Direct intrathecal implantation of mesenchymal stromal cells leads to enhanced neuroprotection via an NFkappaB-mediated increase in interleukin-6 production.
Mesenchymal stromal cell (MSC) therapy has shown promise for the treatment of traumatic brain injury (TBI). Although the mechanism(s) by which MSCs offer protection is unclear, initial in vivo work has suggested that modulation of the locoregional inflammatory response could explain the observed benefit. We hypothesize that the direct implantation of MSCs into the injured brain activates resident neuronal stem cell (NSC) niches altering the intracerebral milieu. To test our hypothesis, we conducted initial in vivo studies, followed by a sequence of in vitro studies. In vivo: Sprague-Dawley rats received a controlled cortical impact (CCI) injury with implantation of 1 million MSCs 6 h after injury. Brain tissue supernatant was harvested for analysis of the proinflammatory cytokine profile. In vitro: NSCs were transfected with a firefly luciferase reporter for NFkappaB and placed in contact culture and transwell culture. Additionally, multiplex, quantitative PCR, caspase 3, and EDU assays were completed to evaluate NSC cytokine production, apoptosis, and proliferation, respectively. In vivo: Brain supernatant analysis showed an increase in the proinflammatory cytokines IL-1alpha, IL-1beta, and IL-6. In vitro: NSC NFkappaB activity increased only when in contact culture with MSCs. When in contact with MSCs, NSCs show an increase in IL-6 production as well as a decrease in apoptosis. Direct implantation of MSCs enhances neuroprotection via activation of resident NSC NFkappaB activity (independent of PI3 kinase/AKT pathway) leading to an increase in IL-6 production and decrease in apoptosis. In addition, the observed NFkappaB activity depends on direct cell contact.
Walker
Peter A
PA
Department of Surgery, University of Texas Medical School at Houston, Houston, Texas 77030, USA.
Harting
Matthew T
MT
Jimenez
Fernando
F
Shah
Shinil K
SK
Pati
Shibani
S
Dash
Pramod K
PK
Cox
Charles S
CS
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D003470:Culture Media; D019610:Cytoprotection / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D007278:Injections, Spinal; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D008156:Luciferases / Q000378:metabolism; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D019919:Prosthesis Implantation; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects / Q000637:transplantation; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D003470:Culture Media; D015850:Interleukin-6; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D008156:Luciferases