Circulating bone marrow-derived endothelial progenitor cells: characterization, mobilization, and therapeutic considerations in malignant disease

Circulating endothelial and angiogenic cells predict hippocampal volume as a function of HIV status

Circulating endothelial cells (CECs) and myeloid angiogenic cells (MACs) have the capacity to stabilize human blood vessels in vivo. Evidence suggests that these cells are depleted in dementia and in persons living with HIV (PWH), who have a higher prevalence of dementia and other cognitive deficits associated with aging. However, the associations of CECs and MACs with MRI-based measures of aging brain health, such as hippocampal gray matter volume, have not been previously demonstrated. The present study examined differences in these associations in 51 postmenopausal women with and without HIV infection. Gray matter volume was quantified using MRI. CECs and MACs were enumerated using fluorescence-activated cell sorting. Analyses examined the association of these cell counts with left and right hippocampal gray matter volume while controlling for age and hypertension status. The main finding was an interaction suggesting that compared to controls, postmenopausal PWH with greater levels of CECs and MACs had significantly greater hippocampus GMV. Further research is necessary to examine potential underlying pathophysiological mechanisms in HIV infection linking morpho-functional circulatory reparative processes with more diminished hippocampal volume in postmenopausal women.

Critical Role of LSEC in Post-Hepatectomy Liver Regeneration and Failure

Liver sinusoids are lined by liver sinusoidal endothelial cells (LSEC), which represent approximately 15 to 20% of the liver cells, but only 3% of the total liver volume. LSEC have unique functions, such as fluid filtration, blood vessel tone modulation, blood clotting, inflammatory cell recruitment, and metabolite and hormone trafficking. Different subtypes of liver endothelial cells are also known to control liver zonation and hepatocyte function. Here, we have reviewed the origin of LSEC, the different subtypes identified in the liver, as well as their renewal during homeostasis. The liver has the exceptional ability to regenerate from small remnants. The past decades have seen increasing awareness in the role of non-parenchymal cells in liver regeneration despite not being the most represented population. While a lot of knowledge has emerged, clarification is needed regarding the role of LSEC in sensing shear stress and on their participation in the inductive phase of regeneration by priming the hepatocytes and delivering mitogenic factors. It is also unclear if bone marrow-derived LSEC participate in the proliferative phase of liver regeneration. Similarly, data are scarce as to LSEC having a role in the termination phase of the regeneration process. Here, we review what is known about the interaction between LSEC and other liver cells during the different phases of liver regeneration. We next explain extended hepatectomy and small liver transplantation, which lead to "small for size syndrome" (SFSS), a lethal liver failure. SFSS is linked to endothelial denudation, necrosis, and lobular disturbance. Using the knowledge learned from partial hepatectomy studies on LSEC, we expose several techniques that are, or could be, used to avoid the "small for size syndrome" after extended hepatectomy or small liver transplantation.

The Therapeutic Potential of Hematopoietic Stem Cells in Bone Regeneration

The repair process of bone fractures is a complex biological mechanism requiring the recruitment and in situ functionality of stem/stromal cells from the bone marrow (BM). BM mesenchymal stem/stromal cells have been widely explored in multiple bone tissue engineering applications, whereas the use of hematopoietic stem cells (HSCs) has been poorly investigated in this context. A reasonable explanation is the fact that the role of HSCs and their combined effect with other elements of the hematopoietic niches in the bone-healing process is still elusive. Therefore, in this review we intend to highlight the influence of HSCs in the bone repair process, mainly through the promotion of osteogenesis and angiogenesis at the bone injury site. For that, we briefly describe the main biological characteristics of HSCs, as well as their hematopoietic niches, while reviewing the biomimetic engineered BM niche models. Moreover, we also highlighted the role of HSCs in translational in vivo transplantation or implantation as promoters of bone tissue repair.

Mobilization of Stem and Progenitor Cells in Septic Shock Patients

Septic shock is associated with multiple injuries to organs and tissues. These events may induce the regenerative response of adult stem cells. However, little is known about how endogenous stem cells are modulated by sepsis. This study analyzed the circulation of hematopoietic stem cells (HSCs), endothelial progenitor cells (EPCs) and very small embryonic-like stem cells (VSELs) in the peripheral blood of patients with septic shock. Thirty-three patients with septic shock and twenty-two healthy control subjects were enrolled in this prospective observational study. Blood samples were collected on the first, third and seventh days of septic shock. Populations of stem cells were analyzed by flow cytometry. Chemotactic mediators were analyzed by HPLC and ELISA. Populations of early HSCs (Lin-CD133+CD45+ and CD34+CD38−) were mobilized to the peripheral blood after an initial decrease. Mobilized HSCs showed significantly increased expression of Ki-67, a marker of cell proliferation. Circulating EPCs and VSELs were mobilized to the blood circulation upon the first day of sepsis. Patients with a greater number of Lin-CD133+CD45+ HSCs and Lin-CD34+CD45− VSELs had a significantly lower probability of 60-day survival. The concentration of CXCL12 was elevated in the blood of septic patients, while the concentration of sphingosine-1-phosphate was significantly decreased. As an emergency early response to sepsis, VSELs and EPCs were mobilized to the peripheral blood, while the HSCs showed delayed mobilization. Differential mobilization of stem cell subsets reflected changes in the concentration of chemoattractants in the blood. The relationship between the probability of death and a large number of HSCs and VSELs in septic shock patients can be used as a novel prognostic marker and may provide new therapeutic approaches.

Circulating endothelial cells and microparticles as diagnostic and prognostic biomarkers in small-cell lung cancer

OBJECTIVES

It has been proposed that circulating endothelial cells (CECs) and microparticles (MPs) may be useful for the assessment of patients with non-small-cell lung cancer (NSCLC). However, little is known about the potential clinical relevance of these biomarkers in small-cell lung cancer (SCLC). Therefore, we investigated the utility of baseline levels of CECs and MPs in SCLC patients.

MATERIALS AND METHODS

An immunomagnetic separation (IMS) technique was used to isolate and quantify CECs in the peripheral blood, while plasma samples were analyzed using flow cytometry for the measurement of circulating MPs.

RESULTS

We prospectively collected data from 56 patients and 41 healthy individuals. Forty-three patients presented at initial diagnosis and 13 patients presented at relapse. Baseline levels of CECs and MPs were significantly higher in SCLC patients either at initial diagnosis or at relapse than in healthy subjects (p < 0.0002 and p < 0.007, respectively). However, estimated tumor volume (ETV) was significantly correlated with basal MP values (p < 0.0001) but not with pretreatment CECs (p =  0.57). The amount of baseline CECs and MPs was significantly lower in patients with an objective response (OR, n = 23) than in those with progressive disease (PD, n = 15) after treatment (p =  0.016 and 0.05, respectively). With cut-off values of 110 cells/mL for CECs and 1257 events/μL for MPs according to receiver operating characteristics (ROC) analysis, baseline levels of these biomarkers were not significantly correlated with either progression-free survival (PFS) or overall survival (OS). However, patients with 6-month PFS displayed significantly decreased pretreatment CEC counts (p =  0.042), whereas basal MP values significantly increased in 1-year survivors compared with those in non-survivors (p =  0.05).

