. Author manuscript; available in PMC: 2016 Apr 1.

Published in final edited form as: Microcirculation. 2015 Apr;22(3):168–182. doi: 10.1111/micc.12176

Table 1. Neurovascular Unit-Specific Mouse Lines Expressing Cre or Fluorescent Proteins.

Promoter	Confirmed vascular cell types	Notes	Repository and stock number (if commercially available)
Tie2-GFP [85] Tie2-Cre [64] Tie2-CreER^T2 [39]	EC	Tie2-GFP is well characterized, specific and widely used for imaging the brain endothelium. Tie2-Cre crossed with reporter mouse produces specific, widespread endothelial cell labeling in brain [92]. Brain expression with the Tie2-Cre ER^T2 line is not well characterized	GFP: 003658 Cre: 008863 CreER^T2 : EMMA:00715 Mugen: M201002
Ephrin-B2-H2BGFP [30]	EC	Predominantly expressed in endothelium of cerebral arterioles and capillaries with faint expression in veins [86]. Individual endothelial cell nuclei can be observed.	007843
hVWF-Cre [26]	EC	Not characterized in detail. Cross with Z/EG reporter showed expression only in brain endothelium.
VE-Cad-Cre [3] VE-Cad-CreER^T2 [83]	EC	Not characterized in detail. Crossing of the inducible line with a LacZ reporter mouse reveals widespread expression in cerebral vasculature [14].	Cre: 006137
PDGFB-iCreER^T2 [25]	EC	Cross with fluorescent reporter leads to widespread labeling of cerebral microvessels [21].
Cx40-GCaMP2 [120]	EC	First generation genetically-encoded calcium sensor exhibits widespread endothelium expression. Has not been used in brain.
Alk1-GFP-Cre [91]	EC	Not characterized in detail. Extensive labeling of brain vasculature when crossed with a lacZ reporter mouse.
NG2-DsRed [141] NG2-mEGFP [57] NG2-Cre [141] NG2-CreER™ [142] NG2^+/YFP (knock-in) [62]	PC, SMC, N	NG2-DsRed most commonly used to image individual pericytes in brain, though NG2- CreER™ mice label a similar but less complete profile of cells when crossed with fluorescent reporters. Constitutive NG2-Cre mice reveal extensive neuronal labeling when crossed with Ai14, and may not be useful for imaging (Fig. 2). Oligodendrocyte precursors are also targeted by the NG2 promotor.	DsRed: 008241 mEGFP: 022735 Cre: 008533 CreER™: 008538
B-actin-GFP [98]	PC, EC	Brain pericyte and endothelial cells are broadly labeled for in vivo imaging of microvascular walls [37]. Identity of other labeled cell types unclear.	003291
Rgs5^+/GFP (knock-in) [93]	PC	Evidence of selective labeling of individual brain pericytes [99]. Homozygous mouse shows altered hemodynamics.
PDGFRβ-Cre [27]	PC, SMC, EC, N	Targeting of smooth muscle cells is well established. Pericytes, endothelial cells and some neurons are known to be targeted, but extent of expression is not well characterized (personal communication with V. Lindner).
α-SMA-GFP [137] α-SMA-RFPCherry [104] α-SMA- Cre [133] α-SMA- CreER^T2 [130] α-SMA-exMLCK [59]	PC, SMC	RFPCherry variant shows widespread labeling of arterial SMCs in brain, but pericytes of classical morphology were not reported. The GFP variant has not been evaluated in the brain. The inducible Cre line showed SMC expression when crossed with reporters, but other cell types were not examined in detail. The exMLCK line expresses a FRET-based Ca²⁺-sensor, and has not been used to study cerebral vasculature.
