Modulation of Endocannabinoid Tone in Osteoblastic Differentiation of MC3T3-E1 Cells and in Mouse Bone Tissue over Time.

Magdalena Kostrzewa,Roberta Verde,Alessia Ligresti,Fabiana Piscitelli,Federica Scotto Di Carlo,Ali Mokhtar Mahmoud,Fernando Gianfrancesco

doi:10.3390/cells10051199

Magdalena Kostrzewa, Roberta Verde + Show 5 more

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https://doi.org/10.3390/cells10051199

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Abstract

Bone is a highly complex and metabolically active tissue undergoing a continuous remodeling process, which endures throughout life. A complex cell-signaling system that plays role in regulating different physiological processes, including bone remodeling, is the endocannabinoid system (ECS). Bone mass expresses CB1 and CB2 cannabinoid receptors and enzymatic machinery responsible for the metabolism of their endogenous ligands, endocannabinoids (AEA and 2-AG). Exogenous AEA is reported to increase the early phase of human osteoblast differentiation in vitro. However, regarding this cell context little is known about how endocannabinoids and endocannabinoid-related N-acylethanolamines like PEA and OEA are modulated, in vitro, during cell differentiation and, in vivo, over time up to adulthood. Here we characterized the endocannabinoid tone during the different phases of the osteoblast differentiation process in MC3T3-E1 cells, and we measured endocannabinoid levels in mouse femurs at life cycle stages characterized by highly active bone growth (i.e., of juvenile, young adult, and mature adult bone). Endocannabinoid tone was significantly altered during osteoblast differentiation, with substantial OEA increment, decline in 2-AG and AEA, and consistent modulation of their metabolic enzymes in maturing and mineralized MC3T3-E1 cells. Similarly, in femurs, we found substantial, age-related, decline in 2-AG, OEA, and PEA. These findings can expand existing knowledge underlying physiological bone cell function and contribute to therapeutic strategies for preventing bone-related metabolic changes accruing through lifespan.

Highlights

Bone is a highly intricate and metabolically active tissue that serves indispensable functions such as the structural and mechanical integrity essential for locomotion and protection of vital organs, maintenance of mineral homeostasis, and hematopoiesis
In a murine model of accelerated aging, decreased osteoblastogenesis within bone marrow was associated with diminished bone formation in the remodeling cancellous bone and low bone mineral density (BMD) [5]
The bone nodule formation and mineralization observed in our cells by means of alizarin red staining demonstrate the accomplishment of osteoblast maturation most likely associated with alkaline phosphatase (ALP) activity

Summary

Introduction

Bone is a highly intricate and metabolically active tissue that serves indispensable functions such as the structural and mechanical integrity essential for locomotion and protection of vital organs, maintenance of mineral homeostasis, and hematopoiesis. The consonance between bone structure and functionality is maintained by a tightly coordinated remodeling process in which mineralized matrix is removed by osteoclasts and afterward replaced with newly formed bone tissue, produced by osteoblasts [1] Alteration of such a finely regulated metabolism changes strength or mass of bone structure, leading to bone diseases, such as osteoarthritis or osteoporosis, and to higher fracture risk [2,3,4]. Skeletal structure in mice undergoes substantial changes with advancing age as cancellous bone volume continuously decreases from 1.5 to 24 months of age in C57BL/6J male mice [6,10] These changes are in line with those occurring in human aging [9]; rodent models serve as suitable tools for studying age-related bone loss

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