CONCLUSION

Our results suggest that baseline CECs and MPs may be predictive biomarkers of tumor response and long-term survival in SCLC patients.

Generation of an anti-angiogenic endothelial progenitor cell line via endostatin gene transfer

The viability of endothelial progenitor cells (EPCs) as a therapeutic treatment for neovascularization (NV) was subject to investigation in the present study. Furthermore, endostatin has previously been demonstrated to be an inhibitor of angiogenesis and a suppressant of vascular leakage. The aim of the present study was to generate transgenic EPCs with anti-angiogenic effects for the treatment of ocular NV. EPCs were obtained from rat peripheral blood samples and then verified. A lentiviral-endostatin-green fluorescent protein recombinant construct was generated and used to infect EPCs. Transfected cells were then subjected to puromycin selection. Reverse transcription-quantitative polymerase chain reaction and a western blot assay were then applied in order to determine both the endostatin mRNA and protein expression levels, respectively. In addition, vascular endothelial growth factor (VEGF) expression levels were also detected in order to observe the anti-angiogenic effect of the endostatin-transfected EPCs. Following puromycin (1 µg/ml) selection for 4 days, a stable endostatin-transfected EPC line was generated. In this stable endostatin-transfected EPC line, the expression levels of endostatin increased; whereas the expression levels of VEGF decreased. The results of the present study revealed that EPCs can be genetically modified to overexpress endostatin, which may provide the cells with an anti-angiogenic effect via increased expression of endostatin and decreased expression of VEGF. Thus, EPCs genetically modified to overexpress endostatin may serve as a potential therapeutic agent for ocular NV treatment.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

MFSD2A Promotes Endothelial Generation of Inflammation-Resolving Lipid Mediators and Reduces Colitis in Mice

BACKGROUND & AIMS

Alterations in signaling pathways that regulate resolution of inflammation (resolving pathways) contribute to pathogenesis of ulcerative colitis (UC). The resolution process is regulated by lipid mediators, such as those derived from the ω-3 docosahexaenoic acid (DHA), whose esterified form is transported by the major facilitator superfamily domain containing 2A (MFSD2A) through the endothelium of brain, retina, and placenta. We investigated if and how MFSD2A regulates lipid metabolism of gut endothelial cells to promote resolution of intestinal inflammation.

METHODS

We performed lipidomic and functional analyses of MFSD2A in mucosal biopsies and primary human intestinal microvascular endothelial cells (HIMECs) isolated from surgical specimens from patients with active, resolving UC and healthy individuals without UC (controls). MFSD2A was knocked down in HIMECs with small hairpin RNAs or overexpressed from a lentiviral vector. Human circulating endothelial progenitor cells that overexpress MFSD2A were transferred to CD1 nude mice with dextran sodium sulfate-induced colitis, with or without oral administration of DHA.

RESULTS

Colonic biopsies from patients with UC had reduced levels of inflammation-resolving DHA-derived epoxy metabolites compared to healthy colon tissues or tissues with resolution of inflammation. Production of these metabolites by HIMECs required MFSD2A, which is required for DHA retention and metabolism in the gut vasculature. In mice with colitis, transplanted endothelial progenitor cells that overexpressed MFSD2A not only localized to the inflamed mucosa but also restored the ability of the endothelium to resolve intestinal inflammation, compared with mice with colitis that did not receive MFSD2A-overexpressing endothelial progenitors.

CONCLUSIONS

Levels of DHA-derived epoxides are lower in colon tissues from patients with UC than healthy and resolving mucosa. Production of these metabolites by gut endothelium requires MFSD2A; endothelial progenitor cells that overexpress MFSD2A reduce colitis in mice. This pathway might be induced to resolve intestinal inflammation in patients with colitis.

Suppressing angiogenesis regulates the irradiation-induced stimulation on osteoclastogenesis in vitro

Ionizing radiation-induced bone loss is a potential health concern in radiotherapy, occupational exposure, and astronauts. Although impaired bone vasculature and reduced proliferation of bone-forming osteoblasts has been implicated in this process, it has not been clearly characterized that whether radiation affects the growth of bone-resorbing osteoclasts. The molecular crosstalk between different cell populations in the skeletal system has not yet been elucidated in detail, especially between the increased bone resorption at early stage of post-irradiation and bone marrow-derived endothelial progenitor cells (BM-EPCs). In order to further understand the mechanisms involved in radiation-induced bone loss at the cellular level, we assessed the effects of irradiation on angiogenesis of BM-EPCs and osteoclastogenesis of receptor activator for nuclear factor-κB ligand (RANKL)-stimulated RAW 264.7 cells and crosstalk between these cell populations. We herein found significantly dysfunction of BM-EPCs in response to irradiation at a dose of 2 Gy, including inhibited proliferation, migration, tube-forming abilities, and downregulated expression of pro-angiogenesis vascular endothelial growth factors A (VEGF A). Meanwhile, we observed that irradiation promoted osteoclastogenesis of RANKL-stimulated RAW 264.7 cells directly or indirectly. These results provide quantitative evidences of irradiation induced osteoclastogenesis at a cellular level, and strongly suggest the involvement of osteoclastogenesis, angiogenesis and crosstalk between bone marrow cells in the radiation-induced bone loss. This study may provide new insights for the early diagnosis and intervention of bone loss post-irradiation.

Growth Factors in the Pathogenesis of Retinal Neurodegeneration in Diabetes Mellitus

Neurodegeneration is an initial process in the development of diabetic retinopathy (DR).

High quantities of glutamate, oxidative stress, induction of the renin-angiotensin system (RAS) and elevated levels of RAGE are crucial elements in the retinal neurodegeneration caused by diabetes mellitus. At least, there is emerging proof to indicate that the equilibrium between the neurotoxic and neuroprotective components will affect the state of the retinal neurons.

Somatostatin (SST), pigment epithelium-derived factor (PEDF), and erythropoietin (Epo) are endogenous neuroprotective peptides that are decreased in the eye of diabetic persons and play an essential role in retinal homeostasis. On the other hand, insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF) are pivotal proteins which participate in the development of new capillaries and finally cause damage to the retinal neurons. During recent years, our knowledge about the function of growth factors in the pathogenesis of retinal neurodegeneration has increased. However, intensive investigations are needed to clarify the basic processes that contribute to retinal neurodegeneration and its association with damage to the capillary blood vessels. The objective of this review article is to show new insights on the role of neurotransmitters and growth factors in the pathogenesis of diabetic retinopathy. The information contained in this manuscript may provide the basis for novel strategies based on the factors of neurodegeneration to diagnose, prevent and treat DR in its earliest phases.

Circulating Progenitor Cells is Linked to Cognitive Decline in Healthy Adults

OBJECTIVE

Cognitive and cardiovascular disorders share many risk factors. Higher bone-marrow derived progenitor cells (PC) in blood are associated with lower rates of cardiovascular events but the association of PC with cognitive function is unclear. The objective of this study was to assess the association between PC and cognition in a sample of healthy adults enrolled in a cohort study.

