Glucoraphanin Increases Intracellular Hydrogen Sulfide (H2S) Levels and Stimulates Osteogenic Differentiation in Human Mesenchymal Stromal Cell

Laura Gambari,Valentina Citi,Vincenzo Calderone,Renato Iori,Marli Barone,Francesco Grassi,Giuseppe Filardo,Emanuela Amore,Brunella Grigolo

doi:10.3390/nu14030435

Laura Gambari, Valentina Citi + Show 7 more

Open Access

https://doi.org/10.3390/nu14030435

Copy DOI

Abstract

Osteopenia and osteoporosis are among the most prevalent consequences of ageing, urging the promotion of healthy nutritional habits as a tool in preventing bone fractures. Glucosinolates (GLSs) are organosulfur compounds considered relatively inert precursors of reactive derivatives isothiocyanates (ITCs). Recent evidence suggests that GLSs may exert biological properties based on their capacity to release hydrogen sulfide (H2S). H2S-donors are known to exert anabolic function on bone cells. Here, we investigated whether a GLS, glucoraphanin (GRA) obtained from Tuscan black kale, promotes osteogenesis in human mesenchymal stromal cells (hMSCs). H2S release in buffer and intracellular H2S levels were detected by amperometric measurements and fluorimetric/cytofluorimetric analyses, respectively. Alizarin red staining assay and real-time PCR were performed to evaluate mineral apposition and mRNA expression of osteogenic genes. Using an in vitro cell culture model, our data demonstrate a sulforaphane (SFN)-independent osteogenic stimulation of GRA in hMSCs, at least partially attributable to H2S release. In particular, GRA upregulated the expression of osteogenic genes and enhanced mineral apposition while increasing intracellular concentrations of H2S. Overall, this study suggests the feasibility of using cruciferous derivatives as natural alternatives to chemical H2S-donors as adjuvant therapies in the treatment of bone-wasting diseases.

Highlights

Dietary habits are an important determinant of bone health [1]
Recent work reported that GRA behaves as an hydrogen sulfide (H2 S)-donor independent of the hydrolysis to SFN triggered by plant or microbial myrosinase [24]
We showed that GRA, a GLS abundant in several plants belonging to the Brassica species, induces osteogenic differentiation of human mesenchymal stromal cells (hMSCs) while increasing H2 S

Summary

Introduction

Glucosinolates (GLSs) are a group of organosulfur compounds of natural origin, commonly regarded as the precursors of isothiocyanates (ITCs). GLSs are the substrate of the b-thioglucosidase enzyme myrosinase, which triggers the hydrolytic cleavage of the GLS molecule, releasing glucose and originating an unstable aglycone which, at physiological pH, is mostly rearranged to highly reactive ITC [7,8]. Plants belonging to the family of Brassicaceae, known as cruciferous vegetables, are the most abundant source of naturally occurring GLS. Glucoraphanin (4-methylsulphinylbutyl glucosinolate (GRA)), a chemically stable GLS, is abundant in certain cruciferous vegetables, including broccoli, cabbages, cauliflowers, brussels sprouts, rocket, kohlrabi, radish [14]. GRA is converted to sulforaphane (4-methylsulphinylbutyl isothiocyanate (SFN)), a potent inducer of the KEAP1/NRF2/ARE pathway, leading to the activation of a potent antioxidant and detoxifying response in cells [16,17] as well as anti-inflammatory [18,19]

Objectives

Methods

Results

Discussion

Conclusion