Acute exercise-induced glycocalyx shedding does not differ between exercise modalities, but is associated with total antioxidative capacity.

OBJECTIVES: Regular physical exercise is known to protect endothelial integrity. It has been proposed that acute exercise-induced changes of the (anti-)oxidative system influence early (glycocalyx shedding) and sustained endothelial activation (shedding of endothelial cells, ECs) as well as endothelial-cell repair by circulating hematopoietic stem and progenitor cells (HPCs). However, results are not conclusive and data in trained participants performing different exercise modalities is lacking. DESIGN: Eighteen healthy, well-trained participants (9 runners, 9 cyclists; age: 29.7 ±â€¯4.2 yrs) performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with decreasing power profile and 3-min low-intensity in-between. METHODS: Average power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and shortly after exercise, total oxidative and antioxidative capacities (TAC), shedding of syndecan-1, heparan sulfate, hyaluronan, ECs, and circulating HPCs were investigated. RESULTS: TAC decreased from 1.81 ±â€¯0.42 nmol/L to 1.47 ±â€¯0.23 nmol/L post-exercise (p = 0.010) only in runners. Exercise-induced early and sustained endothelial activation were enhanced post-exercise- syndecan-1: 103.2 ±â€¯63.3 ng/mL to 111.3 ±â€¯71.3 ng/mL, heparan sulfate: from 2637.9 ±â€¯800.1 ng/mL to 3197.1 ±â€¯1416.3 ng/mL, both p < 0.05; hyaluronan: 84.3 ±â€¯21.8 ng/mL to 121.4 ±â€¯29.4 ng/mL, ECs: from 6.6 ±â€¯4.5 cells/µL to 9.5 ±â€¯6.2 cells/µL, both p < 0.01; results were not different between exercise modalities and negatively related to TAC concentrations post-exercise. HPC proportions and self-renewal ability were negatively, while EC concentrations were positively associated with circulating hyaluronan concentrations. CONCLUSIONS: These results highlight the importance of the antioxidative system to prevent the endothelium from acute exercise-induced vascular injury - independent of exercise modality - in well-trained participants. Endothelial-cell repair is associated with hyluronan signaling, possibly a similar mechanism as in wound repair.

Comparison of the reliability of Gram-negative and Gram-positive flags of the Sysmex UF-5000 with manual Gram stain and urine culture results.

OBJECTIVES: Recently, the fully automated flow cytometry-based UF-5000 (Sysmex Corboration, Kobe, Japan) urine sediment analyzer was developed providing bacteria (BACT) info flags for more accurate bacterial discrimination of urinary tract infections (UTIs). This study aimed to compare the reliability of the UF-5000 BACT-info flags with manual Gram stain and urine culture as the gold standard method. METHODS: A total of 344 urine samples were analyzed on the UF-5000 and compared with manual microscopic Gram stain and urine cultures. Agreement was assessed by Cohen's kappa (κ) analysis. The Youden index was used to determine the optimal BACT and white blood cell (WBC) cut-off points for discriminating positive and negative urine cultures. RESULTS: Overall 98/344 (28.5%) samples were urine culture positive at a cut-off of ≥105 CFU/mL. "Gram-negative?" UF-5000 BACT-Info flags showed a better concordance of 25/40 (62.5%) with urine culture compared to Gram stain with 30/50 (60%). The results for UF-5000 discrimination of Gram-positive and Gram-negative microorganisms demonstrated a substantial (κ = 0.78) and fair (κ = 0.40) agreement with urine culture. Optimal cut-off points detecting positive urine cultures were 135 BACT/µL (sensitivity [SE]: 92.1%, specificity [SP]: 85.4%, positive predictive value [PPV]: 71%, negative predictive value [NPV]: 96%) and 23 WBC/µL (SE: 73.5%, SP: 84.1%, PPV: 65%, NPV: 89%). CONCLUSIONS: The UF-5000 analyzer (Sysmex) is a reliable diagnostic tool for UTI screening. The displayed BACT-Info flags allow a quick diagnostic orientation for the clinician. However, the authors suggest verifying the automated Gram categories with urine culture.

