Preparation And Application Of Electro - Spun Fibers For Tissue Brackets

At present, tissue engineeringscaffolds prepared by electrospinning has been widely applied in tissue repair and regenerative medicine. Electrospinning shows the advantage of being able to prepare nanofiber mats with large specific surface area,high porosity, good uniformity of continuous fiber, superfine fiber diameter and within the extracellular matrix collagen fibers similar(50~500 nm), which mimic the structure of natural extracellular matrix. We report in this research the electrospinning of thermosensitive and oriented electrospun nanofibers and the application in cell sorting and orientation for cell sheet engineering. Secondly, high cell-loading scaffolds were prepared by synchronous MSCs electrospun/PEUU polymer electrospinning technique. The specific contents are as follows:1. Poly(N-isopropylacrylamide-co-N-hydroxysuccinimide ester) was synthesized by free radical polymerization followed by gelatin grafting to obtain biocompatible thermosensitive poly(N-isopropylacrylamide)-g-gelatin(PNIPA-Gel). Electrospinning was then applied to fabricate aligned thermoresponsive PNIPA-Gel nanofiber mats.Cell coculture study showed that this kind of nanofiber mats performed different surface adhesion to rat fibroblast cells and phoenix cells at 37 oC, phoenix cells can then be sorted out firstly by gradient cooling treatment. The fibroblast cells that had attached on the nanofiber mats were allowed to proliferate to reach confluence. These fibroblast cells tended to elongate along with the oriented direction of the nanofibers during culture and finally formed oriented cell sheets. This kind of aligned cell sheet could easily detach from nanofiber mats by simply low temperature treatment. This technique is simple and can easily harvest target cells and aligned cell sheets with minimum invasion, which has the potential to be applied in tissue engineering and regenerative medicine.2. Biodegradable poly(ester-urethane)ureas(PEUU) were synthesized usingpoly(?-caprolactone) diol(PCL2000) to react with L-lysine ethyl ester diisocyanate(LDI) followed by chain extending with 1,4-butyl diamine(BDA). The structure was characterized by1H-NMR, Fourier transform infrared(FTIR). Mechanical property testing showed that their initial modulus were from 65.2±8.5 to 79.7±9.4 MPa,burst strength were from 5.9±0.8 to 8.9±1.8MPa,tensile strength were from 17.9±3.2 to42.6±2.4 MPa, breaking stain were from 946.6±97.2 to 1099.9±77.0%. The average mass loss for the hydrolytic degradation was only about 13 % in 56 days. The morphological and biomechanical characters of the tessuis scaffolds electrospuned from the as-prepared PEUU were also examined. As the solution concentration was varied from 12 to 18%(w/v), the fiber diameter was progressively increased, and the scaffold tensile strength was enhanced from 4.2±0.7 MPa to 9.6±0.8 MPa, burst strength from 3.4±0.4 to 4.3±0.2 MPa. By using the synchronous cell electrospun /PEUU polymer electrospinning technique, one of PEUU polymer electrospinning, the other one of MSC cell electrospun, can rapid preparation of high flexibility, high cell load electrospun scaffolds for tissue engineering, A large number of MSCs can be evenly distributed in the electrospun scaffolds for tissue engineering, and can grow well. Quantitative real-time PCR(Q-RT-PCR) analysis results showed that up-regulation expression of osteonectin and down-regulation expression of COL2(α1)of MSCs, indicating that MSCs still maintain a certain multiple differentiation potential.