Functional characterization, localization, and inhibitor sensitivity of the TPR-FGFR1 fusion in 8p11 myeloproliferative syndrome.

Myeloid and lymphoid neoplasms with fibroblast growth factor receptor 1 (FGFR1) abnormalities, also known as 8p11 myeloproliferative syndrome (EMS), represent rare and aggressive disorders, associated with chromosomal aberrations that lead to the fusion of FGFR1 to different partner genes. We report on a third patient with a fusion of the translocated promoter region (TPR) gene, a component of the nuclear pore complex, to FGFR1 due to a novel ins(1;8)(q25;p11p23). The fact that this fusion is a rare but recurrent event in EMS prompted us to examine the localization and transforming potential of the chimeric protein. TPR-FGFR1 localizes in the cytoplasm, although the nuclear pore localization signal of TPR is retained in the fusion protein. Furthermore, TPR-FGFR1 enables cytokine-independent survival, proliferation, and granulocytic differentiation of the interleukin-3 dependent myeloid progenitor cell line 32Dcl3, reflecting the chronic phase of EMS characterized by myeloid hyperplasia. 32Dcl3 cells transformed with the TPR-FGFR1 fusion and treated with increasing concentrations of the tyrosine kinase inhibitors ponatinib (AP24534) and infigratinib (NVP-BGJ398) displayed reduced survival and proliferation with IC50 values of 49.8 and 7.7 nM, respectively. Ponatinib, a multitargeted tyrosine kinase inhibitor, is already shown to be effective against several FGFR1-fusion kinases. Infigratinib, tested only against FGFR1OP2-FGFR1 to date, is also efficient against TPR-FGFR1. Taking its high specificity for FGFRs into account, infigratinib could be beneficial for EMS patients and should be further investigated for the treatment of myeloproliferative neoplasms with FGFR1 abnormalities.

Disruption of the ARID1B and ADAMTS6 loci due to a t(5;6)(q12.3;q25.3) in a patient with developmental delay.

Here, we report on a male patient with developmental delay, speech impairment, mild dysmorphic features, and borderline intellectual disability, bearing a de novo balanced t(5;6)(q11;q25.3). By combining FISH and long distance inverse PCR, we identified two genes, ADAMTS6 and ARID1B, which were disrupted at the translocation breakpoints. Due to the opposing transcriptional directions of the two genes, no fusion transcripts could be formed. ADAMTS6 on chromosome 5 encodes a zinc metalloprotease. To date, there has been no information about the substrates and the exact role of this enzyme protein. ARID1B on chromosome 6 is involved in chromatin remodeling and transcriptional activation and is known to play a role in neural development. To our knowledge, this is the fourth translocation involving ARID1B reported in association with intellectual disability. ARID1B haploinsufficiency has already been described in patients with intellectual disabilities with or without corpus callosum abnormalities, Coffin-Siris syndrome and autism (OMIM 614562 and OMIM 614556). A review of patients with ARID1B mutations reveals their broad phenotypic variability. The phenotype of the present patient is of the mildest described to date and further underscores this observation. We conclude that the most prominent and consistent clinical findings in patients with ARID1B haploinsufficiency are developmental delay, speech impairment and intellectual disability and propose that patients with unresolved genetic background and these clinical findings should be considered for ARID1B mutation screening.

Single-nucleotide polymorphism array-based characterization of ring chromosome 18.