Exercise-Induced Circulating Hematopoietic Stem and Progenitor Cells in Well-Trained Subjects.

It has been proposed that exercise-induced systemic oxidative stress increases circulating hematopoietic stem and progenitor cell (HPC) number in active participants, while HPC clonogenicity is reduced post-exercise. However, HPCs could be protected against exercise-induced reactive oxygen species in a trained state. Therefore, we characterized the acute exercise-induced HPC profile of well-trained participants including cell number, clonogenicity, and clearance. Twenty-one healthy, well-trained participants-12 runners, 9 cyclists; age 30.0 (4.3) years-performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with 3-min low-intensity in-between, which is known to elicit oxidative stress. Average power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and 10 min after exercise, CD34+/45dim cell number and clonogenicity, total oxidative (TOC), and antioxidative (TAC) capacities, as well as CD31 expression on detected HPCs were investigated. TOC significantly decreased from 0.093 (0.059) nmol/l to 0.083 (0.052) nmol/l post-exercise (p = 0.044). Although HPC proportions significantly declined below baseline (from 0.103 (0.037)% to 0.079 (0.028)% of mononuclear cells, p < 0.001), HPC concentrations increased post-exercise [2.10 (0.75) cells/µl to 2.46 (0.98) cells/µl, p = 0.002] without interaction between exercise modalities, while HPC clonogenicity was unaffected. Relating HPC concentrations and clonogenicity to exercise session specific (anti-) oxidative parameters, no association was found. CD31 median fluorescent intensity expression on detected HPCs was diminished post-exercise [from 1,675.9 (661.0) to 1,527.1 (558.9), p = 0.023] and positively correlated with TOC (r rm = 0.60, p = 0.005). These results suggest that acute exercise-reduced oxidative stress influences HPC clearance but not mobilization in well-trained participants. Furthermore, a well-trained state protected HPCs' clonogenicity from post-exercise decline.

Comparison of the diagnostic performance of two automated urine sediment analyzers with manual phase-contrast microscopy.

Background Recently, several manufacturers have launched automated urinalysis platforms. This study aimed to compare the diagnostic performance of the UF-5000 (Sysmex Corporation, Kobe, Japan) and the cobas® u 701 (Roche Diagnostics, Rotkreuz, Switzerland) urine sediment analyzers with manual phase-contrast microscopy as the reference method. Methods A total of 195 urine samples were analyzed on both automated platforms and subjected to manual microscopic examination. Agreement was assessed by Cohen's kappa (κ) analysis. Sensitivities and specificities were calculated. Results The agreement of the UF-5000 with manual microscopy was almost perfect (κ > 0.8) for red (RBC) and white blood cells (WBC), renal tubular epithel cells, hyaline casts, bacteria (BACT) and yeast (YLC), substantial (κ = 0.61-0.80) for squamous epithel cells (SEC) and pathologic casts, and moderate (κ = 0.41-0.60) for transitional epithel cells. The cobas® u 701 showed substantial agreement (κ = 0.61-0.80) for WBC, moderate agreement (κ = 0.41-0.60) for hyaline casts, and fair agreement (κ = 0.21-0.40) for RBC, SEC, non-squamous epithel (NEC), pathologic casts, BACT and YLC. The UF-5000 sensitivities ranged between 98.5% for RBC and 83.3% for pathological casts. The cobas® u 701 showed sensitivities between 83.0% for WBC and 31.6% for YLC. Conclusions The UF-5000 (Sysmex) analyzer showed a better diagnostic agreement with manual phase-contrast microscopy compared to the cobas® u 701 (Roche) module. The Sysmex platform showed reliable results for urine sediment analysis. However, pathological samples should be verified with manual microscopy.

