Myelin-associated glycoprotein combined with chitin conduit inhibits painful neuroma formation after sciatic nerve transection

Studies have shown that myelin-associated glycoprotein (MAG) can inhibit axon regeneration after nerve injury. However, the effects of MAG on neuroma formation after peripheral nerve injury remain poorly understood. In this study, local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in rats. After 8 weeks of combined treatment, the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection, the mRNA expression of nerve growth factor, a pain marker, in the proximal nerve stump was decreased, the density of regenerated axons was decreased, the thickness of the myelin sheath was increased, and the ratio of unmyelinated to myelinated axons was reduced. Moereover, the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were decreased. The combined treatment exhibited superior effects in these measures to chitin conduit treatment alone. These findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic pain. This study was approved by the Animal Ethics Committee of Peking University People’s Hospital (approval No. 2019PHE027) on December 5, 2019.