Research Impact of Changes to Guidelines

An ongoing research project is studying antibodies obtained by sacrificing mice.  Following a review of its policies regarding animal subjects, the sponsoring institution determines that only in vitro methods may be used for this in the future.  Any such change in procedure will invalidate all prior results, of course.  Would it be appropriate for the project staff to contract with another institution, where guidelines still allow the original procedure, and send mice there from time to time for antibody harvesting?  If not, would it be appropriate to contract with another institution to perform the entire procedure, using their own mice and only returning the antibodies for final analysis?