MATERIALS AND METHODS

A random sample of employees at Emory University and Georgia Institute of Technology were followed for 4 years and underwent yearly vascular and cognitive assessment (N = 430, mean age = 49.2 years, 70% women, and 27% African-American). Cognition was assessed using computerized versions of 15 cognitive tests and principal component analysis was used for deriving cognitive scores: executive function, memory and working memory. PC were defined as mononuclear cells with specific surface markers (7 phenotypes). Decreased cognition in a domain was defined as performing below the lowest quartile for the corresponding domain at baseline. Generalized estimating equations were used to investigate associations between PC and cognition.

RESULTS

Higher PC levels at baseline were associated with lower risk of cognitive decline in the executive and working memory domains during the follow-up period (P < 0.002 for all PC phenotypes). Further, the degree of decline in PC over the follow-up period was correlated with a corresponding decline in performances in all 3 cognitive domains over the same period (All P < 0.002).

CONCLUSION

Lower PC and greater yearly declines in PC are associated with greater cognitive decline. These findings suggest the role for PC in neurocognitive aging.

Modulation of Endothelial Injury Biomarkers by Traditional Chinese Medicine LC in Systemic Lupus Erythematosus Patients Receiving Standard Treatments

LC is an herbal remedy effectively reduced therapeutic dosage of glucocorticoid for systemic lupus erythematosus (SLE) patients in clinical trial (ISRCTN81818883). This translational research examined the impact of LC on biomarkers of endothelial injury in the enrolled subjects. Fifty seven patients with SLE were randomized to receive standard treatment without or with LC supplements. Blood samples were taken serially for quantification of endothelial progenitor cells (EPCs), circulating endothelial cells (CECs) and serological factors. The proportion of EPCs in the placebo group continued to increase during trial and was further elevated after withdrawal of standard treatment. The EPC ratio of LC group remained stationary during the entire observation period. The CEC ratio in placebo group exhibited an increasing trend whereas that in LC group declined. The ratio of apoptotic CECs had an increasing trend in both groups, to a lesser extent in LC group. After treatment, the levels of VEGF and IL-18 have a trend declined to a level lower in the LC group than the placebo group. No significant alteration was noted in serum levels of IFN-α, IL-1β and IL-6. The reduction of the steroid dosage by adding LC might be correlated with less extensive endothelial injury in SLE patients.

Functional and Biological Role of Endothelial Precursor Cells in Tumour Progression: A New Potential Therapeutic Target in Haematological Malignancies

It was believed that vasculogenesis occurred only during embryo life and that postnatal formation of vessels arose from angiogenesis. Recent findings demonstrate the existence of Endothelial Precursor Cells (EPCs), which take partin postnatal vasculogenesis. EPCs are recruited from the bone marrow under the stimulation of growth factors and cytokines and reach the sites of neovascularization in both physiological and pathological conditions such as malignancies where they contribute to the “angiogenic switch” and tumor progression. An implementation of circulating EPCs in the bloodstream of patients with haematological malignancies has been demonstrated. This increase is strictly related to the bone marrow microvessel density and correlated with a poor prognosis. The EPCs characterization is a very complex process and still under investigation. This literature review aims to provide an overview of the functional and biological role of EPCs in haematological malignancies and to investigate their potential as a new cancer therapeutic target.

Melanoma cell therapy: Endothelial progenitor cells as shuttle of the MMP12 uPAR-degrading enzyme

The receptor for the urokinase-type plasminogen activator (uPAR) accounts for many features of cancer progression, and is therefore considered a target for anti-tumoral therapy. Only full length uPAR mediates tumor progression. Matrix-metallo-proteinase-12 (MMP12)-dependent uPAR cleavage results into the loss of invasion properties and angiogenesis. MMP12 can be employed in the field of “targeted therapies” as a biological drug to be delivered directly in patient's tumor mass. Endothelial Progenitor Cells (EPCs) are selectively recruited within the tumor and could be used as cellular vehicles for delivering anti-cancer molecules. The aim of our study is to inhibit cancer progression by engeneering ECFCs, a subset of EPC, with a lentivirus encoding the anti-tumor uPAR-degrading enzyme MMP12. Ex vivo manipulated ECFCs lost the capacity to perform capillary morphogenesis and acquired the anti-tumor and anti-angiogenetic activity. In vivo MMP12-engineered ECFCs cleaved uPAR within the tumor mass and strongly inhibited tumor growth, tumor angiogenesis and development of lung metastasis.

The possibility to exploit tumor homing and activity of autologous MMP12-engineered ECFCs represents a novel way to combat melanoma by a “personalized therapy”, without rejection risk.

The i.v. injection of radiolabelled MMP12-ECFCs can thus provide a new theranostic approach to control melanoma progression and metastasis.

Increased pre-surgical numbers of endothelial progenitor cells and circulating endothelial cells in colorectal cancer fail to predict outcome

INTRODUCTION

The endothelium and angiogenesis are therapeutic targets in cancer. Response to treatment may be assessed by laboratory plasma markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. We hypothesised that these markers, obtained before surgery, would predict 2-year outcome after surgery with or without anti-angiogenic therapy for colorectal cancer (CRC).

METHODS

We recruited 154 patients with CRC, of whom 51 were treated with surgery alone, 74 were treated with standard chemotherapy (5-fluorouracil) and 29 were treated with standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery. CD34(+)/CD45(-)/CD146(+) CECs and CD34(+)/CD45(-)/CD309 [KDR](+) EPCs were measured by flow cytometry and plasma markers by ELISA.

RESULTS

After a mean of 2.1 years follow-up (range 1.9-2.3 years), 52 of the patients (33.7 %) experienced a poor outcome (radiological and/or histological evidence of tumour spread or recurrence, or death [n = 26]). In univariate analysis, poor outcome was linked to Dukes' stage (p < 0.001), American Joint Committee on Cancer (AJCC) stage (p < 0.001), type of treatment (surgery alone, standard chemotherapy with or without anti-antigenic therapy) (p = 0.047), CECs (p < 0.02) and EPCs (p < 0.01). In subsequent binary logistic regression analysis, only Dukes' stage (hazard ratio 2.3, 95 % confidence interval 1.0-5.3, p = 0.047) and modified AJCC stage (4.62, 1.88-11.33, p < 0.001) predicted a poor outcome.

CONCLUSION

Endothelial cell markers (CECs, EPCs, vWf, soluble E selectin) and growth factors (VEGF and angiogenin), measured before surgery, have nothing extra to offer in predicting 2-year outcome in colorectal cancer when compared to Dukes' or AJCC stage.

Effect of standard chemotherapy and antiangiogenic therapy on plasma markers and endothelial cells in colorectal cancer

Introduction:

The importance of the endothelium in angiogenesis and cancer is undisputed, and its integrity may be assessed by laboratory markers such as circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), plasma von Willebrand factor (vWf), soluble E selectin, vascular endothelial growth factor (VEGF) and angiogenin. Antiantigenic therapy may be added to standard cytotoxic chemotherapy as a new treatment modality. We hypothesised that additional antiangiogenic therapy acts in a contrasting manner to that of standard chemotherapy on the laboratory markers.

Methods:

We recruited 68 patients with CRC, of whom 16 were treated with surgery alone, 32 were treated with surgery followed by standard chemotherapy (5-flurouracil), and 20 were treated with surgery followed by standard chemotherapy plus anti-VEGF therapy (Avastin). Peripheral blood was taken before surgery, and again 3 months and 6 months later. CD34⁺/CD45⁻/CD146⁺ CECs and CD34⁺/CD45⁻/CD309[KDR]⁺ EPCs were measured by flow cytometry, plasma markers by ELISA.

