The ratio of VEGF/PEDF expression in bone marrow mesenchymal stem cells regulates neovascularization

Angiogenesis, or neovascularization, is a finely balanced process controlled by pro- and anti-angiogenic factors. Vascular endothelial growth factor (VEGF) is a major pro-angiogenic factor, whereas pigment epithelial-derived factor (PEDF) is the most potent natural angiogenesis inhibitor. In this study, the regulatory role of bone marrow stromal cells (BMSCs) during angiogenesis was assessed by the endothelial differentiation potential, VEGF/PEDF production and responses to pro-angiogenic and hypoxic conditions. The in vivo regulation of blood vessel formation by BMSCs was also explored in a SCID mouse model. Results showed that PEDF was expressed more prominently in BMSCs compared to VEGF. This contrasted with human umbilical vein endothelial cells (HUVECs) where the expression of VEGF was higher than that of PEDF. The ratio of VEGF/PEDF gene expression in BMSCs increased when VEGF concentration reached 40 ng/ml in the culture medium, but decreased at 80 ng/ml. Under CoCl2- induced hypoxic conditions, the VEGF/PEDF ratio of BMSCs increased significantly in both normal and angiogenic culture media. There was no expression of endothelial cell markers in BMSCs cultured in either pro-angiogenic or hypoxia culture conditions when compared with HUVECs. The in vivo study showed that VEGF/PEDF expression closely correlated with the degree of neovascularization, and that hypoxia significantly induced pro-angiogenic activity in BMSCs. These results indicate that, rather than being progenitors of endothelial cells, BMSCs play an important role in regulating the neovascularization process, and that the ratio of VEGF and PEDF may, in effect, be an indicator of the pro- or antiangiogenic activities of BMSCs

Preliminary Evaluation of the Capacity of Surface-Active Phospholipids to Provide Semipermeability in a Saline Filtration Environment

Background: Semipermeability to fluid transport is one of the principal attributes of a tissue like articular cartilage. Consequently, this characteristic can be exploited in attempts to understand the functional roles of the biological layer of Surface Active Phospholipids (SAPL) which form on its surfaces. A previous study, relevant to peritoneal SAPL was carried out in which hypertonic glucose solution was dialysed against physiological saline through SAPL membrane and concluded that SAPL possessed semipermeability. Our analysis extends this previous study by dialysing hypertonic and hypotonic saline solutions against physiological saline via SAPL membranes which is more relevant to the articular joint environment. Material and Methods: Membranes were produced from either synthetic or bovine cartilage SAPL and used to carry out tests involving the dialysis of hypotonic and hypertonic sodium chloride solutions against physiological saline, using an Ussing chamber to hold both the membranes and dialysis fluids. Results: The dialysis produced osmotic pressures which are commensurate with our experimental constraints, but strongly indicated that it is indeed possible to generated osmotic pressures using SAPL membranes, indicating the semipermeability of this lipid structure. Conclusion: It is widely accepted that the collagen-proteoglycan membrane provides the semipermeability of articular despite the low levels of osmotic pressure recorded in our experiments, our results demonstrate that SAPL aggregation can constitute a semipermeable layer with a strong capability to contribute to the semipermeablity of the collagen-proteoglycan system especially on the surface of the tissue. Consequently its deficiency, as seen in osteoarthritis could lead/contribute to cartilage dysfunction

A cross-sectional analysis of undergraduate medical student attitudes towards interprofessional education

No abstract available

Application of hyperbaric oxygen in bone tissue engineering : effect of hyperbaric oxygen treatment on bone marrow stem cells

and non-union of bony fractures has been proposed since 1966, little has been known about the effect of HBOT on bone marrow stem cells (BMSC). The aim of this study is to investigate the effect of HBO treatment on osteogenetic differentiation of BMSC and potential application in bone tissue engineering. Adhesive stromal cells harvested from bone marrow were characterized by mesenchymal differentiation potential, cell surface markers and their proliferation capacity. Mesenchymal stem cells, which demonstrated osteogenic, chondrogenic and adipogenic differentiation potential and expressed positively for CD 29, CD 44, CD 73, CD 90, CD 105, CD 166 and negatively for CD34 and CD 45, were selected and treated in a laboratory-scale HBO chamber using different oxygen pressures and exposure times. No obvious effect of HBO treatment on BMSC proliferation was noticed. However, cytotoxic effects of HBO were considerably less pronounced when cells were cultured in medium supplemented with 10% FBS in comparison to medium supplemented with 2% FCS, as was evaluated by WST-1 assay. Under HBO treatment, bone nodules were formed in three days, which was clearly revealed by Von Kossa staining. In contrasts, without HBO treatment, bone nodules were not detected until 9-12 days using the same inducing culture media. Calcium deposition was also significantly increased after three days of HBO treatments compared to no HBO treatment. In addition it was also found that oxygen played a direct role in the enhancement of BMSC osteogenic differentiation, which was independent of the effect of air pressure

