Enhanced nestin expression and small blood vessels in human pituitary adenomas

PEREZ MILLAN MI; BERNER, S.I.; LUQUE, G.; DE BONIS, C.; SEVLEVER, G.; BECU VILLALOBOS, DAMASIA; CRISTINA C

PITUITARY

SPRINGER

Lugar: Berlin; Año: 2013 vol. 16 p. 303 - 310

1386-341X

The role of angiogenesis in human pituitary tumor progression is questioned. Our aim was to characterize the morphologic changes that occur in the vasculature of pituitary adenomas, in correlation with the expression of  nestin, a protein found in endothelial cells of newly formed vessels of developing organs. We also evaluated the relation of angiogenic markers and nestin with Ki-67 index. Immunohistochemical studies were performed on paraffin  embedded samples of 47 pituitary adenomas and six normal  pituitaries. We determined microvessel density (number of CD31? or CD34? vessels per square millimetre), vascular  area (cumulative area occupied by vessels), average vessel  size, and further classified vessels as small (@ lm2) or  large ([100 lm2). We correlated the above parameters with  nestin expression and Ki-67 index. Lower vascular areacompared to normal tissue was found in adenomas  (p.05). Interestingly, pituitary adenomas had signifi cantly more small vessels than control pituitaries (p.04 for CD31 and CD34). In tumors many capillaries were positive for nestin, while scarce staining was detected in controls, so that nestin positive area was significantly higher in tumors. Furthermore, nestin area correlated positively with the % of small vessels. Ki-67 correlated neither with vascular area nor with nestin expression. In human pituitary tumors there was a predominance of small capillaries in correlation with increased expression of the progenitor marker nestin. We suggest that angiogenesis is an active 36process in these tumors, in spite of their low total vascular area when compared to normal pituitaries