Phenylketonuria (PKU) is a genetic disorder of metabolism characterized by a pathological elevation of phenylalanine (Phe) in the body stemming from a dysfunctional phenylalanine hydroxylase enzyme (PAH). The resulting high concentrations of Phe (5-10x) can result in severe intellectual disability, behavioral problems, and neurological deficits (e.g. seizures). Strict control of dietary Phe is the primary treatment for PKU current guidelines require diet therapy to be continued for life, which markedly exacerbates the problem of non-compliance, especially in older children and adults. An alternative treatment for PKU involves the ?replacement? of the endogenous PAH with a different Phe metabolizing enzyme such as phenylalanine ammonia lyase (PAL). Orally administered PAL reduced plasma Phe levels, but this effect was transient as the destruction of PAL by harsh environment of the gastrointestinal tract (g.i.t) necessitated huge doses of the enzyme. We have designed a novel technology to reduce dietary Phe levels in the g.i.t. by oral administration of microencapsulated PAL. Preliminary studies have demonstrated that we can successfully encapsulate PAL (PALE) in ethyl cellulose using a patented emulsion-dispersion technique. However, PALE exhibits ~30% of the activity of unencapsulated enzyme (PALU) in solution limiting its implementation in its current form. The goal of this proposal is to optimize the formulation parameters to encapsulate PAL and characterize its properties in vitro enabling future development efforts.
Phenylketonuria is an inborn error of metabolism, characterized by mutations in the enzyme phenylalanine hydroxylase causing a pathological elevation of phenylalanine in the blood. Orally active enzyme replacement therapy has shown initial promise but limited efficacy as native processes break down the exogenous enzymes resulting in a transient reduction in phenylalanine levels. Microencapsulation of enzymes in a porous and non-toxic membrane represents an innovative way to prolong stability and functionality in the destructive environment of the gastrointestinal tract and has the potential to help alleviate the enormous burden experienced by patients.
