Nd stored at 280uC. For tissue staining, samples were fixed in formalin and embedded in paraffin. Table 1 shows the characteristics of the enrolled subjects. Compared with control subjects, DTAAD patients were more likely to have a history of smoking and hypertension.Quantitative Homatropine (methylbromide) real-time PCRTotal RNA was isolated with the Trizol (Invitrogen) method, and cDNA was synthesized with iScrip cDNA Synthesis Kit (Biorad Laboratories) from 1 mg of total RNA. Real-time PCR was performed with the cDNA samples and SYBR Green Supermix (Bio-rad Laboratories) by using a Bio-Rad iCycler iQ RealTime PCR Systems (Bio-rad Laboratories), and the formation of PCR products was monitored by using the SYBR green method. All samples were amplified in triplicate. The relative changes in the amount of transcripts in each sample were 25033180 determined by normalizing with the 18S ribosomal RNA levels. The sequences of the primers for Notch1 used in real-time PCR were as follows: forward primer 59-GCAGTTGTGCTCCTGAAGAA-39; reverse primer 59-CGGGCGGCCAGAAAC-39.Double immunofluorescence stainingFor double immunofluorescence staining, paraffin-embedded tissues were cut into 4 mm sections, deparaffinized, rehydrated, and then subjected to antigen retrieval. Tissue sections were incubated with primary antibodies overnight at 4uC, followed by incubation with secondary antibodies for 1 hour at room temperature. The nuclei were counterstained for visualization with 49, 6- diamidino-2-phenylindole. The primary antibodies used were anti-Stro-1 (R D Systems, Minneapolis, MN), antiCD34 (Cell Signaling Technology), anti-SM22-a (Abcam, Cambridge, MA), anti-ER-TR7 (Santa Cruz Biotechnology), antiCD68 (Abcam), anti-Notch1 (Santa Cruz Biotechnology), antiactivated Notch1 (Abcam), BIBS39 custom synthesis anti-Jagged1 (Santa Cruz Biotechnology), anti-Delta (Santa Cruz Biotechnology), and anti-Hes1 (EMD Millipore). Table 2 provides detailed information on the primary antibodies. The secondary antibodies used were Alexa Fluor 488-, Alexa Fluor 568-, and Alexa Fluor 647-conjugated anti-immunoglobulin G (Invitrogen, Carlsbad, CA). Slides treated with normal immunoglobulin G only were used as negative controls. Quantification of the staining results was performed by randomly selecting 4 fields in each slide (n = 4 in each group), and counting target cells at a magnification of 6600 using the software ImagePro Plus 6.0 (Media Cybernetics, Bethesda, MD).Table 1. Patient characteristics.aCharacteristicsControl (n = 12)TAA (n 
= 14) 64.865.5 6 (43 ) 14 (100 ) 13 (93 ) 2 (14 ) 5 (36 ) 6.460.TAD (n = 16) 63.865.6 11 (69 ) 12 (75 ) 16 (100 ) 1 (6 ) 5 (31 ) 6.361.pValues 0.07 0.1 0.01 0.001 0.2 0.5 0.Age (y) Men History of smoking Hypertension Diabetes mellitus Taking anti-lipid medication59.168.2 4 (33 ) 6 (50 ) 6 (50 ) 4 (33 ) 2 (17 )Aortic diameter at sample site NA (cm)a Age and aortic diameter were compared by using one-way analysis of variance. All other variables were compared by using Pearson’s chi-squared test. NA = not applicable; TAA = thoracic aortic aneurysm; TAD = thoracic aortic dissection. doi:10.1371/journal.pone.0052833.tNotch Signaling in Aortic Aneurysm and DissectionTable 2. Primary antibodies used in the study.Antibody Anti-cleaved Notch1 (D3B8) Anti-Notch1 (D6F11)Source 4147 Cell Signaling 4380 Cell SignalingHost Rabbit RabbitSpecificity Cleaved Notch1 intracellular domain (NICD) (,110 kDa) Full-length (,300 kDa) and the transmembrane/intracellular region NTM (,120 kDa) Human