title: Neural stem cells transplanted to the subretinal space of rd1 mice delay retinal degeneration by suppressing microglia activation.
abstract: Retinal degeneration (RD) is an inherited eye disease characterized by irreversible photoreceptor loss. Conventionally, the activation of the resident microglia is secondary to the disease. Stem cell-based therapy has recently made rapid progress in treating RD. Although it has been demonstrated that the effect of stem cell therapy may include immunomodulation, the specific mechanisms have not been clarified.
  
  
  
  Immunocytochemistry, terminal deoxynucleotidyl transferase UTP nick end labelling (TUNEL) assay and Western blot were used to analyze the microglia activation and photoreceptor apoptosis in the retina of rd1 mice. GFP-C17.2 neural stem cells (NSCs) were transplanted into the subretinal space to study the immunomodulatory and neuroprotective effects. The transwell co-culture of BV2 cells with GFP-C17.2 was performed to study the proliferation, apoptosis and secretion levels of inflammatory factors. Real time-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were performed to explore the gene and protein level of factors secreted by NSCs and microglia.
  
  
  
  TUNEL-positive cells were primarily distributed in the inner nuclear layer (INL) of rd1 mice on P8d, appeared in the outer nuclear layer (ONL) on P10d and peaked on P14d. Meanwhile, microglia migrated to the ONL and reached the maximum level, accompanied by the changes in the levels of fractalkine and its unique receptor CX3CR1 protein. After transplantation of NSCs on P7d into the subretinal space of rd1 mice, the activated microglia were inhibited and the degeneration of ONL was delayed. In addition, microglia activation was suppressed by co-cultured NSCs in vitro. The gene and protein level of tissue inhibitor of metalloproteinase (TIMP1) in NSCs was elevated, whereas that of matrix metalloproteinase (MMP9) in BV2 microglia was markedly suppressed in this co-culture system.
  
  
  
  Transplanted NSCs in the retina exerted immunomodulatory effects on microglia, thus delaying the degeneration of photoreceptors.
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Zhengya
authors.initials: Z
authors.lastname: Li
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Yuxiao
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Qiyou
authors.initials: Q
authors.lastname: Li
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China.
authors.forename: Langyue
authors.initials: L
authors.lastname: Xue
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China. Electronic address: haiweixu2001@163.com.
authors.forename: Haiwei
authors.initials: H
authors.lastname: Xu
authors.affiliation: Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing, China; Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing, China. Electronic address: qinzyin@aliyun.com.
authors.forename: Zheng Qin
authors.initials: ZQ
authors.lastname: Yin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D000073883:CX3C Chemokine Receptor 1; D002460:Cell Line; D054428:Chemokine CX3CL1 / Q000378:metabolism; D018920:Coculture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D056747:Immunomodulation / Q000276:immunology; D020287:In Situ Nick-End Labeling; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D017628:Microglia / Q000378:metabolism*; D058953:Neural Stem Cells / Q000637:transplantation*; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology*; D060888:Real-Time Polymerase Chain Reaction; D019707:Receptors, Chemokine / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D012162:Retinal Degeneration / Q000517:prevention & control / Q000628:therapy*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D000073883:CX3C Chemokine Receptor 1; C095235:CX3CR1 protein, human; D054428:Chemokine CX3CL1; C471885:Cx3cr1 protein, mouse; D019707:Receptors, Chemokine; C560825:Timp1 protein, mouse; D019715:Tissue Inhibitor of Metalloproteinase-1; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse
keywords: immunomodulation; microglial cells; neural stem cells; retinal degeneration; transplantation