Objective. The aim of this study was to assess the vascular endothelium morphofunctional state of the brain microcirculatory bed in rats with nitrite-induced Alzheimer's type dementia on the background of stem cells administration. Methods. 14 days after the experiment's end, the endothelin-1, VEGF-A, eNOS, von Willebrand factor were determined in blood serum by the enzyme immunoassay and photometric methods in rats with a model of nitrite-induced dementia (14 and 28 days of sodium nitrite intraperitoneal introduction) with and without mesenchymal stem cells (MSCs) administration. The brain slices were stained according to the Einarson's method and immunohistochemically by staging the reaction with antibodies to VEGF. Results. With an increase in the sodium nitrite administration period, the degree of damage of brain capillaries and neurons increased, dystrophy of "surviving" neurons developed and ability to produce VEGF decreased. After 14 days of "regeneration period" in groups without MSCs administration, further stimulation of VEGF production by endotheliocytes, cortex and hippocampus neurons of varying degrees was observed. In groups where stem cells were introduced, the number of capillaries increased, with endothelial hyperplasia in some cases. Conclusion. In animals with nitrite-induced dementia, dose-dependent damage to the endothelium of the capillary bed is noted. From the first day damage the vascular regeneration can be proved by VEGF expression. The stem cells administration more effectively stimulates capillary regeneration, as evidenced by a noticeable increase of the number of brain capillaries.