Mast cells and hemangioma

Hemangioma is a primary tumor of the microvasculature in which angiogenesis is initially excessive, followed by spontaneous regression of the newly formed vessels, with the cellular parenchyma gradually being replaced with fibrofatty tissue. Mast cells, which are highly heterogenous in terms of their morphology, function, and metabolic products, have been implicated in the pathophysiology of hemangioma. Csaba stain shows that mast cells are predominantly of the biogenic amine phenotype throughout the development of hemangioma. The predominance of this phenotype remains unaltered following successful steroid therapy, although their number increases fourfold. Mast cells, all of which stain positive for tryptase, and those that stain positive for chymase as well, have been identified in hemangioma biopsy specimens throughout the three developmental phases. The total number of mast cells is highest during the involuting phase, less in the involuted phase, and least in the proliferative phase. The proportion of mast cells that contain both tryptase and chymase decreases from the proliferative through involuting to the involuted phase. This decreasing proportion of mast cells that contain both tryptase and chymase with ongoing involution parallels that of progressive deposition of the extracellular matrix as indicated by increasing fibrosis and fatty deposition. The short-chain type VIII collagen, thought to play a key role in angiogenesis, has been detected throughout the developmental phases of hemangioma. It has been postulated that this collagen, which is produced early in new vessel development, provides a substratum to facilitate the migration of endothelial cells. It may also facilitate the deposition of other extracellular constituents and influence cell movement and the maintenance of cell phenotypes. The intracellular localization of type VIII collagen in mast cells only in the early proliferative phase suggests that there is an active synthesis by mast cells during this phase. The increasing extracellular localization during hemangioma development may be caused by an increased secretion of protein from intracellular stores. The increased number of mast cells during the involuting phase indicates that these cells may play a role in the regression of hemangioma. This is in contrast to the large body of evidence showing the proangiogenic role of mast cells. The proportion of proliferating mast cells decreases, whereas the proportion of mast cells positive for clusterin/apolipoprotein J increases with ongoing involution of hemangioma. Clusterin/apolipoprotein J expression has been considered as a prominent marker of apoptotic cell loss. The presence of clusterin/apolipoprotein J granules both in the adjacent endothelial cells and in capillary lumens suggests that mast cells may be secreting this apoptotic modulator to promote the regression of hemangioma. Certain effectors produced by mast cells may participate in the development of hemangioma. It has been proposed that one of the functions of mast cells is to release factors leading to the regression of hemangioma. The evidence suggests that although mast cells may have a function in the endothelial proliferation in hemangioma, they also play a crucial role in the regression of this tumor. However, the roles of mast cells in the life cycle of hemangioma are likely to be complex and may involve stimulators of angiogenesis in the proliferative phase but inhibitors in later phases.     

Role of pigment epithelium-derived factor in the involution of hemangioma: Autocrine growth inhibition of hemangioma-derived endothelial cells

Hemangioma is a benign tumor derived from abnormal blood vessel growth. Unlike other vascular tumor counterparts, a hemangioma is known to proliferate during its early stage but it is followed by a stage of involution where regression of the tumor occurs. The critical onset leading to the involution of hemangioma is currently not well understood. This study focused on the molecular identities of the involution of hemangioma. We demonstrated that a soluble factor released from the involuting phase of hemangioma-derived endothelial cells (HemECs) and identified pigment epithelium-derived factor (PEDF) as an anti-angiogenic factor that was associated with the growth inhibition of the involuting HemECs. The growth inhibition of the involuting HemECs was reversed by suppression of PEDF in the involuting HemECs. Furthermore, we found that PEDF was more up-regulated in the involuting phase of hemangioma tissues than in the proliferating or the involuted. Taken together, we propose that PEDF accelerates the involution of hemangioma by growth inhibition of HemECs in an autocrine manner. The regulatory mechanism of PEDF expression could be a potential therapeutic target to treat hemangiomas.     