Acute Exercise in Hypobaric Hypoxia Attenuates Endothelial Shedding in Subjects Unacclimatized to High Altitudes.

Travel of unacclimatized subjects to a high altitude has been growing in popularity. Changes in endothelial shedding [circulating endothelial cells (ECs)] and hematopoietic stem and progenitor cells (CPCs) during physical exercise in hypobaric hypoxia, however, are not well understood. We investigated the change in ECs and CPCs when exposed to high altitude, after acute exercise therein, and after an overnight stay in hypobaric hypoxia in 11 healthy unacclimatized subjects. Blood withdrawal was done at baseline (520 m a.s.l.; baseline), after passive ascent to 3,883 m a.s.l. (arrival), after acute physical exercise (±400 m, postexercise) and after an overnight stay at 3,883 m a.s.l. (24 h). Mature blood cells, ECs, and CPCs were assessed by a hematology analyzer and flow cytometry, respectively. The presence of matrix metalloproteinases (MMPs), their activity, and hematopoietic cytokines were assessed in serum and plasma. EC and CPC concentrations significantly decreased after exercise (p = 0.019, p = 0.007, respectively). CPCs remained low until the next morning (24 h, p = 0.002), while EC concentrations returned back to baseline. MMP-9 decreased at arrival (p = 0.021), stayed low postexercise (p = 0.033), and returned to baseline at 24 h (p = 0.035 to postexercise). MMP-activity did not change throughout the study. Circulating MMP-9 concentrations, but not MMP-activity, were associated with EC concentrations (r rm = 0.48, p = 0.010). CPC concentrations were not linked to hematopoietic cytokines. Acute exercise at high altitude attenuated endothelial shedding, but did not enhance regenerative CPCs. Results were not linked to endothelial matrix remodeling or CPC mobilization. These results provide information to better understand the endothelium and immature immune system during an active, short-term sojourn at high altitude.

25OH-Vitamin D3 Levels in Obesity and Metabolic Syndrome-Unaltered in Young and not Correlated to Carotid IMT in All Ages.

Contradictory results exist for levels of vitamin D measured in patients with cardiovascular disease (CVD), obesity and metabolic syndrome (MetS). To clarify this, we investigated 527 participants of the STYJOBS/ EDECTA cohort (NCT00482924), with ages between 10 and 65 years. A cross-sectional analysis of anthropometry, carotid intima media thickness (IMT), and laboratory measurements for 25OH-Vitamin D3 (vitD), glucose metabolism, ultra-sensitive C-reactive protein (US-CRP), interleukin-6 (IL-6), lipids, liver-, renal-parameters, and kynurenine to tryptophan ratio were made for a selection of persons who were either obese or of normal weight. The homeostasis model assessment insulin resistance (HOMA) was also measured. As compared to the normal weight controls, significantly decreased blood levels of vitD were found in overweight/obese adults, which were not observed in the juveniles. Nevertheless, both overweight/obese juveniles and adults had significantly increased US-CRP, IL-6, HOMA, triglyceride, and LDL-cholesterol levels, and significantly decreased HDL-cholesterol levels. Juveniles with MetS displayed unchanged levels of vitD as compared to overweight/obese juveniles without MetS. Although IMT was significantly increased in both juvenile and adult overweight/obese subjects, vitD and IMT levels were not correlated. Assuming a minimum threshold of 20 ng/ml for the establishment of "low" or "normal" vitD levels, no significant alteration in IMT, metabolic, and inflammatory markers was observed in juveniles with a low vitD-status . In conclusion, although metabolic and inflammatory symptoms of obesity are displayed in juveniles, their vitD levels are unaffected. This, together with the complete lack of association with carotid IMT in both juveniles and adults, argues against a causative role of vitD in obesity-associated vascular pathology.

Exercise-induced norepinephrine decreases circulating hematopoietic stem and progenitor cell colony-forming capacity.

