ESPE Abstracts

Background: Obesity is characterized by an increase in fat mass caused by an increase in adipocyte number and adipocyte size and is often associated with adipose tissue (AT) dysfunction contributing to metabolic impairment. It is suspected that adipocyte progenitor cells play an important role during healthy and obesity-related AT expansion. Studies in adults showed that the stroma vascular fraction (SVF) of AT is composed of different progenitor cell subpopulations with different abilities to proliferate and differentiate. We want to characterize the adipose progenitor cell marker MSCA1 as an obesity-related factor in AT of lean and obese children.

Methods: The percentage of adipocyte progenitor cells within the SVF we determined by flow cytometry using the specific surface marker MSCA1. In addition, we investigated a possible association between MSCA1 expression in isolated adipocytes and cells of the SVF and serum levels of MSCA1, measured by ELISA, in lean (n=35) and obese (n=30) children of our Leipzig Childhood AT cohort.

Results: Based on previous studies of Anne Bouloumié-Diehl et al., we established a protocol for isolating adipocyte progenitor cells in SVF from subcutaneous AT (scAT). We detected, similar to these studies, 12.6% ± 3% (mean ± SEM) MSCA1 positive adipocyte progenitor cells in SVF from scAT of adult women (n=7). Moreover, we measured MSCA1 expression in scAT samples as well as serum levels in lean and obese children. MSCA1 expression increases with increasing age of the children in SVF cells (P<0.05) and adipocytes (P<0.001). We observed no gender-specific differences in the expression of MSCA1. Interestingly and in accordance with adult studies, adipocyte MSCA1 expression was significantly higher in obese compared to lean children. For the expression of MSCA1 in SVF cells, however, no significant correlation between lean and obese children was obtained. Our data showed no association between MSCA1 expression in AT and circulating MSCA1 in the serum. We could not find a significant difference in serum levels between obese and lean children.

Conclusions: In conclusion higher adipocyte MSCA1 expression but not MSCA1 serum levels and SVF MSCA1 expression are related to obesity in children. Currently, we are investigating whether AT MSCA1 expression and/or serum levels are suitable as a surrogate marker for the number of MSCA1 positive progenitor cells in AT of children.