EIectrospinning of bioresorbable polymers for tissue engineering scaffolds


Since the inception of the field of tissue engineering, there has been a considerable effort to develop an "Ideal" tissue engineering scaffold. To date, investigators have developed materials such as collagen, poly(glycolic acid) (PGA), poly(lactic acid) (PLA), and polycaprolactone (PCL) for use in matrix construction with frequently unacceptable results. The construction of an "Ideal" tissue engineering scaffold requires that multiple criteria are met. The first criterion is that the material be biocompatible and function without interrupting other physiological processes. This functionality includes an ability to promote normal cell growth and differentiation while maintaining three-dimensional orientation/space for the cells. Additionally, the scaffold should not induce any adverse tissue reaction. Another criterion involves the production of the scaffold. Scaffold production must include efficient material and construction parameters. The construction must also involve a process by which the scaffold can be easily reproduced to a wide range of shapes and sizes. Once implemented in vitro or in vivo, the material should be completely resorbable, leaving only native tissue. The method of electrospinning provides a simple method to achieve the goals of an "Ideal" tissue engineering scaffold. Electrospinning is the deliberate application of the phenomenon of electrostatic spraying which occurs when electrical forces at the surface of the polymer solution overcome the surface tension, creating a polymer solution jet. The jet produces a fiber with diameters in the micron to nanoscale range (down to 50 nm) as the solvent evaporates. The biodegradable polymer scaffold production (flexible, quick, and simple) utilizes the jet formation of the polymer-based solution from a nozzle to a grounded rotating mandrel. We have successfully electrospun PGA and PLA as pure polymers, co-polymers, and blends with each other as well as with PCL in order to develop novel tissue engineering scaffolds. The electrospinning process allows the production of PGA scaffolds comprised of 100 nm to 1.5 micron diameter fibers. For the PLA and PLA/PCL blends, the fiber diameter produced ranges from 8-10 microns. Obviously, with various composition and fiber dimensions, we can tailor both the mechanical properties and the degradation rates of the electrospun scaffoldings. The electrospinning process also allows us to control fiber orientation in the final fibrous scaffolds, ranging from completely random to predominately aligned. Thus, with these very promising results, it may now be possible to utilize this technology to create the "Ideal" tissue engineering scaffold (mimic tissue structure on demand). © 2006 American Chemical Society.

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