An extracorporeal hollow-fiber reactor for phenylketonuria using immobilized phenylalanine ammonia lyase.

A hollow-fiber hemodialyzer with immobilized phenylalanine ammonia lyase was tested in vitro for depletion of blood phenylalanine in a recirculating system. A sustained reduction of phenylalanine was obtained in less than 1 h. The product of phenylalanine deamination, trans-cinnamic acid, is a nontoxic compound metabolized to benzoic acid by the liver and eliminated in the urine as hippuric acid. As a model, this reactor may be relevant not only for the short-term management of hyperphenylalaninemia (particularly in pregnant phenylketonuric mothers), but for other metabolic diseases as well, provided that a biocatalyst effective on the accumulating substance is available.