Endothelial progenitor cells in cardiovascular disorders

The important role of the vascular endothelium in cardiovascular health is increasingly recognized. However, mature endothelial cells possess limited regenerative capacity. There is therefore much interest in circulating endothelial progenitor cells (EPCs) among the scientific community, especially into their purported role in maintenance of endothelial integrity and function, as well as postnatal neovascularization. It has been suggested that these cells might not only be responsible for the continuous recovery of the endothelium after injury/damage, but also might take part in angiogenesis, giving the hope of new treatment opportunities. Indeed, there is accumulating evidence showing reduced availability and impaired EPC function in the presence of both cardiovascular disease and associated comorbid risk factors. Thus, many studies into the potential for use of EPCs in the clinical setting are being undertaken. The goal of this review article is to provide an overview of data relevant to the clinical role of EPCs and perspectives for treatment of cardiovascular disorders.     

12/15-lipoxygenase–derived lipid peroxides control receptor tyrosine kinase signaling through oxidation of protein tyrosine phosphatases

Protein tyrosine phosphatases (PTPs) are regulated through reversible oxidation of the active-site cysteine. Previous studies have implied soluble reactive oxygen species (ROS), like H₂O₂, as the mediators of PTP oxidation. The potential role(s) of peroxidized lipids in PTP oxidation have not been described. This study demonstrates that increases in cellular lipid peroxides, induced by disruption of glutathione peroxidase 4, induce cellular PTP oxidation and reduce the activity of PDGF receptor targeting PTPs. These effects were accompanied by site-selective increased PDGF β-receptor phosphorylation, sensitive to 12/15-lipoxygenase (12/15-LOX) inhibitors, and increased PDGF-induced cytoskeletal rearrangements. Importantly, the 12/15-LOX–derived 15-OOH-eicosatetraenoic acid lipid peroxide was much more effective than H₂O₂ in induction of in vitro PTP oxidation. Our study thus establishes that lipid peroxides are previously unrecognized inducers of oxidation of PTPs. This identifies a pathway for control of receptor tyrosine kinase signaling, which might also be involved in the etiology of diseases associated with increased lipid peroxidation.     

芍药苷对日本血吸虫病肝纤维化小鼠CTGF PDGF及TNF-α的影响

目的观察芍药苷对日本血吸虫感染小鼠肝脏结缔组织生长因子（CTGF）、血小板衍化生长因子（PDGF）蛋白表达水平和血清中肿瘤坏死因子α（TNF-α）水平的影响,探讨芍药苷预防血吸虫病肝虫卵肉芽肿及纤维化的作用机制。方法小鼠随机分为A～E5组,A组不感染血吸虫尾蚴,为正常对照组;B、C、D、E4组小鼠感染尾蚴后6周以吡喹酮灌胃杀虫,剂量为400mg/（kg·d）,连续2d。B、C、D3组杀虫后给予芍药苷,剂量分别为30、60、120mg/（kg·d））,E组不给芍药苷,为感染对照组。5组小鼠均在芍药苷给药8周后处死,取血及肝脏。HE及Masson胶原纤维染色观察肝虫卵肉芽肿面积及纤维化程度,采用免疫组化技术检测CTGF和PDGF蛋白表达情况,采用ELISA法检测小鼠血清中TNF-α水平。结果芍药苷高剂量的D组与感染对照E组相比,肝组织中CTGF和PDGF蛋白表达明显减少,血清中TNF-α水平也明显下降（P均〈0.05）;而中、低剂量B组和C组的CTGF、PDGF和TNF-α水平亦较E组减少,但差异无统计学意义（P均〉0.05）。结论芍药苷抗血吸虫病肝纤维化作用呈剂量依赖性,在吡喹酮杀虫处理基础上联合应用高剂量芍药苷,可通过减少肝组织CTGF和PDGF蛋白表达,降低血清中TNF-α水平,减轻肝纤维化程度。     

Treatment of patients with non-alcoholic fatty liver disease: current views and perspectives.

