compared. Although ultimately a tubular construct is used, planar, composite structures were used for convenient monitoring and analysis. The bottom layer or the main bulk of the nerve guide was a PHBV foam that was prepared by lyophilization. Aligned and randomly oriented PHBV/collagen (2:1) fiber mats, to be placed on this bottom layer were made by electrospinning directly on the PHBV foam. PHBV/collagen (2:1) foam to serve as a 3D disorganized medium was also made by lyophilization. Crosslink ng of the b layer gu des was made by dehydrothermal treatment (DHT) at 150 ̊C for 24 h. Mercury porosimetry showed that porosity of the PHBV foam was 85%, and the pore size was between 5 and 200 μm. Diameter of the fibers were measured by scanning electron microscope and found to be inbetween 200-900 nm. In situ biodegradation test revealed that weight loss of uncrosslinked guides (no DHT) were less than the crosslinked ones (15% after 28 days), and therefore, crosslinking of the scaffolds with DHT was abandoned. Aligned fiber-foam (AF-Fo) and random fiber-foam (RF-Fo) nerve guides were seeded with rat bone marrow stromal cells (rBMSCs) and cultured for 7 days. Cell behavior and differentiation to neural cells on these constructs was examined. Cell attachment and proliferation were found to be better on the RF-Fo construct. The neural differentiation level of the cells were same on both bilayer. No conclusive evidence for the positive contribution of an aligned interior could be observed. It was concluded that the nerve guides prepared had proper porosity, pore size and degradation rate which would allow cell growth at the spinal cord injury site.

Subject Keywords

Tissue scaffolds., Nerve tissue., Mesenchymal stem cells, Spinal cord compression., Spinal cord, Tissue engineering.

URI

http://etd.lib.metu.edu.tr/upload/12616233/index.pdf
https://hdl.handle.net/11511/22963

Collections

Graduate School of Natural and Applied Sciences, Thesis