Characterization of vascular endothelial progenitor cells from chicken bone marrow

BACKGROUND: Endothelial progenitor cells (EPC) are a type of stem cell used in the treatment of atherosclerosis, vascular injury and regeneration. At present, most of the EPCs studied are from human and mouse, whereas the study of poultry-derived EPCs has rarely been reported. In the present study, chicken bone marrow-derived EPCs were isolated and studied at the cellular level using immunofluorescence and RT-PCR. RESULTS: We found that the majority of chicken EPCs were spindle shaped. The growth-curves of chicken EPCs at passages (P) 1, -5 and -9 were typically “S”-shaped. The viability of chicken EPCs, before and after cryopreservation was 92.2% and 81.1%, respectively. Thus, cryopreservation had no obvious effects on the viability of chicken EPCs. Dil-ac-LDL and FITC-UAE-1 uptake assays and immunofluorescent detection of the cell surface markers CD34, CD133, VEGFR-2 confirmed that the cells obtained in vitro were EPCs. Observation of endothelial-specific Weibel-Palade bodies using transmission electron microscopy further confirmed that the cells were of endothelial lineage. In addition, chicken EPCs differentiated into endothelial cells and smooth muscle cells upon induction with VEGF and PDGF-BB, respectively, suggesting that the chicken EPCs retained multipotency in vitro. CONCLUSIONS: These results suggest that chicken EPCs not only have strong self-renewal capacity, but also the potential to differentiate into endothelial and smooth muscle cells. This research provides theoretical basis and experimental evidence for potential therapeutic application of endothelial progenitor cells in the treatment of atherosclerosis, vascular injury and diabetic complications

Simulation and Experimental Analysis of Tool Wear and Surface Roughness in Laser Assisted Machining of Titanium Alloy

A three-dimensional cutting simulation prediction model based on DEFORM-3D finite element software was developed and experimentally validated, with a maximum error of 21.1% between the experimental and simulation results. The effects of the difference in cutting mechanism between conventional machining (CM) and laser-assisted machining (LAM) of TC6 titanium alloy on the tool wear and the surface roughness were investigated in terms of the cutting force and the cutting temperature. The depth of the laser-heated layer was mainly responsible for the difference in the cutting mechanism between the two methods. When the depth of the heating layer was smaller than the cutting depth, the tool wear of the LAM was larger than that of the CM. When the depth of the heating layer was larger than the cut depth, the surface roughness of the LAM was higher than that of the CM. Range analysis revealed that the cutting speed had the largest effect on the maximum wear depth of the rake face. Based on linear regression analysis, the cutting depth had a larger effect on the surface roughness in LAM. The average error between the linear regression prediction equation and the experimental results for surface roughness was 4.30%

Discrete characteristic and edge effect during subsurface microhardness measurement of Ti-6Al-4V alloy

This paper investigates the discrete characteristic and edge effect of subsurface microhardness of Ti-6Al-4V alloy. The results show that the discrete degree of Ti-6Al-4V alloy microhardness decreases with increasing loading force. When the loading force is 200 gf, only five microhardness measurements are needed to reduce the interference of discrete characteristic. Importantly, the edge effect was found during measuring the subsurface microhardness of Ti-6Al-4V alloy. The edge effect means that the microhardness value is little when its indentation position is close to a workpiece edge. Finite element analysis reveals that the low support strength of workpiece edge is responsible for the edge effect. This study further clarifies that a Vickers indenter is not suitable for characterizing the machined subsurface microhardness on account of the limitations of edge effect and indenter size

Cutting performance and tool wear in laser-assisted grinding of SiCf/SiC ceramic matrix composites

