PREPARATION OF A MACROPOROUS BIODEGRADABLE POLYLACTIDE IMPLANT FOR NEURONAL TRANSPLANTATION

This article reports the production of a surgical implant meeting seve ral specific requirements such as biocompatibility, biodegradability, macroporosity, and flexibility. Porosity was controlled by an original method consisting of the aggregation of calibrated poly-D,L-lactide m icroparticles. The size of the interstices between the aggregated micr ospheres was in a direct relationship to the microsphere diameter. A f irst approach was based on coating the microspheres with poly(vinyl al cohol) followed by chemically crosslinking the coating layers that wer e in mutual contact. This method was disregarded because of the acute cytotoxicity of glutaraldehyde used as the crosslinking agent, the abs ence of macroporosity, and the complete lack of flexibility. A physica l technique of aggregation was then tested, which relied on the plasti cization of poly-D,L-lactide microspheres with triethylcitrate to the point where microspheres strongly adhered to each other when they were in contact. This method has proved to be straightforward and definite ly superior to the chemical approach, particularly with respect to cyt otoxicity, control of macroporosity, and flexibility. A polymer suppor t was thus successfully produced which was biodegradable, macroporous (interconnected pores of 10-100 mu m in diameter), and flexible. This potential medical device is presently being used for neuronal transpla ntation in the central nervous system. (C) 1995 John Wiley & Sons, Inc .