A recent study showed that ergometry increased circulating hematopoietic stem and progenitor cell (CPC) numbers, but reduced hematopoietic colony forming capacity/functionality under normoxia and normobaric hypoxia. Herein we investigated whether an exercise-induced elevated plasma free/bound norepinephrine (NE) concentration could be responsible for directly influencing CPC functionality. Venous blood was taken from ten healthy male subjects (25.3+/-4.4 yrs) before and 4 times after ergometry under normoxia and normobaric hypoxia (FiO2<0.15). The circulating hematopoietic stem and progenitor cell numbers were correlated with free/bound NE, free/bound epinephrine (EPI), cortisol (Co) and interleukin-6 (IL-6). Additionally, the influence of exercise-induced NE and blood lactate (La) on CPC functionality was analyzed in a randomly selected group of subjects (n = 6) in vitro under normoxia by secondary colony-forming unit granulocyte macrophage assays. Concentrations of free NE, EPI, Co and IL-6 were significantly increased post-exercise under normoxia/hypoxia. Ergometry-induced free NE concentrations found in vivo showed a significant impairment of CPC functionality in vitro under normoxia. Thus, ergometry-induced free NE was thought to trigger CPC mobilization 10 minutes post-exercise, but as previously shown impairs CPC proliferative capacity/functionality at the same time. The obtained results suggest that an ergometry-induced free NE concentration has a direct negative effect on CPC functionality. Cortisol may further influence CPC dynamics and functionality.

Interleukin 10-coated nanoparticle systems compared for molecular imaging of atherosclerotic lesions.

Atherosclerosis (AS) is one of the leading causes of mortality in high-income countries. Early diagnosis of vulnerable atherosclerotic lesions is one of the biggest challenges currently facing cardiovascular medicine. The present study focuses on developing targeted nanoparticles (NPs) in order to improve the detection of vulnerable atherosclerotic-plaques. Various biomarkers involved in the pathogenesis of atherosclerotic-plaques have been identified and one of these promising candidates for diagnostic targeting is interleukin 10 (IL10). IL10 has been shown to be a key anti-inflammatory responding cytokine in the early stages of atherogenesis, and has already been used for therapeutic interventions in humans and mice. IL10, the targeting sequence, was coupled to two different types of NPs: protamine-oligonucleotide NPs (proticles) and sterically stabilized liposomes in order to address the question of whether the recognition and detection of atherosclerotic-lesions is primarily determined by the targeting sequence itself, or whether it depends on the NP carrier system to which the biomarker is coupled. Each IL10-targeted NP was assessed based on its sensitivity and selectivity toward characterizing atherosclerotic-plaque lesions using an apolipoprotein E-deficient mouse as the model of atherosclerosis. Aortas from apolipoprotein E-deficient mice fed a high fat diet, were stained with either fluorescence-labeled IL10 or IL10-coupled NPs. Ex vivo imaging was performed using confocal laser-scanning microscopy. We found that IL10-targeted proticles generated a stronger signal by accumulating at the surface of atherosclerotic-plaques, while IL10-targeted, sterically stabilized liposomes showed a staining pattern deeper in the plaque compared to the fluorescence-labeled IL10 alone. Our results point to a promising route for enhanced in vivo imaging using IL10-targeted NPs. NPs allow a higher payload of signal emitting molecules to be delivered to the atherosclerotic-plaques, thus improving signal detection. Importantly, this allows for the opportunity to visualize different areas within the plaque scenario, depending on the nature of the applied nanocarrier.

Laboratory medicine for molecular imaging of atherosclerosis.