Reluctant borrowers? Examining the demand and supply of finance for high growth SMEs in the UK

Publisher PD

The geography of job creation in high-growth firms : the implications of ‘growing abroad’

The authors wish to thank Scottish Enterprise for funding the research reported in this paper.In recent years there has been an upsurge of interest by policy makers in high growth firms (HGFs). Interest in these dynamic firms has primarily been driven by their prodigious ability to create new employment. Despite this, very little is known about the complex corporate geographies of these firms and their internationalisation processes. Using quantitative and qualitative data, this paper explores this issue by examining Scottish HGFs. HGFs were found to adopt more aggressive forms of international expansion, such as overseas acquisitions, than their non-HGF counterparts. As a result of these complex growth processes, a large proportion of HGF employment growth is generated outside Scotland. The paper concludes that the regional development impact of HGFs for small peripheral economies in the UK is more limited than originally envisaged. The implications of the study for further research and public policy are examined.Publisher PDFPeer reviewe

Entrepreneurial uncertainty during the Covid-19 crisis : mapping the temporal dynamics of entrepreneurial finance

Funding: University of St Andrews.This paper illustrates how chronic uncertainty caused by crisis events affects the availability of entrepreneurial sources of finance for start-ups and small and medium-sized enterprises (SMEs). To explore this line of argument, this paper examines Crunchbase real-time data examining entrepreneurial finance investments in China during unfolding Covid-19 crisis. The paper shows that these equity investments slumped dramatically in the immediate aftermath of the Covid-19 virus, resulting in a year on year decrease of 60% in the total volume of investment raised between quarter 1 in 2019 and quarter 1 in 2020. Importantly, the paper found early-stage seed investments falling the steepest, suggesting nascent start-ups are those most heavily affected by the crisis. While the global financial crisis heavily hit debt markets, the relational nature of equity investments may mean entrepreneurial finance is even more susceptible to major upheaval caused by the Covid-19 crisis. Overall, enterprise policy makers need to become better attuned at monitoring real-time data sources to mitigate chronic entrepreneurial uncertainty via strategic policy responses.PostprintPeer reviewe

Employee voice through open-book accounting : the benefits of informational transparency

This paper explores the concept of open-book accounting. It illustrates the benefits of open-book reporting policies in terms of their potential ability to correct informational asymmetries, and it sets out some ideas for a future research agenda centred around the concept. The discussion is grounded in large part in the experiences of employee-owned businesses because such organisations are at the forefront of informational transparency innovations in social accounting. But the broader principle of sharing organisational information with employees and training them to process financial and strategic information is applicable to any organisation. It is argued that open-book accounting, especially in the context of employee-owned businesses, provides an exciting alternative to mainstream accounting and financial controls and a welcome addition to the social accounting literature.PostprintPeer reviewe

Enhancing in vivo vascularized bone formation by cobalt chloride-treated bone marrow stromal cells in a tissue engineered periosteum model

The periosteum plays an indispensable role in both bone formation and bone defect healing. In this study we constructed an artificial in vitro periosteum by incorporating osteogenic differentiated bone marrow stromal cells (BMSCs) and cobalt chloride (CoCl(2))-treated BMSCs. The engineered periostea were implanted both subcutaneously and into skull bone defects in SCID mice to investigate ectopic and orthotopic osteogenesis and vascularization. After two weeks in subcutaneous and four weeks in bone defect areas, the implanted constructs were assessed for ectopic and orthotopic osteogenesis and vascularization by micro-CT, histomorphometrical and immunohistochemical methods. The results showed that CoCl(2) pre-treated BMSCs induced higher degree of vascularization and enhanced osteogenesis within the implants in both ectopic and orthotopic areas. This study provided a novel approach using BMSCs sourced from the same patient for both osteogenic and pro-angiogenic purposes in constructing tissue engineered periosteum to enhance vascularized osteogenesis

Financing in the United States capital market: Accounting and reporting considerations for foreign issuers;

https://egrove.olemiss.edu/dl_dhs/1051/thumbnail.jp