Results:

In each of the three groups, CECs and EPCs fell at 3 months but were back at pre-surgery levels at 6 months (P<0.05). VEGF was lower in both 3-and 6-month samples in the surgery-only and surgery plus standard chemotherapy groups (P<0.05), but in those on surgery followed by standard chemotherapy plus anti-VEGF therapy, low levels at 3 months (P<0.01) increased to pre-surgery levels at 6 months. In those having surgery and standard chemotherapy, soluble E selectin was lower, whereas angiogenin was higher at 6 months than at baseline (both P<0.05).

Conclusions:

We found disturbances in endotheliod cells regardless of treatment, whereas VEGF returned to levels before surgery in those on antiangiogenic therapy. These observations may have clinical and pathophysiological implications.

Bone marrow-derived stromal cell therapy in cirrhosis: clinical evidence, cellular mechanisms, and implications for the treatment of hepatocellular carcinoma

Current treatment options for hepatocellular carcinoma (HCC) are often limited by the presence of underlying liver disease. In patients with liver cirrhosis, surgery, chemotherapy, and radiation therapy all carry a high risk of hepatic complications, ranging from ascites to fulminant liver failure. For patients receiving radiation therapy, cirrhosis dramatically reduces the already limited radiation tolerance of the liver and represents the most important clinical risk factor for the development of radiation-induced liver disease. Although improvements in conformal radiation delivery techniques have improved our ability to safely irradiate confined areas of the liver to increasingly higher doses with excellent local disease control, patients with moderate-to-severe liver cirrhosis continue to face a shortage of treatment options for HCC. In recent years, evidence has emerged supporting the use of bone marrow-derived stromal cells (BMSCs) as a promising treatment for liver cirrhosis, with several clinical studies demonstrating sustained improvement in clinical parameters of liver function after autologous BMSC infusion. Three predominant populations of BMSCs, namely hematopoietic stem cells, mesenchymal stem cells, and endothelial progenitor cells, seem to have therapeutic potential in liver injury and cirrhosis. Preclinical studies of BMSC transplantation have identified a range of mechanisms through which these cells mediate their therapeutic effects, including hepatocyte transdifferentiation and fusion, paracrine stimulation of hepatocyte proliferation, inhibition of activated hepatic stellate cells, enhancement of fibrolytic matrix metalloproteinase activity, and neovascularization of regenerating liver. By bolstering liver function in patients with underlying Child's B or C cirrhosis, autologous BMSC infusion holds great promise as a therapy to improve the safety, efficacy, and utility of surgery, chemotherapy, and hepatic radiation therapy in the treatment of HCC.

The Primary Study of CD90(+)CD34(-)and Sca-1(+) Stem Cells Mobilized by EPO Plus G-CSF in Mice

To investigate effects of recombinant human erythropoietin (rhEPO) plus recombinant human granulocyte colony stimulating factor (rhG-CSF) on mobilization of CD90(+)CD34(-) and Sca-1(+) stem cells in mice. rhEPO 1000 IU·kg(-1)·d(-1) per mice alone or plus rhG-CSF 250 μg·kg(-1)·d-1(-1)per mice was administered to mice for five days, the peripheral blood was collected at 6 hours, 1, 3,5 and 7 days after the last administration. The number of white blood cells (WBC) and mononuclear cells (MNC) was counted. The level of CD34, CD90 and Sca-1 mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR).The expressions of CD90(+)CD34(-) in absolute nuclear cells of peripheral blood was detected by flow cytometry. The results indicate that compared to mobilizing by rhG-CSF, rhEPO or plus rhG-CSF did not significantly enhance the number of WBC and MNC, on the fifth and the seventh day after the last administration, both the expression of CD34,CD90 and Sca-1 mRNA and the proportion of CD90(+)CD34(-) cells dramatically raised in rhEPO or in addition to rhG-CSF groups. We conclude that rhEPO or plus rhG-CSF had a strong capacity of mobilization of stem cells. The alteration of expression of CD34, CD90 and Sca-1 mRNA after the administration of rhEPO or combined with rhG-CSF indicated that this agents might potentially alter the peripheral blood graft content.

Angiogenin outperforms VEGF, EPCs and CECs in predicting Dukes' and AJCC stage in colorectal cancer

BACKGROUND

Circulating endothelial cells (CECs), endothelial progenitor cells (EPCs), Willebrand factor (vWf), soluble E-selectin, vascular endothelial growth factor (VEGF) and angiogenin are of interest in cancer vascular biology. However, few studies have looked at more than one in combination. We set out to determine which would be best in predicting the Dukes' and American Joint Committee on Cancer (AJCC) scores in colorectal cancer patients.

METHODS

We recruited 154 patients with colorectal cancer, 29 healthy controls and 26 patients with benign bowel disease. CD34(+) /CD45(-) /CD146(+) CECs and CD34(+) /CD45(-) /CD309[KDR](+) EPCs were measured by flow cytometry, plasma markers by ELISA.

RESULTS

All research indices were raised in colorectal cancer (P < 0·05) compared to control groups. Although CECs (P < 0·05), EPCs (P < 0·01) and angiogenin (P < 0·01) increased stepwise across the four Dukes' stages and four AJCC stages, only angiogenin remained significant in multiple regression analysis (P = 0·003 for Dukes, P = 0·01 for AJCC). Angiogenin levels were higher in Dukes' stages C and D compared to stage A, and AJCC stages 4-6 and 7-10 compared to stage 1 (all P < 0·05). Adding a second research marker to angiogenin did not markedly improve this relationship.

CONCLUSION

Although we found disturbances in endotheliod cells and plasma markers of the endothelium and growth factors, only angiogenin levels were independently associated with progression of the Dukes' stage and AJCC stage, with the association with Duke's stage being stronger. We suggest that angiogenin is a potential biomarker in risk stratification for colorectal cancer, and may aid clinical decision making.

Update on oncolytic viral therapy - targeting angiogenesis

Oncolytic viruses (OVs) have the ability to selectively replicate in and lyse cancer cells. Angiogenesis is an essential requirement for tumor growth. Like OVs, the therapeutic effect of many angiogenesis inhibitors has been limited, leading to the development of more effective approaches to combine antiangiogenic therapy with OVs. Angiogenesis can be targeted either directly by OV infection of vascular endothelial cells, or by arming OVs with antiangiogenic transgenes, which are subsequently expressed locally in the tumor microenvironment. In this review, we describe the development and targeting of OVs, the role of angiogenesis in cancer, and the progress made in arming viruses with antiangiogenic transgenes. Future developments required to optimize this approach are addressed.

Endothelial progenitor cells may participate in stress-induced tumour angiogenesis

Epidemiological and animal studies have suggested that chronic stress promotes tumourigenesis by promoting tumour angiogenesis. However, underlying mechanisms have not been fully elucidated. Endothelial progenitor cells (EPCs) are a group of bone marrow-derived cells that have an important function in neovascularisation of various tumour growths. In this study, chronic stress was hypothesised to increase tumour angiogenesis via sympathetic neurotransmitter-induced activation of EPCs through α1 adrenoreceptor (AR)-extracellular regulated protein kinases and β2 AR-endothelial nitric oxide synthase signal pathways. This hypothesis should be tested in several clinical and animal studies. Results may have implications on the development of new anti-tumour drugs.

