Petros Minasi

Brief secondhand smoke exposure depresses endothelial progenitor cells activity and endothelial function: sustained vascular injury and blunted nitric oxide production.

OBJECTIVES This study sought to analyze the effects of acute secondhand smoke (SHS) exposure on the number and function of endothelial progenitor cells (EPCs) over 24 h. BACKGROUND Secondhand smoke increases the risk of vascular disease and is a major public health concern, but the mechanism(s) of action are not fully understood. METHODS Healthy nonsmokers (age SEM 30.3 +/- 1.3 years, n = 10) were exposed to 30 min of SHS yielding cotinine levels commonly observed in passive smokers and to smokefree air on 2 separate days. Measurements were taken before exposure (baseline), immediately after (0 h), and at 1 h, 2.5 h, and 24 h after. The EPCs (CD133(+)/KDR(+), CD34(+)/KDR(+)) and endothelial microparticles (EMPs: CD31(+)/CD41(-), CD144(+), CD62e(+)) were determined in blood using flow cytometry. The EPC chemotaxis toward vascular endothelial growth factor was measured. Endothelial function was assessed as flow-mediated dilation (FMD) using ultrasound. RESULTS Secondhand smoke exposure increased EPCs and plasma vascular endothelial growth factor and completely abolished EPC chemotaxis during 24 h after exposure. Secondhand smoke increased EMPs and decreased FMD. Although FMD returned to baseline at 2.5 h, EMPs and vascular endothelial growth factor levels remained elevated at 24 h, suggesting endothelial activation and injury with functional impairment of the vascular endothelium. Exposure to smokefree air had no effect. Incubation of EPCs from nonexposed subjects with plasma isolated from SHS-exposed subjects in vitro decreased chemotaxis by blockade of vascular endothelial growth factor-stimulated nitric oxide production. CONCLUSIONS Brief exposure to real-world levels of SHS leads to sustained vascular injury characterized by mobilization of dysfunctional EPCs with blocked nitric oxide production. Our results suggest that SHS not only affects the vascular endothelium, but also the function of EPCs.

Circulating Endothelial Microparticle Levels Predict Hemodynamic Severity of Pulmonary Hypertension

RATIONALE Circulating microparticles (MPs) are submicron membrane fragments shed from damaged or activated vascular cells. Endothelial MPs are a biological marker of dysfunctional endothelium. Vascular remodeling and endothelial dysfunction are involved in pulmonary hypertension (PH). OBJECTIVES We tested the hypothesis that circulating MPs are increased in patients with PH and that identifiable subgroups of MPs predict the hemodynamic severity of this condition progression. METHODS Patients (n = 24; age, 54 +/- 4 yr) undergoing right heart catheterization for precapillary PH without any endothelium-active vasodilator therapy participated in the study. Age- and sex-matched healthy control subjects (n = 20) were included. Endothelial (PECAM(+) [CD31(+)]/ CD41(-), VE-cadherin(+) [CD144(+)], and E-selectin(+) [CD62e(+)]), platelet (CD41(+)), leukocyte-derived (CD45(+)), and annexin V(+) MPs were measured by flow cytometry in platelet-free plasma from venous blood. MEASUREMENTS AND MAIN RESULTS Levels of circulating endothelial PECAM(+), VE-cadherin(+), E-selectin(+), and leukocyte-derived MPs, but not platelet and annexin V(+) MPs, were increased in subjects with PH compared with control subjects (P < 0.01 each). PECAM(+) and VE-cadherin(+) MP levels significantly correlated with mean pulmonary artery pressure (r = 0.92 and r = 0.87, respectively), pulmonary vascular resistance (r = 0.78 and r = 0.73), and mean right atrial pressure (r = 0.43, and r = 0.46) and correlated inversely with cardiac index (r = -0.59 and r = -0.52). These relationships were not observed for other MP subgroups, and persisted in multivariate analysis after adjustment for confounding factors. CONCLUSIONS In subjects with precapillary PH, levels of circulating endothelial and leukocyte MPs were increased compared with control subjects. In addition, levels of PECAM(+) and VE-cadherin(+), but not E-selectin(+), endothelial MPs predicted hemodynamic severity of the disease.

Injection of bone marrow cell extract into infarcted hearts results in functional improvement comparable to intact cell therapy.

We compared therapeutic benefits of intramyocardial injection of unfractionated bone marrow cells (BMCs) versus BMC extract as treatments for myocardial infarction (MI), using closed-chest ultrasound-guided injection at a clinically relevant time post-MI. MI was induced in mice and the animals treated at day 3 with either: (i) BMCs from green fluorescent protein (GFP)-expressing mice (n = 14), (ii) BMC extract (n = 14), or (iii) saline control (n = 14). Six animals per group were used for histology at day 6 and the rest followed to day 28 for functional analysis. Ejection fraction was similarly improved in the BMC and extract groups versus control (40.6 +/- 3.4 and 39.1 +/- 2.9% versus 33.2 +/- 5.0%, P < 0.05) with smaller scar sizes. At day 6 but not day 28, both therapies led to significantly higher capillary area and number of arterioles versus control. At day 6, BMCs increased the number of cycling cardiomyocytes (CMs) versus control whereas extract therapy resulted in significant reduction in the number of apoptotic CMs at the border zone (BZ) versus control. Intracellular components within BMCs can enhance vascularity, reduce infarct size, improve cardiac function, and influence CM apoptosis and cycling early after therapy following MI. Intact cells are not necessary and death of implanted cells may be a major component of the benefit.