Non-alcoholic fatty liver disease is considered a component of the metabolic syndrome associated with obesity. Problems still exist concerning non-alcoholic fatty liver disease patients in clinical practice, for example: (a) how to diagnose non-alcoholic fatty liver disease and its type; (b) how to select patients candidate to treatment; (c) how to treat selected patients. Non-alcoholic fatty liver disease includes steatosis and non-alcoholic steatohepatitis, but only non-alcoholic steatohepatitis evolves into cirrhosis and the absolute risk of mortality for non-alcoholic fatty liver disease is low. As yet, no tools, other than liver biopsy, are available to differentiate the various types of non-alcoholic fatty liver disease. Many drugs are, currently, under study to treat non-alcoholic fatty liver disease, even if well-performed trials are until necessary to define the best treatment. At the moment, the entity of the problem and the characteristics of patients frequently put the physician, in clinical practice, to choose the therapeutic approach arbitrarily which is considered more effective for each individual patient. Probably the future will consider the possibility of treating non-alcoholic fatty liver disease with more than one drug, by considering the various aspects and degree of this syndrome. Actually each physician should select the individual treatment on the basis of his/her knowledge and experience, by never forgetting the old saying 'primum non nocere'. However, the epidemiological entity of the problem, the characteristics of the patients, generally young, the frequent lack of clinical evidence of involvement of the liver, are all the factors that require vast well-performed clinical trials in order to define the best therapeutic approach for each individual patient.     

A Pleural Effusion Caused by Fibrous Hematopoietic Tumor Successfully Treated With Prednisolone in a Patient With Agnogenic Myeloid Metaplasia With Myelofibrosis

A 46-year-old woman suffering from agnogenic myeloid metaplasia (AMM) since 1994 was being followed as an outpatient. In November 1999, she exhibited respiratory failure caused by massive pulmonary effusion, which was speculated to have been produced by chest tumors. A biopsy specimen revealed findings compatible with fibrous hematopoietic tumor (FHT): prominent fibroblasts and fibrosis with scantv megakaryocytes. Serum concentrations of transforming growth factor (TGF)-beta and platelet-derived growth factor (PDGF) were significantly higher than those of other cases of AMM without FHT. The effusion did not respond to administrations of various chemotherapeutic agents, but after prednisolone administration, the effusion disappeared and the tumors also diminished. TGF-beta and PDGF were the possible causes of FHT formation, and for such fibrotic extramedullary regions, the administration of prednisolone should be considered.     

Platelet-derived growth factor involvement in myocardial remodeling following infarction

Cardiac remodeling occurs in the infarcted heart (MI). The underlying regulatory mechanisms are under investigation. Platelet-derived growth factor (PDGF) is a family of growth factors that stimulates cell growth, differentiation and migration. Herein, we sought to determine whether PDGF is involved in cardiac repair/remodeling following MI. The temporal and spatial expressions of PDGF isoforms (A, B, C and D) and PDGF receptor (PDGFR)-α and β as well as cell types expressing PDGF were examined in the infarcted rat heart. Sham-operated rats served as controls. We found that the normal myocardium expressed all PDGF isoforms, and cell types expressing PDGF were primarily interstitial cells. Following MI, PDGF-A and D were significantly increased in the infarcted myocardium during 6 weeks of the observation period and cells expressing PDGF-A and D were primarily endothelial cells, macrophages and myofibroblasts (myoFb). PDGF-B and C expressions were, however, reduced in the infarcted heart. In the noninfarcted myocardium, PDGF-D expression was increased in the late stage of MI and cells expressing PDGF-D were predominantly fibroblasts. Both PDGFR-α and β were significantly increased in the infarcted myocardium in the early and late stages of MI and in the noninfarcted myocardium in the late stage of MI. Enhanced PDGF-A, PDGF-D and PDGFR are coincident with angiogenesis, and inflammatory and fibrogenic responses in the infarcted myocardium, suggesting their regulation on cardiac repair. Elevated PDGF-D in the noninfarcted myocardium suggests its involvement in the development of interstitial fibrosis that appears in the late stage of MI.     

