The present invention is based on the discovery that a true tissue
morphogen such as OP-1 provided systemically, alone in its mature dimeric
form, or as part of a soluble complex, can induce new replacement tissue
regeneration at a localized, permissive defect site distal to the site of
administration. Specifically, systemically administered protein is
sufficient to induce formation of new functional replacement tissue,
sufficient to repair a local defect in a tissue, including skeletal or
orthopedic tissues, liver, pancreas, lung, cardiac, renal, uterine,
intestinal, gastrointestinal tissue. (As used herein, "orthopedic" or
"skeletal" or "joint" or "chondrogenic" tissue is understood to encompass
the skeletal and skeletal joint tissues: bone, cartilage, tendon,
ligament, and synovial membrane tissues.) It further has been discovered
that a single injection of morphogenic protein is sufficient to induce
the desired biological effect, and that administration is not
time-sensitive, provided mesenchymal progenitor cells are accessible to
the defect site. That is, morphogenic protein can be provided to an
individual having a local permissive defect site, shortly after creation
of the defect, or at some significant time later, including, without
limitation, after the initiation of fibrotic tissue formation. Thus,
means now are available for enhancing restoration of tissue function
and/or repair or regeneration of functional replacement tissue by
systemically administering morphogenic protein, at times significantly
after creation of the defect. The methods and formulations can be used to
repair local defects without requiring surgical intervention; can enhance
the rate and quality of new replacement tissue formation, particularly in
compromised individuals with a reduced capacity to undergo spontaneous
healing, and can be used to induce new tissue formation even after the
initiation of fibrosis at the defect site. This discovery is disclosed in
copending U.S. Patent Application filed on even date herewith, the
disclosure of which is incorporated herein by reference.