Multi-layer hydrogel capsules for encapsulation of cells and cell aggregates

A population of hydrogel capsules consisting essentially of hydrogel capsules that have a mean diameter, as measured by confocal microscopy, of at least 1.1 mm and less than 8 mm, wherein the hydrogel capsules:

• (i) encapsulate mammalian cells selected from the group consisting of hepatocytes, islet cells, undifferentiated precursors of islet cells, partially differentiated precursors of islet cells, parathyroid cells, cells of intestinal origin, insulin-producing cells derived from stem cells, and insulin-producing cells derived from adult cells;
• (ii) consist of two hydrogel layers and an optional acellular core as a third layer, wherein the two hydrogel layers contain a first inner, hydrogel layer comprising the mammalian cells, and a second outer, cell-free hydrogel layer, and wherein the first and second hydrogel layers independently have a three-dimensional open-lattice polymeric structure formed by crosslinking of a biocompatible hydrogel-forming polymer;
• and
• (iii) are spheres or ellipsoids having semi-principal axes within 10% of each other.