Effects of dihydrotestosterone on adhesion and proliferation via PI3-K/Akt signaling in endothelial progenitor cells.

The protective effects of male hormones on the cardiovascular system are still in dispute. There is now ample evidence that testosterone level is negatively correlated to the incidence and mortality of cardiovascular disease in men. Endothelial progenitor cells (EPCs) play a vital role in endothelial healing and vascular integrity, which are useful for promoting cardiovascular health. In this study, we investigated the effects of dihydrotestosterone (DHT), a non-aromatizable androgen, on human EPC function and the activation of the phosphatidylinositol-3-kinase (PI3-K)/Akt pathway in vitro. EPCs were incubated with a series of concentrations (1, 10, or 100 nmol/L in DMSO) of DHT for 24 h or with 10 nmol/L DHT for different time (6, 12, 24, 48 h). EPC adhesion and proliferation and the activation of Akt were assayed by cell counting, 5-ethynyl-2'-deoxyuridine incorporation assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blot analysis. Our data demonstrated that DHT significantly increased the proliferative activity and adhesive ability of EPCs in a dose- and time-dependent manner, maximum at 10 nmol/L, 24 h (p < 0.05). Western blot analysis revealed that DHT promoted the phosphorylation of Akt, and the effects of different concentrations of DHT on Akt phosphorylation were consistent with those on EPC proliferation and adhesion (p < 0.05). However, the enhancing effects of DHT on EPCs decreased with administration of the pharmacological PI3-K blocker LY294002 (p < 0.05). In conclusion, DHT can modulate EPC proliferation and adhesion and the PI3-K/Akt pathway plays an important role in this process.

Effect of sex on biomechanical properties of the proper hepatic artery in pigs and humans for liver xenotransplant.

OBJECTIVES: This study investigated the relation between biomechanical properties of the proper hepatic artery and sex in pigs and humans to provide the theoretical basis for selecting suitable donor in pig-to-human liver xenotransplant. MATERIALS AND METHODS: The proper hepatic arteries of 32 Chinese Hubei white pigs (8 males, 8 females, 8 castrated males, and 8 ovariectomized females) and 10 deceased donors (5 human men, 5 human women) were obtained. The pressure-diameter relations of the proper hepatic arteries were measured on biomechanical test equipment to calculate the incremental elastic modulus (Einc), pressure-strain elastic modulus (Ep), volume elastic modulus (Ev), and compliance. Each sample was sliced into 5-µm frozen sections and stained with hematoxylin-eosin. RESULTS: There were significant differences in Einc (F=10.24; P = .001), Ep (F=3.75; P = .001), and Ev (F=3.41; P = .002) of the proper hepatic arteries of female, male, and gonadectomized pigs; females had the lowest elastic modulus and the gonadectomized group had the highest (P < .01). There was a significant difference in compliance of the porcine proper hepatic arteries between the sexes, highest in the female group and lowest in the gonadectomized group (P < .01). No difference in the elastic modulus and compliance of the proper hepatic artery between the male pig and the human man. There was no difference between the female pig and the human woman. CONCLUSIONS: There were differences in the biomechanical properties of the proper hepatic arteries of the female, male, and gonadectomized pigs. The biomechanical properties of the human men/women proper hepatic artery match those of the porcine male/female hepatic artery. The correlation between sex and biomechanical properties of the proper hepatic artery in pigs could imply that a pig of the same sex should be chosen for pig-to-human liver xenotransplant.

Morphological and biomechanical remodeling of the hepatic portal vein in a swine model of portal hypertension.

OBJECTIVES: To obtain the morphological and biomechanical remodeling of portal veins in swine with portal hypertension (PHT), so as to provide some mechanical references and theoretical basis for clinical practice about PHT. METHODS: Twenty white pigs were used in this study, 14 of them were subjected to both carbon tetrachloride- and pentobarbital-containing diet to induce experimental liver cirrhosis and PHT, and the remaining animals served as the normal controls. The morphological remodeling of portal veins was observed. Endothelial nitric oxide synthase expression profile in the vessel wall was assessed at both mRNA and protein level. The biomechanical changes of the hepatic portal veins were evaluated through assessing the following indicators: the incremental elastic modulus, pressure-strain elastic modulus, volume elastic modulus, and the incremental compliance. RESULTS: The swine PHT model was successfully established. The percentages for the microstructural components and the histological data significantly changed in the experimental group. Endothelial nitric oxide synthase expression was significantly downregulated in the portal veins of the experimental group. Three incremental elastic moduli (the incremental elastic modulus, pressure-strain elastic modulus, and volume elastic modulus) of the portal veins from PHT animals were significantly larger than those of the controls (P < 0.05), whereas the incremental compliance of hepatic portal vein decreased. CONCLUSIONS: Our study suggests that the morphological and biomechanical properties of swine hepatic portal veins change significantly during the PHT process, which may play a critical role in the development of PHT and serve as potential therapeutic targets during clinical practice.

