Derivation of a new hematopoietic cell line with endothelial features from a patient with transformed myeloproliferative syndrome: a case report

BACKGROUND

During embryonal development primitive hematopoiesis can be observed first in the yolk sac, in which both hematopoietic and endothelial cells are derived from a common precursor, the hemangioblast. Whether cells with this dual differentiation potential persist during postnatal life is unknown.

METHODS

A cell line was derived from a patient with secondary acute leukemia. Because of its ability to grow in soft agar and in SCID mice, this cell line was analyzed for expression of differentiation antigens by fluorescence-activated cell sorter analysis, immunocytochemistry, fluorescent in situ hybridization (FISH) analysis with simultaneous cell surface staining, and polymerase chain reaction (PCR).

RESULTS

A new cell line was established from a patient with essential thrombocytosis that transformed into acute leukemia. The patient's initial clinical presentation included skin and lymph node infiltrations that were taken for an angiosarcoma due to positivity for CD34, CD31, and von Willebrand factor on immunohistology. In addition to hematopoietic markers, leukemic cells expressed endothelial antigens such as CD62E, CD105, and bound Ulex europäeus lectin-1. Immunocytochemistry revealed positive staining for vascular endothelial growth factor receptor type 2 (KDR), Tie-2/Tek, the angiopoietin receptor, and vascular endothelial cadherin. These results were confirmed by PCR analysis. Simultaneous staining for CD62E and FISH analysis showed that cells with endothelial characteristics belonged to the leukemia. FISH analysis of histologic sections of the lymph node infiltration confirmed this manifestation as part of the leukemic process. The derived cell line, UKE-1, forms colonies in soft agar and is tumorigenic in SCID mice.

CONCLUSIONS

This new cell line, UKE-1, appears to combine hematopoietic and endothelial features, indicating the close ontogenic relation of both lineages.

Melanoma-associated expression of vascular endothelial growth factor and its receptors FLT-1 and KDR

The expression patterns of vascular endothelial growth factor (VEGF) and its two receptors, flt-1 and KDR, were assessed in normal human melanocytes, transformed melanocytes expressing the simian virus 40 Tgene (SV40T), and melanoma cells derived from primary and metastatic lesions. Constitutive expression of VEGF, flt-1, and KDR mRNA and proteins was observed in the majority of primary and metastatic melanoma cell lines, and in SV40T-transformed melanocytes. VEGF expression in melanoma cell lines was further enhanced by exogenous growth factors including insulin and fetal calf serum. By contrast, neonatal melanocytes did not express VEGF or VEGF receptors and VEGF expression could not be induced by exogenous growth factors. Exogenous VEGF had no significant effects on melanoma cell proliferation or on production of a transcriptional target for VEGF, urokinase-type plasminogen activator. Down-regulation of VEGF expression in the metastatic melanoma cell line WM164 through transfection of a VEGF antisense construct similarly did not affect proliferation of the transfected cells in the presence or absence of exogenous VEGF. In summary, coexpression of VEGF and its receptors is a tumor-associated phenomenon in melanoma development. However VEGF production does not support autocrine proliferation of the melanoma cell lines tested.

Apoptosis in meatal skin, cholesteatoma and squamous cell carcinoma of the ear

Apoptosis in normal meatal skin, cholesteatoma and squamous cell carcinoma (SCC) of the ear was investigated by using morphological analysis and in-situ specific labelling of fragmented DNA. In meatal skin, apoptotic cells were localized mainly in the granular layers, but were not so restricted in cholesteatoma, while in SCC they were even more dispersed. The apoptotic index (AI) was low (1.59 +/- 0.10 SEM) in normal skin. It was increased in cholesteatoma (2.09 +/- 0.11), and was intermediate in SCC (1.72 +/- 0.14). By contrast, the mitotic index (MI) increased from 0.19 +/- 0.02 in normal skin, to 0.25 +/- 0.01 in cholesteatoma and to 0.25 +/- 0.02 in SCC. Our findings indicate that apoptosis is involved in the epithelial homeostasis of meatal skin, cholesteatoma and SCC of the ear. The hyperproliferation of epithelial cells in cholesteatoma is counteracted by an increased apoptosis rate, while in SCC the increased cell proliferation without a compensatory increase in apoptosis may be associated with the malignant transformation.

