FOPPY mice have been developed to produce extra BMP
protein in mouse muscles and they form heterotopic bone
very similar to FOP bone. While awaiting the arrival of mice with
real FOP, the well-known and beloved FOPPY mice continue to
enlighten us. In collaboration with Dr.Lixin Kan and his colleagues
from Northwestern University in Chicago, we conducted detailed
studies (supported by a grant from The Center for Research in
FOP and Related Disorders) to examine the origin of inflammatory
cells that trigger heterotopic ossification following injury as well
as the origin of cells that respond to the increased BMP signal to
form cartilage and bone.
While the results are preliminary, there are some major surprises.
For the meanwhile, let's just say that some normally silent
progenitor cells (or stem cells) in connective tissue are recruited
into action following injury to carry-out the detailed instructions
of cellular and molecular sabotage necessary to form heterotopic
bone. Our ongoing work in the FOPPY mice is aimed at
identifying these cells, deciphering their clandestine
molecular conversations, and using them to probe the process of
heterotopic ossification in FOP. If the same cells are involved in
real FOP, molecular "silver bullets" to "take out" those sleeper
cells may be a therapeutic approach worth pursuing.