Abstract: A method of determining a suitable microreactor for a predetermined host including identifying a suitable microreactor diameter, optionally identifying a minimum second matrix thickness, and optionally identifying a microreactor having a centrally located microcapsule.

Abstract: Microcapsules and composite microreactors are prepared that immunoisolate living cells such as islet cells or genetically engineered cells. A reduced volume microcapsule is formed by coating a gel matrix particle with a polyamino acid of 15,000 daltons or less molecular weight to reduce volume of the particle by at least 30% as compared to volume prior to coating. A composite microreactor includes the microcapsule containing cell embedded in a gel matrix and provides a molecular weight cutoff that prevents molecules larger than about 400,000 daltons from containing the living cell. A double composite microreactor includes an internal particle that includes an internal particle gel matrix containing a living cell and having a coating, a particle that includes the internal particle embedded in a particle gel matrix and a coating, and a gel super matrix in which the particle is embedded. At least one of the coatings is a volume reducing coating of polyamino acid of 15,000 daltons or less molecular weight.

Abstract: The invention covers a method of implanting a living donor cell into a host animal without inflammatory response or rejection of the donor cell by the host animal, by obtaining an uncoated particle of a biocompatible, temperature-independent gel that encapsulates the living donor cell, wherein the uncoated particle provides a molecular weight cutoff that prevents host animal immune cells from entering the particle, yet does not have to prevent entry of host animal IgG and complement into the particle, and implanting the uncoated particle into the host animal.

Abstract: The invention covers a method of implanting a living donor cell into a host animal without inflammatory response or rejection of the donor cell by the host animal, by obtaining an uncoated particle of a biocompatible, temperature-independent gel that encapsulates the living donor cell, wherein the uncoated particle provides a molecular weight cutoff that prevents host animal immune cells from entering the particle, yet does not have to prevent entry of host animal IgG and complement into the particle, and implanting the uncoated particle into the host animal.