Fibrin Regulates Schwann Cells

Abstract

Injured or diseased peripheral nerves are often accessible to molecules in the circulatory system that can interfere with nerve repair and regeneration. Deposition of fibrin (converted from blood-derived fibrinogen) in such regions correlates with inhibition of nerve remyelination. Akassoglou et al. report that when the mouse sciatic nerve is damaged, fibrin promotes Schwann cell proliferation rather than differentiation, thereby inhibiting myelin production. Absence of fibrin in mice accelerated Schwann cell differentiation to a myelinating, nonproliferating state. Treatment of cultured Schwann cells with fibrin activated mitogen-activation protein kinase and also inhibited expression of myelin and fibronectin, an extracellular matrix protein that stimulates Schwann cell differentiation. The authors propose that fibrin-induced proliferation may be required to accommodate regenerating, elongating axons. Subsequent degradation of fibrin would then allow Schwann cells to differentiate and produce new myelin. K. Akassoglou, W.-M. Yu, P. Akpinar, S. Strickland, Fibrin inhibits peripheral nerve remyelination by regulating Schwann cell differentiation. Neuron 33 , 861-875 (2002). [Online Journal]