It has long been the holy grail of cell encapsulation to treat 
diabetes with insulin producing cells that are shielded from 
rejection or clearance by the host immune system. Indeed, 
the idea has been around for more than 50 years with the 
first demonstration in an animal model being published in 
1980 and the first patient treated being reported in 1994. In 
the meantime, more clinical experience has been accrued 
with the use of encapsulated cells for the treatment of 
human diabetes. Most of these studies have focused on the 
use of alginate as the encapsulation material and although 
some promising data has been obtained and is reviewed in 
this article, it is still far from being a product that can be 
routinely applied. Cellulose sulphate has excellent 
properties making it ideal for cell encapsulation and has 
been shown to be safe in 27 patients. Moreover, data has 
been obtained showing safety and efficacy in a rat model of 
diabetes supporting that cellulose sulphate might be the 
material of choice for this application.