DNA Methylation-Dependent Regulation of Lipoprotein Lipase Expression During Human Mesenchymal Stem Cell Differentiation into Adipocytes

Abstract

Background: Lipoprotein lipase (LPL) is a critical enzyme in lipid metabolism that hydrolyzes triglyceride-rich lipoproteins. While its role in mature adipose tissue is well understood, the epigenetic regulation of LPL during mesenchymal stem cell (MSC) differentiation into adipocytes remains poorly characterized. This study aimed to investigate the temporal expression pattern of LPL and its relationship with DNA methylation during adipogenic differentiation of human bone marrow-derived MSCs. Methods: Human bone marrow MSCs were isolated and characterized using flow cytometry for specific surface markers (CD34, CD31, CD90, and CD105). Cells were differentiated into adipocytes over 14 days and osteoblasts over 21 days using specific differentiation media. Differentiation was confirmed through Oil Red O and Alizarin Red staining respectively. LPL gene expression was analyzed using both qualitative RT-PCR and quantitative real-time PCR at day 0 (undifferentiated) and day 14 (differentiated) timepoints. DNA methylation patterns were assessed using methylation-specific PCR (MSP) following bisulfite conversion, with collagen gene serving as an internal control. Results: Flow cytometry confirmed MSC identity through positive expression of CD166, CD13, CD105, and CD44. Successful adipogenic differentiation was demonstrated by Oil Red O-positive lipid droplet accumulation, while osteogenic differentiation was confirmed by Alizarin Red S staining of calcium deposits. LPL gene expression was absent in undifferentiated MSCs but showed significant expression in differentiated adipocytes at day 14, coinciding with morphological changes and lipid accumulation. Conclusion: This study demonstrates that LPL expression is epigenetically regulated during MSC differentiation into adipocytes, with significant changes in both gene expression and DNA methylation patterns. The temporal correlation between LPL expression, methylation status, and adipogenic differentiation suggests that LPL serves as a key molecular switch in this process.