Circulating endothelial progenitor cells in gynaecological cancer

Objectives

To compare the frequency and absolute numbers of circulating endothelial progenitor cells (EPCs) in healthy control subjects and patients with gynaecological cancer, and to test the hypothesis that cancer treatment lowers EPC numbers.

Methods

Patients with cervical or ovarian cancer and healthy control subjects provided peripheral blood samples for the isolation of mononuclear cells. EPCs were identified by quadruple immunofluorescence staining and flow cytometry as CD45–/CD34+/CD133+/vascular endothelial growth factor receptor 2 (VEGFR2)+ cells.

Results

In total, 28 participants were enrolled. Circulating EPCs were present at higher frequencies (and in greater absolute numbers) in patients with cervical or ovarian cancer ( n = 14) than in controls ( n = 14). Concurrent chemoradiation therapy or surgery significantly reduced the frequency and number of EPCs in patients with gynaecological cancer, compared with pretreatment levels.

Conclusions

EPC levels decline throughout cancer treatment; their measurement may therefore be a useful surrogate marker to monitor treatment response.

Characterization of the melanoma brain metastatic niche in mice and humans

Brain metastases occur in 15% of patients with melanoma and are associated with a dismal prognosis. Here, we investigate the architectural phenotype and stromal reaction of melanoma brain metastasis in mice and humans. A syngeneic, green fluorescence protein (GFP)-expressing murine B16-F1 melanoma clone was introduced via intracardiac injection, and was examined in vivo in comparison with human specimens. Immunofluorescence analyses of the brain metastases revealed that F4/80⁺ macrophages/microglia were most abundant at the tumor front, but rare in its core, where they were found only around blood vessels (P = 0.01). Similar pattern of infiltration was found in CD3⁺ T cells (P < 0.01). Infiltrating T cells were prominently CD4⁺ compared with CD8⁺ T cells (P < 0.001). Blood vessels (CD31⁺) were less abundant at the tumor front than in its center (12 ± 1 vs. 4 ± 0.6 vessels per high-power field [HPF], P < 0.001). In contrast, there were few vessels at the tumor front, but their diameter was significantly larger at the front (8236 μm² vs. 4617 μm² average cross-sectional area, P < 0.005). This is the first comparative analysis of melanoma brain metastases showing similar stromal reaction in murine models and human specimens. Our results validate the utility of this murine model of melanoma brain metastases for investigating the mechanism of the human disease.

Profiles of circulating endothelial cells and serum cytokines during adjuvant chemoradiation in rectal cancer patients

INTRODUCTION

This research aimed to demonstrate the correlation of circulating endothelial cells (CECs) count and serum cytokine levels with side effects and prognosis in rectal cancer patients receiving adjuvant chemoradiation.

METHODS

Eleven patients received proctectomy, chemoradiotherapy and follow-up for 4 years. Fifty-five blood samples were taken before radiation and during the course. The quantities of CECs were estimated by flow cytometry, and serological factors were measured by ELISA.

RESULTS

The CEC level in patients without tumor recurrence was significantly lower than in patients with tumor recurrence (p < 0.01). The IL-6 and TGF-β1 levels exhibited a similar profile (p < 0.01). For morbidity, the mean CEC level in patients with grade 3 diarrhea was significantly greater than patients with grades 1 (p < 0.001) and 2 diarrhea (p < 0.005).

CONCLUSIONS

Levels of CECs, serum IL-6, TGF-β1 and TNF-α during post-operative chemoradiation in rectal cancer patients might be candidate biomarkers for prognosis and morbidity (NCT00325871).

The level of circulating endothelial progenitor cells may be associated with the occurrence and recurrence of chronic subdural hematoma

OBJECTIVES

The onset of chronic subdural hematoma may be associated with direct or indirect minor injuries to the head or a poorly repaired vascular injury. Endothelial progenitor cells happen to be one of the key factors involved in hemostasis and vascular repair. This study was designed to observe the levels of endothelial progenitor cells, white blood cells, platelets, and other indicators in the peripheral blood of patients diagnosed with chronic subdural hematoma to determine the possible relationship between the endothelial progenitor cells and the occurrence, development, and outcomes of chronic subdural hematoma.

METHOD

We enrolled 30 patients with diagnosed chronic subdural hematoma by computer tomography scanning and operating procedure at Tianjin Medical University General Hospital from July 2009 to July 2011. Meanwhile, we collected 30 cases of peripheral blood samples from healthy volunteers over the age of 50. Approximately 2 ml of blood was taken from veins of the elbow to test the peripheral blood routine and coagulation function. The content of endothelial progenitor cells in peripheral blood mononuclear cells was determined by flow cytometry.

RESULTS

The level of endothelial progenitor cells in peripheral blood was significantly lower in preoperational patients with chronic subdural hematomas than in controls. There were no significant differences between the two groups regarding the blood routine and coagulation function. However, the levels of circulating endothelial progenitor cells were significantly different between the recurrent group and the non-recurrent group.

CONCLUSIONS

The level of circulating endothelial progenitor cells in chronic subdural hematoma patients was significantly lower than the level in healthy controls. Meanwhile, the level of endothelial progenitor cells in recurrent patients was significantly lower than the level in patients without recurrence. Endothelial progenitor cells may be related to the occurrence and recurrence of chronic subdural hematoma.

Angiogenic and vasculogenic factors in the vitreous from patients with proliferative diabetic retinopathy

This study was conducted to determine levels of angiogenic and endothelial progenitor cell mobilizing (vasculogenic) factors in vitreous fluid from proliferative diabetic retinopathy (PDR) patients and correlate their levels with clinical disease activity. Vascular endothelial growth factor (VEGF), soluble vascular endothelial growth factor receptor-2 (sVEGFR-2), stem cell factor (SCF), soluble c-kit (s-kit), endothelial nitric oxide synthase (eNOS), and prostaglandin E2 (PGE2) levels were measured by ELISA in vitreous samples from 34 PDR and 15 nondiabetic patients. eNOS was not detected. VEGF, sVEGFR-2, SCF, and s-kit levels were significantly higher in PDR with active neovascularization compared with quiescent PDR and nondiabetic patients (P < 0.001; 0.007; 0.001; <0.001, resp.). In contrast, PGE2 levels were significantly higher in nondiabetic patients compared with PDR patients (P < 0.001). There were significant correlations between levels of sVEGFR-2 versus SCF (r = 0.950, P < 0.001), sVEGFR-2 versus s-kit (r = 0.941, P < 0.001), and SCF versus s-kit (r = 0.970, P < 0.001). Our findings suggest that upregulation of VEGF, sVEGFR-2, SCF, and s-kit supports the contributions of angiogenesis and vasculogenesis in pathogenesis of PDR.

