Stereologic evaluation of the vasculature in a MX1 xenotransplanted tumourmodel after combinations of treatment with ifosfamide, hyperthermia and irradiation

The vascularization of tumours is a critical parameter of their growing and metastatic behaviour. However, little is known about the morphologic react ions of the microvasculature, especially the capillary bed of tumours and t he adjacent tissue. In this study, the vessels in MX1 xenotransplants in at hymic nu/nu nude mice were quantified and the angioarchitecture was visuali zed with the aim of presenting stereologic parameters of vessels based on a morphometric analysis of post mortem tissue blocks which were processed by standard histological procedures. In order to study changes of the microva sculature of MX1 tumours, the xenotransplanted nude mice were treated by di fferent therapeutic regimens. Standardized hyperthermia, ifosfamide and irr adiation therapies were applied. Special interest was focused on early chan ges of capillaries and of the pre- as well as post-terminal vascular bed. T he stereologic evaluation of capillaries and larger vessels immediately aft er the therapy with ifosfamide and hyperthermia shows an increase of the me an capillary sizes. Furthermore, tumour samples after the 5th day of irradi ation (5 x 2 Gy) and combinations of irradiation and chemotherapy treatment have been investigated. After 5 days of irradiation, a significant decreas e of the vascular density was found. The results presented here clearly sho w that the timing and the mode of therapy influence the capillary morpholog y and periterminal vasculature of xenotransplanted MX1 tumours.