Electrospun fish gelatin fibrous scaffolds with improved bio-interactions due to carboxylated nanodiamond loading

This work emphasizes the potential of COOH-functionalized nanodiamond (NDs) particles to improve bio-interactions when embedded into fish gelatin electrospun fibers.

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer-ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical-chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.

Histopathologic evaluation of liver metastases from colorectal cancer in patients treated with FOLFOXIRI plus bevacizumab

BACKGROUND

The FOLFOXIRI regimen produces a high rate of radiological and histopathological responses. Bevacizumab added to chemotherapy showed an improvement in pathological response and necrosis of colorectal liver metastases (CLMs). FOLFOXIRI plus bevacizumab produced promising early clinical results and is under investigation in several randomised trials, although no data are currently available on its effects on response of CLMs and on liver toxicities.

METHODS

Starting from 499 patients enrolled in first-line phase II/III trials, we selected on the basis of tissue sample availability 18 patients treated with FOLFOXIRI/XELOXIRI and 24 patients treated with FOLFOXIRI plus bevacizumab who underwent secondary resection of CLMs. The 28 untreated patients who underwent primary resection of CLMs were included as control group. Responses of CLMs and chemotherapy-induced toxicities were assessed.

RESULTS

Among the patients, 63% of those treated with FOLFOXIRI plus bevacizumab, as compared with 28% of those treated with only FOLFOXIRI/XELOXIRI, showed a histopathological response (P=0.033). In the two groups, 52% and 12.5%, respectively, showed necrosis ≥50% (P=0.017). The incidence of liver toxicities was not significantly increased in patients treated with FOLFOXIRI plus bevacizumab.

CONCLUSION

The addition of bevacizumab to FOLFOXIRI produces high rates of pathologic responses and necrosis of CLM without increasing liver toxicity.

Adjuvant chemotherapy seems beneficial for invasive intraductal papillary mucinous neoplasms

AIMS

The incidence of intraductal papillary mucinous neoplasm (IPMN) is rising and these neoplasms now represent up to 25% of resected pancreatic neoplasms. The optimal postoperative management of resected invasive IPMN is still debated in the absence of large prospective clinical trials and of validated prognostic factors in this setting. The objective of our study was to identify potential prognostic factors and to investigate the role of adjuvant therapies for patients radically resected for invasive IPMN.

METHODS

We retrospectively reviewed clinical and pathological data regarding a large series of patients with invasive IPMN who underwent surgical resection in the last six years at University Hospital of Pisa.

RESULTS

Sixty-four patients were considered for the analysis, thirty-three of whom received adjuvant chemotherapy with gemcitabine. In our series node involvement and high tumoral grade emerged as the major pathologic prognostic factors. Patients treated with adjuvant chemotherapy with gemcitabine experienced a longer disease-free survival than those who received surgery alone.

CONCLUSIONS

Gemcitabine-based chemotherapy seems beneficial as adjuvant treatment for patients with resected invasive IPMN.

The good, the bad and the ugly: a tale of miR-101, miR-21 and miR-155 in pancreatic intraductal papillary mucinous neoplasms

BACKGROUND

This multicenter study evaluated three candidate microRNAs (miRNAs) (miR-21, miR-155 and miR-101) as potential biomarkers in intraductal papillary mucinous neoplasms (IPMNs) of the pancreas.

PATIENTS AND METHODS

miRNA expression was quantified by quantitative RT-PCR in 86 laser-microdissected specimens, including 65 invasive IPMNs, 16 non-invasive IPMNs and 5 normal pancreatic ductal tissues. Univariate and multivariate analyses compared miRNAs and clinical parameters with overall (OS) and disease-free survival (DFS).

RESULTS

miR-21 and miR-155 were up-regulated in invasive IPMNs compared with non-invasive IPMNs, as well as in non-invasive IPMNs compared with normal tissues. Conversely, miR-101 levels were significantly higher in non-invasive IPMNs and normal tissues compared with invasive IPMNs. High levels of miR-21 were associated with worse OS [hazard ratio (HR) = 2.47, 95% confidence interval (CI) = 1.37-5.65, P = 0.0047]. Patients with high-miR-21 expression also had a shorter median DFS (10.9 versus 29.9 months, P = 0.01). Multivariate analysis confirmed miR-21 as independently prognostic for mortality and disease progression (death risk: HR = 3.3, 95% CI = 1.5-7.0, P = 0.02; progression risk: HR = 2.3, 95% CI = 1.2-4.8, P = 0.02), as well as positive lymph-node status (death risk: HR = 2.6, 95% CI = 1.1-6.3, P = 0.03; progression risk: HR = 2.2, 95% CI = 1.0-4.8, P = 0.04).