smMHC-Cre [106] smMHC-Cre-GFP [134] smMHC-CreER^T2 [132] smMHC-GCaMP2 [60]	PC, SMC, A, N	Crossing the Cre-GFP line with Ai14 reporters reveals sparse labeling of individual pericytes, astrocytes and neurons, in addition to widespread but incomplete labeling of SMCs (Shih and Kleinfeld, unpublished). The GCaMP2 expressing line has been used to visualize SMC calcium dynamics in vivo, and appears to only label SMCs [65].	Cre-GFP: 007742 CreER^T2: 019079
SM22α/ transgelin- Cre [54, 73] SM22α/ transgelin - CreER^T2 [69]	SMC	Constitutive Cre version may not label vasculature of the brain [40], but further characterization warranted. Inducible Cre version also not yet characterized or used in brain studies.	Cre: 004746
hGFAP-Cre [145] mGFAP-Cre [43] hGFAP-CreER [24] hGFAP-CreER^T2 [42, 53] hGFAP-eGFP [96, 144]	A	Crossing constitutive hGFAP-cre mice with reporters reveals neuronal expression, due to early Cre activity in neuronal progenitors [76]. Inducible forms appear to label individual astrocytes more specifically [12]. GFAP-eGFP mice label a subset of astrocytes in most CNS structures, and have been used to image individual astrocytes and their perivascular endfeet in vivo [58]. There is a labeling bias towards activated astrocytes, which express higher levels of GFAP.	hGFAP-Cre: 004600 mGFAP-Cre: 012886 hGFAP- CreER^T2: 012849 hGFAP-eGFP: 003257
GLAST- CreER^T2 [84, 117, 129] GLAST-DsRed [107]	PC, A	Crossing Pfrieger lab strain [117] with YFP reporter enabled imaging of individual pericytes in spinal cord that serve a scar- forming function [45]. Brain pericyte expression not reported. Götz and Nathans lab strains predominantly express Cre in protoplasmic astrocytes and in a minority of other cell types [84]. GLAST is expressed in some GFAP-negative cells, and extent of labeling can be varied by altering tamoxifen dose [107]. DsRed variant only expresses well in cerebellum [107].	CreER^T2: 012586 (Nathans lab)
Glt1-eGFP [107]	A	Labels nearly all GFAP-positive cells in cortex. Has been used to label individual astrocytes and their perivascular endfeet [105].
Aldh1l1-GFP [44] Aldh1l1-tdTomato [44] Aldh1l1-Cre [44]	A, N	Labels a greater number of astrocytes than does GFAP lines [8]. Aldh1l1-GFP line labels occasional oligodendrocytes and is more specific but less bright than Glt1-GFP animals [135]. Aldh1l1-Cre animals occasionally label some oligodendrocytes, neurons, and neural stem cells [38]. TdTomato variant has not been characterized.	GFP: MMRRC: 011015-UCD tdTomato: MMRRC: 036700-UCD Cre: 023748
Cx30-CreER^T2 [117]	A	Crossing with a reporter enabled visualization of individual astrocytes in all brain regions. Appears specific to astrocytes.
FGFR3-iCreER^T2 [138]	A, N	Highly efficient, widespread labeling of astrocytes with occasional neurons and oligodendrocytes also labeled. The ability to image individual cells depends in part upon the reporter mouse used.
PV-Cre [52] PV-ChR2-eYFP [140]	N	Nearly all neurons expressing Cre were GABAergic but some glutamatergic were noted [125]. Optogenetically stimulating PV interneurons elicits vasoconstriction in vitro. A ChR2-eYFP line may be useful to translate these findings in vivo.	Cre: 008069 ChR2-eYFP: 012355
5-HT3A-GFP [44]	N	Highly specific to 5-HT3a-expressing subtype of GABAergic neurons [72]. Individual cells were imaged in superficial cortex. These neurons release vasoconstrictive and vasodilatory molecules [100].	MMRRC: 000273-UNC
SST-ires-Cre [122] SST-CreER [122]	N	Targets somatostatin-expressing interneurons. The CreER version exhibits low recombination efficiency compared to the constitutive driver.	Cre: 013044 CreER^T2: 010708
VIP-ires-Cre [122]	N	Targets a small subset of vasoactive intestinal peptide-expressing interneurons.	010908
nNOS-CreER^T2 [122]	N	Labels both Type I and II neuronal nitric oxide synthase-expressing interneurons when crossed with Ai9 reporters.	014541
