PDGFRα inhibition reduces myofibroblast expansion in the fibrotic rim and enhances recovery after ischemic stroke
Jil Protzmann, Manuel Zeitelhofer, Christina Stefanitsch, Daniel Torrente, Milena Z. Adzemovic, Kirils Matjunins, Stella J.I. Randel, Sebastian A. Lewandowski, Lars Muhl, Ulf Eriksson, Ingrid Nilsson, Enming J. Su, Daniel A. Lawrence, Linda Fredriksson
Jil Protzmann, Manuel Zeitelhofer, Christina Stefanitsch, Daniel Torrente, Milena Z. Adzemovic, Kirils Matjunins, Stella J.I. Randel, Sebastian A. Lewandowski, Lars Muhl, Ulf Eriksson, Ingrid Nilsson, Enming J. Su, Daniel A. Lawrence, Linda Fredriksson
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Research Article Neuroscience Vascular biology

PDGFRα inhibition reduces myofibroblast expansion in the fibrotic rim and enhances recovery after ischemic stroke

Abstract

Ischemic stroke is a major cause of disability in adults. Early treatment with thrombolytics and/or thrombectomy can significantly improve outcomes; however, following these acute interventions, treatment is limited to rehabilitation therapies. Thus, identification of therapeutic strategies that can help restore brain function in the post-acute phase remains a major challenge. Here we report that genetic or pharmacologic inhibition of the PDGF-CC/PDGFRα pathway, which has previously been implicated in stroke pathology, significantly reduced myofibroblast expansion in the border of the fibrotic scar and improved outcome in a sensory-motor integration test after experimental ischemic stroke. This was supported by gene expression analyses of cerebrovascular fragments showing upregulation of profibrotic/proinflammatory genes, including genes of the TGF pathway, after ischemic stroke or intracerebroventricular injection of active PDGF-CC. Further, longitudinal intravital 2-photon imaging revealed that inhibition of PDGFRα dampened the biphasic pattern of stroke-induced vascular leakage and enhanced vascular perfusion in the ischemic lesion. Importantly, we found PDGFRα inhibition to be effective in enhancing functional recovery when initiated 24 hours after ischemic stroke. Our data implicate the PDGF-CC/PDGFRα pathway as a crucial mediator modulating post-stroke pathology and suggest a post-acute treatment opportunity for patients with ischemic stroke targeting myofibroblast expansion to foster long-term CNS repair.

Authors

Jil Protzmann, Manuel Zeitelhofer, Christina Stefanitsch, Daniel Torrente, Milena Z. Adzemovic, Kirils Matjunins, Stella J.I. Randel, Sebastian A. Lewandowski, Lars Muhl, Ulf Eriksson, Ingrid Nilsson, Enming J. Su, Daniel A. Lawrence, Linda Fredriksson

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Figure 5

PDGFRα signaling drives expansion of the myofibroblast scar after MCAO.

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PDGFRα signaling drives expansion of the myofibroblast scar after MCAO. ...
Representative images of immunofluorescent stainings and quantifications in brain sections from vehicle and imatinib pretreated mice (A–E) and GFAP-Cre;PDGFRα floxed mice (F–H) collected at 7 dpi. (A) Ipsilateral overview from staining for PDGFRβ. (B) High-magnification images from the fibrotic rim of costaining for PDGFRβ and GFAP. Asterisks: PDGFRβ expression within the astroglial scar. (C) High-magnification images from the fibrotic rim of PDGFRα and PDGFRβ costaining. Two-headed arrows: PDGFRαhiPDGFRβhi cells; arrowheads; PDGFRαloPDGFRβhi cells. (D) High-magnification images from the fibrotic rim of costaining for PDGFRβ and ASMA. Arrows: ASMA+PDGFRβ+ vSMCs. (E) Quantification of PDGFRβ+ scar thickness in the fibrotic rim (demarcated in A) (n = 7–9). Ipsilateral overviews (F) and high-magnification images from the fibrotic rim (G) of staining for PDGFRα and GFAP in GFAP-Cre;PDGFRα floxed mice. (H) Quantification of PDGFRα+ scar thickness in the fibrotic rim (demarcated in F). n = 17 controls (ctrl), n = 8 PDGFRα knockouts (KO). Single-plane (A) and maximum-intensity projections (B–D and G) of confocal images, and stitched epifluorescent tiles (F). Dashed lines demarcate the PDGFRβ+ dense scar (A–D) and the myofibroblast scar (F and G) in the fibrotic rim. Data points represent individual animals and bars the group mean ± SEM. Two-tailed, unpaired t test with Welch’s correction (E and H). ***P < 0.001. Scale bars: 500 μm (A and F); 100 μm (B and D); 50 μm (C and G).