Endothelin and endothelin receptors A and B in the human testis

Human testicular capillaries interconnect Leydig cells and seminiferous tubules. Microcirculation and blood flow are therefore essential for the maintenance of spermatogenesis. The expression and the localisation of ET (endothelin) and its receptors in testicular tissue, in seminiferous tubules and in human testicular capillaries were studied. ET-1 mRNA was detected in whole testicular tissue and in seminiferous tubules whereas isolated testicular capillaries were negative. Big ET-1 (Big endothelin 1) and ET peptides were localised in Leydig and Sertoli cells whereas interstitial and intramural capillaries (within the lamina propria) remained unstained. ET was also found in mature spermatids. ET-A (endothelin receptor A) mRNA was detected in seminiferous tubules and whole testicular tissue whereas testicular blood vessels were negative. ET-A immunostaining was displayed in Leydig and Sertoli cells and in spermatids. ET-B (endothelin receptor B) mRNA was detected in whole testicular tissue, seminiferous tubules and in testicular capillaries. ET-B peptide was prominent in Leydig cells, peritubular cells, endothelial cells and pericytes of interstitial and intramural capillaries as well as in vascular endothelial and smooth muscle cells. From these results we conclude that ET produced in Leydig and Sertoli cells can act in a paracrine manner via ET-B on the human testicular microvasculature and the peritubular cells. The presence of both ET-A and ET-B in Leydig cells and of ET-A in Sertoli cells leads to the assumption that ET could influence these cells as an autocrine factor.

Levels of vascular endothelial growth factor, hepatocyte growth factor/scatter factor and basic fibroblast growth factor in human gliomas and their relation to angiogenesis

Angiogenesis is a possible target in the treatment of human gliomas. To evaluate the role of 3 growth factors, vascular endothelial growth factor (VEGF), hepatocyte growth factor/scatter factor (HGF/SF) and basic fibroblast growth factor (bFGF), in the angiogenic cascade, we determined their levels in extracts of 71 gliomas by enzyme-linked immunosorbent assay (ELISA). The levels of bFGF were only marginally different between gliomas of World Health Organization (WHO) grade II (low grade) and grades III and IV (high grade). In contrast, the mean concentrations of VEGF were 11-fold higher in high-grade tumors and those of HGF/SF 7-fold, respectively. Both were highly significantly correlated with microvessel density (p < 0.001) as determined by immunostaining for factor VIII-related antigen. In addition, VEGF and HGF/SF appeared to be independent predictive parameters for glioma microvessel density as determined by multiple regression analysis. We measured the capacity of all 3 factors to induce endothelial tube formation in a collagen gel. In this assay, bFGF was found to be an essential cofactor with which VEGF as well as HGF/SF were able to synergize independently. According to the concentrations of angiogenic factors, extracts from high-grade tumors were significantly more potent in the tube formation assay than the low-grade extracts (p = 0.02). Adding neutralizing antibodies to bFGF, VEGF and HGF/SF together with the extracts, tube formation was inhibited by up to 98%, 62% and 54%, respectively. Our findings suggest that bFGF is an essential cofactor for angiogenesis in gliomas, but in itself is insufficient as it is present already in the sparsely vascularized low-grade tumors. Upon induction of angiogenesis in high-grade tumors, bFGF may synergize with rising levels of not only VEGF but possibly also with HGF/SF, which appears here to be an independent angiogenic factor.

Isolation and culture of human neuromicrovascular endothelial cells for the study of angiogenesis in vitro

Neovascularization in the adult central nervous system occurs as a response to several pathophysiological conditions such as ischemia, wound repair, or neoplasia. Endothelial cells from different blood vessel types, different organs, and different species are heterogeneous; therefore, the appropriate cell type should be used to study specific aspects of vascular pathology. We have developed a method to isolate human cerebral microvascular endothelial cells (CMECs) from small, freshly obtained specimens of normal brain adherent to human arteriovenous malformations (AVMs). The isolation procedure involves enzymatic digestions and gradient centrifugations, yielding over 95% pure primary cultures. Alternative isolation methods using magnetic beads, panning, or cloning were not superior with regard to cell purity or yield. CMECs were identified by their immunoreactivity for vWF, CD34, EN4, binding of Ulex europeus lectin, and uptake of DiI-Ac-LDL. They displayed ultrastructural features characteristic of blood-brain barrier endothelial cells and expressed GLUT-1. CMECs were subcultured; however, prolonged culture led to reduced culture purity. Vascular endothelial growth factor, basic fibroblast growth factor and hepatocyte growth factor/scatter factor stimulated the directional motility of CMECs, with dose-response profiles similar to human umbilical vein endothelial cells (HUVECs). In contrast, to stimulate proliferation, lower concentrations of growth factors tended to be necessary for CMECs than for the large vessel endothelial cells. CMECs formed capillary tube-like structures in an in vitro angiogenesis assay using matrigel. This study expands the spectrum of available tissue sources for the isolation of human neuromicrovascular endothelial cells, which are essential for the in vitro study of blood-brain barrier function and cerebral angiogenesis.