Atherosclerotic plaques are the main cause of life threatening clinical endpoints like myocardial infarction and stroke. To prevent these endpoints, the improved early diagnosis and treatment of vulnerable atherosclerotic vascular lesions are essential. Although originally applied for anticancer treatment, recent advances have also showed the considerable potential of nanotechnology for atherosclerosis. Otherwise, one domain of laboratory medicine is the investigation of new biomarkers. Recent research activities have identified the usability of biomarker-targeted nanoparticles for molecular imaging and pharmacologic modification of vulnerable atherosclerotic lesions leading to myocardial infarction or stroke. These investigations have established a new research interface between laboratory medicine, nanotechnology, cardiology/neurology, and radiology. In this review, we discuss inflammatory pathophysiologic mechanisms and biomarkers associated with a vulnerable atherosclerotic plaque phenotype. Further, we will emphasize cardiovascular relevant functionalized nanoparticle biomarker constructs which were developed within the cooperation interface between Laboratory Medicine (anti-inflammatory biomarkers), Nano-Medicine (nanoparticle development), and Radiology (molecular imaging).

Human mesenchymal progenitor cells derived from alveolar bone and human bone marrow stromal cells: a comparative study.

The aim of the present study was to evaluate the potential of intraoral harvested alveolar bone as an alternative source of multipotent mesenchymal stromal cells for future applications in oral and maxillofacial tissue engineering. Explant cultures were established from 20 alveolar bone samples harvested from the oblique line immediately before wisdom tooth removal. Morphology and proliferation characteristics of the in vitro expanded cells, referred to as human alveolar bone-derived cells (hABDCs), were studied using phase-contrast microscopy. Immunocytochemical analysis of their surface marker expression was conducted using monoclonal antibodies defining mesenchymal stromal cells. To evaluate their multilineage differentiation potential, hABDCs were induced to differentiate along the osteogenic, adipogenic, and chondrogenic lineage and compared to bone marrow mesenchymal stromal cells (hBMSCs) on mRNA and protein levels applying RT-PCR and cytochemical staining methods. hABDCs showed typical morphological characteristics comparable to those of hBMSCs such as being mononuclear, fibroblast-like, spindle-shaped, and plastic adherent. Immunophenotypically, cells were positive for CD105, CD90, and CD73 while negative for CD45, CD34, CD14, CD79α, and HLA-DR surface molecules, indicating an antigen expression pattern considered typical for multipotent mesenchymal stromal cells. As evidenced by RT-PCR and cytochemistry, hABDCs showed multilineage differentiation and similar chondrogenic and osteogenic differentiation potentials when compared to hBMSCs. Our findings demonstrate that human alveolar bone contains mesenchymal progenitor cells that can be isolated and expanded in vitro and are capable of trilineage differentiation, providing a reservoir of multipotent mesenchymal cells from an easily accessible tissue source.

Molecular evidence for the bi-clonal origin of neuroendocrine tumor derived metastases.

BACKGROUND: Reports on common mutations in neuroendocrine tumors (NET) are rare and clonality of NET metastases has not been investigated in this tumor entity yet. We selected one NET and the corresponding lymph node and liver metastases as well as the derivative cell lines to screen for somatic mutations in the primary NET and to track the fate of genetic changes during metastasis and in vitro progression. RESULTS: Applying microarray based sequence capture resequencing including 4,935 Exons from of 203 cancer-associated genes and high-resolution copy number and genotype analysis identified multiple somatic mutations in the primary NET, affecting BRCA2, CTNNB1, ERCC5, HNF1A, KIT, MLL, RB1, ROS1, SMAD4, and TP53. All mutations were confirmed in the patients' lymph node and liver metastasis tissue as well as early cell line passages. In contrast to the tumor derived cell line, higher passages of the metastases derived cell lines lacked somatic mutations and chromosomal alterations, while expression of the classical NET marker serotonin was maintained. CONCLUSION: Our study reveals that both metastases have evolved from the same pair of genetically differing NET cell clones. In both metastases, the in vivo dominating "mutant" tumor cell clone has undergone negative selection in vitro being replaced by the "non-mutant" tumor cell population. This is the first report of a bi-clonal origin of NET derived metastases, indicating selective advantage of interclonal cooperation during metastasis. In addition, this study underscores the importance to monitor cell line integrity using high-resolution genome analysis tools.

