Extracerebral Tissue Damage in the Intraluminal Filament Mouse Model of Middle Cerebral Artery Occlusion

Abstract

Middle cerebral artery occlusion is the most common model of focal cerebral ischemia in the mouse. In the surgical procedure, the external carotid artery (ECA) is ligated; however, its effect on the tissue supplied by the vessel has not been described so far. C57BL/6 mice underwent 1 h of transient MCAO (tMCAO) or sham surgery. Multi-spectral optoacoustic tomography was employed at 30 min after surgery to assess oxygenation in the temporal muscles. Microstructural changes were assessed with magnetic resonance imaging and histological examination at 24 h and 48 h after surgery. Ligation of the ECA resulted in decreased oxygenation of the left temporal muscle in most sham-operated and tMCAO animals. Susceptible mice of both groups exhibited increased T2 relaxation times in the affected muscle with histological evidence of myofibre degeneration, interstitial edema, and neutrophil influx. Ligatures had induced an extensive neutrophil-dominated inflammatory response. ECA ligation leads to distinct hypoxic degenerative changes in the tissue of the ECA territory and to ligature-induced inflammatory processes. An impact on outcome needs to be considered in this stroke model.

Noninvasive detection of acute cerebral hypoxia and subsequent matrix-metalloproteinase activity in a mouse model of cerebral ischemia using multispectral-optoacoustic-tomography

“…Surgeries for tMCAO and sham were performed as described before. 26 Anaesthesia was initiated using 3% isoflurane (Abbott, Cham, Switzerland) in a 1∶4 oxygen/air mixture and maintained at 2%. Before the surgical procedure, a local analgesic (Lidocaine, 0.5%, 7 mg∕kg, Sintectica S.A., Switzerland) was administered subcutaneously (s.c.…”

“…A MSOT inVision 128 imaging system (iThera Medical, Germany) was used as described previously. 26 Briefly, a tunable (680 to 980 nm) optical parametric oscillator pumped by an Nd:YAG laser provides 9-ns excitation pulses at a framerate of 10 Hz with a wavelength tuning speed of 10 ms and a peak pulse energy of 100 mJ at 730 nm. Ten arms, each containing an optical fiber bundle, provide even illumination of a ringshaped light strip with a width of ∼8 mm.…”

Non-invasive detection of matrix-metalloproteinase activity in a mouse model of cerebral ischemia using multispectral optoacoustic tomography

“…Thirteen male C57BL/6J mice (Janvier, France), weighting 20-25 g, 10-weeks-of-age were included in the study. Nine mice underwent tMCAO surgery, and four mice underwent sham-operation as described before [12]. During surgery, mice were given local analgesia and kept under isoflurane anaesthesia, maintaining the body temperature at 36.5 ± 0.5 °C.…”

“…MMP-activatable probe was incubated with human recombinant MMP-9 or trypsin in vitro and the solution was placed in an agar phantom. A MSOT inVision 128 imaging system (iThera Medical, Germany) was used as described previously [12]. Briefly, a tunable (680-980 nm) optical parametric oscillator pumped by an Nd:YAG laser provides 9 ns excitation pulses at a framerate of 10 Hz with a wavelength tuning speed of 10 ms and a peak pulse energy of 100 mJ at 730 nm.…”

“…In tMCAO mouse MMP activity was observed in the ischemic lesion delineated on T 2 -weighted MR images compared to contralateral hemisphere and sham-operated animals at 48 h after reperfusion (Figure 3). Extracerebral MMP activity was observed in animals likely caused by muscle damage that is caused by the ligation of the extracarotid artery which is required in the tMCAO model [12] In non-injected tMCAO mice, no MMP signal was observed over the lesion. We quantified the lesion size in tMCAO mice in vivo using T 2 -weighted MRI at 48 h after reperfusion and ex vivo using TTC staining (Figure 4).…”