Stro-1 Total CD34 protein S.Nd stored at 280uC. For tissue staining, samples were fixed in formalin and embedded in paraffin. Table 1 shows the characteristics of the enrolled subjects. Compared with control subjects, DTAAD patients were more likely to have a history of smoking and hypertension.Quantitative Real-time PCRTotal RNA was isolated with the Trizol (Invitrogen) method, and cDNA was synthesized with iScrip cDNA Synthesis Kit (Biorad Laboratories) from 1 mg of total RNA. Real-time PCR was performed with the cDNA samples and SYBR Green Supermix (Bio-rad Laboratories) by using a Bio-Rad iCycler iQ RealTime PCR Systems (Bio-rad Laboratories), and the formation of PCR products was monitored by using the SYBR green method. All samples were amplified in triplicate. The relative changes in the amount of transcripts in each sample were 25033180 determined by normalizing with the 18S ribosomal RNA levels. The sequences of the primers for Notch1 used in real-time PCR were as follows: forward primer 59-GCAGTTGTGCTCCTGAAGAA-39; reverse primer 59-CGGGCGGCCAGAAAC-39.Double immunofluorescence stainingFor double immunofluorescence staining, paraffin-embedded tissues were cut into 4 mm sections, deparaffinized, rehydrated, and then subjected to antigen retrieval. Tissue sections were incubated with primary antibodies overnight at 4uC, followed by incubation with secondary antibodies for 1 hour at room temperature. The nuclei were counterstained for visualization with 49, 6- diamidino-2-phenylindole. The primary antibodies used were anti-Stro-1 (R D Systems, Minneapolis, MN), antiCD34 (Cell Signaling Technology), anti-SM22-a (Abcam, Cambridge, MA), anti-ER-TR7 (Santa Cruz Biotechnology), antiCD68 (Abcam), anti-Notch1 (Santa Cruz Biotechnology), antiactivated Notch1 (Abcam), anti-Jagged1 (Santa Cruz Biotechnology), anti-Delta (Santa Cruz Biotechnology), and anti-Hes1 (EMD Millipore). Table 2 provides detailed information on the primary antibodies. The secondary antibodies used were Alexa Fluor 488-, Alexa Fluor 568-, and Alexa Fluor 647-conjugated anti-immunoglobulin G (Invitrogen, Carlsbad, CA). Slides treated with normal immunoglobulin G only were used as negative controls. Quantification of the staining results was performed by randomly selecting 4 fields 
in each slide (n = 4 in each group), and counting target cells at a magnification of 6600 using the software ImagePro Plus 6.0 (Media Cybernetics, Bethesda, MD).Table 1. Patient characteristics.aCharacteristicsControl (n = 12)TAA (n = 14) 64.865.5 6 (43 ) 14 (100 ) 13 (93 ) 2 (14 ) 5 (36 ) 6.460.TAD (n = 16) 63.865.6 11 (69 ) 12 (75 ) 16 (100 ) 1 (6 ) 5 (31 ) 6.361.pValues 0.07 0.1 0.01 0.001 0.2 0.5 0.Age (y) Men History of smoking Hypertension Diabetes mellitus Taking anti-lipid medication59.168.2 4 (33 ) 6 (50 ) 6 (50 ) 4 (33 ) 2 (17 )Aortic diameter at sample site NA (cm)a Age and aortic diameter were compared by using one-way analysis of variance. All other variables were compared by using Pearson’s chi-squared test. NA = not applicable; TAA = thoracic aortic aneurysm; TAD = thoracic aortic dissection. doi:10.1371/journal.pone.0052833.tNotch Signaling in Aortic Aneurysm and DissectionTable 2. Primary antibodies used in the study.Antibody Anti-cleaved Notch1 (D3B8) Anti-Notch1 (D6F11)Source 4147 Cell Signaling 4380 Cell SignalingHost Rabbit RabbitSpecificity Cleaved Notch1 intracellular domain (NICD) (,110 kDa) Full-length (,300 kDa) and the transmembrane/intracellular region NTM (,120 kDa) Human Stro-1 Total CD34 protein S.