Tiaml和Rac1在皮肤血管瘤组织中的表达及意义

目的 探讨Tiaml和Rac1在人皮肤血管瘤组织中的表达及其临床意义.方法 收集武汉大学人民医院病理科2008年-2011年皮肤毛细血管瘤存档蜡块40例,其中男性15例,女性25例.采用免疫组织化学S-P法检测40例皮肤血管瘤增生期、退化期及正常皮肤组织Tiaml和Rac1表达水平,采用HPIAS-1000图文报告管理系统对Tiaml和Rac1的表达进行定量分析,并用SPSS11.5软件对各组免疫组织化学反应阳性颗粒的平均光密度、阳性面积率做单因素方差分析和SNK（q）检验.结果 （1）增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,Tiaml呈高表达,正常皮肤组及退化组血管内皮细胞中可见少量的棕黄色颗粒,Tiaml呈低表达.增生期组Tiaml的表达明显高于退化期组和正常皮肤组（P〈0.05）,而后两组比较差异无统计学意义（P〉0.05）.（2）增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,Rac1呈高表达,正常皮肤组及退化组血管内皮细胞中可见少量的棕黄色颗粒,Rac1呈低表达.增生期组Rac1的表达明显高于退化期组和正常皮肤组（P〈0.05）,而后两组比较差异无统计学意义（P〉0.05）.结论 Tiaml和Rac1在血管瘤增生期均呈高表达,表明Tiaml和Rac1在血管瘤的发生和发展中起了重要作用.     

Bmi-1和EZH2基因在皮肤血管瘤组织中的表达及意义

目的探讨Bmi-1和EZH2基因在血管瘤组织中的表达及其意义。方法收集武汉大学人民医院病理科2008年-2011年皮肤毛细血管瘤存档蜡块40例,其中男性15例,女性25例。采用免疫组织化学S～P法检测40例皮肤血管瘤增生期、退化期及正常皮肤组织Bmi-1和EZH2基因表达水平,采用HPIAS-1000图文报告管理系统对Bmi-l和EZH2基因的表达进行定量分析,并用SPSSll．5软件对各组免疫组织化学反应阳性颗粒的平均光密度、阳性面积率做单因素方差分析和SNK（q）检验。结果（1）Bmi-1的表达增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,Bmi-1呈高表达,正常皮肤组及退化组血管内皮细胞中可见少量的棕黄色颗粒,Bmi-1呈低表达。增生期组Bmi-1的表达明显高于退化期组和正常皮肤组（P〈0．05）,而后两组比较差异无统计学意义（P〉0．05）。（2）EZH2的表达增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,EZH2呈高表达,正常皮肤组及退化组血管内皮细胞中可见少量的棕黄色颗粒,EZH2呈低表达。增生期组EZH2的表达明显高于退化期组和正常皮肤组（P〈o．05）,而后两组比较差异无统计学意义（P〉0．05）。结论Bmi-1和EZH2基因在血管瘤增生期均呈高表达,表明Bmi-1和EZH2基因均参与了血管瘤的发生和发展。     

皮肤血管瘤组织中WT-1、Bcl-2、P53的表达及意义

目的研究肾母细胞瘤基因（WT-1）、Bcl-2和P53在增生期、退化期血管瘤及正常组织中的表达,探讨其意义及相互关联。方法采用免疫组化SP法检测人皮肤血管瘤组织中WT1、Bcl-2和P53在增生期、退化期及正常皮肤组织中血管内皮细胞中的表达水平,利用计算机成像分析技术检测不同时期皮肤血管瘤与正常皮肤组织WT1、Bcl-2和P53的平均光密度及其阳性面积率。结果1.WT-1在退化期血管瘤中有较强表达,而在增生期血管瘤和正常皮肤组织中表达微弱或不表达（P〈0.05）。2.Bcl-2在增生期血管瘤的表达明显高于退化期血管瘤和正常皮肤组织（P〈0.01）;Bcl-2在退化期血管瘤的表达与正常皮肤组织相比,差异无显著性（P〉0.05）。3.p53基因在增生期血管瘤组织中表达水平高于退化期,差异有极显著性意义（P〈0.01）,退化期血管瘤p53基因表达水平与正常皮肤组织相比,差异无显著性意义（P〉0.05）。结论1.WT-1可能通过促进内皮细胞凋亡而抑制血管瘤的增生;2.Bcl-2可能是通过抑制内皮细胞的凋亡,使其增殖和凋亡失衡;3.P53可能促进了血管瘤增生期内皮细胞的增殖,使血管内皮细胞大量生成。     

