Mesenchymal Stem Cells Improve Cognitive Impairment and Reduce Aß Deposition via Promoting AQP4 Polarity and Relieving Neuroinflammation in Rats With Chronic Hypertension-Induced Cerebral Small-Vessel Disease.

Cerebral small-vessel disease (CSVD) is the main cause of vascular cognitive impairment (VCI), and the accumulation of amyloid ß-protein (Aß) may be significantly involved in CSVD-induced VCI. The imbalance between Aß production and clearance is believed to be an important pathological mechanism of Aß deposition in Alzheimer disease. In this study, we aimed to disclose the roles of aquaporin 4 (AQP4) and neuroinflammation in CSVD, which were the key factors for Aß clearance and production, respectively, and the effect of mesenchymal stem cells (MSCs) on Aß deposition and these two factors. The stroke-prone renovascular hypertensive (RHRSP) rats were grouped and received MSC and MSC + AS1517499 (an inhibitor of pSTAT6). The latter was used to explore the underlying mechanism. The cognitive function, white matter lesions, Aß expression, expression, and polarity of AQP4, neuroinflammation and the STAT6 pathway were investigated. Compared with sham-operated rats, RHRSP rats showed spatial cognitive impairment, white matter lesions and Aß deposition. Moreover, AQP4 polarity disorder and neuroinflammatory activation were found, which were linked to Aß deposition. Treatment with MSCs markedly improved cognitive tasks and reduced Aß deposition but failed to reduce white-matter lesions. Furthermore, MSCs not only promoted AQP4 polarity but also alleviated neuroinflammation probably through the STAT6 pathway. The present study demonstrated that Aß deposition, AQP4 polarity disorder and neuroinflammation might be involved in CSVD and the regulatory effects of MSCs on them suggested potential therapeutic value for CSVD.

Peroxisome proliferator-activated receptor-γ agonist pioglitazone ameliorates white matter lesion and cognitive impairment in hypertensive rats.

AIMS: Cerebrovascular white matter lesion (WML) is a major subtype of cerebral small vessel disease. Clinical drugs are not available for WML. We investigated whether peroxisome proliferator-activated receptor-γ agonist pioglitazone, with properties of vascular protection and antiinflammation, exerts beneficial effect in hypertensive WML rats. METHODS: Stroke-prone renovascular hypertensive rats (RHRSP) were treated with pioglitazone for 12 weeks. Morris water maze experiment was conducted to assess cognition. WML was observed by Luxol fast blue staining. Smooth muscle actin-alpha, collagen I, collagen IV, glial fibrillary acidic protein, and ionized calcium-binding adaptor molecule-1 were evaluated by immunohistochemistry. Interleukin-1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) in brain and soluble intercellular adhesion molecule-1 (sICAM-1) in serum were detected. RESULTS: Pioglitazone significantly attenuated WML in corpus callosum, caudate putamen, external capsule, and internal capsule. Cognitive impairment in RHRSP was ameliorated by pioglitazone. Pioglitazone attenuated arteriolar remodeling and reduced sICAM-1 level in serum. Pioglitazone decreased the proliferation of microglia and astrocyte and lowered the expression of proinflammatory cytokines IL-1ß and TNF-α in the white matter. CONCLUSIONS: Long-term treatment of pioglitazone has beneficial effect on hypertension-induced WML and cognition decline, which may partly through its effect on attenuation of arteriolar remodeling, endothelial activation, and brain inflammation.