title: Low-frequency electrical stimulation induces the proliferation and differentiation of peripheral blood stem cells into Schwann cells.
abstract: BACKGROUND
  Functional recovery after peripheral nerve injury remains a tough problem at present. Specifically, a type of glial cell exists in peripheral nerves that promotes axonal growth and myelin formation and secretes various active substances, such as neurotrophic factors, extracellular matrix and adherence factors. These substances have important significance for the survival, growth and regeneration of nerve fibers. Numerous recent studies have shown that electrical stimulation can increase the number of myelinated nerve fibers. However, whether electrical stimulation acts on neurons or Schwann cells has not been verified in vivo. This study investigates low-frequency electrical stimulation-induced proliferation and differentiation of peripheral blood stem cells into Schwann cells and explores possible mechanisms.
  
  
  METHODS
  Peripheral blood stem cells from Sprague-Dawley rats were primarily cultured. Cells in passage 3 were divided into 4 groups: a low-frequency electrical stimulation group (20 Hz, 100 μs, 3 V), a low-frequency electrical stimulation+PD98059 (blocking the extracellular signal-regulated kinase [ERK] signaling pathway) group, a PD98059 group and a control group (no treatment). After induction, the cells were characterized. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazoliumbromide assay was employed to measure the absorbance values at 570 nm in the 4 groups. A Western blot assay was used to detect the expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4) in each group.
  
  
  RESULTS
  No significant difference in cell viability was detected before induction. Peripheral blood stem cells from the 4 groups differentiated into Schwann cells. Phosphorylated ERK 1/2, cyclin D1 and CDK4 protein levels were highest in the low-frequency electrical stimulation group and lowest in the ERK blockage group. Phosphorylated ERK 1/2, cyclin D1 and CDK4 protein levels in the low-frequency electrical stimulation+ERK blockage group were lower than those in the low-frequency electrical stimulation group but higher than those in the ERK blockage group.
  
  
  CONCLUSIONS
  Low-frequency electrical stimulation contributed to the proliferation of peripheral blood stem cells cultured in vitro and induced differentiation into Schwann cells. The ERK signaling pathway underlies cell proliferation and differentiation.
authors.affiliation: Rehabilitation Medicine Center (XG, JF, JB, JW, WP), The Second Hospital of Jiaxing, Jiaxing, China; and Molecular Biology Laboratory (CZ), Jiaxing University, Jiaxing, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Gu
authors.forename: Jianming
authors.initials: J
authors.lastname: Fu
authors.forename: Jing
authors.initials: J
authors.lastname: Bai
authors.forename: Chengwen
authors.initials: C
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Wenping
authors.initials: W
authors.lastname: Pan
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000096:biosynthesis; D051358:Cyclin-Dependent Kinase 4 / Q000096:biosynthesis; D004558:Electric Stimulation; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012583:Schwann Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: C530106:Ccnd1 protein, rat; D005419:Flavonoids; D047428:Protein Kinase Inhibitors; D019938:Cyclin D1; C495903:Cdk4 protein, rat; D051358:Cyclin-Dependent Kinase 4; D048052:Mitogen-Activated Protein Kinase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one