Ezrin和Fascin蛋白在血管瘤中异常表达的研究

目的应用免疫组织化学方法检测不同时期血管瘤组织中膜细胞骨架链接蛋白Ezrin和Fascin蛋白的表达,以探讨其在血管瘤发生、发展过程中的作用机制。方法收集武汉大学人民医院病理科2005年9月-2009年12月皮肤毛细血管瘤存档蜡块50例,其中男性25例,女性25例。采用免疫组织化学S-P法检测50例皮肤血管瘤增生期、退化期及正常皮肤组织中Ezrin和Fascin的表达水平,采用HPIAS-1000图文报告管理系统对Ezrin和Fascin的表达进行定量分析,并用SPSS11.5软件对各组免疫组织化学反应阳性颗粒的平均光密度、阳性面积率做单因素方差分析和SNK(q)检验。结果 (1)Ezrin的表达增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,Ezrin呈高表达,正常皮肤组及退化组血管内皮细胞中可见少量的棕黄色颗粒,Ezrin表达弱。增生期组Ezrin的表达明显高于退化期组和正常皮肤组(P0.05),而后两组比较差异无统计学意义(P0.05)。(2)Fascin的表达增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,Fascin呈高表达,正常皮肤组及退化组血管内皮细胞细胞中可见少量的棕黄色颗粒,Fascin表达弱。增生期组Fascin的表达明显高于退化期组和正常皮肤组(P0.05),而后两组比较差异无统计学意义(P0.05)。结论Ezrin和Fascin在血管瘤增生期均上调表达,表明Ezrin和Fascin均与血管瘤的发生、发展有密切关系。     

Recruitment of Type I Collagen Producing Cells from the Microvasculaturein Vitro

We have previously suggested that microvascular pericytes can differentiate into fibroblast-like, type I collagen-producing cells during excessive dermal scarringin vivo(Sundberg, C., Ivarsson, M., Gerdin, B., and Rubin, K.,Lab. Invest.74, 454–468, 1996). Here we have investigated to what extent pericytes derived from microvessels of full-term human placenta exhibited this capacityin vitro.Vascular fragments of human term placenta were isolated by enzymatic digestion and separation in Percoll. Their microvascular origin was ascertained by confocal microscopy using antibodies specific for endothelial cells (PAL-E) and pericytes (high-molecular-weight–melanoma-associated antigen). When vascular fragments were culturedin vitro,large cells with irregular edges migrated out from the fragments. After 4–6 days in culture, these cells started to proliferate and reached near confluence after approximately 8 days. The cultures were not overgrown by clones of cells with a high proliferative capacity, as demonstrated by cell membrane fluorescence staining and Ki67 expression. Expression of PAL-E, high-molecular-weight–melanoma-associated antigen, smooth muscle α-actin, desmin, and collagen synthesis (prolyl-4-hydroxylase and type I procollagen, as well as collagen pro-α1(I) mRNA) were followed during a culture period of 8 days. The cells were PAL-E negative but expressed high-molecular-weight–melanoma-associated antigen, smooth muscle α-actin, and desmin. Based on morphology and expression of the various markers, the outgrowing cells were identified as pericytes. With time in culture the cells decreased their expression of all these markers and increased their expression of prolyl-4-hydroxylase, type I procollagen, and collagen pro-α1(I) mRNA. Metabolic labeling and SDS–PAGE analysis of labeled proteins revealed that type I collagen was the major collagen species synthesized in the cultures. Our results support the hypotheses that pericytes can leave the vasculature and differentiate into collagen-producing cells and that cultured “fibroblasts” are derived from pericytes.     

