Intravital imaging in spontaneously hypertensive stroke-prone rats-a pilot study.
BACKGROUND
There is growing evidence that endothelial failure and subsequent blood brain barrier (BBB) breakdown initiate cerebral small vessel disease (CSVD) pathology. In spontaneously hypertensive stroke-prone rats (SHRSP) endothelial damage is indicated by intraluminal accumulations of erythrocytes (erythrocyte thrombi) that are not observed with current magnetic resonance imaging techniques. Two-photon microscopy (2 PM) offers the potential for real-time direct detection of the small vasculature. Thus, within this pilot study we investigated the sensitivity of 2 PM to detect erythrocyte thrombi expressing initiating CSVD phenomena in vivo.


METHODS
Eight SHRSP and 13 Wistar controls were used for in vivo imaging and subsequent histology with haematoxylin-eosin (HE). For 2 PM, cerebral blood vessels were labeled by fluorescent Dextran (70 kDa) applied intraorbitally. The correlation between vascular erythrocyte thrombi observed by 2 PM and HE-staining was assessed. Artificial surgical damage and parenchymal Dextran distribution were analyzed postmortem.


RESULTS
Dextran was distributed within the small vessel walls and co-localized with IgG.Artificial surgical damage was comparable between SHRSP and Wistar controls and mainly affected the small vasculature. In fewer than 20% of animals there was correlation between erythrocyte thrombi as observed with 2 PM and histologically with HE.


CONCLUSIONS
Contrary to our initial expectations, there was little agreement between intravital 2 PM imaging and histology for the detection of erythrocyte thrombi. Two-photon microscopy is a valuable technique that complements but does not replace the value of conventional histology.
Department of Neurology, Otto-von-Guericke-University, Leipziger Strasse 44, 39120 Magdeburg, Germany. Solveig.niklass@med.ovgu.de.
Solveig
S
Niklass
Stoyan
S
Stoyanov
Cornelia
C
Garz
Celine Z
CZ
Bueche
Stine
S
Mencl
Klaus
K
Reymann
Hans-Jochen
HJ
Heinze
Roxana O
RO
Carare
Christoph
C
Kleinschnitz
Stefanie
S
Schreiber