[View Larger Version of this Image]
Figure S6. Structural comparison of preestablished KS tumors from treated versus untreated animals. KS tumors were harvested from animals 17 d after implantation of 3 x 106 KS cells into the right flanks of an athymic nude mouse and 10 d after the first of three injections of 3 x 106 MSCs into the tail vein. (A) Hematoxylin and eosin staining of tumors reveal smaller nests of KS cells and enhanced compartmentalization by inflammatory cells and fibrous tissue compared with tumors from untreated animals, which display a more sheetlike growth of tumor cells with fewer inflammatory cells and less fibrous tissue. (B) Immunohistochemical staining using an antibody against mouse neutrophils (rat anti-mouse neutrophil antibody NIMP-R14) reveals a profound increase in the host neutrophilic response (as evidenced by small, rounded, dark brown/black positive staining cells, which are denoted by arrows) in tumors from animals treated with MSCs compared with tumors from untreated animals. Representative images from similar locations of tumors from untreated (KS) or treated (KS + MSC) animals are shown.