Chat-ires-Cre [108] Chat-CreER [109] Chat-eGFP [121] Chat-mhChR2-YFP [140]	N	Targets cholinergic neurons of basal forebrain, cortex, striatum and other brain structures. The cortices of mhChR2-YFP and eGFP mice are densely packed with transgene expressing fibers projecting from the basal forebrain. The inducible CreER mice exhibit sparse recombination enabling visualization of full axon and dendritic arbors of cholinergic neurons. These complementary tools have not yet been used to study cholinergic modulation of cerebral blood flow in vivo.	Cre: 006410 CreER: 008364 eGFP: 007902 mhChR2-YFP: 014546
Thy1-YFP-H [36] Thy1-GFP-M [36] Thy1-GCaMP3 [22] Thy1-ChR2-YFP [4] Thy1-NpHR 2.0-YFP [123]	N	Specific for projection neurons in CNS. Labeling in cortex for Thy1-YFP-H and primarily restricted to layer 5 neurons, and sparse layer 2/3 neurons. Thy1-GFP-M exhibits very sparse labeling that permits individual neurons and processes to be observed. Thy1-GCaMP3 mice are useful for calcium imaging. Thy1-ChR2-YFP mice have been used to optically evoke hemodynamic responses.	YFP-H: 003782 GFP-M: 007788 GCaMP3: 017893 ChR2-YFP: 007612 NpHR 2.0- YFP:- 012334
Reporter Lines
Fluorescent reporters Ai 3/6/9/14 [78] Z/EG [97] mT/mG [87] RCE:dual [118]	Cre-dependent expression of fluorescent proteins is possible by placing a floxed transcriptional STOP sequence upstream of a fluorescent protein coding sequence and downstream from a strong, universal promoter such as that of chicken β actin (CAG) or Rosa26. This is the genetic basis for nearly all mouse reporter lines. Some reporter lines such as Z/EG and mT/mG have the additional feature that cells will switch from the expression of one transgene to another when Cre recombinase is active. There are many generations of fluorescent reporter mouse lines (reviewed in [1]), the most recent of which come from the Allen Institute, which offer the brightest and most universal labeling to date [78]. The Ai9/Ai14 reporters are bright, high sensitivity reporters expressing tdTomato, while Ai6 expresses eGFP and Ai3 expresses YFP. RCE:dual mice carry two STOP codons which can be removed independently by Cre of Flp recombinases, leading to eGFP expression.		Ai3: 007903 Ai6: 007906 Ai9: 007909 Ai14: 007914 Z/EG: 003920 mT/mG: 007576 RCE:dual: MMRRC 032036-JAX
Cell activator or inhibitor Ai27/Ai32 [77] Ai35/Ai39 [77]	These lines are useful to target optogenetic actuators to NVU cells. A27 (ChR2-tdTomato) and Ai32 (ChR2-YFP) drive the expression of light-gated ion channel Channelrhodopsin-2, to depolarize target cells. Ai35 (Arch3-GFP) and Ai39 (NpHR3.0- EYFP) expression a light-gated proton pump and chloride pump, respectively, for hyperpolarizing target cells.		Ai27: 012567 Ai32: 012569 Ai35: 012735 Ai39: 014539
Cell activity sensors Ai38 [139] Ai95/Ai96 Ai78D	The Ai38 line enables expression of the genetically-encoded calcium sensor GCaMP3 in target cells. A new variant, GCaMP6, exhibits superior sensitivity to older versions and a reporter mouse line was being developed at the time of writing. Lines optimized for fast (GCaMP6f, Ai95) and slow calcium transients (GCaMP6s, Ai96) will be available. The Ai78D line enables expression of the FRET-based voltage-sensitive fluorescent protein Butterfly 1.2 that has been used for single cell resolution of voltage fluctuations in vivo and was being developed at the time of writing [2].		Ai38: 014538 Ai95: 024105 Ai78D: 023528

A- astrocyte, EC- endothelial cell, N- neuron, PC- pericyte, SMC- smooth muscle cell. Repository stock numbers are from The Jackson Laboratory, unless otherwise noted. Other repositories include 1) Integrated Functional Genomics in Mutant Mouse Models as Tools to Investigate the Complexity of Human Immunological Disease (Mugen), 2) European Mutant Mouse Archive (EMMA), and 3) Mutant Mouse Regional Resource Centers (MMRRC). If a mouse line is not commercially available, the principal investigator whose lab developed the mouse may offer assistance.