Abstract: The invention relates to methods for promoting maturation of islet cells from pre-weaned mammals for the purpose of optimizing the islets for their use as donor tissue for xenotransplantation. The method of the invention removes the pancreas from donor animals and reduces the pancreas tissue to fragments that are greater than the size of an intact islet while retaining islets in their whole, insulin-producing condition. The method of the invention also serially cultures the digested tissue in novel maturation media that enhance the glucose responsiveness of the cultured islets, and selects islets that are sufficiently glucose-responsive for use in transplantation procedures.

Abstract: The present invention provides novel, biocompatible matrices for cell encapsulation and transplantation. It further provides methods for delivering agents to encapsulated cells and to the local environment of a host system. The invention also provides methods for targeting and manipulating particular cells and/or proteins of the host system. In a composition aspect of the invention, a composition including a collection of capsules is provided. The capsules comprise an inner core, and the inner core is covered by an outer shell composed of a positive polyelectrolyte and a negative polyelectrolyte. The inner core of the capsules contains at least one cell.