Frontiers in Neurology (Mar 2018)

Local Delivery Is Critical for Monocyte Chemotactic Protein-1 Mediated Site-Specific Murine Aneurysm Healing

  • Siham Hourani,
  • Kartik Motwani,
  • Daisuke Wajima,
  • Hanain Fazal,
  • Chad H. Jones,
  • Sylvain Doré,
  • Koji Hosaka,
  • Brian L. Hoh

DOI
https://doi.org/10.3389/fneur.2018.00158
Journal volume & issue
Vol. 9

Abstract

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BackgroundLocal delivery of monocyte chemotactic protein-1 (MCP-1/CCL2) via our drug-eluting coil has been shown to promote intrasaccular aneurysm healing via an inflammatory pathway.ObjectiveIn this study, we validate the importance of local MCP-1 in murine aneurysm healing. Whether systemic, rather than local, delivery of MCP-1 can direct site-specific aneurysm healing has significant translational implications. If systemic MCP-1 is effective, then MCP-1 could be administered as a pill rather than by endovascular procedure. Furthermore, we confirm that MCP-1 is the primary effector in our MCP-1 eluting coil-mediated murine aneurysm healing model.MethodsWe compare aneurysm healing with repeated intraperitoneal MCP-1 versus vehicle injection, in animals with control poly(lactic-co-glycolic) acid (PLGA)-coated coils. We demonstrate elimination of the MCP-1-associated tissue-healing response by knockout of MCP-1 or CCR2 (MCP-1 receptor) and by selectively inhibiting MCP-1 or CCR2. Using immunofluorescent probing, we explore the cell populations found in healed aneurysm tissue following each intervention.ResultsSystemically administered MCP-1 with PLGA coil control does not produce comparable aneurysm healing, as seen with MCP-1 eluting coils. MCP-1-directed aneurysm healing is eliminated by selective inhibition of MCP-1 or CCR2 and in MCP-1-deficient or CCR2-deficient mice. No difference was detected in M2 macrophage and myofibroblast/smooth muscle cell staining with systemic MCP-1 versus vehicle in aneurysm wall, but a significant increase in these cell types was observed with MCP-1 eluting coil implant and attenuated by MCP-1/CCR2 blockade or deficiency.ConclusionWe show that systemic MCP-1 concurrent with PLGA-coated platinum coil implant is not sufficient to produce site-specific aneurysm healing. MCP-1 is a critical, not merely complementary, actor in the aneurysm healing pathway.

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