OBJECTIVE: To study genotype-phenotype correlation of ring chromosome 18 [r(18)] in 9 patients with 46,XN karyotype. STUDY DESIGN: In 9 patients with a de novo 46,XN,r(18) karyotype (7 females, 2 males), we performed high-resolution single-nucleotide polymorphism array analysis (Illumina Human Omni1-QuadV1 array in 6 patients, Affymetrix 6.0 array in 3 patients), investigation of parental origin, and genotype-phenotype correlation. RESULTS: No breakpoint was recurrent. Single metaphases with loss of the ring, double rings, or secondarily rearranged rings were found in some cases, but true mosaicism was present in none of these cases. In 3 patients, additional duplications in 18p (of 1.4 Mb, 2 Mb, and 5.8 Mb) were detected. In 1 patient, an additional deletion of 472 kb in Xp22.33, including the SHOX gene, was found. Parental origin of r(18) was maternal in 2 patients and paternal in 4 patients, and formation was most likely meiotic. Karyotype was normal in all investigated parents (n = 15). At birth, mean maternal age was 30 years (n = 9) and mean paternal age was 34.4 years (n = 9). CONCLUSION: Genotype-phenotype correlation revealed extensive clinical variability but no characteristic r(18) phenotype. Severity of clinical signs were generally correlated with the size of the deletion. Patients with large deletions in 18p and small deletions in 18q exhibited mainly symptoms related to 18p-, whereas those with large deletions in 18q and small deletions in 18p had symptoms of 18q-.

Isolation and characterization of CD133+CD34+VEGFR-2+CD45- fetal endothelial cells from human term placenta.

The phenotypes and functions of endothelial cells (EC), a heterogeneous cell population, vary along the vascular tree and even in the same organ between different vessels. The placenta is an organ with abundant vessels. To enhance further knowledge concerning placenta derived EC, we develop a new method for isolation, purification and culture of these EC. Moreover, in order to investigate the peculiarity of placenta derived EC we compare their phenotypic and functional characteristics with human dermal lymphatic endothelial cells (HDLEC) and human umbilical vein endothelial cells (HUVEC). Freshly isolated placenta derived EC displayed an elongated shape with pale cytoplasm and showed the typical cobblestone pattern of EC but also a swirling pattern when confluent. FISH-analyses of the isolated EC from placentae of male fetus revealed an XY genotype strongly indicating their fetal origin. Characterisation of placenta derived fetal EC (fEC) underlined their blood vessel phenotype by the expression of vWF, Ulex europaeus lectin-1, HLA-class I molecules, CD31, CD34, CD36, CD51/61, CD54, CD62E, CD105, CD106, CD133, CD141, CD143, CD144, CD146, VEGFR-1, VEGFR-2, EN-4, PAL-E, BMA120, Tie-1, Tie-2 and α-Tubulin. In contrast to previous reports the expression of lymphatic markers, like VEGFR-3, LYVE-1, Prox-1 and Podoplanin was consistently negative. Haematopoietic surface markers like CD45 and CD14 were also always negative. Various functional tests (Dil-Ac-LDL uptake, Matrigel assay and TNF-α induced upregulation of CD62E and CD54) substantiated the endothelial nature of propagated fEC. At the ultrastructural level, fEC harboured numerous microvilli, micropinocytic vesicles at their basis, were rich in intermediate filaments and possessed typical Weibel - Palade bodies. In conclusion, the placenta is a plentiful source of fetal, microvascular, blood EC with an expression profile (CD34+, CD133+, VEGFR-2+, CD45-) suggestive of an endothelial progenitor phenotype.

Effects of deletion and duplication in a patient with a 46,XX,der(7)t(7;17)(q36;p13)mat karyotype.

Exact breakpoint determination by DNA-array has dramatically improved the analysis of genotype-phenotype correlations in chromosome aberrations. It allows a more exact definition of the most relevant genes and particularly their isolated or combined impact on the phenotype in an unbalanced state. Here, we report on a 21-year-old female with severe growth retardation, severe intellectual disability, hypoplasia of the corpus callosum, unilateral sacral hypoplasia, tethered cord, various minor facial dysmorphisms, and a telomeric deletion of about 4.4 Mb in 7q36.2->qter combined with a telomeric duplication of about 8 Mb in 17pter->p13.1. Fine mapping was achieved with the Illumina® Infinium HumanOmni1-Quad v1.0 BeadChip. Most of the major clinical features correspond to the well-known effects of haploinsufficiency of the MNX1 and SHH genes. In addition, review of the literature suggests an association of the 17p duplication with specific facial dysmorphic features and skeletal anomalies, but also an aggravating effect of the duplication-deletion for severe growth retardation as well as sacral and corpus callosum hypoplasia by one or more genes located on the proximal half of the segmental 17p duplication could be elaborated by comparison with other patients from the literature carrying either the deletion or the duplication found in our patient.