Human lymphocytes produce urocortin, but not corticotropin-releasing hormone

Hypothalamic corticotropin-releasing hormone (CRH) is the principal regulator of the hypothalamus-pituitary-adrenal axis in mammals. In addition, immunoreactive CRH is also present at peripheral sites, where it is thought to act as a proinflammatory peptide. However, the source of peripheral CRH has remained obscure. Human lymphocytes were shown to produce immunoreactive CRH, yet the data on CRH mRNA expression in these cells are equivocal. More recently, Vaughan et al. discovered a new member of the CRH family, termed urocortin. Urocortin was shown to act through the same receptors as CRH. The current study was designed to investigate both mRNA and protein expression of CRH and urocortin in human lymphocytes. Using a commercial CRH(1-41) radioimmunoassay, we demonstrate that normal human lymphocytes and Jurkat T lymphoma cells produce significant amounts of immunoreactive peptide. However, no CRH mRNA was detectable by RT-PCR in these cells. In contrast, a band of the correct size and sequence was amplified with urocortin-specific primers. Immunocytochemical analysis of human lymphocytes using antibodies that could distinguish between CRH and urocortin revealed significant expression of urocortin but not of CRH, consistent with our RT-PCR data. We conclude that human lymphocytes produce urocortin, but not CRH.

Functional expression and localization of vascular endothelial growth factor and its receptors in the human epididymis

Blood supply is essential for the maintenance of epididymal function. Since there is no considerable neovascularization in the epididymis, this tissue could represent a suitable model to study the vascular endothelial growth factor (VEGF) effect for vascular permeability. We studied the expression and function of VEGF and its receptors fms-like tyrosine kinase (Flt-1) and fetal liver kinase (designated as kinase insert domain-containing receptor, KDR in the human) in the human epididymis. VEGF and VEGF receptors mRNA were detected in the human epididymal tissue. VEGF protein was localized in peritubular and in ciliated cells of efferent ducts as well as in peritubular and basal cells of the epididymal duct. Vascular endothelial cells did not express VEGF. Flt-1 protein was localized in ciliated cells of efferent ducts and in lymphatic vessels. Vascular endothelial cells were negative for Flt-1 but positive for KDR. In vitro VEGF165 treatment of epididymal tissue induced endothelial fenestrations and opening of interendothelial junctions. Additionally, we observed for the first time that VEGF could induce transendothelial gaps. We conclude that these gaps might be of importance not only for molecular transport but also for cell passage across the vessel wall, which may be significant for tumor metastasis. VEGF may act as a paracrine effector to influence the permeability of lymphatic vessels via Flt-1, and of blood vessels via KDR.

Region-specific expression of the androgen receptor in the human epididymis

The expression of the androgen receptor in the human epididymis was analysed by ribonuclease protection, in-situ hybridization and immunohistochemistry. Androgen receptor mRNA and protein could be detected throughout the entire organ, albeit in different quantities, in the caput, corpus and cauda regions, respectively. Also positive, though only weakly, was the ductus deferens, while the efferent ducts were devoid of specific signals. In-situ transcript hybridization and immunocytochemistry localized androgen receptor mRNA and protein primarily to the epithelium of the epididymal duct. In the ductal epithelial cells androgen receptor immunoreactivity showed a distinct nuclear distribution. While peritubular cells occasionally displayed weak signals, interstitial cells as well as blood vessels were consistently negative throughout the entire organ. The observed pattern of androgen receptor expression in the human epididymis supports the notion that the structure and function of the epididymis is differentially controlled by androgens in a region-specific manner, whereas it would not seem compatible with a direct role for androgens in the regulation of epididymal blood flow.