Retinoic acids up-regulate steroidogenic acute regulatory protein gene

Rat osteoprogenitor cells were used to examine the effects of bFGF on DNA synthesis and the expression of osteoblast (OB)-related genes. bFGF, as low as 0.1 ng/ml, stimulated DNA synthesis. bFGF also increased the mRNA level of osteopontin (OP) and decreased that of type I collagen (COL I). When cultures were grown in dexamethasone (DEX) to induce OB lineage commitment, the expression of COL I, alkaline phosphatase (AP) and OP was greatly enhanced. Subsequent incubation with bFGF partially negated the stimulatory effect of DEX on AP and COL I mRNAs. bFGF also inhibited the expression of osteocalcin mRNA in cells grown in 1,25(OH)₂D₃ and DEX. Combined effects of bFGF with IGF-I or PDGF on DNA synthesis and OP expression were examined. bFGF+IGF-I, but not bFGF+PDGF, was more effective than PDGF alone. By comparing cells from adult and old animals, we found that bFGF-induced mitogenic activity was reduced significantly with age. In contrast, the effect of bFGF on the expression of OB genes was not significantly altered by age. These findings suggest that bFGF plays a dual role as a local positive and negative regulator on proliferation and osteogenic lineage expression, respectively, in osteoprogenitor cells, and that the mitogenic activity in response to bFGF was impaired in aging.     

Platelet-Derived Growth Factor Enhances Granulopoiesis Via Bone Marrow Stromal Cells

Platelet-derived growth factor (PDGF), a growth factor for connective tissue cells, stimulates erythropoiesis and megakaryocytopoiesis in vitro but the effect of PDGF on granulocyte proliferation remains unknown. The effect of the recombinant human PDGF-BB isoform on granulopoiesis was investigated in this study. The results show that PDGF significantly stimulated murine colony-forming unit-granulocyte-monocyte (CFU-GM) proliferation in a dose-dependent manner (1 to 100 ng/mL) using murine bone marrow cells (n = 4). Maximum stimulation was obtained with 50 ng/mL of PDGF (P < .01). The effect of PDGF on murine CFU-GM proliferation was compared with that of interleukin (IL)-3, IL-6, granulocyte-monocyte colony-stimulating factor (GM-CSF), and acidic fibroblast growth factor (aFGF) at their optimal doses. The stimulating activity of PDGF was higher than that of aFGF but lower than that of IL-3, IL-6, or GM-CSF. There is no synergistic effect between PDGF and IL-3 or IL-6, but a significant enhancing effect was observed in IL-3 plus IL-6. PDGF also stimulated the growth of CFU-GM with CFU-megakaryocyte in the presence of bone marrow stromal cells. We also found that PDGF had similar a effect on human CFU-GM proliferation using bone marrow mononuclear cells (MNC). However, the increase in PDGF-stimulated CFU-GM proliferation was inhibited by anti-GM-CSF, anti-IL-3, and anti-IL-6 antibodies (n = 4), suggesting that endogenously produced GM-CSF, IL-3, and IL-6 may play a role in the PDGF-induced CFU-GM proliferation. Furthermore, PDGF (1 to 100 ng/mL) did not show any effect on CFU-GM proliferation when replacing bone marrow MNC with immunomagnetic selection-enriched CD34+ cells from human cord blood (n = 5; purity, 91% +/- 6.5%). This study indicates that PDGF may indirectly enhance CFU-GM proliferation by inducing the bone marrow stromal cells to produce GM-CSF, IL-3, or IL-6.     

血小板源生长因子及其受体在烧伤肉芽组织和增生性瘢痕中的表达

目的探讨血小板源生长因子 (PDGF)及其受体在瘢痕增生过程中的作用。方法采用多克隆抗体并以免疫组织化学方法检测 9例正常真皮、7例肉芽组织及 34例增生性瘢痕标本中的PDGF及其受体和Ⅰ型胶原的表达情况。结果PDGF及其受体在肉芽组织和增生性瘢痕中的表达明显增强 ,在 6个月以内的增生性瘢痕中达到高峰 ,此后逐渐减弱 ;而正常真皮组织中仅少数标本呈微弱表达 (P <0 .0 5 )。结论PDGF及其受体表达的增强可能与瘢痕的增生密切相关