Urokinase plasminogen receptor and the fibrinolytic complex play a role in nerve repair after nerve crush in mice, and in human neuropathies

PLoS One. 2012;7(2):e32059. doi: 10.1371/journal.pone.0032059. Epub 2012 Feb 21.

Abstract

Remodeling of extracellular matrix (ECM) is a critical step in peripheral nerve regeneration. In fact, in human neuropathies, endoneurial ECM enriched in fibrin and vitronectin associates with poor regeneration and worse clinical prognosis. Accordingly in animal models, modification of the fibrinolytic complex activity has profound effects on nerve regeneration: high fibrinolytic activity and low levels of fibrin correlate with better nerve regeneration. The urokinase plasminogen receptor (uPAR) is a major component of the fibrinolytic complex, and binding to urokinase plasminogen activator (uPA) promotes fibrinolysis and cell movement. uPAR is expressed in peripheral nerves, however, little is known on its potential function on nerve development and regeneration. Thus, we investigated uPAR null mice and observed that uPAR is dispensable for nerve development, whereas, loss of uPAR affects nerve regeneration. uPAR null mice showed reduced nerve repair after sciatic nerve crush. This was a consequence of reduced fibrinolytic activity and increased deposition of endoneurial fibrin and vitronectin. Exogenous fibrinolysis in uPAR null mice rescued nerve repair after sciatic nerve crush. Finally, we measured the fibrinolytic activity in sural nerve biopsies from patients with peripheral neuropathies. We showed that neuropathies with defective regeneration had reduced fibrinolytic activity. On the contrary, neuropathies with signs of active regeneration displayed higher fibrinolytic activity. Overall, our results suggest that enforced fibrinolysis may facilitate regeneration and outcome of peripheral neuropathies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Animals
  • Extracellular Matrix / drug effects
  • Extracellular Matrix / metabolism
  • Female
  • Fibrin / metabolism
  • Fibrinolysis* / drug effects
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Middle Aged
  • Myelin Sheath / drug effects
  • Myelin Sheath / metabolism
  • Myelin Sheath / pathology
  • Nerve Crush*
  • Nerve Regeneration / drug effects
  • Nerve Regeneration / physiology*
  • Peripheral Nervous System Diseases / drug therapy
  • Peripheral Nervous System Diseases / metabolism*
  • Peripheral Nervous System Diseases / pathology
  • Peripheral Nervous System Diseases / physiopathology*
  • Receptors, Urokinase Plasminogen Activator / deficiency
  • Receptors, Urokinase Plasminogen Activator / metabolism*
  • Recombinant Proteins / pharmacology
  • Recombinant Proteins / therapeutic use
  • Sciatic Nerve / drug effects
  • Sciatic Nerve / metabolism
  • Sciatic Nerve / pathology
  • Sciatic Nerve / physiopathology
  • Urokinase-Type Plasminogen Activator / pharmacology
  • Urokinase-Type Plasminogen Activator / therapeutic use

Substances

  • Receptors, Urokinase Plasminogen Activator
  • Recombinant Proteins
  • Fibrin
  • Urokinase-Type Plasminogen Activator