Critical role of scavenger receptor-BI-expressing bone marrow-derived endothelial progenitor cells in the attenuation of allograft vasculopathy after human apo A-I transfer.

Allograft vasculopathy is the leading cause of death in patients with heart transplantation. Accelerated endothelial regeneration mediated by enhanced endothelial progenitor cell (EPC) incorporation may attenuate the development of allograft vasculopathy. We investigated the hypothesis that modulation of EPC biology and attenuation of allograft vasculopathy by increased high-density lipoprotein cholesterol after human apo A-I (AdA-I) transfer requires scavenger receptor (SR)-BI expression in bone marrow-derived EPCs. After AdA-I transfer, the number of circulating EPCs increased 2.0-fold (P < .001) at different time points in C57BL/6 mice transplanted with SR-BI(+/+) bone marrow but remained unaltered in mice with SR-BI(-/-) bone marrow. The effect of high-density lipoprotein on EPC migration in vitro requires signaling via SR-BI and extracellular signal-regulated kinases and is dependent on increased nitric oxide (NO) production in EPCs. Human apo A-I transfer 2 weeks before paratopic artery transplantation reduced intimal area at day 21 3.7-fold (P < .001) in mice with SR-BI(+/+) bone marrow but had no effect in mice with SR-BI(-/-) bone marrow. AdA-I transfer potently stimulated EPC incorporation and accelerated endothelial regeneration in chimeric SR-BI(+/+) mice but not in chimeric SR-BI(-/-) mice. In conclusion, human apo A-I transfer accelerates endothelial regeneration mediated via SR-BI expressing bone marrow-derived EPCs, thereby preventing allograft vasculopathy.

Phenotypic variability of a deletion and duplication 6q16.1 → q21 due to a paternal balanced ins(7;6)(p15;q16.1q21).

Constitutional insertional translocations are rare findings in clinical cytogenetics. Here, we report on the unbalanced segregation of a balanced paternal insertional translocation ins(7;6)(p15;q16.1q21) to three children. Investigations by conventional karyotyping, FISH with locus-specific probes, microsatellite marker analysis, and SNP-array based copy number analysis revealed a direct orientation of the inserted segment, a size of 11.3 Mb, and breakpoints between rs4370337 and rs12660854 and rs12110990 and rs4946730 on 6q16.1 and 6q21, respectively, as well as within BAC clone RP11-182J2 on 7p15. A 17-year-old daughter inherited the der(6) chromosome and was affected by severe mental retardation, obesity, and minor anomalies. Two further children inherited the der(7) chromosome. A daughter shows an almost unremarkable phenotype and only minor features in neuropsychological testing at 19 years of age. Her 14-year-old half-brother demonstrates a mild delay in cognitive development most likely jointly caused by the chromosomal rearrangement and asphyxia during delivery. The patient with the deletion confirms the previously reported phenotype of severe mental retardation and obesity in patients with del(6)(q16.2), while both patients with partial trisomy for the same segment of chromosome 6 are further examples for a generally less severe phenotype associated with duplications than with deletions, and even for the recent insight that chromosomal aneusomies of several megabases may go without major clinical consequences.

"Essentially" pure trisomy 3q27 --> qter: further delineation of the partial trisomy 3q phenotype.

Partial duplication 3q is a well defined clinical entity characterized by growth retardation, cryptorchism, microcephaly, and characteristic dysmorphisms. Most patients present with large duplications or are associated with a second chromosomal imbalance, which makes the definition of the phenotype difficult. Here, we report on a 4-year and 8-month-old girl with pre- and postnatal measurements in the high normal range, developmental delay, minor dysmorphic features, and a de novo unbalanced 3/4 translocation with trisomy 3q27 --> qter and monosomy of the subtelomeric region of 4p. Conventional karyotyping, FISH with probes from the Wolf-Hirschhorn syndrome critical region and chromosome 4p locus-specific probes, microsatellite marker-based haplotyping, and SNP microarray copy number analysis revealed a terminal 4p deletion of less than 500 kb with a breakpoint distal to the Wolf-Hirschhorn syndrome critical region, a chromosome 3q duplication of around 15.3 Mb, with origin of the rearrangement in paternal meiosis. Thus, our case clearly characterizes the phenotype of pure partial duplication 3q more exactly, and moreover, indicates that small chromosome rearrangements might lead to growth in the upper normal range or even cause overgrowth.

