Abstract P144: Bioinformatic Profiling of the Transcriptional Response of Adult Porcine Bone Marrow Stem Cell during Exposure to Hypoxia
Background: Cell-based transplantation therapy in a large animal model has been shown to improve angiogenesis and function of ischemic myocardium. These improvements may be due to the endothelial progenitor cells from bone marrow derived stem cells (BMC) generated under ischemic or hypoxic conditions. However the molecular activities of porcine BMC (PBMC) are largely unknown. Thus, a comprehensive gene expression pattern for PBMC is needed to advance the preclinical work necessary for future human treatment.
Methods: Fifteen PBMC were cultured in the medium of EGM 2 for 4 weeks, and then incubated either in a monitored hypoxic chamber (1% O2, 5% CO2) (H) or in normal culture conditions (normoxia, N) for 6, 12, 24 and 48 hrs. Twenty RNAs comprising 5 Ns and 15 Hs (6, 12 and 24hr) were hybridized to Affymetrix Porcine arrays. An additional 40 samples were prepared for data confirmation by qRTPCR and Western blot. Data normalization and pattern recognition in each of these subgroups were achieved using R package 2.4 and GeneSpringGX. Homologous gene search and functional classification based on NCBI Pig Genomic Resources and DAVID Bioinformatics Resources 2007.
Results: Significant gene expression levels among the four groups were identified. The patterns of three hypoxia (H) groups were clearly distinct from that of normoxia (N) group. However, the expression pattern of 12hr H was more similar to 24hr H than that of 6hr H. Of 23,928 probes, 394 genes were statistically regulated rapidly in 6hr Hs vs. Ns, including HIF2alpha, VEGFA, PDGFA, ANGPT2, CXCL14 and PGD. Only 182 genes were modulated in 12hr Hs, but 84% (152/182) of the genes appeared either with 6hr or 24hr H groups. 227 genes were significantly over- or down- regulated in 24hr Hs, among the 94 genes were overlapped with 6hr and 12hr Hs. Notably, the 94 genes were the most differentially modulated in all three H groups, some of the genes were known involving in the processes of hypoxic stress, response to inflammatory, wounding, apoptosis and angiogenesis. The 94 genes are considered as hypoxic targets for further study.
Conclusions: Our results confirmed the role of several genes involved in hypoxic or ischemic states, and captured a set of genes that associated the PBMC response to hypoxic or ischemic surroundings.