CONCLUSIONS

miR-21, miR-155 and miR-101 showed significant differences in invasive versus non-invasive IPMNs. miR-21 emerged as an independent prognostic biomarker in invasive IPMNs and should be validated in prospective studies.

Fixed dose rate (FDR) gemcitabine (G) and capecitabine (C) in patients with metastatic biliary tract cancer (BTC): Final results of phase II trial

e15510

Background: The combination of fixed dose rate (FDR) gemcitabine (C) and capecitabine (G) has been demonstrated to be well tolerated in patients with advanced cancers. To determine the activity and safety of this combination in metastatic metastatic biliary tract cancer patients, a phase II trial was conducted. Methods: Patients with unresectable BTC who had pathologically confirmed adenocarcinoma, no prior chemotherapy, ECOG PS < 2 and measurable disease were enrolled. Treatment consisted of FDR G at 800 mg/m(2) infused in 80 minutes on days 1 and 8 every 21 days with C administered orally bid in equal doses (650 mg/m2 bid) for 14 days (28 doses). Results: Between Feb 2005 and Sept 2008, 30 pts were enrolled. Median age was 67 (45–86) with 14 males. 30 pts were evaluable for response and toxicity. A total of 219 cycles were administered (median, 8; range, 2–16). One patient achieved CR and 8 pts achieved PR giving an overall response rate of 30.0% in intention-to-treat population (95% CI, 19.2–42.6%). And 11 pts (36.6%) had stable disease. The median time to progression of all patients was 7.4 months (mo) (95% CI, 3.2–19.5). The median overall survival was 15.3 mo (95% CI, 4.6–27.9). Grade 3/4 neutropenia and thrombocytopenia were noted in 13.3% and 6.6% of the pts, respectively. Grade 2/3 non-hematologic toxicities were asthenia (50.0 % of pts), diarrhea (16.6%), stomatitis (23.3%) and hand-foot syndrome (6.6%). There was no treatment-related death. Gemcitabine was skipped at least once/reduced in 20%/15% of the patients, respectively. Capecitabine was skipped at least once/reduced in 20%/25% of the patients, respectively. Conclusions: The combination of FDR gemcitabine and capecitabine in this three week cycle is safe and seems to have advantages in activity over other regimens in advanced biliary cancer.

No significant financial relationships to disclose.

Phase II capecitabine and gemcitabine fixed dose rate (FDR) in patients with advanced pancreatic cancer

e15530

Background: The aims of this phase II trial are to determine the activity and the safety of the new combination modality with Gemcitabine fixed dose rate (FDR) infusion and Capecitabine in patients with advanced pancreatic cancer. Methods: Patients with unresectable pancreatic cancer who had pathologically confirmed adenocarcinoma, no prior chemotherapy, ECOG PS < 2 and measurable disease were enrolled. Gemcitabine (800 mg/mq IV infused in 80 minutes on days 1 and 8) and Capecitabine (650 mg/mq orally twice daily for 14 days) were administered and repeated every 21 days. Results: 47 patients were enrolled between January 2004 and October 2008. Median age was 66 (range: 37–79), 18 female and 29 male. A total of 299 cycles were administered, median cycles for patient were 6 (range: 1–17). CR was observed in one patient (2.1 %) and 10 patients achieved PR (21.3 %) giving an overall response rate of 23.4 % in intention-to-treat population. 22 pts (46.8 %) had stable disease obtaining an overall tumour control of 70.2 %. The median time to progression was 5.2 months (95 % CI, 2.4–7.6); the median overall survival was 8.4 months (95 % CI, 5.5–20). Grade 3–4 neutropenia was observed in 29.8 % of subjects, thrombocytopenia in 6.4 %. Grade 1–2 non-hematological toxicities were asthenia (61.7 %), diarrhea (29.8%), stomatitis (29.8 %) and hand foot syndrome (2.1 %). There were no treatment-related deaths. Gemcitabine was skipped at least once/reduced in 51/10.6 % of the patients, respectively. Capecitabine was skipped at least once/reduced in 16/8 % of the patients, respectively. Conclusions: The combination of FDR Gemcitabine and Capecitabine with this modality of infusion is feaseble, safe and seems to be active.