Molecular characterization of a de novo ring chromosome 6 in a growth retarded but otherwise healthy woman.

The phenotype of patients with a ring chromosome 6 can be highly variable ranging from almost normal to severe malformations and mental retardation. Size and structure of the ring chromosome as well as the level of mosaicism are important factors for the clinical phenotype. Here, we report on a 25-year-old woman with short stature, minor scoliosis, normal fertility, appropriate psychomotor development, minor dysmorphisms, and a de novo ring chromosome 6. Conventional karyotyping as well as molecular cytogenetic and molecular investigations of DUSP22 on 6p and RP1-191N21.4 on 6q by a new technical approach indicated breakpoints less than 240 kb and less than 190 kb proximal to the telomeres of 6p and 6q, respectively. In addition, formation of the ring chromosome from the paternal chromosome was demonstrated. Thus this case clearly shows that in patients with ring chromosomes without loss of euchromatic material mitotic instability of the ring chromosome is the most important reason for growth retardation and minor congenital anomalies.

Fludarabine/intermediate-dose cytarabine with or without allogeneic hematopoietic stem cell transplantation in poor-risk leukemia: a single center experience.

Disease recurrence has been and remains the leading cause of treatment failure in patients with high-risk leukemia. We retrospectively analyzed outcome in 61 patients with high-risk leukemia receiving a combination of fludarabine and intermediate-dose cytarabine as induction (n = 11) or salvage therapy (n = 35). Thirty-six patients having a suitable stem cell donor proceeded to allogeneic hematopoietic stem cell transplantation (HSCT). Ten patients received fludarabine-based salvage therapy without consecutive allogeneic transplantation and 15 patients received fludarabine/intermediate-dose cytarabine because of disease relapse following allogeneic stem cell transplantation. In patients without prior allogeneic HSCT (n = 46) the complete remission rate (CR) was 41% with a CR rate of 46 and 14% in patients with acute myeloid leukemia (AML) and with acute lymphoblastic leukemia (ALL), respectively. Overall survival for patients achieving a CR was 41 versus 0% for patients not achieving CR (P < 0.0001). The best outcome was observed in patients receiving an allogeneic HSCT in CR following fludarabine/ intermediate-dose cytarabine (47 vs. 0% for patients not in CR at the time of allografting, P = 0.01). All 10 patients receiving fludarabine/intermediate-dose cytarabine without subsequent allogeneic HSCT died within 3 years either of disease relapse/progression or infection. Only 1/15 (7%) patients receiving fludarabine/intermediate-dose cytarabine because of relapse following allogeneic HSCT became a long-term survivor. By multivariate analysis achieving CR, receiving an allogeneic HSCT, and being in first relapse or untreated were the only parameters that significantly determine the outcome. Although preliminary only high-risk AML patients having a stem cell donor are candidates for fludarabine/intermediate-dose cytarabine and only those achieving a CR should be referred to subsequent allogeneic HSCT. All other patients with high-risk leukemia are candidates for experimental therapies within controlled trials.

Genetic analyses in a variant of Mayer-Rokitansky-Kuster-Hauser syndrome (MURCS association).

Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is characterized by the congenital absence of uterus and upper part of the vagina as a result of Mullerian duct agenesis. The combination of MRKH syndrome with renal anomalies and cervicothoracic dysplasia is known as MURCS association (Mullerian aplasia, Renal anomalies, and Cervicothoracic Somite dysplasia). The etiology remains poorly understood. We delineate this disease by reporting on a 16-year-old patient showing the cardinal features of MURCS association accompanied by a persistent left superior vena cava and atrial septal defect, orofacial clefting, and mild reduction deformities of the left hand. Fluorescence in situ hybridization did not show major deletions or duplications of the DiGeorge/VCFS (velocardiofacial syndrome) region at chromosome 22q11.1 as well as the TBX5/TBX3 region at 12q24.1. In addition, sequencing of the TP63L (p63) gene, residing at 3q27, remained normal in the presented patient. Thus, we provide further evidence for the genetic heterogeneity of MURCS association.