Estrogen and progesterone receptors and estrogen receptor-related antigen (ER-D5) in human epididymis

Estrogen receptor mRNA expression was detected in the head and tail parts of the human epididymis by means of reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemical labelling showed that ciliate and nonciliate cells from the epithelium of the efferent ductules possessed strong to moderate nuclear staining for estrogen and progesterone receptors. The epididymal duct was negative for both antigens. Vascular endothelial cells also showed estrogen receptor, but no progesterone receptor immunolabelling in all regions of the organ. Immunoreactivity for the estrogen receptor-related antigen (ER-D5) was seen in the cytoplasm of ciliated and nonciliated epithelial cells from the efferent ductules, in the basal cells of some epididymal duct profiles as well as in myofibroblasts of the lamina propria, endothelial cells and smooth muscle cells of the vessel walls. The results obtained suggest that the epithelial cells of the efferent ductules of the human epididymis may be main target structures of estrogens and progestins.

Expression of FLT4 and its ligand VEGF-C in acute myeloid leukemia

FLT4 represents a recently cloned member of class III receptor tyrosine kinases which include receptors for the angiogenic growth factor VEGF, namely FLT1 and KDR. The ligand of FLT4 has been identified as VEGF-C which shares sequence homology with VEGF and P1GF. In the adult FLT4 shows a restricted expression pattern that is limited to lymphatic endothelia and endothelia of some high endothelial venules (HEV). FLT4 has also been detected in some tumor cell lines including the hematopoietic line HEL. We therefore investigated expression of FLT4 and its ligand VEGF-C in fresh samples from patients with AML. Using a sensitive PCR method we detected FLT4 m-RNA in 15 of 41 patients with de novo AML at diagnosis or relapse and in three of 12 patients with secondary AML. FLT4 expression was confirmed by immunocytochemistry in a subgroup of the studied patient population. FLT4 was also found in leukemic cell line U937, but not TF-1 and KG1a. VEGF-C expression was found in leukemic samples of four of seven FLT4-positive and four of six FLT4-negative patients. U937 cells also produced VEGF-C m-RNA. Interestingly, FLT4 expression was not detected in bone marrow samples of 15 normal volunteer donors or in CD34-positive cells from three additional donors. Possible autocrine and paracrine growth stimulation of leukemic blasts by VEGF-C is currently being investigated in our laboratory.

Vascular endothelial growth factor and its receptors in normal human testicular tissue

Expression of vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), and its receptors Flt-1 and KDR (Flk-1 in mouse) and their localization in the human testis were analyzed by means of reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. VEGF mRNA was detected in the human testicular tissue and in fragments of seminiferous tubules by means of RT-PCR, while fragments of blood vessels isolated from testes were negative. Western blotting procedure using a specific VEGF antibody, revealed two protein bands corresponding to 24 and 49 kDa in the extracts prepared from the whole testis and in the seminiferous tubules while no such bands were found in isolated fragments of human testicular blood vessels. Also immunohistochemically, human testicular blood vessels show no VEGF immunoreactivity, while Leydig cells and Sertoli cells were positive. The mRNA of the VEGF receptor Flt-1 was found to be expressed in human testicular tissue, in isolated fragments of testicular blood vessels and in seminiferous tubules as determined by RT-PCR procedure. In accordance with these results, the Flt-1 protein was immunohistochemically localized in Leydig, Sertoli and perivascular cells. Endothelial cells of certain segments of human testicular microvasculature also stained positive for Flt-1. Expression of VEGF receptor, KDR, could be demonstrated in human testicular tissue, in isolated seminiferous tubules and in isolated fragments of human testicular blood vessels by means of RT-PCR. Immunohistochemically, the KDR protein was localized in endothelial cells and perivascular cells of capillaries within the lamina propria of seminiferous tubules. Leydig cells and Sertoli cells show KDR immunoreactivity, too. Thus we demonstrate the presence of both types of VEGF receptors Flt-1 and KDR on Leydig as well as on Sertoli cells which are normal non-endothelial cells, suggesting hitherto unrecognized and novel functions for such receptors. The results obtained permit us to suggest VEGF as a paracrine mitogenic and angiogenic factor, responsible for modulating the capillarization of the human testicular tissue and maintaining the functions of testicular microvasculature. VEGF may also influence the permeability of capillaries passing through the groups of Leydig cells and those localized within the lamina propria of human seminiferous tubules. The differences in the expression pattern of the VEGF receptors in the human testicular tissue probably reflect different VEGF effects in different compartments of human testis.

