213 TRANSCRIPTOMIC COMPARISON BETWEEN PORCINE ADIPOSE AND BONE MARROW MESENCHYMAL STEM CELLS DURING IN VITRO OSTEOGENIC AND ADIPOGENIC DIFFERENTIATION

Abstract

Previous data support the use of adipose-derived stem cells (ASC) as an alternative to bone marrow as a source of adult stem cells for therapeutic purposes. The aims of the present study were to directly compare the transcriptome of ASC and bone marrow-derived mesenchymal stem cells (BMSC) in order to uncover potential functional differences between the two mesenchymal stem cells (MSC), to identify differentially expressed genes (DEG) and related functions that may drive MSC to become bone or adipose and to identify potential markers for adipogenic and osteogenic differentiation. ASC and BMSC, isolated from subcutaneous adipose tissue and femurs of 3 adult pigs were differentiated in vitro along the osteogenic and adipogenic lineage for up to 4 wk. At 0, 2, 7 and 21 days of differentiation, RNA was extracted for microarray analysis. Data were normalized by Lowess and statistical analysis run using ANOVA with Benjamini-Hochberg false discovery rate (FDR) correction. Data mining was carried out using Ingenuity Pathway Analysis and DAVID. Analysis of undifferentiated MSC for genes with the highest expression and DEG between MSC and fully differentiated tissues uncovered MSC being featured by low immunity and high angiogenic capacity. The direct comparison between differentiation lineages indicated that the expression of a limited number of genes has to change in order to determine cell fate. Functional analysis of the DEG between differentiation lineages indicated that osteogenesis is characterised by larger cell proliferation and cytoskeleton organisation with a crucial role of G-proteins compared to adipogenesis. On the other hand, adipogenesis is driven by PPAR signalling, has greater angiogenesis, lipid metabolism, migration and tumorigenesis capacity compared to osteogenesis. The direct comparison between ASC and BMSC during the same differentiation uncovered that ASC is featured by a greater lipid metabolism compared to BMSC, while BMSC has a more pronounced cell growth and proliferation than ASC. In addition, we uncovered 39 specific gene markers for adipogenesis and 65 for osteogenesis. NAD(P)H dehydrogenase quinone 1 (NQO1), aquaporin 3 (AQP3), stearoyl-CoA desaturase (SCD), fatty acid binding protein 3 and 5 (FABP3 and FABP5) and ferritin light polypeptide (FTL) were among the best adipogenic markers. Hemopexin (HPX), collagenase type 3α (COL3A1), annexin A8-like 1 (ANXA8L1), flotillin 2 (FLOT2) and periostin or osteoblast specific factor (POSTN) were among the best osteogenic markers. Overall, the data indicated that the transcriptome of the two MSC are similar across the conditions studied. In addition, despite the limited DEG between the two MSC, the enrichment of several functions/pathways might indicate differences in therapeutic application.

This work was support by the Illinois Regenerative Medicine Institute (IDPH # 63080017).