Use of high throughput genomic tools for the study of endothelial cell biology

A novel methodology to probe endothelial differential gene expression profile reveals novel genes

Endothelial dysfunction is a major feature of vascular diseases. A practical, minimally invasive method to effectively "probe" gene transcription for an individual patient's endothelium has potential to "customize" assessment for an individual at risk of vascular disease as well as pathophysiologic insight in an in vivo human, clinical context. Published literature lacks a methodology to identify endothelial differential gene expression in individuals with vascular disease. We describe a methodology to do so. The aim of this study was to specifically utilize (a) cutaneous microvascular biopsy, (b) laser capture microdissection, (c) cDNA amplification, (d) suppression subtractive hybridization, (e) high-throughput sequencing techniques, (f) real-time polymerase chain reaction (PCR), and (g) in combination of these methods, to profile differential gene expression in the context of cardiovascular and cerebrovascular disease. Endothelial cells were obtained by laser capture microdissection from a patient and a healthy sibling's microvascular biopsy tissues. Endothelial RNA was extracted, reverse transcribed, and amplified to ds cDNA. Suppression subtractive hybridization was used to establish an endothelial differential gene expression library. Real-time PCR confirmed SERP1, caspase 8, IGFBP7, S100A4, F85, and F147 up-regulation between 1.4- and 3.47-fold. The authors have successfully established a methodology to profile endothelial differential gene expression and identified six differentially expressed genes. This minimally invasive novel method has potential wide application in the customized assessment of many patients suffering vascular diseases.

Inflammatory manifestations of experimental lymphatic insufficiency

BACKGROUND

Sustained lymph stagnation engenders a pathological response that is complex and not well characterized. Tissue inflammation in lymphedema may reflect either an active or passive consequence of impaired immune traffic.

METHODS AND FINDINGS

We studied an experimental model of acute post-surgical lymphedema in the tails of female hairless, immunocompetent SKH-1 mice. We performed in vivo imaging of impaired immune traffic in experimental, murine acquired lymphatic insufficiency. We demonstrated impaired mobilization of immunocompetent cells from the lymphedematous region. These findings correlated with histopathological alterations and large-scale transcriptional profiling results. We found intense inflammatory changes in the dermis and the subdermis. The molecular pattern in the RNA extracted from the whole tissue was dominated by the upregulation of genes related to acute inflammation, immune response, complement activation, wound healing, fibrosis, and oxidative stress response.

CONCLUSIONS

We have characterized a mouse model of acute, acquired lymphedema using in vivo functional imaging and histopathological correlation. The model closely simulates the volume response, histopathology, and lymphoscintigraphic characteristics of human acquired lymphedema, and the response is accompanied by an increase in the number and size of microlymphatic structures in the lymphedematous cutaneous tissues. Molecular characterization through clustering of genes with known functions provides insights into processes and signaling pathways that compose the acute tissue response to lymph stagnation. Further study of genes identified through this effort will continue to elucidate the molecular mechanisms and lead to potential therapeutic strategies for lymphatic vascular insufficiency.