|High Islet Density
To minimize trauma, the volume of the final implant should be minimized, as a rule only 2-5 times the volume of the islet. Some devices are mostly 'dead space' and therefore are too large for convenient implantation.
The figure shows some configurations where islets are less than 5% of the total device volume. Islet Sheets can have high tissue density, at least 35% islets.
Data on only a few sheets have been published. Almost all have a low tissue density. (Click here for more.)
The Islet Sheet
The Islet Sheet can be made to a very high islet cell density. The photo to the left shows lightly colored islets crowded close together in the sheet. The fibers are strands of the paper mesh used to strengthen the sheet and permit it to be sutured in place.
The electron micrograph micrograph to the right similarly shows that about a third of the volume of the sheet is islet of Langerhans.