Sciatic nerve regeneration in KLF7-transfected acellular nerve allografts

Abstract

Objective: Krüppel-like Factor 7 (KLF7) is a transcription factor that promotes axon regeneration in the central nervous system. Here, we assessed whether KLF7 stimulates regeneration after peripheral nerve injury.

Methods: C57BL/6 mice received an acellular nerve allograft (ANA) injected with either adeno-associated virus 2 (AAV2) vector or AAV2-KLF7 for sciatic nerve gap repair. After 4 weeks, KLF7 was detected by RT-PCR, western blot and immunohistochemistry in regenerated nerves. Axonal regeneration and functional recovery were examined by immunohistochemistry, Fluorogold (FG) and cholera toxin B (CTB) retrograde neural tracing, sciatic function index (SFI), angle of ankle, Hargreaves test and electrophysiological analysis.

Results: With AAV2-KLF7 injection, KLF7 expression increased in regenerated nerves, and amplitude, score of SFI, angle of ankle and FG-labelled spinal cord neurons were increased. We observed elevated CTB-labelled neurons in dorsal root ganglia (DRG), neurofilaments, P₀ (peripheral myelin) and S100 and decreased latency period and withdrawal latencies in the Hargreaves test. The SFI was significantly correlated with amplitude and regenerated axon number. Tyrosine kinase A (TrkA) and B (TrkB) receptors were also increased in the DRG.

Conclusions: Our findings suggest that KLF7 promoted peripheral nerve axonal regeneration, further supporting a role for KLF7 as a growth-promoting transcription factor in the injured nervous system.

Keywords:

• KLF7
• Axonal regeneration
• Acellular nerve allograft
• Peripheral nerve injury

Abbreviations:

• acellular nerve allograft (ANA)
• adeno-associated virus 2 (AAV2)
• central nervous system (CNS)
• cholera toxin B (CTB)
• day (d)
• dorsal root ganglia (DRG)
• electroneurogram (ENG)
• Fluorogold (FG)
• glial fibrillary acidic proteins (GFAP)
• Krüppel-like Factor 7 (KLF7)
• neurofilaments (NF)
• peripheral nervous system (PNS)
• sciatic function index (SFI)
• small proline-rich repeat protein 1A (SPRR1A)
• tyrosine kinase A (TrkA)

Acknowledgements

The authors would like to thank the staff of the Experimental Animal Center of China Medical University for providing excellent animal care. The authors also acknowledge Clarity Manuscript Consultants, LLC for assistance with language and grammar review and editing of the manuscript.

Additional information

Funding

This work was supported by the Science Fund Project of the Natural Science Foundation of China [grant number 81371362], [grant number 81374007]; Science Fund Project of Heilongjiang Provincial Health and Family Planning Commission [grant number 2014211], [grant number 2012285]; Natural Science Foundation of Heilongjiang, China [grant number H201491].