Exercise increases the frequency of circulating hematopoietic progenitor cells, but reduces hematopoietic colony-forming capacity.

Circulating hematopoietic progenitor cells (CPCs) may be triggered by physical exercise and/or normobaric hypoxia from the bone marrow. The aim of the study was to investigate the influence of physical exercise and normobaric hypoxia on CPC number and functionality in the peripheral blood as well as the involvement of oxidative stress parameters as possibly active agents. Ten healthy male subjects (25.3±4.4 years) underwent a standardized cycle incremental exercise test protocol (40 W+20 W/min) under either normoxic (FiO2 ∼0.21) or hypoxic conditions (FiO2<0.15, equals 3,500 m, 3 h xposure) within a time span of at least 1 week. Blood was drawn from the cubital vein before and 10, 30, 60, and 120 min after exercise. The number of CPCs in the peripheral blood was analyzed by flow cytometry (CD34/CD45-positive cells). The functionality of cells present was addressed by secondary colony-forming unit-granulocyte macrophage (CFU-GM) assays. To determine a possible correlation between the mobilization of CPCs and reactive oxygen species, parameters for oxidative stress such as malondialdehyde (MDA) and myeloperoxidase (MPO) were obtained. Data showed a significant increase of CPC release under normoxic as well as hypoxic conditions after 10 min of recovery (P<0.01). Most interestingly, although CD34+/CD45dim cells increased in number, the proliferative capacity of CPCs decreased significantly 10 min after cessation of exercise (P<0.05). A positive correlation between CPCs and MDA/MPO levels turned out to be significant for both normoxic and hypoxic conditions (P<0.05/P<0.01). Hypoxia did not provoke an additional effect. Although the CPC frequency increased, the functionality of CPCs decreased significantly after exercise, possibly due to the influence of increased oxidative stress levels.

Link between leptin and interleukin-6 levels in the initial phase of obesity related inflammation.

The mechanisms underlying the pathogenesis of obesity-related atherosclerosis remain to be clarified. To investigate the preclinical phase, interleukin-6 (IL-6) plasma levels were analyzed together with clinical, anthropometric, inflammatory, and metabolic variables in a well-defined cohort of 677 young and middle-aged overweight/obese and normal-weight subjects. In the juvenile and adult overweight/obese study group, IL-6 levels were increased significantly compared with normal-weight, age-matched controls (P < 0.001). In both juveniles and adults, higher levels of IL-6 were observed in obese compared with overweight participants. Subjects with metabolic syndrome (MS) had significantly higher IL-6 levels than those without MS. In juveniles, leptin, and in adults, the waist-to-height ratio, turned out to be the best predictor of IL-6 plasma levels in a multiple stepwise regression model. Taken together, in every age group, interleukin-6 is associated positively with the grade of overweight. Interestingly, leptin, which is the best known adipokine, is associated predictively with interleukin-6 plasma levels only in juveniles, which may indicate an important role of this molecule in the initiation of obesity-related inflammation.

Modification of the alkaline comet assay with human mesenchymal stem cells.

MSCs (mesenchymal stem cells) are planned foruse in regenerative medicine to offset age-dependent alterations. However, MSCs are affected by replicative senescence associated with decreasing proliferation potential, telomere shortening and DNA damage during in vitro propagation. To monitor in vitro senescence, we have assessed the integrity of DNA by the alkaline comet assay. For optimization of the comet assay we have enhanced the stability of comet slides in liquid and minimized the background noise of the method by improving adhesion of agarose gels on the comet slides and concentrating cells on a defined small area on the slides. The modifications of the slide preparation increase the overall efficiency and reproducibility of the comet assay and minimize the image capture and storage. DNA damage of human MSCs during in vitro cultivation increased with time, as assessed by the comet assay, which therefore offers a fast and easy screening tool in future efforts to minimize replicative senescence of MSCs in vitro.

