Extended Data Figure 2. Scf is expressed by most endothelial cells but not by Tcf21⁺ perivascular cells in the liver; Cy+21d G-CSF does not significantly change the recombination pattern of Tcf21-Cre/ER in the spleen, bone marrow or liver.

To identify Cre alleles that recombine in spleen, but not bone marrow, stromal cells we assessed the gene expression profile of spleen Scf-GFP⁺VE-cadherin⁻ stromal cells (Extended Data Table 1). Nestin, NG2 (Cspg4), and Prx1 were low or undetectable (data not shown). Nestin-Cre³¹, NG2-Cre³², NG2-Cre/ER³³, and Prx1-Cre³⁴ did not recombine widely or specifically in Scf-GFP⁺ stromal cells in the spleen (data not shown). Pdgfra and Pdgfrb were expressed by spleen Scf-GFP⁺ stromal cells but neither Pdgfra-Cre/ER³⁵ nor Pdgfrb-Cre³⁶ recombined efficiently (data not shown). Sm22 (Tagln), Myh11, Sma (Acta2), and Tcf21 were significantly more highly expressed by spleen than bone marrow Scf-GFP⁺ stromal cells (Extended Data Table 1). Sm22-Cre³⁷, Myh11-Cre³⁸, and Sma-Cre/ER³⁹ recombined in few spleen Scf-GFP⁺ stromal cells (data not shown). However, Tcf21-Cre/ER recombined in perivascular stromal cells in the spleen but not bone marrow (Figure 2). a-c, Under normal conditions, Scf-GFP was expressed by most VE-cadherin⁺ endothelial cells (arrowheads in a) but not by Tcf21⁺ stromal cells (arrows in a) in the liver (n=3 mice from 3 independent experiments). d, e, EMH induced by Cy+21day G-CSF did not alter the general distribution (d) or perivascular localization (e) of Tomato⁺ cells in the spleens of Tcf21^cre/ER; R26^tdTomato mice as compared to normal mice (Fig. 2a and 2d). f, g, Tomato expression was undetectable in the bone marrow of Tcf21^cre/ER; R26^tdTomato mice after Cy+G-CSF treatment irrespective of whether the bone marrow was analyzed by whole-mount imaging (f) or flow cytometry (g). h, i, EMH induced by Cy+G-CSF did not significantly change the frequency (h) or perivascular localization (i, arrows) of Tomato⁺ cells in the livers of Tcf21^cre/ER; R26^tdTomato mice. (d-i, n=3 mice from 3 independent experiments)