Potent induction of chondrocytic differentiation of human adipose‐derived adult stem cells by bone morphogenetic protein 6

Abstract

Objective. Recent studies have identified an abundant source of multipotent progenitor cells in subcutaneous human adipose tissue, termed human adiposederived adult stem cells (ADAS cells). In response to specific media formulations, including transforming growth factor ␤1 (TGF␤1), these cells exhibit significant ability to differentiate into a chondrocyte-like phenotype, expressing cartilage-specific genes and proteins such as aggrecan and type II collagen. However, the influence of other growth factors on the chondrogenic differentiation of ADAS cells is not fully understood. This study was undertaken to investigate the effects of TGF␤1, TGF␤3, insulin-like growth factor 1, bone morphogenetic protein 6 (BMP-6), and dexamethasone, in various combinations, on the chondrogenic potential of ADAS cells in alginate beads.Methods. The chondrogenic response of alginateencapsulated ADAS cells was measured by quantitative polymerase chain reaction, 3 H-proline and 35 S-sulfate incorporation, and immunolabeling for specific extracellular matrix components.Results. Significant differences in chondrogenesis were observed under the different culture conditions for all outcomes measured. Most notably, BMP-6 upregulated AGC1 and COL2A1 expression by an average of 205-fold and 38-fold, respectively, over day-0 controls, while down-regulating COL10A1 expression by ϳ2-fold.Conclusion. These findings suggest that BMP-6 is a potent inducer of chondrogenesis in ADAS cells, in contrast to mesenchymal stem cells, which exhibit increased expression of type X collagen and a hypertrophic phenotype in response to BMP-6. Combinations of growth factors containing BMP-6 may provide a novel means of regulating the differentiation of ADAS cells for applications in the tissue-engineered repair or regeneration of articular cartilage.

2010 Nicolas Andry Award: Multipotent Adult Stem Cells from Adipose Tissue for Musculoskeletal Tissue Engineering

“…2). In contrast to bone marrow MSCs, which exhibit increased expression of type X collagen in response [26] to BMP-6, these findings suggest that BMP-6 serves as a potent regulator of ASC chondrogenesis. This finding has been confirmed, and data indicate that BMP-6 may be especially important for ASC chondrogenesis owing to differences in TGF-b receptor expression as compared with MSCs [39].…”

“…By measures of cell surface markers, ASCs show expression profiles that are similar but distinct in comparison to bone marrow MSCs. However, the response of ASCs to growth factors and biomaterial scaffolds may differ significantly from MSCs [21,26]. For example, it has been shown that the addition of BMP-6 significantly enhances ASC chondrogenesis, suggesting that conditions for optimal ASC differentiation may be distinct from those required for MSCs [26,39].…”

“…[33] Chondrogenic Potential of Human ASCs Our work has focused primarily on the ability of ASCs to produce cartilaginous tissue molecules for potential application in the repair of tissues such as articular cartilage, meniscus, or intervertebral disc (eg, [4,20,22,26,27,82,83]). Through numerous studies, it was shown that under specific conditions, ASCs can express the genes and proteins for several cartilage-specific molecules, including type II collagen and aggrecan, without expression of hypertrophic chondrocyte markers such as type X collagen [26]. Nonetheless, under different defined conditions, ASCs can be induced to synthesize type I and type II collagen, suggesting that a fibrocartilaginous phenotype also is possible [5].…”

“…In a series of studies, it was shown that the chondrogenic potential of ASCs depends on numerous culture conditions such as the expansion/growth media used, the number of passages, and the composition of the extracellular matrix [4,20,24,26,27].…”

“…Using further screens of numerous different growth factors, it was found that BMP-6 applied in solution [26] or through genetic transfection of ASCs [20] greatly enhances the chondrogenic potential of ASC cells encapsulated in alginate beads. In particular, soluble BMP-6 upregulated aggrecan and collagen II expression by an average of 205-fold and 38-fold, respectively, over Day 0 controls, while downregulating collagen X expression (as a marker of hypertrophic differentiation) by twofold.…”