text: Many other medical conditions have been targeted with encapsulation therapies, especially those involving a deficiency in some biologically derived protein. One of the most successful approaches is an external device that acts similarly to a dialysis machine, only with a reservoir of pig hepatocytes surrounding the semipermeable portion of the blood-infused tubing.  This apparatus can remove toxins from the blood of patients suffering severe liver failure. Other applications that are still in development include cells that produce ciliary-derived neurotrophic factor for the treatment of ALS and Huntingtons disease, glial-derived neurotrophic factor for Parkinsons disease, erythropoietin for anemia, and HGH for dwarfism. In addition, monogenic diseases such as haemophilia, Gaucher's disease and some mucopolysaccharide disorders could also potentially be targeted by encapsulated cells expressing the protein that is otherwise lacking in the patient.