Differential expression of ABH histo-blood group antigens and LAMPs in infantile hemangioma

Summary Although infantile hemangioma (IH) are the most common tumors of infancy, the mechanism of their proliferation and involution remains vague. Proliferation, differentiation and death of endothelial cells are the basic processes involved in their pathobiology. Here we hypothesize that the glycoconjugates ABH histo-blood group antigens (HBGA) and lysosome-associated membrane proteins (LAMPs) might be implied in both the differentiation and death of endothelial cells during vascular remodeling in IH. Proliferating and involuting IH were examined immunohistochemically for HGBA and LAMP expression together with vWF and CD31. Proliferative and apoptotic indices were determined. LAMPs were found in immature endothelium of proliferating IH. In involution an increased number of immunopositive cells stained with higher intensity was detected. The enhanced expression might be associated with augmented autophagy required for tissue remodeling during tumor involution. HBGA presented an opposite pattern of expression – they stained intensely the endothelium of mature capillaries, while the immature ones were positive for vWF. The presence of HBGA in endothelial cells of IH may be related to the differentiation process only, as well as to endothelial adhesion and angiogenesis. Novel evidence for differential expression of HBGA and LAMPs in proliferative and involutive phases of IH is presented.     

The vascular-associated lymphoid tissue: a new site of local immunity

Recent data suggest that atherosclerosis might be a systemic (auto)immune reaction against heat shock protein 60, first occurring at notorious local predilection sites, i.e. the intima at arterial branching points. The local infiltration of mononuclear cells, mainly macrophage-derived foam cells, T cells and smooth-muscle cells in atheromatous plaques, have long been described. During the past few years, research has been concentrated on the early stages in the development of atherosclerosis, and on healthy arteries from young individuals unaffected by arterial disease. In this review, we summarize data characterizing pre-existing mononuclear cell infiltrations in healthy arteries from children and teenagers. These arterial accumulations at regions known to be predilection sites for the later development of atherosclerosis consist mostly of activated T cells, macrophages and dendritic cells, with only a few mast cells and virtually no B or natural killer cells. In analogy to the mucosa-associated lymphoid tissue, we termed these accumulations 'vascular-associated lymphoid tissue', and assumed a similar function as a local immunosurveillance system, monitoring the bloodstream for potentially harmful endogenous or exogenous antigens. In addition to the remarkable accumulation of mononuclear cells, the vascular-associated lymphoid tissue regions are characterized by a typical distribution of extracellular matrix proteins: collagen type I, collagen type III, fibronectin and tenascin are expressed preferentially in the vascular-associated lymphoid tissue region, whereas collagen type IV, collagen type V, collagen type VI and laminin show a homogenous distribution throughout all regions of the intima. Vascular adhesion molecules type 1, intercellular adhesion molecules type 1 and P-selectin are already present on the healthy endothelial cells of young children. Interactions between adhesion molecules, extracellular matrix components and cellular elements of the vascular-associated lymphoid tissue may provide the basis for the cellular accumulations in the vascular-associated lymphoid tissue regions and the possible development of atherosclerotic lesions later in life.     

EZH2和CBX7在皮肤血管瘤中的异常表达及意义

目的探讨EZH2和CBX7在血管瘤中的的异常表达及临床意义。方法收集武汉大学人民医院病理科2005年9月一2009年12月皮肤毛细血管瘤存档蜡块50例,其中男性25例,女性25例。采用免疫组织化学S-P法检测50例皮肤血管瘤增生期、退化期及正常皮肤组织中EZH2和CBX7的表达水平,采用图像分析系统对EZH2和CBX7的表达进行定量分析,并用SPSS13．0软件对各组免疫组织化学反应阳性颗粒的平均光密度、阳性面积率做单因素方差分析和SNK（q）检验。结果增生期血管瘤血管内皮细胞中可见密集分布的棕黄色颗粒,EZH2和CBX7呈高表达,退化组及正常皮肤组血管内皮细胞中可见少量的棕黄色颗粒,EZH2和CBX7表达弱。增生期组EZH2和CBX7的表达明显高于退化期组和正常皮肤组（P〈0．05）,而后两组比较差异无统计学意义（P〉0．05）。结论EZH2和CBX7在血管瘤增生期均上调表达,表明EZH2和CBX7均与血管瘤内皮细胞的增殖密切相关。     