Endothelial progenitor cells: current issues on characterization and challenging clinical applications

Since their discovery about a decade ago, endothelial precursor cells (EPC) have been subjected to intensive investigation. The vision to stimulate respectively suppress a key player of vasculogenesis opened a plethora of clinical applications. However, as research opened deeper insights into EPC biology, the enthusiasm of the pioneer era has been damped in favour of a more critical view. Recent research is focused on three major questions: The fact that the number of EPC in peripheral blood is exceedingly low has consistently raised suspicion whether these cells can plausibly have an impact on physiological or pathophysiological processes. Secondly, whereas the key role of EPC in tumourigenesis has been strongly emphasized by various groups in the past, recent publications are challenging this hypothesis. Thirdly, the lack of consensus on EPC-defining markers and standardized protocols for their detection have repeatedly led to difficulties concerning comparability between papers. In this current review, an overview on recent findings on EPC biology is given, their challenging clinical implications are discussed and the perplexity underlying the current controversial debate is illustrated.

Non-invasive imaging of endothelial progenitor cells in tumor neovascularization using a novel dual-modality paramagnetic/near-infrared fluorescence probe

Objective

Bone-marrow derived endothelial progenitor cells (EPCs) play an important role in tumor neovasculature. Due to their tumor homing property, EPCs are regarded as promising targeted vectors for delivering therapeutic agents in cancer treatment. Consequently, non-invasive confirmation of targeted delivery via imaging is urgently needed. This study shows the development and application of a novel dual-modality probe for in vivo non-invasively tracking of the migration, homing and differentiation of EPCs.

Methods

The paramagnetic/near-infrared fluorescence probe Conjugate 1 labeled EPCs were systemically transplanted into mice bearing human breast MDA-MB-231 tumor xenografts. Magnetic resonance imaging (MRI) and near-infrared (NIR) fluorescence optical imaging were performed at different stages of tumor development. The homing of EPCs and the tumor neovascularization were further evaluated by immunofluorescence.

Results

Conjugate 1 labeled EPCs can be monitored in vivo by MRI and NIR fluorescence optical imaging without altering tumor growth for up to three weeks after the systemic transplantation. Histopathological examination confirmed that EPCs were recruited into the tumor bed and then incorporated into new vessels two weeks after the transplantation. Tumor size and microvessel density was not influenced by EPCs transplantation in the first three weeks.

Conclusions

This preclinical study shows the feasibility of using a MRI and NIR fluorescence optical imaging detectable probe to non-invasively monitor transplanted EPCs and also provides strong evidence that EPCs are involved in the development of endothelial cells during the tumor neovascularization.

In vivo evolution of tumor-derived endothelial cells

The growth of a malignant tumor beyond a certain, limited size requires that it first develop an independent blood supply. In addition to providing metabolic support, this neovasculature also allows tumor cells to access the systemic circulation, thus facilitating metastatic dissemination. The neovasculature may originate either from normal blood vessels in close physical proximity to the tumor and/or from the recruitment of bone marrow-derived endothelial cell (EC) precursors. Recent studies have shown that human tumor vasculature ECs may also arise directly from tumor cells themselves and that the two populations have highly similar or identical karyotypes. We now show that, during the course of serial in vivo passage, these tumor-derived ECs (TDECs) progressively acquire more pronounced EC-like properties. These include higher-level expression of EC-specific genes and proteins, a greater capacity for EC-like behavior in vitro, and a markedly enhanced propensity to incorporate into the tumor vasculature. In addition, both vessel density and size are significantly increased in neoplasms derived from mixtures of tumor cells and serially passaged TDECs. A comparison of early- and late-passage TDECs using whole-genome single nucleotide polymorphism profiling showed the latter cells to have apparently evolved by a process of clonal expansion of a population with a distinct pattern of interstitial chromosomal gains and losses affecting a relatively small number of genes. The majority of these have established roles in vascular development, tumor suppression or epithelial-mesenchymal transition. These studies provide direct evidence that TDECs have a strong evolutionary capacity as a result of their inherent genomic instability. Consequently such cells might be capable of escaping anti-angiogenic cancer therapies by generating resistant populations.

Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces

OBJECTIVES

Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces.

MATERIALS AND METHODS

EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction.

RESULTS

Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces.

CONCLUSIONS

The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities.

CLINICAL RELEVANCE

In correlation with recent clinical studies these results underline the hypothesis that EPC could promote and increase neovascularization by secreting paracrine factors which support osseointegration of dental implants.

Tumor microenvironment in the brain

In addition to malignant cancer cells, tumors contain a variety of different stromal cells that constitute the tumor microenvironment. Some of these cell types provide crucial support for tumor growth, while others have been suggested to actually inhibit tumor progression. The composition of tumor microenvironment varies depending on the tumor site. The brain in particular consists of numerous specialized cell types such as microglia, astrocytes, and brain endothelial cells. In addition to these brain-resident cells, primary and metastatic brain tumors have also been shown to be infiltrated by different populations of bone marrow-derived cells. The role of different cell types that constitute tumor microenvironment in the progression of brain malignancies is only poorly understood. Tumor microenvironment has been shown to be a promising therapeutic target and diagnostic marker in extracranial malignancies. A better understanding of tumor microenvironment in the brain would therefore be expected to contribute to the development of improved therapies for brain tumors that are urgently required due to a poor availability of treatments for these malignancies. This review summarizes some of the known interactions between brain tumors and different stromal cells, and also discusses potential therapeutic approaches within this context.

Endothelial progenitor cells and circulating endothelial cells in early prostate cancer: a comparison with plasma vascular markers

BACKGROUND

Separate studies indicate that endothelial perturbation, as demonstrated by abnormal endothelial progenitor cells (EPCs), circulating endothelial cells (CECs), and plasma markers such as von Willebrand factor (vWf) and soluble E selectin (sEsel) are present in cancer. However, there are no reports where these indices are compared. Accordingly, we hypothesized altered EPCs and CECs in prostate cancer that would correlate with vWf, sEsel, and prostate specific antigen (PSA).

METHODS

We recruited 29 men with biopsy proven prostate cancer, with 25 with benign prostate disease and 27 free of prostate disease. CECs were defined on flow cytometry as being CD34+, CD146+, CD45-, and CD309-, EPCs were similarly defined as being CD34+, CD309+,CD45-, and CD146-. vWf, sEsel, and PSA were measured by immunoassay.

RESULTS

Despite higher PSA, sE-sel, and vWf in prostate cancer (all P < 0.02), neither EPCs, CECs, nor their ratio, were significantly different. EPCs and CECs correlated significantly with each other in each group (r > 0.48, P < 0.01) but failed to correlate with any plasma marker.

CONCLUSION

Unlike plasma endothelial markers, CECs and EPCs may play little part in the pathophysiology of early prostate cancer.

Circulating bone-marrow-derived endothelial precursor cells contribute to neovascularization in diabetic epiretinal membranes

PURPOSE

The role of vasculogenesis, recruitment and differentiation of circulating bone-marrow-derived endothelial precursor cells into mature endothelium in proliferative diabetic retinopathy (PDR) remains undefined. We investigated the presence of bone-marrow-derived endothelial precursor cells and the expression of the chemotactic pathway SDF-1 ⁄CXCL12)CXCR4 in PDR epiretinal membranes.

METHODS

Membranes from eight patients with active PDR and nine patients with inactive PDR were studied by immunohistochemistry using antibodies against CD133, vascular endothelial growth factor receptor-2 (VEGFR-2), CD14, SDF-1 and CXCR4.

