ABSTRACT: Angiogenesis and lymphangiogenesis have important roles in cancer progression and chronic inflammatory diseases, but efficient therapies against these diseases have been hampered by the lack of identified vascular lineage-specific markers and growth factors. Using transcriptional profiling of matched pairs of human dermal blood vascular and lymphatic endothelial cells, we first identified 236 lymphatic and 342 blood vascular signature genes. In silico analyses of the biologic pathways associated with these genes revealed lineage-specific functions for each cell type. Using a selection of 85 identified vascular lineage-specific genes, we developed a TaqMan RT-PCR-based, microfluidic card-formatted low-density microvascular differentiation array (LD-MDA) that was used to reliably identify and quantify the degree of lineage-specific differentiation in different types of endothelial cells, and to detect admixture of lymphatic endothelial cells in commercial preparations of microvascular endothelial cells. Application of Prediction Relevance Ranking and analysis of variance of LD-MDA expression profiles of 43 lesional skin samples obtained from patients with the chronic inflammatory disease psoriasis led to identification of cytokines which are significantly associated with angiogenesis or lymphangiogenesis in vivo. In particular, interleukin-7 and fibroblast growth factor-12 were identified as novel (lymph)angiogenic factors. This technology provides a novel tool to quantify lineage-specific vascular differentiation and to characterize (lymph)angiogenesis in clinical samples obtained from angiogenic diseases. Keywords: Quantitative real time RT-PCR, cell type comparison Guided by the gene array results, we selected 54 LEC-specific genes and 31 BEC-specific genes, based upon their consistent and strong specific expression in LEC or BEC, as well as on their assignment to important biological pathways. In addition, the five pan-endothelial cell marker genes PECAM-1, vWF, KDR, TEK, CDH5 and the six endogenous control genes ACTB, GAPDH, PGK1, PPIA, RPLP0 and S18 were included in the design of the LD-MDA. The LD-MDA was then used to evaluate the lineage-specific differentiation of a total of 10 independent lines of primary human dermal LEC, of 8 independent lines of primary human dermal BEC, of two independent lines of HUVEC cells, of the immortalized human microvascular endothelial cell line HMEC-1, of the immortalized human epidermal keratinocyte line HaCaT, and of primary human dermal fibroblasts. After extraction of total RNA, the mRNA expression levels of the 96 genes were analyzed by quantitative RT-PCR using the 7900HT Real-Time PCR System (Applied Biosystems).
