Michael Morin, left, and David Frazier, right, of Latham & Watkins.

Former researchers at the University of Connecticut's Stem Cell Institute helped test a breakthrough in regenarative medicine. But they did not invent it and should not be listed on patents that describe it, a federal judge has ruled.

Friday's decision by U.S. District Judge Allison Burroughs comes in the first virtual patent bench trial in Massachusetts and ends a long-running dispute between Astellas Pharma Inc. and ImStem Biotechnology Inc.