A potential strategy to avoid or further reduce potential rejection of an organ by a recipient may be to ‘slow’ accumulate the presence of the foreign body into the system over a long period of time. This could work potentially with both biological and synthetic (plastic and metal) organs.
Developing a tolerance to the foreign body would likely reduce the shock to the system instead of only suppressing the immune response. It also has the added benefit of giving advance notice of whether the reaction to a foreign body will be strong or weak. You can likely multiply the foreign body surface proteins to try some level of exposure and continue it as a course.
Just a random thought.