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THE EFFECT OF OXYSTEROL ON OSTEOGENESIS IN HUMAN ADIPOSE DERIVED STEM CELLS
Presenter: Patricia Zuk, PhD
Co-Authors: Li A; Buck A; Hokugo A; Sorice S; Lee J; Jarrahy R
UCLA REBAR Lab

Background: Adipose-derived stem cells (ASCs) have been identified as a potential source of cells for use in bone tissue engineering due to their ready availability, ease of harvest, and susceptibility to osteogenic induction. Bone morphogenetic protein (BMP) has been shown to augment the osteogenic potential of ASCs in vitro and in vivo. Clinical applications of BMPs, however, are limited due to its exorbitant cost and side effect profile. Oxysterols are naturally occurring products of cholesterol metabolism. We have previously demonstrated the ability of oxysterols in inducing osteogenic differentiation in pluripotent rabbit bone marrow stromal cells via the Hedgehog (Hh) signaling pathway. Our results have shown that oxysterols have an efficacy similar to that of BMP-2 in inducing osteogenesis in rabbit cells. In this study, we examine the ability of oxysterol to induce osteogenesis in human ASCs.

Methods: ASCs were isolated from raw human lipoaspirates from patients. Cells were plated onto conventional tissue culture plates in control medium and harvested between passages 2 and 3. Cells were then incubated with various concentrations of oxysterol in conventional osteogenic media. We then measured alkaline phosphatase (ALP) activity, the expression of bone-related genes via RT-PCR and mineralization via the Von Kossa calcification assay.

Results: ALP activity in ASCs treated with oxysterol was significantly higher compared to controls. Bone related genes in ASCs treated with oxysterol were expressed at higher levels than in control groups. Mineralization in cells treated with oxysterol were also significantly increased.

Conclusion: Oxysterols have an osteoinductive effect on human ASCs in vitro. However, ASCs harvested from different individuals demonstrate different capacities for osteogenic induction. Further studies examining this phenomenon as well as the mechanisms of this influence are underway with the aim of determining specific signaling pathways implicated in this process.


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