Isolation, Culture, and Characterization of Human Fetal Trabecular Meshwork Cells

Purpose: To isolate and characterize fetal trabecular meshwork (FTM) cells for study in culture. Cultured adult trabecular meshwork (TM) cells often possess a slower rate of growth and restricted number of population doublings, limiting the ability to perform expanded testing. Methods: Fetal eyes from 24-week gestation abortions were delicately dissected to isolate the developing trabecular meshwork tissue. Three primary cultures were achieved and passaged. Light microscopy was used to compare the FTM cells to two cultured adult TM cell lines. Immunocytochemistry and Western blot analysis were utilized to identify specific protein expression. Results: The FTM cells demonstrated similar microscopic characteristics to adult TM cells, including monolayer formation, cobblestone pattern, and comparable size. FTM cells exhibited faster, more consistent doubling times when compared with adult TM cells. They grew rapidly even after passage 8, whereas their adult counterparts slowed significantly with each successive passage and failed to reach confluence at passages 4 to 5. Immunofluorescent staining was positive for actin, vimentin, fibronectin, laminin, aquaporin-1, CD-44, and myocilin in both FTM and adult TM cells. In both fetal and adult cells, Western blots showed substantial increase in myocilin after exposure to dexamethasone. Conclusions: Characterization by microscopy and immunocytochemistry suggest that FTM cells have properties similar to adult TM cells. Fetal tissues may be a useful source of abundant, rapidly dividing FTM cells for in vitro investigation. The ability to do expanded research in this field may contribute to a better understanding of the molecular mechanisms in glaucoma development.

Cytokine Combination Therapy With Long-Acting Erythropoietin and Granulocyte Colony Stimulating Factor Improves Cardiac Function But is Not Superior Than Monotherapy in a Mouse Model of Acute Myocardial Infarction

BACKGROUND Erythropoietin (EPO) and granulocyte colony stimulating factor (GCSF) are potential novel therapies after myocardial infarction (MI). We first established the optimal and clinically applicable dosages of these drugs in mobilizing hematopoietic stem cells (HSC), and then tested the efficacy of monotherapy and combination therapy post-MI. METHODS AND RESULTS Optimal doses were established in enhanced green fluorescent protein (eGFP) + chimeric mice (n = 30). Next, mice underwent MI and randomized into 4 groups (n = 18/group): 1) GCSF; 2) EPO; 3) EPO+GCSF; and 4) control. Left ventricular (LV) function was analyzed pre-MI, at 4 hours and at 28 days post-MI. Histological assessment of infarct size, blood vessels, apoptotic cardiomyocytes, and engraftment of eGFP+ mobilized cells were analyzed at day 28. LV function in the control group continued to deteriorate, whereas all treatments showed stabilization. The treatment groups resulted in less scarring, increased numbers of mobilized cells to the infarct border zone (BZ), and a reduction in the number of apoptotic cardiomyocytes. Both EPO groups had significantly more capillaries and arterioles at the BZ. CONCLUSION We have established the optimal doses for EPO and GCSF in mobilizing HSC from the bone marrow and demonstrated that therapy with these agents, either as monotherapy or combination therapy, led to improvement of cardiac function post-MI. Combination therapy does not seem to have additive benefit over monotherapy in this model.

Protective effect of passive immunization on herpetic retinitis of newborn rabbits

We studied the protective effects of passive immunization with virus specific antibody in newborn rabbits inoculated subcutaneously with type 2 herpes simplex virus (HSV-2). Newborn rabbits given anti-HSV-2 antibody intraperitoneally (IP) on days 0, 2 and 4 post infection had smaller herpetic skin lesions and reduced mortality when compared to controls. In addition, the IP treatment using this schedule reduced virus growth in the skin lesions and virus dissemination, so that it decreased the frequency of herpetic retinitis. When the IP antibody administration was started at 24 hours post virus inoculation, according to the schedule days 1, 3 and 5, there was less protection; larger skin lesions, higher mortality, and greater evidence of virus dissemination. Also HSV-infected mononuclear cells (MNCs) treated with anti-HSV serum resulted in a significant reduction in the number of infected MNCs. The results of these studies suggest that anti-HSV-2 antibody contributes to protection against HSV-2 infection of skin as well as eyes, probably by inactivation of the virus locally at the skin inoculation site, and by combating the hematogenous spread of HSV-infected MNCs as well as free virus to various organs including the eye.

Role of lymphocyte and antibody in the pathogenesis of immune-mediated herpetic uveitis

We investigated the role of various immune components in the pathogenesis of immune-mediated experimental herpetic uveitis. Inbred III/J strain of rabbits were sensitized with an intravitreal injection of 10(3) PFU of type 1 herpes simplex virus (HSV), and sensitized cervical lymph node (LN) cells were obtained on postinfection day 12. Intravitreal injection to the normal III/J rabbit eye of HSV antigen with either sensitized LN cells or anti-HSV serum failed to induce uveitis, whereas intravitreal injection of HSV-antigen with both sensitized LN cells and anti-HSV serum produced severe uveitis within six hours. The combination of sensitized LN cells, HSV-antigen and normal rabbit serum, or that of normal LN cells, HSV antigen and anti-HSV serum, did not induce uveitis. Further studies using B lymphocyte and T lymphocyte fractions from sensitized LN showed that only the combination of sensitized T lymphocytes, HSV antigen and anti-HSV serum regularly produced uveitis following intravitreal injection. These results indicate that the interaction of HSV antigen, sensitized T lymphocytes and anti-HSV antibody may play a role in the pathogenesis of immune-mediated herpetic uveitis.