The potential therapeutic applications of encapsulated cells are enorm
ous. In the US alone, it has been estimated that nearly half-a-trillio
n dollars are spent each year to care for patients who suffer tissue l
oss or dysfunction. Over 6 million patients suffer from neurodegenerat
ive disorders such as Alzheimer's disease and Parkinson's disease, ove
r 14 million patients suffer from diabetes, and millions more from liv
er failure, hemophilia, and other diseases caused by the loss of speci
fic vital cellular functions. It appears likely that by the end of the
decade clinical trials of encapsulated cells to treat many of these d
iseases will become a reality. The Food and Drug Administration has al
ready authorized studies to evaluate the safety and biological activit
y of several types of systems. A number of issues will have to be addr
essed, including the sourcing of raw materials, the design and buildin
g of manufacturing facilities, the scale-up and optimization process,
storage and distribution of the product, and quality control.