Additive Effects of Sonic Hedgehog and Nell-1 Signaling in Osteogenic Versus Adipogenic Differentiation of Human Adipose-Derived Stromal Cells

Abstract

A theoretical inverse relationship exists between osteogenic (bone forming) and adipogenic (fat forming) mesenchymal stem cell (MSC) differentiation. This inverse relationship in theory partially underlies the clinical entity of osteoporosis, in which marrow MSCs have a preference for adipose differentiation that increases with age. Two pro-osteogenic cytokines have been recently studied that each also possesses antiadipogenic properties: Sonic Hedgehog (SHH) and NELL-1 proteins. In the present study, we assayed the potential additive effects of the biologically active N-terminus of SHH (SHH-N) and NELL-1 protein on osteogenic and adipogenic differentiation of human primary adipose-derived stromal cell (hASCs). We observed that both recombinant SHH-N and NELL-1 protein significantly enhanced osteogenic differentiation and reduced adipose differentiation across all markers examined (alkaline phosphatase, Alizarin red and Oil red O staining, and osteogenic gene expression). Moreover, SHH-N and NELL-1 directed signaling produced additive effects on the proosteogenic and antiadipogenic differentiation of hASCs. NELL-1 treatment increased Hedgehog signaling pathway expression; coapplication of the Smoothened antagonist Cyclopamine reversed the pro-osteogenic effect of NELL-1. In summary, Hedgehog and Nell-1 signaling exert additive effects on the pro-osteogenic and antiadipogenic differentiation of ASCs. These studies suggest that the combination cytokines SHH-N + NELL-1 may represent a viable future technique for inducing the osteogenic differentiation of MSCs.

Novel Wnt Regulator NEL-Like Molecule-1 Antagonizes Adipogenesis and Augments Osteogenesis Induced by Bone Morphogenetic Protein 2

“…Prior studies from our research group have confirmed that multiple cell types are NELL-1 responsive. For example, NELL-1 induction of osteogenesis is best studied in BMSCs 39 but also has been reported in committed osteoblasts, 67 adipose-derived stem cells, 72 and perivascular stem cells. 73,74 Although complex, Understanding the cellspecific responses to NELL-1 and BMP2 treatment may allow for future refinements in protein-based methods of tissue engineering.…”

Identification of Novel EZH2 Targets Regulating Osteogenic Differentiation in Mesenchymal Stem Cells

“…O steogenic differentiation of bone marrow mesenchymal stem/stromal cells (MSCs) [1,2] is associated with the repression of adipogenic differentiation [3][4][5]. This reciprocal relationship between adipogenesis and osteogenesis is modulated by molecules such as Msx2, which promote osteogenesis and suppress adipogenesis [6,7].…”

Osteogenic differentiation of amniotic fluid mesenchymal stromal cells and their bone regeneration potential

“…Several cell signaling cascades are involved in this cell fate decision between osteo and adipogenesis [11] . The master regulator of osteogenesis is Runx2, the gene target of many signaling pathways, including but not limited to transforming growth factorbeta 1 (TGFβ1), BMP [12] , Wingless type (Wnt) [13] , Hedgehog (HH) [14] , and (NEL) like protein type 1 (NELL1) [15] . Thus, considering the crucial role of MSCs in bone healing, the strategy of using the osteogenic potential of such cells transplanted into the bone defect seems promising [7,16] .…”