Loss of myocardial capillary endothelial-cell alkaline phosphatase (ALP) activity in primary endothelial cell culture

Primary cultures of rat myocardial capillary endothelial cells were established and characterized. A range of typical endothelial cell-specific markers were retained in vitro. Cell kinetic studies in confluent endothelial-cell cultures in vitro revealed a roughly 50-fold increase in the proportion of cells in s-phase, indicating a very considerable shortening of cell turnover time, compared to in vivo conditions. Alkaline phosphatase enzyme activity and encoding mRNA are strongly expressed in myocardial capillary endothelial cells in vivo, but were not detectable in vitro. This was true in cell cultures from two strains of rat, which revealed significantly different enzyme expression levels in vivo. In co-cultures of pericytes and endothelial cells, positive ALP enzyme reaction was detected in pericytes, which in vivo show only very weak enzyme reactivity. Treatment of cell cultures with ≤10 M retinoic acid had no effect in pure endothelial cell cultures, but did increase ALP expression of pericytes in co-cultures. The observation of a loss of endothelial ALP expression in vitro supports other in vitro as well as our own in vivo observations, indicating a negative correlation of ALP expression and proliferative activity of endothelial cells.     

Alterations in the dynamics of inflammation, proliferation and apoptosis in subcutaneous implants of lupus-prone mice

Wound repair is a complex process that involves inflammation, proliferation, extracellular matrix deposition/remodeling and apoptosis. Autoimmune diseases profoundly affect the healing process. We have used histological parameters to characterize the recruitment of mast cells and the proliferative activity and apoptosis in the fibrovascular tissue induced by subcutaneous polyether-polyurethane sponge implants in lupus-prone New Zealand White (NZW) and in control Balb/c mouse strains at days 10 and 21 post implantation. Fibrovascular tissue infiltration (hematoxylin and eosin staining), mast cell number (Dominici staining) and cellular proliferation (AgNOR staining) peaked early (day 10) but collagen deposition (picrosirius red staining) and apoptosis remained high in implants of NZW mice during the experimental period. In contrast, implants of Balb/c animals showed a progressive increase in mast cell recruitment and cellular proliferation but apoptosis fell from day 10 to 21 post-implantation. This divergent response early mast cells recruitment, excessive collagen deposition and disturbed removal of apoptotic cells from the site of injury in NZW mice implies that the genotype trait of NZW mice is a determining factor in abnormal healing response.     

Expression of vascular endothelial growth factor receptors in the human endometrium: modulation during the menstrual cycle

Angiogenesis is fundamental for human endometrial development and differentiation necessary for implantation. These vascular changes are thought to be mediated by the vascular endothelial growth factor (VEGF), whose specific receptors have not been examined in detail thus far. We conducted the present study to determine, by immunocytochemistry and computerized image analysis of the functionalis, the expression and modulation of the receptors Flk-1/KDR and Flt-1, which mediate VEGF effects on endothelial mitogenicity, chemotaxis, and capillary permeability. VEGF receptors are expressed mainly in endometrial endothelial cells, with variations of intensity and number of stained capillaries related to the phase of the cycle. The number of capillaries immunostained for Flk-1/KDR was maximal in the proliferative phase (ratio Flk-1/CD34: 1), twice as high as the number of Flt-1-expressing capillaries (ratio Flt-1/CD34: 0.47). The staining intensity for Flk-1 decreased during the late proliferative and early secretory phases, to increase again in the midsecretory period. The number of Flt-1-labeled capillaries was about 2-fold higher in the secretory than in the proliferative phase; however, the proportion of Flt-1-positive cells did not change, owing to the associated increase in vascular density that characterizes progression of the functionalis from the proliferative to the secretory stage. The staining intensity for Flt-1 was higher during the late proliferative and secretory phases (especially in the midsecretory phase) and the premenstrual period. In contrast, the proportion of capillaries expressing Flk-1/KDR decreased in the secretory phase (ratio Flk-1/Von Willebrand factor: 0.55). Enhanced expression of Flk-1/KDR, and of Flt-1, on narrow capillary strands at the beginning of and during the proliferative phase may account for the rapid capillary growth associated with endometrial regeneration following menstrual shedding. The high coexpression of Flk-1/KDR and Flt-1 observed on capillaries during the midsecretory period correlates with an increase of endometrial microvascular density and of permeability characteristic of this phase of the cycle, which is a prerequisite for implantation. Finally, strong expression of Flt-1, but not Flk-1/KDR, was observed on dilated capillaries during the premenstrual period and the late proliferative phase, suggesting preferential association of Flt-1 with nonproliferating capillaries at those times; activation of this receptor by VEGF could be involved in premenstrual vascular hyperpermeability, edema, and extravasation of leukocytes. In addition to the endothelial localization, we found that epithelial cells expressed Flt-1 and Flk-1/KDR. We conclude that Flt-1 and Flk-1/KDR in the functionalis are modulated in parallel or independently according to the phase of the cycle, and that these changes are responsible for VEGF actions on endometrial vascular growth and permeability. The molecular mechanisms concerning these regulations will require further investigation.     