Morphological and biomechanical remodelling of the hepatic artery in a swine model of portal hypertension.

OBJECTIVES: To obtain the biomechanical and morphological remodelling of hepatic arteries in swine with portal hypertension. METHODS: A number of 20 white pigs was used, of which 14 were subjected to liver cirrhosis and portal hypertension (PHT) induced by carbon tetrachloride and pentobarbital; the rest were used as the control group. The biomechanical remodelling of the hepatic arteries was measured, namely, the incremental elastic modulus (E inc), pressure-strain elastic modulus (E p), volume elastic modulus (E v), the incremental compliance (C), the opening angle and the stained microstructural components of the vessels. RESULTS: The percentages for the microstructural components and the histologic data significantly changed in the experimental group, three incremental elastic moduli (E inc, E p, and E v) of the experimental group were significantly larger than those of the control group (P < 0.05); the compliance of hepatic arteries decreased greatly (P < 0.05) too. The opening angle (OA) was considerably larger than that of control group (P < 0.05). CONCLUSIONS: The study suggests that the morphological and biomechanical properties of swine hepatic arteries have changed significantly during the process of portal hypertension and that from biomechanical aspects, the hepatic arteries have also suffered from extensive remodelling, which in turn deteriorates the existing portal hypertension.

The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation.

BACKGROUND: Pigs are currently considered the most likely source of organs for human xenotransplantation because of anatomical and physiological similarities to humans, and the relative ease to be bred in large numbers. Along with the fast development of the genetic engineering and organ transplant immunity medical science, the research of liver xenotransplantation suffers the very big valuing in recent years. Whether the livers from different species after transplanting can perform the normal function, depends on the function regeneration and lucid rates of hepatic portal vein. The objective of this study was to investigate the age effect on biomechanical properties of pig hepatic portal vein to pave the way for seeking a reliable biomaterial for future pig-to-human liver xenotransplantation. METHODS: The biomechanical remodelling of the hepatic portal vein of pigs for 1,2,3,4,5 and 6 months (n = 6 per month) were measured in this study. The blood vessel was given periodic permanent loading and unloading, and repeated force-deformation data were obtained. The incremental modulus (Einc), the longitudinal incremental modulus (Ep), the circumferential incremental modulus (Ev), incremental compliance (C) and wall thickness were calculated based on the recorded pressure-diameter curves from experimental data. RESULTS: The incremental modulus, pressure strain modulus and the volume modulus of the pig hepatic portal vein increases with the age increased (P < 0.01), while the compliance decreased with the increasing of the age (P < 0.01). CONCLUSIONS: Our present study suggests that the biomechanical properties of the pig hepatic portal vein are age dependent, the pig hepatic portal vein with biomechanical properties that match those of human hepatic portal vein should be chosen for liver xenotransplantation.

Quantitative analysis of the microstructure of human umbilical vein for assessing feasibility as vessel substitute.

We explored the feasibility of human umbilical vein (HUV) as a small-caliber vessel substitute. HUVs of 50 fetuses were collected on spontaneous miscarriage or labor with the pregnant women's permission. Gestational age ranged 24-42 weeks, and parturients were 20-30 years old. Each sample was sliced into 5 mum frozen transverse sections and stained with hematoxylin-eosin (HE), Weigert, aniline blue, and orange yellow G. The geometric morphological indexes and microstructural component were measured by a computer image analysis system. The media thickness was 0.186, 0.203, 0.237, 0.264, and 0.268 mm at 24-27, 28-32, 33-36, 37-40, and 41-42 weeks, respectively (F = 133.35, p < 0.01); diameters were 1.861, 1.962, 2.303, 2.464, and 2.465 mm (F = 37.35, p < 0.01), respectively. The media thickness and diameter of HUVs increased with gestational age. The elastin content of media increased at 24-40 weeks, but the collagen content and collagen/elastin (C/E) ratio decreased. Elastin content in the proximal segment was higher than in the distal segment [10.16, 6.36 Aa%, (Aa% is the unit of relative content, ie, the ratio of absolute areas to the total tested area of smooth muscle, collagen and elastin in the vascular wall) F = 5.77-12.3, p < 0.05], with the collagen to elastin (C/E) ratio increasing from the proximal to the distal segment (F = 7.63-13.4, p < 0.05). Our results suggest that the microstructural component of HUVs (2.0-3.0 mm caliber) at 37-40 weeks of gestation was similar to that of the small-caliber arteries and had moderate amounts of collagen and elastin and good elasticity, i.e., a good C/E ratio; therefore, HUV may be a substitute for small-caliber arteries (e.g., brachial, ulnar, radial, right coronary, anterior tibial, and posterior tibial). HUV is one of several graft materials that may be used when autogenous saphenous vein is absent or inadequate.