No significant financial relationships to disclose.

A multicenter phase II study of the combination of oxaliplatin, irinotecan and capecitabine in the first-line treatment of metastatic colorectal cancer

The triple drug combination consisting of irinotecan, oxaliplatin and 5-fluorouracil (FOLFOXIRI) has demonstrated higher activity and efficacy compared to the doublet FOLFIRI. 5-Fluorouracil could be substituted in FOLFOXIRI regimen by capecitabine, an oral fluoropyrimidine with similar efficacy. Recently, a dose-finding trial has demonstrated the feasibility of the combination of irinotecan, oxaliplatin and capecitabine (XELOXIRI) and established their recommended doses. The aim of this study was to evaluate the activity of XELOXIRI. A total of 36 patients with unresectable metastatic colorectal cancer received irinotecan 165 mg m⁻² and oxaliplatin 85 mg m⁻² on day 1 plus capecitabine 2000 mg m⁻² per day orally in two doses from day 1 to day 7, every 2 weeks. Grade 3–4 toxicities were infrequent, expect for neutropenia and diarrhoea, which were each observed in 30% of patients. Two complete and twenty-two partial responses were obtained, corresponding to an overall response rate of 67% (95% CI 51.4–82%). After a median follow-up of 17.7 months, the median progression-free and overall survival were 10.1 and 17.9 months, respectively.

The substitution of 5-fluorouracil with capecitabine, in combination with irinotecan and oxaliplatin, is feasible and does not impair the activity of the regimen. However, the XELOXIRI combination is associated with a high incidence of diarrhoea and, therefore, should be considered as a not preferable alternative to FOLFOXIRI.

Correlation between cytidine deaminase genotype and gemcitabine deamination in blood samples

Cytidine deaminase (CDA) is the major enzyme of gemcitabine inactivation. The aim of this study was to determine whether the CDA Lys27Gln polymorphism influenced gemcitabine deamination in blood samples from 90 lung cancer patients. The polymorphism was studied with Taqman probes-based assay; CDA activity was evaluated by HPLC in cytoplasmic extracts from red blood cells. Mean enzymatic activity was significantly lower in patients carrying the CDA Lys27Lys than in patients with the Lys27Gln or Gln27Gln protein (P < 0.05). CDA genotyping may be useful in screening patients before gemcitabine treatment, in order to identify subjects with lower CDA activity and potentially better clinical outcomes after gemcitabine-based chemotherapy.

First line chemotherapy with planned sequential administration of gemcitabine followed by docetaxel in elderly advanced non-small-cell lung cancer patients: a multicenter phase II study

This multicenter phase II study evaluated, in chemonaive patients with stage IIIB–IV NSCLC, age ⩾70 and with a performance status 0–2, the activity, efficacy and tolerability of planned sequential administration of gemcitabine 1200 mg m⁻² on days 1 and 8 every 3 weeks for three courses followed by three cycles of docetaxel 37.5 mg m⁻² on days 1 and 8 every 3 weeks, provided there was no evidence of disease progression. A total of 56 patients entered the study. According to intention-to-treat analysis, the objective response rate was 16.0% (95% CI 7.6–28.3%); 23 patients (41.0%) had stable disease and 24 patients (43%) had progressive disease. Five patients who had a stable disease after three courses of gemcitabine obtained a conversion to partial response by docetaxel. Median time to progression was 4.8 months (95% CI 3.6–6.0 months) and median duration of survival was 8.0 months (95% CI 5.6–10.5 months). The 1-year survival rate was 34%. No grade 4 haematological toxicity was observed and grade 3 neutropenia and thrombocytopenia were reported in 5.4 and 3.6% of the patients, respectively. Grade 3/4 mucositis and grade 3 diarrhoea, both occurred in 3.6% of the patients and grade 3 asthenia was observed in 9% of patients. One patient reported a grade 4 skin toxicity. No treatment-related deaths occurred. Sequential gemcitabine and docetaxel is a well-tolerated and effective regimen in elderly advanced NSCLC patients.

