Morphological and functional features of human omental and subcutaneous adipose-derived stem cells isolated from obese patients

In the last years, the relevance and the interest in adipose tissues have greatly grown due to the knowledge of the presence of human Adipose-derived Stem Cells (hASC), which has been shown to differentiate into several cell lineages. The aim of this study is to characterize adipose progenitor cells subpopulations isolated from subcutaneous or visceral fat in normal and severe obese patients. The different state in the two kinds of patients could, indeed, influence the hASC phenotype and thus their proliferation capacity and differentiation potential. The surgeons performed the harvesting of adipose tissue from subcutaneous and visceral areas, both in 10 normal and 10 obese (BMI> 35 Kg/m2) subjects, who already needed a surgical intervention for different reasons. The fat was collected and immediately processed to obtain the progenitor cells, as previously described (L De Girolamo et al., 2007). The experiments have been performed at 4th passage when the cells appeared to form an homogenous population with similar size and granularity. The proliferation rate was quite similar in hASC isolated from subcutaneous tissues of normal and obese patients with a doubling time of 118 ± 61 and 96 ± 7 hours, respectively. However, hASC isolated from visceral tissue of obese patients showed a very lower rate of proliferation (doubling time of 227 ± 71 hours). Colony formation of the hASC population was determined by Fibroblast-Colony Forming Unit (CFU-F) assay. The clonogenic potential of hASC obtained from subcutaneous normal and obese patients was variable but higher than that showed by the hASC isolated from omental tissues. The immunophenotype of hASC has been analyzed by cytofluorimetry, evaluating the expression of the surface markers CD13, CD29, CD44, CD54, CD90 e CD105, CD133, CD14, CD34, CD45, CD71 e CD166. The results showed that the phenotypic profile of hASC was similar in the different tissues. In conclusions the hASC isolated from normal and obese subcutaneous and visceral tissues showed different biological behaviours. The gene expression profile of the hASC isolated from visceral and subcutaneous tissues of normal and obese subjects will be analyzed, as well as their potential to differentiate into osteogenic, chondrogenic and adipogenic lineages. Defining the molecular and cellular components of obesity offers the foundation for identifying appropriate targets to ameliorate the management of the obesity.