Localization of endothelin-1 and endothelin-receptors A and B in human epididymis

Expression of mRNA of endothelin-1 (ET-1) and its receptors, endothelin receptor A (ET-A) and endothelin receptor B (ET-B), in human epididymis was assessed by reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemistry was performed on longitudinal sections through whole normal human epididymides. ET-1 mRNA was detected in caput, corpus and cauda epididymidis. Immunohistochemically, ET-1 was localized mainly in ciliated cells of efferent ducts and in some principal cells of epididymal duct. Larger arteries, but not epididymal microvasculature, contained ET-1 immunoreactivity. ET-A and ET-B mRNAs were detected in caput, corpus and cauda epididymidis. In efferent ducts, ET-A immunoreactivity was localized in ciliated cells. In the proximal region of the epididymal duct, ET-A immunostaining was localized mainly in basal cells whereas the distal region was devoid of ET-A immunoreactivity. Throughout the epididymis, blood vessels stained positive for ET-B. Furthermore, ET-B immunoreactivity was found in ciliated cells of efferent ducts and in basal cells of the distal epididymal duct. The fact that ciliated cells of efferent ducts contain ET-1 and both types of receptors indicates that ET-1 acts as an autocrine factor in these cells. ET-1 produced by efferent ducts and epididymal duct may control epididymal blood flow in a paracrine manner via ET-B receptors in epididymal blood vessels.

Angioarchitecture of the human spermatic cord

Human spermatic cords were investigated by means of cast preparations, light-microscopic examination and computer-aided 3-dimensional reconstructions from serial sections of paraffin-embedded material. After leaving the testis, the testicular veins formed two principal groups co-existing side by side. Numerous veno-venous anastomoses could be observed within each individual group, whereas only a few mutual intergroup anastomoses were found. The testicular artery ran within one group but showed no close topographical relationship to the other group. Light microscopy of the serial sections revealed that the group of veins with no close topographical relationship to the testicular artery ran at a distance of several centimeters embedded within fatty tissue. With the help of computer-aided 3-dimensional reconstructions, a spatial picture of the vascular organization was obtained. These results allowed the following classification of the veins of the pampiniform plexus. Group-I veins formed a tight plexus around the testicular artery by means of veno-venous anastomoses. Group-II veins formed veno-venous anastomoses between each other and ran over at a sizeable distance embedded in fatty tissue but showed no close topographical relationship to the testicular artery. Group-III vessels formed veno-venous anastomoses between group-I and group-II. Group IV veins formed arterio-venous anastomoses with the testicular artery. Based on the differences in wall structure and diameter, a subclassification in group-I and group-II was undertaken. This organization of the veins of the human pampiniform plexus should further the understanding of physiological processes, such as the transfer of hormones and other substances from the veins to the testicular artery and vice versa. It should also facilitate the tracing of the veins during antegrade sclerosing.

Vascular endothelial growth factor, a possible paracrine growth factor in human acute myeloid leukemia

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine involved in angiogenesis, inflammation, and wound healing. It is secreted by a variety of tumor cell lines, including hematopoietic lines. Therefore, we investigated expression of VEGF and its receptors on fresh leukemic blasts. VEGF-specific transcripts were detected by polymerase chain reaction (PCR) in 20 of 28 patients with de novo acute myeloid leukemia (AML) and in 3 of 5 patients with secondary AML. Using immunocytochemistry, we found VEGF protein in 2 leukemic cell lines and in 8 AML patients, in concordance with PCR results. Supernatants of fresh leukemic cells from 24 AML patients contained significantly more VEGF than supernatants from bone marrow cells of 9 normal donors or of CD34-enriched cells from 3 normal volunteer donors as determined by an enzyme-linked immunosorbent assay. VEGF possesses two high-affinity receptors, KDR and FLT1. Using a sensitive nested PCR assay, we detected expression of FLT1 in 10 of 20 patients with de novo AML and 3 of 5 patients with secondary AML. KDR was expressed in 4 of 22 patients with de novo AML and 1 of 4 with secondary AML. To study possible paracrine growth stimulation of AML blasts, endothelial cells from human umbilical cords were incubated with increasing concentrations of VEGF. A dose-dependent increase of granulocyte-macrophage colony-stimulating factor secretion from endothelial cells was identified.