Kaposi-like lesions in SCID mice injected with PAX2-expressing HMECs and in vivo angiogenesis induced by uninfected or HHV-8–infected HMECs and HMEC-AS. (A-D) HMECs (106) transfected with sense cDNA coding for PAX2 and control HMECs transfected with the empty vector were injected in diluted Matrigel subcutaneously in SCID mice. Mice were killed after 6 days, and Matrigel plugs were submitted to histologic analysis. (A-C) Representative micrographs of Matrigel-containing HMEC-S (A,B) and control HMECs (C). HMEC-S showed formation of vessels containing blood erythrocytes (A; Masson trichrome staining) and proliferative lesions (B; hematoxylin/eosin staining). Inset shows the presence of spindle-shaped cells. Angiogenesis and proliferative lesions were absent in control HMECs (C; Masson trichrome staining). (D) Morphometric analysis of new formed vessels within Matrigel. Data are mean plus or minus SD of 5 individual experiments. Mann-Whitney nonparametric test was performed (*P < .05, HMEC-S vs control HMECs). (E-J) Cells were implanted subcutaneously in SCID mice within growth factor-reduced Matrigel, and the formation of organized vascular structures was evaluated after 6 days. (E) Morphometric analysis of vessels formed in section of Matrigel plugs stained by Masson's trichrome staining. Only the vascular structures containing red blood cells were counted as vessels. Data are mean plus or minus SD of 5 individual experiments. Mann-Whitney nonparametric test was performed (*P < .05, HHV-8–infected HMECs vs uninfected HMEC; §P < .05, infected HMEC-AS vs infected HMECs). (F-I) Representative micrographs showing the proliferative lesions and the formation of canalized vessels in mice implanted with HMECs infected with HHV-8 (F,G) and absence of proliferative lesions and of patent vessels in mice implanted with HMEC-AS infected with HHV-8 (H,I). (J) Representative micrographs showing the human nature of vessels formed by HHV-8-infected HMECs. The sections of Matrigel plugs were staining with antihuman CD31 and hHLA class I as described in “In vivo angiogenesis assay.” Pictures were obtained using a Zeiss LSM5 Pascal confocal laser scanning microscope equipped with a Helium/Neon 543 mm laser, an Argon 450-530 mm laser and an EC planar NEORFluar 63×/1.3 oil DIC objective lens. Acquisition software was Zeiss LSMS version 3.2. Original magnifications were ×150 (A-C,F,H,J), ×250 (G,I).
