Microreactor and method of determining a microreactor suitable for a predetermined mammal

A microreactor comprising:

• a. a microcapsule comprising a first matrix and a living agent disposed in said first matrix;
• b. a semipermeable membrane surrounding said microcapsule;
• and
• c. a second matrix surrounding said semipermeable membrane, said microreactor, when implanted a higher order mammal for at least 14 days, exhibiting no greater than 25% fibrosis.

A microreactor comprising:

• a microcapsule;
• a semipermeable membrane surrounding said microcapsule, said semipermeable membrane comprising a component capable of eliciting a fibrotic response from a higher order mammal;
• and
• a second matrix surrounding said semipermeable membrane,
• said second matrix being of a thickness sufficient to prevent nucleation of fibrosis by said semipermeable membrane when said microreactor is implanted in a higher order mammal for at least 14 days.

A method of identifying a microreactor suitable for implantation in a predetermined mammal, said method comprising:

• implanting at least one microcapsule in a plurality of the predetermined mammal, the average diameter of the at least one microcapsule implanted in the mammals of one set of mammals being different from the average diameter of the at least one microcapsule implanted in the mammals of at least one other set of mammals;
• explanting said microcapsules from the mammals after a period predetermined to be sufficient to elicit a fibrotic response;
• analyzing the amount of fibrosis present on the surface of the explanted microcapsules;
• determining whether the microcapsules of a set exhibit an average of no greater than 25% fibrosis,
• if such a microcapsule is present, identifying the average diameter of the microcapsule as being suitable for implantation in the mammal;
• and
• if such a microcapsule is not present, repeating said implanting, explanting, analyzing and determining until a microcapsule exhibiting no greater than 25% fibrosis is present, and identifying the average diameter of said microcapsule.

A method of identifying a microreactor suitable for implantation in a predetermined mammal, said method comprising:

• implanting at least one microreactor in a plurality of the predetermined mammal, said microreactor comprising a microcapsule, a semipermeable membrane surrounding said microcapsule and a second matrix surrounding said semipermeable membrane, the composition of said semipermeable membrane being capable of eliciting a fibrotic response from the predetermined mammal,
• the second matrix thickness of the microreactors implanted in the mammals of one set of mammals being different from the second matrix thickness of the microreactors implanted in the mammals of at least one other set of mammals;
• explanting said microreactors from said mammals after a period predetermined to be sufficient to elicit a fibrotic response to a foreign body from the predetermined mammal;
• determining whether the microreactors of a set are, on average, free of nucleated fibrosis;
• and,
• if a microreactor is free of nucleated fibrosis, identifying the thickness of the second matrix of the microreactor as being suitable for implantation in the predetermined mammal,
• if a microreactor exhibits nucleated fibrosis, repeating said implanting, explanting and determining until a second matrix thickness suitable for implantation in the predetermined mammal is identified.

A method of selecting a microreactor for implantation in a mammal, said method comprising:

• a. identifying a microreactor comprising
• i. a microcapsule said microcapsule comprising
• a first matrix,
• a living agent disposed in said first matrix, and
• a semipermeable membrane surrounding said first matrix, and
• ii. a second matrix surrounding said semipermeable membrane, said microcapsule being essentially centrally located in said second matrix, the average distance between the exterior surface of said microcapsule and the exterior surface of said second matrix being at least 600 um,
• b. removing said microreactor from a plurality of microreactors.