Ceramic matrix composites have high hardness, so their machining requires high grinding forces that cause severe wear of the grinding head. To investigate this problem, the present study investigated the cutting performance of conventional grinding (CG) and laser-assisted grinding (LAG) of SiC _f /SiC ceramic matrix composites using electroplated diamond grinding heads. Firstly, a three-dimensional transient heat transfer model based on a Gaussian heat source was developed to observe the surface and internal temperature field distributions of SiC _f /SiC ceramic matrix composites subjected to laser irradiation. Secondly, the effects of laser heating temperature on the workpiece surface on the grinding forces were analysed. It was found that the axial and feed grinding forces were more than 40% lower under LAG than CG due to the removal mechanism of the SiC matrix changing from brittle fracture to ductile fracture and the oxidation reactions occurred in the SiC _f /SiC ceramic matrix composites. Thirdly, the material removal mechanism was analysed by observing the morphology of machined surfaces, which showed that ductile removal from the SiC matrix occurs during LAG. Finally, it is also founded that the mean height of exposed abrasive grains from machined surface was reduced by 1.02 μ m, 12.52 μ m in LAG and CG respectively. The forms of wear caused by abrasive grains were studied. Under CG, the abrasive grains mainly exhibit cleavage fractures; while under LAG, micro-abrasion is the main wear form

Characterization of vascular endothelial progenitor cells from chicken bone marrow

Abstract Background Endothelial progenitor cells (EPC) are a type of stem cell used in the treatment of atherosclerosis, vascular injury and regeneration. At present, most of the EPCs studied are from human and mouse, whereas the study of poultry-derived EPCs has rarely been reported. In the present study, chicken bone marrow-derived EPCs were isolated and studied at the cellular level using immunofluorescence and RT-PCR. Results We found that the majority of chicken EPCs were spindle shaped. The growth-curves of chicken EPCs at passages (P) 1, -5 and -9 were typically “S”-shaped. The viability of chicken EPCs, before and after cryopreservation was 92.2% and 81.1%, respectively. Thus, cryopreservation had no obvious effects on the viability of chicken EPCs. Dil-ac-LDL and FITC-UAE-1 uptake assays and immunofluorescent detection of the cell surface markers CD34, CD133, VEGFR-2 confirmed that the cells obtained in vitro were EPCs. Observation of endothelial-specific Weibel-Palade bodies using transmission electron microscopy further confirmed that the cells were of endothelial lineage. In addition, chicken EPCs differentiated into endothelial cells and smooth muscle cells upon induction with VEGF and PDGF-BB, respectively, suggesting that the chicken EPCs retained multipotency in vitro. Conclusions These results suggest that chicken EPCs not only have strong self-renewal capacity, but also the potential to differentiate into endothelial and smooth muscle cells. This research provides theoretical basis and experimental evidence for potential therapeutic application of endothelial progenitor cells in the treatment of atherosclerosis, vascular injury and diabetic complications.</p

Solexa Sequencing of Novel and Differentially Expressed MicroRNAs in Testicular and Ovarian Tissues in Holstein Cattle

The posttranscriptional gene regulation mediated by microRNA plays an important role in the development and function of male and female reproductive organs and germ cells in mammals, including cattle. In the present study, we identified novel and differentially expressed miRNAs in the testis and ovary in Holstein cattle by combining the Solexa sequencing with bioinformatics. In total 100 and 104 novel pre-miRNAs were identified in testicular and ovarian tissues, encoding 122 and 136 mature miRNAs, respectively. Of these, 6 miRNAs appear to be bovine-specific. A total of 246 known miRNAs were co-expressed in the testicular and ovarian tissues. Of the known miRNAs, twenty-one testis-specific and nine ovary-specific (1-23 reads) were found. Approximately 30.5% of the known bovine miRNAs in this study were found to have &#62;2-fold differential expression within the two respective reproductive organ systems. The putative miRNA target genes of miRNAs were involved in pathways associated with reproductive physiology. Both known and novel tissue-specific miRNAs are expressed by Real-time quantitative PCR analysis in dairy cattle. This study expands the number of miRNAs known to be expressed in cattle. The patterns of miRNAs expression differed significantly between the bovine testicular and ovarian tissues, which provide important information on sex differences in miRNA expression. Diverse miRNAs may play an important regulatory role in the development of the reproductive organs in Holstein cattle.</p