Fig 1.
Confirmation of clodronate-induced monocyte depletion.
A) Gating strategy for blood monocytes. B) Time line showing clodronate-induced monocyte depletion in mice from 24hrs to 72hrs after a single injection of clodronate as compared to sham-depleted (PBS) controls.
Fig 2.
Schematic approach to define the threshold window for segmentation of ‘lesion area’ and the ventricular space.
MR images corresponding to a TBI mouse at 1, 7, and 14 days post-TBI are shown. The schematic approach to define the threshold window for segmentation of ‘lesion area’ (RED outline) and the ventricular space (BLUE outline) is depicted with the first column showing the MR images at different time points in normal gray scale with contrast optimized for whole brain visualization. The center column depicts the corresponding images in an adjusted threshold scale (S.I.~100–500 a.u.) that facilitates visualization of both lesioned area and ventricular space. The last column superimposes the segmentation of regions of interest with RED outlining the lesion area and BLUE outlining the ventricular space. The progressive ventricular enlargement and corresponding reduction of the lesion area are clearly evident and are consistent with loss of brain tissue.
Fig 3.
Clodronate-mediated monocyte depletion attenuates ventricle enlargement but not lesion size after traumatic brain injury.
A) Representative axial T1W MR images of a TBI/Clodronate treated mouse (a-c) and a TBI/PBS treated mouse (d-f) on post-TBI days 1, 7, and 14. ‘Lesion area’ is outlined in RED. B) Representative coronal T1W MR images of the corresponding TBI/Clodronate treated mouse (g-i) and TBI/PBS treated mouse (j-l) at 1, 7, and 14 days post-TBI. The hyperattenuating area denotes the progressive enlargement of ventricle size over time. C) No significant difference in lesion size was detected at any time point between monocyte-depleted and sham-depleted mice (5 ± 1.1mm3 vs 7.3 ± 1.06mm3; p = 0.4). D) At 14 days post-TBI clodronate depletion markedly attenuated ventricle enlargement (5.3 ± 0.9mm3) as compared to sham-depleted mice(13.2 ± 3.1mm3; ** p = 0.02).
Fig 4.
3D renderings of ventricle enlargement in monocyte-depleted vs. sham-depleted mice after traumatic brain injury.
A) Shown in RED is the extent of traumatically injured tissue at post injury days 1, 7, and 14. Shown in light BLUE is the ventricle size. There is a progressive increase in ventricle size and decrease in injured tissue indicating loss of brain tissue and replacement with cerebrospinal fluid over the course of injury. At 14 days post-TBI the increase in ventricle size between B) monocyte-depleted mice (5.3 ± 0.9mm3) and C) sham-depleted mice (13.2 ± 3.1mm3) is markedly attenuated (p = 0.02) indicating preservation of the injured neuronal matter.
Fig 5.
Global fractional anisotropy pattern alterations in monocyte-depleted vs. sham-depleted mice after traumatic brain injury.
A) At 14 days post—injury the volume of fractional anisotropy above threshold was significantly higher in monocyte-depleted mice (123.0 ± 4.4mm3) as compared to sham depleted mice (94.9 ± 4.6mm3; * p = 0.025), although both were lower compared to Naïve mice (216 ± 3.8mm3; ** p<0.0001). B) Side by side 3D-rendered representative images of fractional anisotropy patterns in monocyte-depleted vs. sham-depleted mice. Noticeable is the progressive loss of pattern as the injury progresses. The volume of FA and a representative 3D-rendered FA pattern from a naïve mouse is provided for comparison.
Fig 6.
Representative quantitative fractional anisotropy (FA) map 14-days post injury.
White arrows showing regions of reduced/altered FA patterns in a sham-depleted mouse as compared to a monocyte-depleted mouse.