Analysis of single nucleotide polymorphisms (SNPs) of cytidine deaminase (CDA) and xeroderma pigmentosum group D (XPD) genes for the prediction of clinical response to gemcitabine and cisplatin in advanced non-small cell lung cancer (NSCLC) patients

7219

Background: Detection of genomic differences predictive of drug response may allow to customize chemotherapy to the characteristics of individual patients. Gemcitabine alone or in combination with cisplatin are two of the most common regimens used in the treatment of advanced NSCLC. We investigated the correlation between selected SNPs of genes encoding enzymes involved in the activity of gemcitabine and cisplatin, including CDA, XPD and ERCC1, and the response to chemotherapy. Methods: Forty advanced NSCLC chemo-naïve patients were enrolled into the study; 16 patients, aged > 70 years, were treated with gemcitabine; 24 patients, aged < 70 years, were treated with cisplatin plus gemcitabine. SNPs CDA A79C, XPD A751C, XPD G312A and ERCC1 C118T were analyzed with the ABI PRISM 7900HT Sequence Detection System using TaqMan probe-based assay in DNA obtained from peripheral blood samples. Statistical analysis was performed using Pearson χ2 test, Kaplan-Meier curve and log rank test. Results: Up to now 31 patients, 11 treated with gemcitabine and 20 with cisplatin plus gemcitabine, are evaluable for response with RECIST criteria; correlation between response and genotype are showed in the table. Actuarial progression free survival (PFS) was longer in patients treated with gemcitabine ± cisplatin with CDA A79A genotype than in others (respectively 11.0 vs 2.5 months, p = 0.0092), while no correlation was found between the SNPs of XPD and ERCC1 and PFS in patients receiving cisplatin and gemcitabine. Conclusions: CDA A79A genotype resulted predictive of response and longer PFS in NSCLC patients treated with gemcitabine ± cisplatin. There was also a trend toward significant correlation between XPD A751A and better response in cisplatin-treated patients, while the SNPs in XPD 312 and ERCC1 118 were not associated with response to chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

Prolonged gemcitabine infusion in advanced non-small-cell lung cancer with stable disease after gemcitabine 30-min infusion

BACKGROUND

Although 30-min gemcitabine infusion has become the standard administration, pre-clinical and clinical studies have suggested the possibility that an infusion rate of 10 mg/m(2) per minute may be more effective. The main objective of this study was to investigate whether the pursuance of gemcitabine, administered at a prolonged infusion rate, was able to convert stable disease to objective response after two or three cycle of standard administration. The secondary end-point was the evaluation of the new schedule toxicity.

PATIENTS AND METHODS

Thirty-eight patients, with stage IIIA-B and IV NSCLC already treated by two or three cycles of 30-min gemcitabine infusion, alone or in combination with cisplatin, were enrolled: 26 patients (aged <70 years) were treated with cisplatin 80 mg/m(2) on day 1 plus gemcitabine 1200 mg/m(2) over 120 min on day 1 and 8 every three weeks and 12 patients (aged > or =70 years) were treated with gemcitabine alone 1200 mg/m(2) over 120 min on day 1 and 8 every three weeks, for two courses. Simon's two stage minimax design was applied to calculate the sample size. Assuming p(0) (low conversion rate) 5%, p(1) (target conversion rate of interest) 20%, alpha error 0.05, beta error 0.10 a total of 29 evaluable patients had to be accrued during stage 1. In case at least one objective response was observed, a further nine evaluable patients had to be enrolled into the study during stage 2. The regimen was considered promising if > or =4 objective responses out of 38 evaluable patients were observed.

RESULTS

Thirty-eight patients were evaluable for response and in five patients (with stable disease after two courses of gemcitabine 30' infusion) a partial response was observed (conversion rate 13.1%, 95% confidence interval 4.4-28%). Toxicities were more frequently observed with cisplatin plus 120-min gemcitabine infusion: grade 3-4 neutropenia, thrombocytopenia and anaemia in 28, 22 and 16% of the courses, respectively.

CONCLUSIONS

The prolongation of gemcitabine infusion time is able to convert stable disease to partial response in 13% of the cases. The haematological toxicity seems enhanced with cisplatin plus gemcitabine prolonged infusion.

The neurotransmitter dopamine inhibits angiogenesis induced by vascular permeability factor/vascular endothelial growth factor

Angiogenesis has an essential role in many important pathological and physiological settings. It has been shown that vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), a potent cytokine expressed by most malignant tumors, has critical roles in vasculogenesis and both physiological and pathological angiogenesis. We report here that at non-toxic levels, the neurotransmitter dopamine strongly and selectively inhibited the vascular permeabilizing and angiogenic activities of VPF/VEGF. Dopamine acted through D2 dopamine receptors to induce endocytosis of VEGF receptor 2, which is critical for promoting angiogenesis, thereby preventing VPF/VEGF binding, receptor phosphorylation and subsequent signaling steps. The action of dopamine was specific for VPF/VEGF and did not affect other mediators of microvascular permeability or endothelial-cell proliferation or migration. These results reveal a new link between the nervous system and angiogenesis and indicate that dopamine and other D2 receptors, already in clinical use for other purposes, might have value in anti-angiogenesis therapy.

