In the U.S. more than one million people suffer serious peripheral nerve injuries every year and 20,000 procedures are carried out annually to repair severed peripherals nerves. Nerve guidance channels (NGCs) are hollow conduits used to bridge large gaps of severed peripheral nerves. Current NGC's materials have many drawbacks that often preclude their use or cause failure of the procedure. Therefore, new biomaterials that actively promote nerve regeneration are needed for the fabrication of improved NGCs. Electrically conducting biomaterials are of interest because they can be used to deliver electrical stimulation to responsive cells like osteoblasts, endothelial cells, and neurons. Polypyrrole (PPy) is an electrically conducting polymer that is not cytotoxic and has been demonstrated to favor the regeneration of damaged peripheral nerves in rats. Because PPy is a semiconductor, it can be used to deliver electric stimuli to cultured cells, accelerating their growth, migration and proliferation. Unfortunately PPy is not biodegradable, and NGCs made of PPy must be removed from the body upon healing, requiring a second surgery and causing additional site morbidity. Moreover, PPy, like most conducting polymers, is insoluble and infusible, and has poor mechanical properties. Therefore, it is very difficult to process it into the necessary form. Together, these properties limit the practical applications of PPy in tissue engineering. The objective of this project is to make a biodegradable form of PPy that can be processed from solution, and to test its properties as a support for the regeneration of severed nerves. During the Phase I project TDA successfully prepared a PPy-based biomaterials that are electrically conducting, can be processed from solution and support well neuron growth in vitro. ? ? ?
| Durgam, Hymavathi; Sapp, Shawn; Deister, Curt et al. (2010) Novel degradable co-polymers of polypyrrole support cell proliferation and enhance neurite out-growth with electrical stimulation. J Biomater Sci Polym Ed 21:1265-82 |