α1-adrenergic drugs exhibit affinity to a thapsigargin-sensitive binding site and interfere with the intracellular Ca2+ homeostasis in human erythroleukemia cells.

Even though the erythroleukemia cell lines K562 and HEL do not express α1-adrenoceptors, some α1-adrenergic drugs influence both survival and differentiation of these cell lines. Since Ca2+ is closely related to cellular homeostasis, we examined the capacity of α1-adrenergic drugs to modulate the intracellular Ca2+ content in K562 cells. Because of morphological alterations of mitochondria following α1-adrenergic agonist treatment, we also scrutinized mitochondrial functions. In order to visualize the non-adrenoceptor binding site(s) of α1-adrenergic drugs in erythroleukemia cells, we evaluated the application of the fluorescent α1-adrenergic antagonist BODIPY® FL-Prazosin. We discovered that the α1-adrenergic agonists naphazoline, oxymetazoline and also the α1-adrenergic antagonist benoxathian are able to raise the intracellular Ca2+-content in K562 cells. Furthermore, we demonstrate that naphazoline treatment induces ROS-formation as well as an increase in Δψm in K562 cells. Using BODIPY® FL-Prazosin we were able to visualize the non-adrenoceptor binding site(s) of α1-adrenergic drugs in erythroleukemia cells. Interestingly, the SERCA-inhibitor thapsigargin appears to interfere with the binding of BODIPY® FL-Prazosin. Our data suggest that the effects of α1-adrenergic drugs on erythroleukemia cells are mediated by a thapsigargin sensitive binding site, which controls the fate of erythroleukemia cells towards differentiation, senescence and cell death through modulation of intracellular Ca2+.

α1-Adrenergic drugs modulate differentiation and cell death of human erythroleukemia cells through non adrenergic mechanism.

Preliminary data showed that α1-adrenergic antagonists induce apoptosis and a switch towards megakaryocytic differentiation in human erythroleukemia cells. To test the hypothesis whether survival and differentiation of erythroleukemia cells are under control of α1-adrenergic signalling, we examined α1-adrenoceptor expression of erythroleukemia cells and compared the in vitro effects of α-adrenergic antagonists with those of agonists. We discovered that α1-adrenergic agonists suppress both erythroid differentiation and growth of erythroleukemia cells concomitant with lipofuscin accumulation, autophagy and necrotic cell death. α1-adrenergic agonists also inhibit the in vitro growth of physiologic hematopoietic progenitors obtained from umbilical cord blood with high selectivity for the erythroid lineage. Interestingly, the observed effects could not be related to α1-adrenoceptors, even though agonists and antagonists displayed opposing effects regarding cellular growth and differentiation of erythroleukemia cells. Our data suggest that the effects of α1-adrenergic drugs are related to a non-adrenoceptor binding site, controlling the fate of erythroid progenitor cells towards differentiation and cell death. Since the observed effects are not mediated through adrenoceptors, the physiologic relevance of our data remains unclear, so far. Nevertheless, the identification of the still unknown binding site(s) might disclose new insights into regulation of erythroid differentiation and cell death.

Decline of bone marrow-derived hematopoietic progenitor cell quality during aging in the rat.

Several studies have shown that aging is associated with quantitative and qualitative alterations of the stem and progenitor cell compartment. The current results indicate that there is a significant age-associated decline in the proliferative capacity of rat myeloid progenitor cells. In contrast, no difference was found in the frequency of myeloid progenitor cells in the bone marrow of young versus old rats. Furthermore, a significant shift towards higher proliferative capacity of myeloid progenitors was observed after lifelong voluntary exercise. These data emphasize that aging is accompanied by a loss of proliferative capacity and that voluntary exercise could retard this process.