CD36 associates with CD9 and integrins on human blood platelets

The membrane glycoprotein CD36 is involved in platelet aggregation, inhibition of angiogenesis, atherosclerosis, and sequestration of malaria-parasitized erythrocytes. In this study, immunoprecipitations with anti-CD36 antibodies were performed to identify proteins that associate with CD36 in the platelet membrane. Platelets were solubilized in 1% Triton X-100, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), Brij 96, or Brij 99, and the proteins that coprecipitated with CD36 were identified by peptide mass spectrometry and Western blotting. The tetraspanin protein CD9 and the integrins alphaII(b)beta3 and alpha6beta1 specifically coprecipitated with CD36 from platelets that were solubilized in CHAPS and Brij 99 but not from platelets that were solubilized in Triton X-100. Only CD9 is coprecipitated with CD36 from platelets that were solubilized in Brij 96. Reciprocal immunoprecipitations with antibodies to CD9, alpha6, alphaIIb, or beta3 from Brij 99-solubilized platelets coprecipitated CD36. Coprecipitation of CD36, CD9, and alpha6beta1 was also observed on platelets from a patient with Glanzmann thrombasthenia, indicating that alphaII(b)beta3 is not required for the other proteins to associate. Colocalization of alpha6 and CD36, of CD9 and CD36, and of alpha6 and CD9 was observed on intact platelets prior to solubilization, using double immunofluorescence microscopy. These data indicate that CD36 associates with CD9 and integrins on human blood platelets. These associated proteins may mediate or participate in some of the diverse biological functions of CD36.

Differential expression of thymosin beta-10 by early passage and senescent vascular endothelium is modulated by VPF/VEGF: evidence for senescent endothelial cells in vivo at sites of atherosclerosis

VPF/VEGF acts selectively on the vascular endothelium to enhance permeability, induce cell migration and division, and delay replicative senescence. To understand the changes in gene expression during endothelial senescence, we investigated genes that were differentially expressed in early vs. late passage (senescent) human dermal endothelial cells (HDMEC) using cDNA array hybridization. Early passage HDMEC cultured with or without VPF/VEGF overexpressed 9 and underexpressed 6 genes in comparison with their senescent counterparts. Thymosin beta-10 expression was modulated by VPF/VEGF and was strikingly down-regulated in senescent EC. The beta-thymosins are actin G-sequestering peptides that regulate actin dynamics and are overexpressed in neoplastic transformation. We have also identified senescent EC in the human aorta at sites overlying atherosclerotic plaques. These EC expressed senescence-associated neutral beta-galactosidase and, in contrast to adventitial microvessel endothelium, exhibited weak staining for thymosin beta-10. ISH performed on human malignant tumors revealed strong thymosin beta-10 expression in tumor blood vessels. This is the first report that Tbeta-10 expression is significantly reduced in senescent EC, that VPF/VEGF modulates thymosin beta-10 expression, and that EC can become senescent in vivo. The reduced expression of thymosin beta-10 may contribute to the senescent phenotype by reducing EC plasticity and thus impairing their response to migratory stimuli.

Characterization of Bordetella pertussis strains of recent isolation

During the clinical trial conducted in Italy to evaluate the efficacy of new acellular pertussis vaccines, the most favorable conditions for the recovery and characterization of Bordetella pertussis strains, isolated from children with cough, were adopted. The nasopharyngeal aspirates were collected and sent to the laboratory in refrigerated conditions within 24 hours. Charcoal agar selective and non selective plates were used, and most of the isolates were recovered after 3-4 days of incubation. Confirmation of all suspected colonies included the use of biochemical tests and specific agglutination reaction with B. pertussis antiserum. Serotyping of fimbriae, susceptibility to erythromycin and DNA fingerprinting by Pulsed Field Gel Electrophoresis (PFGE), were performed to characterize B. pertussis isolates and to determine relatedness among different strains. Serotype 1,3 was the most represented in the bacterial population examined. A predominant pulsetype (PTA) characterized most of the isolates accounting for 71.4% of the strains examined. Eight subclones (23.5%) and three unrelated pulsetypes were also found. No resistant strains to erythromycin were detected.

