Las células TC-1 implantadas invaden a las fibras musculares esqueléticas adyacentes en un modelo murino de cáncer / Implanted TC-1 cells invade neighboring skeletal muscle fibers in a cancer murine model

RESUMEN

La línea celular TC-1 se ha utilizado en la evaluación de la inmunoterapia antitumoral. No existen reportes sobre el efecto de las células TC-1 en tejidos adyacentes cuando se implantan en ratones C57BL/6. El objetivo de este trabajo fue evaluar la interacción entre las células TC-1 implantadas y las fibras musculares adyacentes. Se emplearon 8 ratones con células TC-1 implantadas y 3 ratones sin células. Se colectó el sitio del implante de las células tumorales a 10 días, las muestras se procesaron para microscopia de luz y electrónica de transmisión. Se realizaron tinciones con HyE y tricrómico de Masson, histoquímica con PAS, e inmunohistoquímica para identificar citoqueratinas, actina específica de músculo y metaloproteinasa de la matriz-9 (MMP-9). También se comparó el diámetro de las fibras musculares en ambos grupos de estudio. En el análisis histológico se observaron masas de células TC-1 que infiltran el tejido muscular y separan a las fibras entre sí. Las fibras musculares mostraron variaciones en la intensidad de la tinción y disminución de su diámetro. Se observaron masas de células tumorales TC-1 que invaden la fibra hacia el interior y logran atravesar la lámina externa y el sarcolema que las rodea. Se observó positividad a MMP-9 en el citoplasma de las células TC-1, y en el espacio entre las células tumorales y las fibras musculares. En el análisis ultraestructural se observó fragmentación y variaciones en el grosor de la lámina externa y vesículas subsarcolemales en el sitio en donde las células TC-1 invaden las fibras.Ahí, las células TC1 emiten proyecciones de membrana similares a pseudópodos....

ABSTRACT

TC-1 cells implanted in C57BL/6 mice are a model for evaluation of anti-tumor immunotherapy. To date there are no reports on the effect of implanted TC-1 cells upon neighboring striated muscle cells. The objective of this work was to evaluate the morphology of the interaction established among the implanted cells and the striated muscle cells. The study was carried out as follows 8 adult C57BL/6 mice received 5x104 cells IP. As a control, 3 mice received no cells. 10 days after cells injection, no signs of tumor are present yet, and the site of cells injection was collected for morphological studies. Samples were processed for light and transmission electron microscopy. Histological sections were stained with H & E, Masson trichromic method, PAS histochemistry and immunohistochemistry for cytocheratins AE1/AE3, muscle specific actin and for matrix metalloproteinase-9. Cross section diameter of muscle sections was compared among experimental and control groups. The histological evaluation showed groups of tumor cells, infiltrating the spaces among muscle fibers. Muscle fibers showed variations in the cross section diameter as well as in the staining pattern. TC-1 cells were seen very close to muscle cells, invading the lamina externa and sarcolema to finally form groups of cells located within the sarcoplasm. This finding was demonstrated by the specific immunolabel for each kind of cell. Reactivity for metalloproteinase-9 was observed within the tumor cells and in the space mediating between the tumor cells and the muscle fiber. At the ultrastructural level, variations of the thickness of lamina externa were observed, as well as interruptions of this structure. Sarcolema also showed fragmentation, and close to these sites a number of subsarcolemmal vesicles were seen. In the vicinity of the muscle fiber, TC-1 cells formed membrane projections directed towards muscle membrane...