A Bacillus stearothermophilus Esterase Produced by a Recombinant Bacillus brevis Stabilized by Sulfhydryl Compounds

In the microvascular system, pericytes are located at the abdominal side of capillary endothelial cells.

To discover the role of pericytes in the microvascular system, we have analyzed the extracellular proteins secreted from pericytes isolated from microvessel fragments of rat epididymal fat pads and found that they synthesize substantial amounts of basement membrane components such as type IV collagen and laminins. Secretion of type IV collagen was markedly stimulated by ascorbic acid phosphate. Reducing and non-reducing sodium dodecyl sulfate gel electrophoresis showed that pericytes produce six laminin chains assembled into different trimeric isoforms. Two of them were similar to laminin variants produced by aortic and pulmonal endothelial cells but others were suggested to be novel variants.     

Circular excision of hemangioma and purse-string closure: the smallest possible scar

Localized cutaneous infantile hemangioma acts like a tissue expander. This rapidly growing tumor can destroy elastic fibers or cause ulceration resulting in telangiectases, cutaneous laxity, scarring, and fibrofatty residuum. Although surgeons may dispute indications and timing, most would agree that the scar of resection should be minimized. For this reason, circular excision and purse-string closure is particularly applicable for hemangioma at any stage of its evolution. The purposes of this study were to: (1) analyze the results of circular excision/purse-string closure in all three phases of the life cycle of hemangioma; (2) quantify dimensional changes after resection; and (3) compare the scars after theoretical single-stage lenticular excision with those after staged circular excision/purse-string closure. The authors retrospectively analyzed their experience in 25 children with localized hemangioma who underwent circular excision/purse-string closure from 1997 to 2000. Each hemangioma was measured preoperatively and the scars were measured at most recent follow-up (minimum, 6 months). Preoperative and postoperative dimensions were analyzed using SPSS statistical software. The study included 22 girls and three boys, with an average time to follow-up evaluation of 13.1 months. Twenty-one lesions were in the face and scalp, and five were in the extremity. Five tumors were resected in the proliferative phase (either because of ulceration, bleeding, or visual complications) and 21 were excised in the involuting or involuted phase. Six patients had a second-stage procedure: three had another circular excision and three had later lenticular excision. After single circular excision/purse-string closure, the mean long-axial diameter (length) decreased by 45 percent, the mean short-axial width (width) decreased by 73 percent, and the mean scar area was only 15 percent of the original area. All these differences were statistically significant (p = 0.001). The average width/length ratio decreased by 50 percent, indicating a tendency for scars to linearize. There was no difference in linearization for the three phases of hemangioma (p > 0.05); extremity scars became more linear that those on the face (p = 0.01). The authors devised a formula for scar length after lenticular excision/linear closure, assuming a conventional excisional ratio of 3:1 for a circular lesion. Using this equation, the authors predicted that mean scar length after circular excision, followed by lenticular excision, would be 72 percent shorter than the calculated scar that would result from conventional lenticular excision. In three patients who underwent this two-stage approach, the resultant scar was 69 percent shorter. Circular excision of hemangioma and purse-string closure reduces both the longitudinal and transverse dimensions and converts a large circular lesion into a small ellipsoid scar. If subsequent revision to a linear scar is desirable, its length will be the same or slightly less than the diameter of the original lesion. No other excision and closure technique results in a smaller scar. Another advantage of this method is minimal distortion of surrounding structures.     