Caveolae and vesiculo-vacuolar organelles in bovine capillary endothelial cells cultured with VPF/VEGF on floating Matrigel-collagen gels

In situ vascular endothelium is characterized by many cytoplasmic vesicles (caveolae) and vacuoles. In venules these are organized into prominent clusters called vesiculo-vacuolar organelles or VVOs. VVOs provide an important pathway for plasma protein extravasation in response to vasoactive mediators. In contrast, cultured endothelial cells isolated from many sources lack VVOs and generally have few caveolae. Our goal was to preserve VVOs in cultured endothelium. Bovine adrenal microvascular endothelial cells (BCEs) cultured on floating Matrigel-collagen Type I gels with vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) exhibited typical VVOs by electron microscopy. Both in vivo and in culture VVOs were caveolin-positive by immunoelectron microscopy. On the basis of caveolin immunostaining, VVOs could also be detected by light (confocal) microscopy. When BCEs were cultured without VPF/VEGF, caveolin staining was finely punctate and electron microscopy confirmed the near absence of VVOs. BCE VVOs were sensitive to N-ethylmaleimide. Other types of endothelium cultured on Matrigel-collagen gels with or without VPF/VEGF exhibited few caveolae and no VVOs. Therefore, preservation of VVOs in cultured endothelium required a specific combination of endothelial cells (BCEs), surface matrix (Matrigel-collagen), and growth factor (VPF/VEGF). These endothelial cells should be useful for in vitro studies of trans-endothelial transport.

Isolation and characterization of endothelial progenitor cells from mouse embryos

The cardiovascular system develops early in embryogenesis from cells of mesodermal origin. To study the molecular and cellular processes underlying this transition, we have isolated mesodermal cells from murine embryos at E7.5 with characteristic properties of endothelial progenitors by using a combination of stromal cell layers and growth conditions. The isolated embryonic cells displayed unlimited stem-cell-like growth potential and a stable phenotype in culture. RNA analysis revealed that the embryonic cells express the endothelial-specific genes tie-2 and thrombomodulin (TM) as well as the early mesodermal marker fgf-3. The GSL I-B4 isolectin, a marker of early endothelial cells, specifically binds to the isolated cells. The in vitro differentiation with retinoic acid and cAMP led to a 5- to 10-fold induction of flk-1, von Willebrand Factor (vWF), TM, GATA-4 and GATA-6. Electron microscopy revealed that in vitro differentiation is associated with increased amounts of rER and Golgi, and a dramatic increase in secretory vesicles packed with vWF. When cultured in Matrigel, the embryonic cells assume the characteristic endothelial cobblestone morphology and form tubes. Injection into chicken embryos showed incorporation of the embryonic cells in the endocardium and the brain vasculature. The expression of TM, tie-2, GATA-4 and GATA-6 suggests that the isolated embryonic endothelial cell progenitors are derived from the proximal lateral mesoderm where the pre-endocardial tubes form. The properties of the endothelial cell progenitors described here provide a novel approach to analyze mediators, signaling pathways and transcriptional control in early vascular development.

Disruptions in Golgi structure and membrane traffic in a conditional lethal mammalian cell mutant are corrected by epsilon-COP

The CHO cell temperature-sensitive mutant ldlF exhibits two defects in membrane traffic at the nonpermissive temperature (39.5 degrees C): rapid degradation of LDL receptors, possibly caused by endocytic missorting, and disruption of ER-through-Golgi transport. Here, we show that at 39.5 degrees C, the Golgi in ldlF cells dissociated into vesicles and tubules. This dissociation was inhibited by AlF4-, suggesting trimeric G proteins are involved in the dissociation mechanism. This resembled the effects of brefeldin A on wild-type cells. We isolated a hamster cDNA that specifically corrected the ts defects of ldlF cells, but not those of other similar ts mutants (ldlE, ldlG, ldlH, and End4). Its predicted protein sequence is conserved in humans, rice, Arabidopsis, and Caenorhabditis elegans, and is virtually identical to that of bovine epsilon-COP, a component of the coatomer complex implicated in membrane transport. This provides the first genetic evidence that coatomers in animal cells can play a role both in maintaining Golgi structure and in mediating ER-through-Golgi transport, and can influence normal endocytic recycling of LDL receptors. Thus, along with biochemical and yeast genetics methods, mammalian somatic cell mutants can provide powerful tools for the elucidation of the mechanisms underlying intracellular membrane traffic.