Decrease and senescence of endothelial progenitor cells in patients with preeclampsia.

BACKGROUND: In preeclampsia, the precise mechanism of impaired vascular function is still unclear. We hypothesized that cellular function of circulating endothelial progenitor cells (EPCs) might be impaired in patients with preeclampsia. OBJECTIVE: The objective of this study was to investigate the number and status of cellular senescence of EPCs in the circulation of women with preeclampsia. METHODS: Circulating EPCs were cultured from patients with preeclampsia (n = 8) and normotensive pregnant women (n = 7). EPC numbers were assessed by colony-forming unit (CFU) methodology as previously reported. In addition, to assess cellular senescence, we measured endogenous beta-galactosidase activity. Moreover, we assessed whether the serum level of C-reactive protein (CRP), a marker for systemic inflammation, was associated with cellular impairment of EPCs. RESULTS: The number of circulating EPCs was decreased in women with preeclampsia controls (median, 10.0 vs. 34.0 CFU; P < 0.01). The rate of cellular senescence was significantly increased in patients with preeclampsia (33.9%) compared with that in controls (22.9%; P < 0.05). Patients with preeclampsia were divided into two subgroups: the CRP-negative group (CRP, <0.1 mg/dl; n = 4) and the CRP-positive group (CRP, > or =0.1 mg/dl; n = 4). Interestingly, EPC CFU counts were markedly decreased in CRP-positive patients compared with those in CRP-negative patients (5.0 and 25.0 CFU, respectively; P < 0.05). Median values for cellular senescence were greater in the CRP-positive group than in the CRP-negative group, although this did not achieve statistical significance (43.5% and 33.3%, respectively; P = 0.12). CONCLUSION: Depletion and cellular aging of EPCs in patients with preeclampsia might be associated with endothelial dysfunction and could be affected by systemic inflammation.

Circulating endothelial progenitor cells during human pregnancy.

The precise molecular and cellular mechanisms that regulate maternal vascular development during gestation are largely unknown. Endothelial progenitor cells (EPCs), which play an important role in vascular homeostasis, have been discovered in the circulation. We examined the level of circulating EPCs throughout uncomplicated pregnancies (n = 20) and assessed the correlation between serum estradiol levels and the number of EPCs. The number of circulating EPCs increased gradually and paralleled the progression of gestational age. In addition, the number of EPCs correlated significantly with the level of serum estradiol. The present study suggests that EPCs may play an important role in the regulation and maintenance of the placental development and vascular integrity during pregnancy.

Vasopressin-induced contraction of uterus is mediated solely by the oxytocin receptor in mice, but not in humans.

In the non-pregnant mouse myometrium, both arginine vasopressin and oxytocin induced contractions (pD(2)=8.55+/-0.13 and 9.23+/-0.09, respectively). The effect of oxytocin was the most potent, while the maximum contractions induced by these two peptides were almost of the same magnitude. Both vasopressin- and oxytocin-induced contractions were strongly inhibited by an oxytocin receptor antagonist, CL-12-42 (d(CH(2))(5)[Tyr(Me)(2),Thr(4),Tyr-NH(2)(9)]OVT), and weakly inhibited by a vasopressin V(1a) receptor antagonist, SR49059 ((2S)1-[(2R,3S)-5-chloro-3-(2-chlorophenyl)-1-(3,4-dimethoxybenzene-sulfonyl)-3-hydroxy-2,3-dihydro-1H-indole-2-carbonyl]-pyrrolidine-2-carboxamide). Similar results were obtained in the pregnant mouse myometrium. These results suggest that not only oxytocin- but also vasopressin-induced contraction is mediated by the activation of oxytocin receptors in the mouse myometrium. A reverse transcription polymerase chain reaction study failed to reveal mRNA of the vasopressin V(1a) receptor in the mouse myometrium. In contrast, in the non-pregnant human myometrium, vasopressin-induced contraction was inhibited by SR49059. Oxytocin showed no effect on the myometrium. These results suggest that there are significant differences in the functional receptors and contractile responses to vasopressin and oxytocin in the human and mouse uteri.

Increased locomotor activity, increased food and water intake and decreased PVN neurons in H1 calponin gene-deficient mice.

Calponin (h1 or basic) is an actin-binding protein that is expressed abundantly in smooth muscle. Our previous study using h1 calponin-null mutant mice demonstrated that h1 calponin inhibits the shortening velocity of smooth muscle contraction without significantly affecting the amplitude of force production. Furthermore, early onset of osteogenesis and increased bone formation have been reported in mutated mice. In the present study, we examined the effect of h1 calponin depletion on the metabolism and behavior of mice and found that the mutated mice showed increased locomotor activity, as well as increased intake of food and water, associated with the decreased number of neurons in the paraventricular nucleus of the hypothalamus (PVN).

CD38 gene disruption inhibits the contraction induced by alpha-adrenoceptor stimulation in mouse aorta.

CD38 is an ectoenzyme with ADP-ribosyl cyclase and hydrolase activities, which synthesizes cyclic ADP-ribose from NAD and hydrolyzes cyclic ADP-ribose to ADP-ribose. It has been shown that cyclic ADP-ribose is a potent Ca(2+) mobilizing messenger in many cells. To know the physiological role of cyclic ADP-ribose in vascular smooth muscle, we examined the effects of various agonists in the aorta isolated from CD38 knockout (CD38(-/-)) mouse. Western blot analysis showed that CD38 protein was detected in the aorta isolated from wild-type (CD38(+/+)) mouse, but not from CD38(-/-) mouse. In the aortae isolated from both CD38(+/+) and CD38(-/-) mice, KCl, phenylephrine and norepinephrine induced concentration-dependent contraction. KCl produced similar concentration-dependent responses in the aortae from both CD38(+/+) and CD38(-/-) mice. Maximum force of contraction induced by KCl (65 mM) was same in the size. Phenylephrine- and norepinephrine-induced contractions were, however, significantly smaller in the aortae from CD38(-/-) mice than in those from CD38(+/+) mice. 5-Hydroxytryptamine, endothelin-1, caffeine and thapsigargin-induced contractions were not significantly different in these two aortae. These results suggest that CD38 gene disruption inhibits alpha-adrenoceptor-induced vascular contractions and cyclic ADP-ribose-mediated signal transduction system is committed in these responses.

Theonezolide A, a novel marine macrolide, induces drastic shape change in rabbit platelets by reorganization of microtubules.

Theonezolide A, a marine macrolide, and thrombin caused a shape change followed by an aggregation in the rabbit platelets. Theonezolide A-induced platelet shape change, estimated by a decrease in light transmission, appeared to a greater extent than thrombin-induced one. Morphological studies using an electron microscope showed that theonezolide A changed platelet shape with various numbers of long pseudopods, loosing their discoid shape. Theonezolide A-induced shape change was inhibited by a microtubule-stabilizing agent, taxol, but not by an actin-depolymerizing agent, cytochalasin B. In contrast, thrombin-induced shape change was inhibited by cytochalasin B but not by taxol. Confocal fluorescence microscopy showed that circumferential microtubule bundle disappeared in the platelets treated with theonezolide A. Theonezolide A had no direct effect on polymerization of microtubules isolated from bovine brain, indicating that it indirectly causes microtubule reorganization. These results suggest that theonezolide A induces drastic shape change through reorganization of microtubules in rabbit platelets. Thus, theonezolide A is a useful drug to examine microtubule reorganization in the cells.