A novel subset of putative stem/progenitor CD34(+)Oct-4(+) cells is the major target for SARS coronavirus in human lung

Chen, Yongxiong; Chan, Vera Sau-Fong; Zheng, Bojian; Chan, Kelvin Yuen-Kwong; Xu, Xiaoning; To, Leo Yuk-Fai; Huang, Fang-Ping; Khoo, Ui-Soon; Lin, Chen-Lung Steve

To further investigate if CD34 Ï© cells in the non-SARS lung could be infected by SARS-CoV, part of the fresh lung tissue collected from six lung cancer patients ( Table II ) was cut into small blocks (2 -3 mm 3 ) and directly exposed to live virus as similarly described by others ( 23 ) . After 16 h, the ex vivoinfected tissue blocks were fi xed and embedded for IHC-FISH-ISH study. Results showed that though few in number, SARS Ï© cells were identifi ed in samples from four patients ( Fig. 3 B , b and c, red, and Figs. S8 and S9, which are available at http://www.jem.org/cgi/content/full/jem.20070462/DC1). Consistently, these four patients also had detectable CD34 Ï© Oct-4 Ï© cells in the fresh samples studied immediately upon collection ( Table II ) . Furthermore, in line with observations in the SARS-infected lung, the SARS antigen ( Fig. 3 B , b and c, red, and Fig. S8 ) was not colocalized with surfactant A ( Fig. 3 B , b, brown, and Fig. S8 ). SARS Ï© cells could be clearly visualized under a fl uorescence microscope before FISH study ( Fig. 3 B , c) . After FISH/ISH study, SARS Ï© cells indeed mammalian embryonic cells ( 21, 22 ) . Such observations were made in all lung samples from patients recruited for this study who died within 11 d after illness onset ( Table I ) . We thus conclude that the majority of SARS Ï© cells in the SARS lung were a subset of putative stem/progenitor cells expressing CD34, Oct-4, and ACE2.