Extracellular Matrix Mineralization and Osteoblast Gene Expression by Human Adipose Tissue–Derived Stromal Cells

TLDR

Human adipose tissue is a plentiful source of stromal cells useful for tissue engineering. The study aims to show that adipose‑derived stromal cells can exhibit osteoblast‑like differentiation in vitro. Cells were induced with ascorbate, β‑glycerophosphate, dexamethasone, and 1,25‑dihydroxy vitamin D3, resulting in extracellular matrix mineralization visualized by Alizarin Red and von Kossa staining and confirmed by PCR of osteoblast genes. Mineralization produced apatitic calcium phosphate crystals, upregulated osteocalcin and alkaline phosphatase, downregulated adipocyte markers, confirming a multipotent stromal population with potential for bone tissue engineering.

Abstract

Human adipose tissue represents an abundant reservoir of stromal cells with potential utility for tissue engineering. The current study demonstrates the ability of human adipose tissue-derived stromal cells to display some of the hallmarks of osteoblast differentiation in vitro. Following treatment with ascorbate, β-glycerophosphate, dexamethasone, and 1,25 dihydroxy vitamin D3, adipose tissue-derived stromal cells mineralize their extracellular matrix based on detection of calcium phosphate deposits using Alizarin Red and von Kossa histochemical stains. Fourier transform infrared analysis demonstrates the apatitic nature of these crystals. Mineralization is accompanied by increased expression or activity of the osteoblast-associated proteins osteocalcin and alkaline phosphatase. These and other osteoblast-associated gene markers are detected based on polymerase chain reaction. In contrast, the adipocyte gene markers—leptin, lipoprotein lipase, and peroxisome proliferator activated receptor γ2—are reduced under mineralization conditions, consistent with the reciprocal relationship postulated to exist between adipocytes and osteoblasts. The current work supports the presence of a multipotent stromal cell population within human extramedullary adipose tissue. These findings have potential implications for human bone tissue bioengineering.