title: Temporal assessment of vascular reactivity and functionality using MRI during postischemic proangiogenenic vascular remodeling.
abstract: Postischemic angiogenesis is an important recovery mechanism. Both arteries and veins are upregulated during angiogenesis, but eventually there are more angiogenic veins than arteries in terms of number and length. It is critical to understand how the veins are modulated after ischemia and then transitioned into angiogenic vessels during the proangiogenic stage to finally serve as a restorative strength to the injured area. Using a rat model of transient focal cerebral ischemia, the hypercapnic blood oxygen level-dependent (BOLD) response was used to evaluate vascular reactivity, while the hyperoxic BOLD and tissue oxygen level-dependent (TOLD) responses were used to evaluate the vascular functionality at 1, 3, and 7days after ischemia. Vessel-like venous signals appeared on R2* maps on days 3 and 7, but not on day 1. The large hypercapnic BOLD responses on days 3 and 7 indicated that these areas have high vascular reactivity. The temporal correlation between vascular reactivity and the immunoreactivity to desmin and VEGF further indicates that the integrity of vascular reactivity is associated with the pericyte coverage as regulated by the VEGF level. Vascular functionality remained low on days 1, 3, and 7, as reflected by the small hyperoxic BOLD and large hyperoxic TOLD responses, indicating the low oxygen consumption of the ischemic tissues. These functional changes in proangiogenic veins may be critical for angiogenesis.
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
authors.forename: Chien-Hsiang
authors.initials: CH
authors.lastname: Huang
authors.affiliation: Experimental Neuroimaging Laboratory, Department of Neurology and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC, USA.
authors.forename: Yen-Yu Ian
authors.initials: YY
authors.lastname: Shih
authors.affiliation: Department of Medical Imaging and Intervention, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan.
authors.forename: Tiing-Yee
authors.initials: TY
authors.lastname: Siow
authors.affiliation: Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Hsu
authors.affiliation: Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
authors.forename: Chiao-Chi V
authors.initials: CC
authors.lastname: Chen
authors.affiliation: Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
authors.forename: Teng-Nan
authors.initials: TN
authors.lastname: Lin
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan. Electronic address: jaw@ntu.edu.tw.
authors.forename: Fu-Shan
authors.initials: FS
authors.lastname: Jaw
authors.affiliation: Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan. Electronic address: bmcchen@ibms.sinica.edu.tw.
authors.forename: Chen
authors.initials: C
authors.lastname: Chang
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology*; D002550:Cerebral Veins / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D018919:Neovascularization, Physiologic / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D015424:Reperfusion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066253:Vascular Remodeling
keywords: Cerebral ischemia; MRI; Proangiogenesis; Vascular functionality; Vascular reactivity