Patterns of production of collagen-rich deposits in peripheral nerves in response to injury: A pilot study in a rabbit model

Introduction Although collagen-rich deposits are the main component of neural scars, the patterns of their formation are ill defined. Essential to the biosynthesis of collagen fibrils are enzymes catalyzing posttranslational modifications and chaperones that control the formation of the collagen triple helix. Prolyl-4-hydroxylase (P4H) and heat shock protein-47 (HSP47) play a key role, and their production is upregulated during scar formation in human tissues. Alpha smooth muscle actin (SMA) is also produced during fibrotic processes in myofibroblasts that participate in fibrotic response. In injured peripheral nerves, however, the distribution of cells that produce these markers is poorly understood. Methods The goal of this study was to determine the distribution of the SMA-positive, HSP47-positive, and the P4H-positive cells to better understand the formation of collagen-rich fibrotic tissue (FT) in response to peripheral nerve injury. To reach this goal, we employed a rabbit model of crush-injury and partial-transection injury of the sciatic nerves. Results Our study demonstrated that SMA is expressed in a relatively small number of cells seen in neural FT. In contrast, cells producing P4H and HSP47 are ubiquitously present in sites of injury of the sciatic nerves. Conclusion We contemplate that these proteins may serve as valuable markers that define fibrotic activities in the injured peripheral nerves.