Overexpression of the proneural transcription factor ASCL1 in chronic lymphocytic leukemia with a t(12;14)(q23.2;q32.3).

BACKGROUND: Translocations of the IGH locus on 14q32.3 are present in about 8% of patients with chronic lymphocytic leukemia (CLL) and contribute to leukemogenesis by deregulating the expression of the IGH-partner genes. Identification of these genes and investigation of the downstream effects of their deregulation can reveal disease-causing mechanisms. CASE PRESENTATION: We report on the molecular characterization of a novel t(12;14)(q23.2;q32.3) in CLL. As a consequence of the rearrangement ASCL1 was brought into proximity of the IGHJ-Cµ enhancer and was highly overexpressed in the aberrant B-cells of the patient, as shown by qPCR and immunohistochemistry. ASCL1 encodes for a transcription factor acting as a master regulator of neurogenesis, is overexpressed in neuroendocrine tumors and a promising therapeutic target in small cell lung cancer (SCLC). Its overexpression has also been recently reported in acute adult T-cell leukemia/lymphoma.To examine possible downstream effects of the ASCL1 upregulation in CLL, we compared the gene expression of sorted CD5+ cells of the translocation patient to that of CD19+ B-cells from seven healthy donors and detected 176 significantly deregulated genes (Fold Change ≥2, FDR p ≤ 0.01). Deregulation of 55 genes in our gene set was concordant with at least two studies comparing gene expression of normal and CLL B-lymphocytes. INSM1, a well-established ASCL1 target in the nervous system and SCLC, was the gene with the strongest upregulation (Fold Change = 209.4, FDR p = 1.37E-4).INSM1 encodes for a transcriptional repressor with extranuclear functions, implicated in neuroendocrine differentiation and overexpressed in the majority of neuroendocrine tumors. It was previously shown to be induced in CLL cells but not in normal B-cells upon treatment with IL-4 and to be overexpressed in CLL cells with unmutated versus mutated IGHV genes. Its role in CLL is still unexplored. CONCLUSION: We identified ASCL1 as a novel IGH-partner gene in CLL. The neural transcription factor was strongly overexpressed in the patient's CLL cells. Microarray gene expression analysis revealed the strong upregulation of INSM1, a prominent ASCL1 target, which was previously shown to be induced in CLL cells upon IL-4 treatment. We propose further investigation of the expression and potential role of INSM1 in CLL.

Glucocorticoid resistance in two key models of acute lymphoblastic leukemia occurs at the level of the glucocorticoid receptor.

Glucocorticoids (GCs) specifically induce apoptosis in malignant lymphoblasts and are thus pivotal in the treatment of acute lymphoblastic leukemia (ALL). However, GC-resistance is a therapeutic problem with an unclear molecular mechanism. We generated approximately 70 GC-resistant sublines from a GC-sensitive B- and a T-ALL cell line and investigated their mechanisms of resistance. In response to GCs, all GC-resistant subclones analyzed by real-time polymerase chain reaction (PCR) showed a deficient up-regulation of the GC-receptor (GR) and its downstream target, GC-induced leucine zipper. This deficiency in GR up-regulation was confirmed by Western blotting and on retroviral overexpression of GR in resistant subclones GC-sensitivity was restored. All GC-resistant subclones were screened for GR mutations using denaturing high-pressure liquid chromatography (DHPLC), DNA-fingerprinting, and fluorescence in situ hybridization (FISH). Among the identified mutations were some previously not associated with GC resistance: A484D, P515H, L756N, Y663H, L680P, and R714W. This approach revealed three genotypes, complete loss of functional GR in the mismatch repair deficient T-ALL model, apparently normal GR genes in B-ALLs, and heterozygosity in both. In the first genotype, deficiency in GR up-regulation was fully explained by mutational events, in the second by a putative regulatory defect, and in the third by a combination thereof. In all instances, GC-resistance occurred at the level of the GR in both models.

