Stromal stem cells from adipose tissue and bone marrow of age-matched female donors display distinct immunophenotypic profiles

Abstract

Adipose tissue is composed of lipid-filled mature adipocytes and a heterogeneous stromal vascular fraction (SVF) population of cells. Similarly, the bone marrow (BM) is composed of multiple cell types including adipocytes, hematopoietic, osteoprogenitor, and stromal cells necessary to support hematopoiesis. Both adipose and BM contain a population of mesenchymal stromal/stem cells with the potential to differentiate into multiple lineages, including adipogenic, chondrogenic, and osteogenic cells, depending on the culture conditions. In this study we have shown that human adipose-derived stem cells (ASCs) and bone marrow mesenchymal stem cells (BMSCs) populations display a common expression profile for many surface antigens, including CD29, CD49c, CD147, CD166, and HLA-abc. Nevertheless, significant differences were noted in the expression of CD34 and its related protein, PODXL, CD36, CD 49f, CD106, and CD146. Furthermore, ASCs displayed more pronounced adipogenic differentiation capability relative to BMSC based on Oil Red staining (7-fold vs. 2.85-fold induction). In contrast, no difference between the stem cell types was detected for osteogenic differentiation based on Alizarin Red staining. Analysis by RT-PCR demonstrated that both the ASC and BMSC differentiated adipocytes and osteoblast displayed a significant upregulation of lineage-specific mRNAs relative to the undifferentiated cell populations; no significant differences in fold mRNA induction was noted between ASCs and BMSCs. In conclusion, these results demonstrate human ASCs and BMSCs display distinct immunophenotypes based on surface positivity and expression intensity as well as differences in adipogenic differentiation. The findings support the use of both human ASCs and BMSCs for clinical regenerative medicine.

Fig. 1

Immunophenotypic characterization of the ASC and BMSC from age-matched female donors: Flow cytometry histograms for selected surface protein antigens in representative female donors for ASC (left part, green) versus BMSC (right part, red).

Fig. 2

Adipogenic differentiation potential of ASC and BMSC: Histochemical stained Oil Red O photomicrograph of representative ASC and BMSC donor (A) and relative induction of Oil Red O staining (mean ± SD) under adipogenic conditions relative to untreated controls for n =12 or 11 donors for ASC and BMSC lineages, respectively (B).

Fig. 3

Osteogenic differentiation potential of ASC and BMSC: Histochemical stained Alizarin Red photomicrograph of representative ASC and BMSC donor (A) and relative induction of Alizarin Red staining (mean ± SD) under osteogenic conditions relative to untreated controls for n = 12 or 11 donors for ASC and BMSC lineages, respectively (B).

Fig. 4

Expression of adipocyte lineage-associated mRNAs in vitro. Total RNA was isolated from ASCs (n =12) and BMSCs (n =11) treated under pre-adipocyte (black) and adipocyte conditions (white) grown in the respective growth media. RT-PCR analysis was performed to detect expression of adipose markers, PPARg2 (A), C/EBP alpha (B), adiponectin (C), leptin (D), lipoprotein lipase (LPL) (E), and adipocyte fatty acid-binding protein (AP2) (F). The values represent the mean ± standard error bars.

Fig. 5

Expression of osteoblast lineage-associated mRNAs in vitro. Total RNA was isolated from ASCs (n = 12) and BMSCs (n =11) treated under pre-adipocyte (black) and adipocyte conditions (white) grown in the respective growth media. RT-PCR analysis was performed to detect expression of adipose markers, osteonectin (A), E4BP4 (B), GILZ1 (C), GILZ2 (D), RANKL (E), and osteocalcin (F). The values represent the mean ± standard error bars.