RESULTS

Blood vessels expressed CD133, VEGFR-2, CD14, SDF-1 and CXCR4 in 10, 10, 10, seven and seven out of 17 membranes, respectively. There were significant correlations between number of blood vessels expressing CD34 and number of blood vessels expressing CD133 (r(s) = 0.646; p = 0.005), VEGFR-2 (r(s) = 0.704; p = 0.002), CD14 (r(s) = 0.564; p = 0.018) and SDF-1 (r(s) = 0.577; p = 0.015). Stromal cells in close association with blood vessels expressed CD133, VEGFR-2, CD14 and CXCR4 in 10, 12, 13 and 14 membranes, respectively. The number of blood vessels expressing CD133 (p = 0.013), VEGFR-2 (p = 0.005), CD14 (p = 0.008) and SDF-1 (p = 0.005), and stromal cells expressing CD133 (p = 0.003), VEGFR-2 (p = 0.013) and CD14 (p = 0.002) was significantly higher in active membranes than in inactive membranes.

CONCLUSION

Bone-marrow-derived CD133(+) endothelial progenitor cells and CD14(+) monocytes may contribute to vasculogenesis in PDR.

Circulating endothelial cells in patients with chronic lymphocytic leukemia: clinical-prognostic and biologic significance

BACKGROUND

In patients with cancer, circulating endothelial cells (CECs) are increased and are correlated with an aggressive disease course. However, the clinical and biologic significance of CECs in chronic lymphocytic leukemia (CLL) remains uncertain.

METHODS

In 170 patients with CLL, CEC levels were quantified by flow cytometry and were correlated with clinical and biologic data. In addition, CECs were characterized by immunophenotypic, fluorescence in situ hybridization (FISH), and gene expression profile analyses.

RESULTS

In patients with CLL, CECs were increased compared with controls. A higher level of CECs (>20/microL) identified a subset of patients with a more aggressive disease course characterized by a shorter time to first treatment both in univariate and multivariate analyses. In FISH analysis, 7 patients had a significant proportion of CECs and presented with the same cytogenetic lesion of neoplastic lymphocytes and immunophenotypic features of endothelial progenitor cells. The gene expression profile of sorted CECs revealed a molecular pattern, suggesting a derivation from CLL leukemic cells with increased cell survival and proliferation, diminished cell adhesion to extracellular matrix, and enhanced proangiogenic function compared with their normal counterparts.

CONCLUSIONS

The current data suggest that, in CLL, CECs may represent a biologic marker of aggressiveness and disease progression to be considered for new, targeted antiangiogenic treatments.

Hypoxia and pluripotency in embryonic and embryonal carcinoma stem cell biology

Low oxygen availability (hypoxia) is a hallmark of rapidly proliferating tumors and has been suggested to be a characteristic of the embryonic and adult stem cell niche. The idea of relating cancer to stem cells is increasingly popular due to the identification of specific cancer stem cells sharing the typical plasticity and motility of pluripotent stem cells. Hypoxia plays a critical role in early embryonic development and in tumor progression, participating in processes such as angiogenesis, apoptosis, cell migration, invasion and metastasis. Some of the molecular pathways that have been shown to mediate these hypoxia-induced responses, such as the hypoxia inducible factor (HIF)-1alpha and Notch signaling, appear to be active in both embryonic and neoplastic pluripotent stem cells. Nevertheless, the mechanisms underlying these regulatory processes are not yet fully understood. In this review, we attempt to shed some light on the mechanisms involved in hypoxia-dependent processes related to stem cell features and tumor progression, such as the maintenance of the undifferentiated state, cell proliferation, tumor neovascularization, extra-cellular matrix degradation and motility factor up-regulation. With this purpose in mind, we summarize recent observations in embryonic, adult and cancer stem cells that demonstrate the parallelism existing in their hypoxia responses. Finally, based on the observations of our own laboratory and others, we suggest that the comparative analysis of the response to low oxygen levels of embryonic stem cells and cancer stem cells (such as embryonal carcinoma cells), may throw fresh light on our understanding of the mechanisms underlying hypoxia-induced invasiveness and the resistance to anticancer treatments, thereby stimulating the development of novel therapeutic strategies.

Levels of circulating pro-angiogenic cells predict cardiovascular outcomes in patients with chronic heart failure

BACKGROUND

Circulating pro-angiogenic cells (PACs) contribute to vascular and myocardial regeneration. A low level of PACs is associated with worse outcome in patients with coronary heart disease. However, little is known about PACs in heart failure (HF).

METHODS AND RESULTS

Blood was sampled at baseline in 111 patients with HF, 67 from 5 Italian Centers and 44 from Frankfurt, Germany. In cultured mononuclear cells from peripheral blood, PACs were counted as double-stained by tetramethylindocarbocyanine-labeled acetylated LDL and fluorescein-5-isothiocyanate-labeled lectin. Mean age of the patients was 62 years, 12 were females, 66 had ischemic etiology, 26 were in New York Heart Association Class >II. Cutoffs for PACs were assessed by receiver operating characteristic curves, to identify the optimal cutoffs for PAC level in predicting outcomes. Mean level of PACs was 35+/-29 (mean+/-SD) cells/mm(2), 2- to 3-fold lower than in age-matched healthy volunteers, but unrelated to severity of HF, age, or sex. Over 2.5 years, 12 cardiovascular deaths and 47 first hospitalizations for cardiovascular reasons were recorded. After adjustment for demographic and clinical variables, elevated creatinine and natriuretic peptides, and PACs <or=30.5/mm(2) were associated with a 2-fold higher risk of cardiovascular death and hospitalization, as shown by survival curves and by Cox multivariable.

CONCLUSIONS

The level of circulating PACs is an independent predictor of cardiovascular death and hospitalization in patients with chronic HF, it can be assessed in blood samples collected in a multicenter setting, and may offer an accessible tool to assess the role of vascular regeneration in patients with HF.

[Endocrine factors influencing melanoma progression]

According to recent findings that beside cancers traditionally considered as hormone-dependent, several other tumor types show different behavior in the two sexes, indicating the possible role of endocrine factors in the course of these diseases. The possibility that endocrine factors may influence the clinical course of human malignant melanoma is suggested by the higher survival rate in premenopausal vs. postmenopausal women or men of any ages. However, investigations on the sex hormone receptor status of human cutaneous melanomas and experiments attempting to support the epidemiological results yielded conflicting results. In our human melanoma cell lines we failed to detect steroid receptors at protein level, while quantitative PCR demonstrated that their mRNA expression level was orders of magnitude lower compared to the positive control cell lines. Sex hormones did not influence the in vitro features of the human melanoma cells considerably. On the other hand, glucocorticoid receptor was present both at mRNA and protein level, although dexamethasone was effective in vitro only at high doses. Our previous experiments showed that intrasplenic injection of human melanoma cells resulted in a significantly higher number of liver colonies in male than in female SCID mice. We now show that this difference evolves during the first day. After injection into the tail vein we did not observe gender-dependent difference in the efficiency of pulmonary colonization. Examining the pattern of metastasis formation after intracardiac injection, we have found differences between the two sexes in the incidence or number of colonies only in the case of the liver but not in other organs. We concluded that the observed phenomenon is specific to the liver; therefore we investigated the effects of 2-methoxyestradiol, an endogenous metabolite of estradiol produced mainly in the liver, with an estrogen receptor-independent antitumor activity. 2ME2 effectively inhibited melanoma cell proliferation by inducing apoptosis and an arrest in the G2/M phase. The mechanism of action involved microtubules, mitochondrial damage and caspase activation as well. In SCID mice, 2ME2 was effective in reducing primary tumor weight and the number of liver colonies after intrasplenic injection of human melanoma cells, and causing significantly higher rate of apoptotic cells in the colonies.