The effect of IgVH mutational status on the induction of apoptosis by rituximab in patients with heavily pretreated B-cell chronic lymphocytic leukemia: evidence from a clinical phase I/II trial.

We investigated tumor cell apoptosis in vivo in 14 heavily pretreated patients with B-cell chronic lymphocytic leukemia undergoing rituximab monotherapy. Apoptosis induction was more pronounced in patients with mutated IgVH genes than in those with unmutated IgVH genes, independently of the levels of expression of CD20, CD38, and ZAP-70 and of the presence of 17p deletion. Our results suggest an association between IgVH gene mutational status and rituximab-induced apoptosis.

Both donor and recipient origins of smooth muscle cells in vein graft atherosclerotic lesions.

Smooth muscle cell (SMC) accumulation in the inner layer of the vessel wall is a key event in the pathogenesis of atherosclerosis in vein grafts, but the origin of the cells in these lesions has yet to be shown. Herein, we use animal models of vein grafts in transgenic mice to clearly identify the sources of SMCs in atherosclerosis. Vena cava segments were isografted to carotid arteries between four types of transgenic mice, including SM-LacZ expressing beta-galactosidase (beta-gal) in vascular SMCs, SM-LacZ/apoE(-/-), ROSA26 expressing beta-gal in all tissues, and wild-type mice. beta-gal-positive cells were observed in neointimal and atherosclerotic lesions of all vein segments grafted between LacZ transgenic and wild-type mice. Double staining for beta-gal and cell nuclei revealed that about 40% of SMCs originated from hosts and 60% from the donor vessel. This was confirmed by double labeling of the Y-chromosome and alpha-actin in the lesions of sex-mismatched vein grafts. The possibility that bone marrow cells were the source of SMCs in grafts was eliminated by the absence of beta-gal staining in atherosclerotic lesions of chimeric mice. Furthermore, vein SMCs of SM-LacZ mice did not express beta-gal in situ, but did so when these cells appeared in atherosclerotic lesions in vivo, suggesting that hemodynamic forces may be crucial for SMC differentiation. Thus, we provide the first evidence of SMC origins in the atherosclerotic lesions of vein grafts, which will be essential for providing insight into new types of therapy for the disease. The full text of this article is available at http://www.circresaha.org.

High rate of molecular alteration in histologically tumour-free bronchial epithelium of NSCLC patients detected by multicolour fluorescence in situ hybridisation.

Detection of molecular abnormalities could provide an essential tool for the diagnosis of non-small cell lung cancer (NSCLC) and defining patients at risk for early relapse. Fluorescence in situ hybridisation (FISH) targeting 17 gene loci was applied to determine the frequency of molecular alteration in NSCLC probes and adjacent tumour-free bronchial epithelium. FISH was performed on fresh frozen specimens from 76 patients with histologically confirmed NSCLC and 54 specimens of adjacent tumour-free tissue. Routine autopsy lung tissue probes from 7 cancer-free patients served as a control group. Locus-specific (3p14.2, 3p21.2, 3p21.3, 3p25.3, 5p15.2, 7p12, 8q24.12, 9p21, 13q14, and 17p13.1) as well as centromere probes (4, 6, 7, 9, 11 and 16) were used. Molecular alterations using FISH on interphase nuclei were detected in 100% of NSCLC tumour specimens and 89% of microscopically tumour-free tissues of NSCLC patients. In histologically 'normal' epithelium, the most frequent alterations were seen with locus-specific probes for 3p14.2, 3p.21, 3p21.3, 3p25.3 and 7p12 and centromere-specific probes 11 and 16 (12-93%). As expected, the majority of genetic alterations seen in 'premalignant' specimens were found in the correlating tumour probes. None of the tested parameters revealed prognostic significance in univariate Cox analysis. FISH analysis, performing multicolour strategies, demonstrated its power in detecting genetic abnormalities in NSCLC specimens and even in tumour-free sections of tumour patients.

