Bone reinnervation after fracture: A study in the rat

Jian Li, Tashfeen Ahmad, Mariana Spetea, Mahmood Ahmed, Andris Kreicbergs

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85 Citations (Scopus)


Reinnervation after tibial fracture in the rat was studied by analyzing the occurrence of growth-associated protein 43 (GAP-43), a marker for regenerating nerve fibers, and protein gene product 9.5 (PGP-9.5), a marker for mature nerve fibers, by immunohistochemistry. At 3 days postfracture, GAP-43-immunoreactive nerve fibers were first observed in the fracture hematoma and periosteum. At 7 days postfracture, abundant sprouting of GAP-43-positive fibers was seen in the callus, hyperplastic periosteum, and edge of fibrocartilage. In the latter region, the nerve fibers were nonvascular, showing dense ramifications and terminal sprouting close to chondroid cells. At 14 days and 21 days postfracture, many GAP-43-positive fibers were still sprouting into the fibrocartilage and new woven bone. Fine varicose GAP-43-positive fibers also were present in the bone marrow. In contrast to GAP-43, PGP-9.5-positive nerve fibers were observed only occasionally at 3 days postfracture but gradually increased in number from day 14 to 21. Our study shows that intense nerve regeneration occurs in early fracture healing partly unrelated to neovascularization. Considering that neuronal mediators have been shown to participate in local bone formation and resorption, the nerve regeneration observed may prove to be essential for delivery of neuronal mediators required for normal callus formation and/or neovascularization.

Original languageEnglish
Pages (from-to)1505-1510
Number of pages6
JournalJournal of Bone and Mineral Research
Issue number8
Publication statusPublished - 2001
Externally publishedYes


  • Fracture callus
  • Fracture healing
  • Growth-associated protein 43
  • Nerve regeneration
  • Protein gene product 9.5


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