High VEGFR-3-positive circulating lymphatic/vascular endothelial progenitor cell level is associated with poor prognosis in human small cell lung cancer

PURPOSE

The newly identified bone marrow-derived cell population, called lymphatic/vascular endothelial progenitor cells (LVEPC), has been shown to contribute to lymph capillary growth in experimental tumor systems. The clinical significance of these cells has not yet been investigated in a human malignancy. Our aim was to study whether peripheral blood circulating LVEPCs participate in the progression of human small cell lung cancer (SCLC).

EXPERIMENTAL DESIGN

A total of 88 patients with limited-stage SCLC and 32 tumor-free control subjects were included. Peripheral blood circulating LVEPC labeled with CD34 and vascular endothelial growth factor receptor-3 (VEGFR3) antibodies and the serum levels of the key lymphangiogenic molecule VEGF-C were measured by flow cytometry and ELISA, respectively.

RESULTS

CD34-positive/VEGFR3-positive LVEPC levels were significantly increased in patients (versus controls; P<0.01), and there was also a significant relationship between LVEPC counts and lymph node metastasis (P<0.01). High pretreatment circulating LVEPC numbers correlated with poor overall survival (P<0.01). Although we observed significantly elevated VEGF-C concentrations in patients (versus controls; P<0.01), there was no significant correlation between VEGF-C and LVEPC levels. Moreover, no significant differences in peripheral blood VEGF-C levels were seen between patients subgrouped by clinicopathologic variables including tumor and lymph node stages and survival.

CONCLUSIONS

Peripheral blood levels of bone marrow-derived LVEPCs are significantly increased in patients with SCLC and correlate with lymphatic involvement and prognosis. This is the first study that shows evidence of increased numbers of circulating LVEPC in patients with a malignant tumor.

Stem cells of the adult cornea: from cytometric markers to therapeutic applications

The cornea is a major protective shield of the interior of the eye and represents two thirds of its refractive power. It is made up of three tissue layers that have different developmental origins: the outer, epithelial layer develops from the ectoderm overlying the lens vesicle, whereas the stroma and the endothelium have mesenchymal origin. In the adult organism, the outermost corneal epithelium is the most exposed to environmental damage, and its constant renewal is assured by the epithelial stem cells that reside in the limbus, the circular border of the cornea. Cell turnover in the stromal layer is very slow and the endothelial cells probably do not reproduce in the adult organism. However, recent experimental evidence indicates that stem cells may be found in these layers. Damage to any of the corneal layers leads to loss of transparency and low vision. Corneal limbal stem cell deficiency results in severe ocular surface disease and its treatment by transplantating ex vivo expanded limbal epithelial cells is becoming widely accepted today. Stromal and endothelial stem cells are potential tools of tissue engineering and regenerative therapies of corneal ulcers and endothelial cell loss. In the past few years, intensive research has focused on corneal stem cells aiming to improve the outcomes of the current corneal stem cell transplantation techniques. This review summarizes the current state of knowledge on corneal epithelial, stromal and endothelial stem cells. Special emphasis is placed on the molecular markers that may help to identify these cells, and the recently revealed mechanisms that could maintain their "stemness" or drive their differentiation. The techniques for isolating and culturing/expanding these cells are also described.

[Tumor vasculature as a therapeutic target in non-small cell lung cancer]

Despite developments in conventional (chemo)radiotherapy and surgery, survival of non-small cell lung cancer (NSCLC) patients remains poor. Treatments with targeted molecular drugs offer novel therapeutic strategies. Bevacizumab, a recombinant anti-vascular endothelial growth factor (VEGF) antibody, is the antiangiogenic drug at the most advanced stage of development in the therapy of NSCLC. However, a number of questions and future challenges relating to the use of bevacizumab in NSCLC remain. Furthermore, novel agents targeting the pre-existing NSCLC vasculature (i.e. vascular disrupting agents, VDAs) or multiple tyrosine kinase inhibitors have emerged as unique drug classes delivering promising results in several preclinical and clinical studies. Herein, we review the most recent data using these novel targeted agents either alone or in combination with chemotherapy in NSCLC.

Inflammation at the molecular interface of atherogenesis: an anthropological journey

Despite the multifactorial nature of atherosclerosis, substantial evidence has established inflammation as an often surreptitious, yet critical and unifying driving force which promotes disease progression. To this end, research has defined molecular networks initiated by cytokines, growth factors and other pro-inflammatory molecules which promote hallmarks of atherosclerosis such as endothelial dysfunction, macrophage infiltration, LDL oxidation, cell proliferation and thrombosis. Although commonly associated with risk factors such as dyslipidemia, diabetes and hypertension, the global etiology of atherosclerosis may be alternatively attributed to underlying anthropological pressures. The agricultural, industrial and technological revolutions produced alterations in dietary, social and economic factors which have collectively exaggerated the exposure of the human genome to environmental stimuli. Furthermore, advances in sanitation, nutrition, and medicine have increased the lifespan of humans, effectively prolonging blood vessel exposure to these factors. As a result, the vasculature has become conditioned to respond to injury with what is arguably an overzealous immunological response; thus setting the stage for the prevalence of cardiovascular disease, including atherosclerotic plaque development in Western populations. Evidence suggests that each of these alterations can be linked to specific mediators in the inflammatory process. Integration of these factors with an inflammation-based hypothesis of atherosclerosis has yet to be extrapolated to observations in the realms of basic and clinical sciences and is the focus of this review.

Dominant contribution of malignant endothelial cells to endotheliopoiesis in chronic myeloid leukemia

OBJECTIVE

Although it has been well-established that hemangioblasts are present in chronic myeloid leukemia (CML) and contribute to both malignant hematopoiesis and endotheliopoiesis, the real contribution of CML-derived endothelial cells to endotheliopoiesis in CML patients has never been evaluated. The current study sought to determine CML-derived endotheliopoiesis in patients with CML.

MATERIALS AND METHODS

Endothelial cells were isolated from the bone marrow or peripheral blood of six newly diagnosed CML patients using an immunomagnetic approach. The resulting endothelial cells were immediately subjected to fluorescence in situ hybridization analysis to determine BCR-ABL-positive endothelial cells.

RESULTS

The purity of isolated endothelial cells was 94.47% +/- 2.37%. In bone marrow, the BCR-ABL-positive endothelial cells accounted for 70.8% +/- 10.7% of total freshly isolated endothelial cells. In peripheral blood, however, the BCR-ABL-positive endothelial cells accounted for only 20.8% +/- 9.8% of isolated endothelial cells.

CONCLUSION

The present data demonstrate a dominant contribution of CML-derived endothelial cells to endotheliopoiesis in newly diagnosed CML, and provide the rationale for targeting hemangioblasts and angiogenesis in management of CML.