Cyclin E dysregulation and chromosomal instability in endometrial cancer.

Deregulation of cyclin E, an activator of cyclin-dependent kinase 2 (Cdk2), has been associated with a broad spectrum of human malignancies. Yet the mechanism linking abnormal cyclin E expression to carcinogenesis is largely unknown. The gene encoding the F-box protein hCdc4, a key component of the molecular machinery that targets cyclin E for degradation, is frequently mutated in endometrial cancer, leading to deregulation of cyclin E expression. Here we show that hCDC4 gene mutation and hyperphosphorylation of cyclin E, a parameter that usually correlates with hCDC4 mutation, have a strong statistically significant association with polypoidy and aneuploidy in endometrial cancer. On the contrary, elevated expression of cyclin E by itself was not significantly correlated with polyploidy or aneuploidy when tumors of similar grade are evaluated. These data suggest that impairment of cell cycle regulated proteolysis of cyclin E may be linked to carcinogenesis by promoting genomic instability.

Smooth muscle cells in transplant atherosclerotic lesions are originated from recipients, but not bone marrow progenitor cells.

BACKGROUND: Smooth muscle cell (SMC) accumulation in the intima of vessels is a key event in the pathogenesis of transplant atherosclerosis. The traditional hypothesis that SMCs in the lesion are derived from the media of the donor vessel has been challenged by recent observations, but the cell origin is still not well established. METHODS AND RESULTS: Here, we use a simplified model of artery allografts in transgenic mice to clearly identify the source of SMCs in transplant atherosclerosis. Aortic segments donated by BALB/c mice allografted to ROSA26 (C57B/6) mice expressing beta-galactosidase (gal) in all tissues showed that neointimal cells derived exclusively from host cells. It was also demonstrated that SMCs of neointimal and atherosclerotic lesions in vessels allografted to mice expressing beta-gal only in SMCs (SM-LacZ) or to apoE-deficient/SM-LacZ mice originated from the recipient, and not donor vessels. Interestingly, bone marrow transplantation of SM-LacZ beta-gal-expressing cells into aortic allograft recipients revealed completely negative beta-gal staining of neointimal and atherosclerotic lesions. However, a population of beta-gal-positive cells in lesions of allografts was observed in chimeric mice with ROSA26 beta-gal-expressing marrow cells. When bone marrow cells from both ROSA26 and SM-LacZ mice were cultured and stimulated with platelet-derived growth factor-BB, alpha-actin and beta-gal double-positive cells were found, suggesting that bone marrow cells have an ability to differentiate into SMCs. CONCLUSIONS: Thus, we provide strong evidence that SMCs of neointimal and atherosclerotic lesions in allografts are derived from the recipients and that non-bone marrow-derived progenitor cells are a possible source of SMCs in atherosclerotic lesions.

Myelodysplastic/myeloproliferative disease with erythropoietic hyperplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24): first description of a case.

We report on a patient fulfilling the diagnostic criteria of unclassifiable myelodysplastic/myeloproliferative diseases with prominent erythropoietic hyperplasia/dysplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24). The patient presented with B-symptoms, erythroblastemia, thrombopenia, marked eosinophilia, presence of myeloid precursors in the peripheral blood, and decreased erythropoietin level. Nodular peritrabecular polymorphous blasts, dysplastic megakaryocytes, and a diffuse argyrophilic fibrosis were detected in the trephine bone marrow biopsy. Immunohistochemically, the blasts stained positively for glycophorin C and hemoglobin A; the proliferation fraction was nearly 90% in the Ki-67 stain. Expression of the phosphorylated Janus kinase 2 was detected in almost all megakaryocytes and in isolated erythroblast islets, suggesting a probable activation of Janus kinase 2, the jak-2 gene being mapped on 9p24. Ten months after initial diagnosis, the disease progressed to frank acute erythroid leukemia. We report for the first time a myelodysplastic/myeloproliferative disease (erythroid preleukemia) accompanied by the specific chromosomal aberration t(8;9)(p23;p24), distinct histopathology, and clinical and laboratory symptoms, and progress to acute erythroid leukemia.