Immunohistochemical Characterization of Sarcomas in Trp53+/− Haploinsufficient Mice

Abstract

The use of immunohistochemical (IHC) staining in determining and/or confirming the cellular origin of poorly differentiated sarcomas was evaluated in this study. Sarcomatous neoplasms were evaluated in a research study conducted in two strains of p53+/− haploinsufficient mice. The most common neoplasms were undifferentiated sarcomas, followed by osteosarcomas, and rhabdomyosarcomas (RMSs). The RMSs were poorly differentiated and appeared similar to the pleomorphic, or adult type, RMS of humans. All sarcomas stained positive by IHC for the mesenchymal cell intermediate filament vimentin. The RMSs were identified by positive IHC staining for myogenin, a transcription factor specific to skeletal muscle. Osteosarcomas were easily identifiable on hematoxylin and eosin (H&E) stained slides; no generally accepted IHC stain specific for bone is presently available. Some of the undifferentiated sarcomas contained numerous macrophages that stained positive for F4/80, a macrophage marker; the positive-staining cells were considered to be infiltrating macrophages. One-third of the neoplasms observed in this study were associated with subcutaneous implanted electronic microchips, used for animal identification. Based upon histopathologic evaluation and IHC staining, it was not possible to distinguish neoplasms associated with subcutaneous microchips from neoplasms not associated with microchips.

MiR27a Promotes the Development of Macrophage-like Characteristics in 3T3-L1 Preadipocytes

“…Macrophages exhibit phagocytic capacity and the ability to migrate and secret inflammatory factors involved in the immune response 23 - 26 . In addition, macrophages classically express multiple surface antigens such as F4/80, MHC and CD206 27 - 29 .…”