title: Promotion of peripheral nerve regeneration of a peptide compound hydrogel scaffold.
abstract: BACKGROUND
  Peripheral nerve injury is a common trauma, but presents a significant challenge to the clinic. Silk-based materials have recently become an important biomaterial for tissue engineering applications due to silk's biocompatibility and impressive mechanical and degradative properties. In the present study, a silk fibroin peptide (SF16) was designed and used as a component of the hydrogel scaffold for the repair of peripheral nerve injury.
  
  
  METHODS
  The SF16 peptide's structure was characterized using spectrophotometry and atomic force microscopy, and the SF16 hydrogel was analyzed using scanning electron microscopy. The effects of the SF16 hydrogel on the viability and growth of live cells was first assessed in vitro, on PC12 cells. The in vivo test model involved the repair of a nerve gap with tubular nerve guides, through which it was possible to identify if the SF16 hydrogel would have the potential to enhance nerve regeneration. In this model physiological saline was set as the negative control, and collagen as the positive control. Walking track analysis and electrophysiological methods were used to evaluate the functional recovery of the nerve at 4 and 8 weeks after surgery.
  
  
  RESULTS
  Analysis of the SF16 peptide's characteristics indicated that it consisted of a well-defined secondary structure and exhibited self-assembly. Results of scanning electron microscopy showed that the peptide based hydrogel may represent a porous scaffold that is viable for repair of peripheral nerve injury. Analysis of cell culture also supported that the hydrogel was an effective matrix to maintain the viability, morphology and proliferation of PC12 cells. Electrophysiology demonstrated that the use of the hydrogel scaffold (SF16 or collagen) resulted in a significant improvement in amplitude recovery in the in vivo model compared to physiological saline. Moreover, nerve cells in the SF16 hydrogel group displayed greater axon density, larger average axon diameter and thicker myelin compared to those of the group that received physiological saline.
  
  
  CONCLUSIONS
  The SF16 hydrogel scaffold may promote excellent axonal regeneration and functional recovery after peripheral nerve injury, and the SF16 peptide may be a candidate for nerve tissue engineering applications.
authors.affiliation: Department of Orthopaedics, The 2nd Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Guo-Jun
authors.initials: GJ
authors.lastname: Wei
authors.forename: Meng
authors.initials: M
authors.lastname: Yao
authors.forename: Yan-Song
authors.initials: YS
authors.lastname: Wang
authors.forename: Chang-Wei
authors.initials: CW
authors.lastname: Zhou
authors.forename: De-Yu
authors.initials: DY
authors.lastname: Wan
authors.forename: Peng-Zhen
authors.initials: PZ
authors.lastname: Lei
authors.forename: Jian
authors.initials: J
authors.lastname: Wen
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Lei
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Dong
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D005260:Female; D005349:Fibroins / Q000737:chemistry / Q000494:pharmacology; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry* / Q000494:pharmacology; D009416:Nerve Regeneration / Q000187:drug effects*; D010316:Particle Size; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000187:drug effects / Q000293:injuries / Q000648:ultrastructure; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D010455:Peptides; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005349:Fibroins
keywords: hydrogel; peptide; peripheral nerve injury; scaffold; silk fibroin