c-Myc在人皮肤血管瘤不同时期的表达及意义

目的探讨c-myc在血管瘤发生、发展及退化过程中的表达状况及意义.方法采用免疫组织化学(S-P法),检测人血管瘤增生期、退化期及正常皮肤组织血管内皮细胞c-myc的表达水平,利用计算机图像分析技术检测不同时期血管瘤和正常皮肤组织c-myc染色的阳性面积率和平均光密度.结果增生期血管瘤内皮细胞c-myc表达水平明显高于退化期及正常皮肤组织,差异有显著性意义(P<0.01);退化期与正常皮肤组织血管内皮细胞c-myc表达水平差异无显著性意义(P>0.05).结论 c-myc通过促进血管内皮细胞增殖在血管瘤的发生和发展过程中起重要作用.     

Local serum levels of vascular endothelial growth factor in infantile hemangioma: Intriguing mechanism of endothelial growth

The pathogenesis of hemangiomas still remains poorly understood. Dysregulation of angiogenesis has been proposed to play a central role in hemangioma pathogenesis. The aim of our study was to determine the peripheral and local serum levels of VEGF in patients with hemangiomas and vascular malformations. Material and methods: The study group consisted of 52 children with infantile hemangioma (33 with proliferative lesions, 19 with involuting lesions), 14 children with vascular malformations and 36 healthy children. VEGF serum levels were analyzed by an ELISA assay and the values between the groups were compared. Results: The serum peripheral VEGF concentrations in children with proliferative hemangiomas were significantly higher than in patients with involuting hemangiomas, vascular malformations and controls. There was no correlation between the measured cytokine level, hemangioma size, and the age of the patients. The local serum VEGF levels in 29 children with hemangiomas were distinctly lower than in the peripheral blood, both in 20 proliferating hemangiomas (p < 0.0001) and 9 involuting ones (p = 0.007); and the difference between females and males was non-significant (NS p = 0.06). Conclusions: (1) VEGF serum levels vary in the different phases of hemangioma growth and may help to distinguish hemangiomas from vascular malformations; (2) obtained local results may support the intrinsic theory of endothelial cell proliferation in hemangiomas.     

Involvement of metalloprotease-2 in the development of human brain microvessels

The involvement of the metalloprotease-2 (MMP-2) in vessel development was investigated in the human telencephalon by double immunoreactions with antibodies to the enzyme, latent (proMMP-2) and active (aMMP-2) forms, and an antibody against collagen type IV, a constitutive component of the extracellular matrix (ECM) of the vessel basal lamina. MMP-2 is expressed in both 12- and 18-week telencephalic vessels, the proenzyme being mainly localised in endothelial cells and the active form prevailing in -actin-reactive periendothelial cells identified as pericytes. Endothelial cells intensely positive for aMMP-2 were revealed in some microvessels and appeared locally associated with discontinuities of the collagen basal lamina. No detectable expression of MMP-2 was observed in perivascular glial processes revealed by vimentin/glial fibrillary acidic protein immunostainings. Double immunoreactions performed to further investigate telencephalon angiogenesis have demonstrated that both the endothelial cells and pericytes strongly express vascular endothelial growth factor (VEGF). Taken together, the results indicate that MMP-2 is largely involved in human brain angiogenesis and suggest that endothelial cells and pericytes tightly interplay in both angiogenesis mechanisms, by ECM proteolysis, and angiogenesis regulation, by local (autocrine/juxtacrine) VEGF action.Francesco Girolamo and Daniela Virgintino contributed equally to this work