Characterization of Fatty Acid Composition in Bone Marrow Fluid From Postmenopausal Women: Modification After Hip Fracture.

Bone marrow adipose tissue (BMAT) is associated with low bone mass, although the functional consequences for skeletal maintenance of increased BMAT are currently unclear. BMAT might have a role in systemic energy metabolism, and could be an energy source as well as an endocrine organ for neighboring bone cells, releasing cytokines, adipokines and free fatty acids into the bone marrow microenvironment. The aim of the present report was to compare the fatty acid composition in the bone marrow supernatant fluid (BMSF) and blood plasma of postmenopausal women women (65-80 years old). BMSF was obtained after spinning the aspirated bone marrow samples; donors were classified as control, osteopenic or osteoporotic after dual-energy X-ray absorptiometry. Total lipids from human bone marrow fluid and plasma were extracted, converted to the corresponding methyl esters, and finally analyzed by a gas chromatographer coupled with a mass spectrometer. Results showed that fatty acid composition in BMSF was dynamic and distinct from blood plasma, implying significance in the locally produced lipids. The fatty acid composition in the BMSF was enriched in saturated fatty acid and decreased in unsaturated fatty acids as compared to blood plasma, but this relationship switched in women who suffered a hip fracture. On the other hand, there was no relationship between BMSF and bone mineral density. In conclusion, lipid composition of BMSF is distinct from the circulatory compartment, most likely reflecting the energy needs of the marrow compartment. J. Cell. Biochem. 117: 2370-2376, 2016. © 2016 Wiley Periodicals, Inc.

Osteoporosis-associated alteration in the signalling status of BMP-2 in human MSCs under adipogenic conditions.

Postmenopausal osteoporosis is characterized by decreased bone quality and mineral density. Mesenchymal stem cells (MSCs) found in the bone marrow, are pluripotent cells able to differentiate into several phenotypes, including osteoblasts and adipocytes. In osteoporosis, MSCs' commitment and differentiation into osteoblast/adipocyte is unbalanced, favoring adipocyte formation. The osteo and adipogenic processes are modulated by the bone morphogenetic protein-2 (BMP-2). This cytokine regulates the expression of transcription factors PPARγ and Runx 2, but its action on cells under adipogenic conditions is poorly understood. In this work we studied BMP-2 signaling in MSCs obtained from bone marrow of control or osteoporotic volunteer postmenopausal women. MSCs were cultured under basal, adipogenic (AD) or AD plus BMP-2 conditions. The protein content of PPARγ, p-PPARγ, Runx2, bone morphogenetic receptor IA (BMPR IA), phosphorylated Smad-1/5/8 (p-Smad) and Smad 4 were determined by specific western blots. mRNA level for BMPRs was determined by PCR and cell localization of p-Smad-1/5/8 were detected by immunocytochemistry. Control MSCs showed a differential response to both AD and AD plus BMP-2 treatments: BMP-2 exerted an anti-adipogenic effect increasing both transcription factors analyzed. Moreover, p-Smads-1/5/8 were detected in nuclei after short term BMP-2 treatment. Osteoporotic MSCs showed no response to exogenous added BMP-2, as shown by p-PPARγ/PPARγ ratio and Runx2 levels, although BMPR-IA level was significantly higher in osteoporotic than in control MSCs. In addition, staining for p-Smad-1/5/8 in o-MSCs was observed around nuclei at all experimental conditions. Taken together results demonstrate failure of BMP-2 signaling in osteoporotic MSCs.

Aromatase activity of human mesenchymal stem cells is stimulated by early differentiation, vitamin D and leptin.

Human mesenchymal stem cells (hMSCs) are multipotent cells present in bone marrow, which differentiate into osteoblasts and adipocytes, among other lineages. Oestrogens play a critical role in bone metabolism; its action may affect the adipocyte to osteoblast ratio in the bone marrow. In hMSCs, oestrogens are synthesized from C19 steroids by the enzyme aromatase cytochrome P450. In this study, we assessed whether aromatase enzymatic activity varied through early osteogenic (OS) and adipogenic (AD) differentiation. Also, we studied the effect of leptin and 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) on aromatase cell activity. Finally, we analysed whether conditions that modify oestrogen generation by cells affected hMSCs differentiation. For these purposes, hMSCs derived from post-menopausal women (65-86 years old) were cultured under basal, OS or AD conditions, in the presence or the absence of leptin and 1,25(OH)2D3. Aromatase activity was measured by the tritiated water release assay and by direct measurement of steroids synthesized from 3H-labelled androstenedione or testosterone. Our results showed that different OS and AD patterns of aromatase activity developed during the first period of differentiation (up to 7 days). A massive and sharp surge of aromatase activity at 24 h characterized early OS differentiation, while increased but constant aromatase activity was increased through adipogenesis. Both leptin and vitamin D increased aromatase activity during osteogenesis, but not during adipogenesis; finally, we showed that favourable aromatase substrates concentration restrained MSCs adipogenesis but improved osteogenesis. Thus, it could be inferred that a high and early increase of local oestrogen concentration in hMSCs affects their commitment either restraining AD or facilitating OS differentiation, or both.

Concentration of adipogenic and proinflammatory cytokines in the bone marrow supernatant fluid of osteoporotic women.

Osteoporosis is characterized by low bone mass, microarchitectural deterioration of bone tissue leading to increased bone fragility, and a resulting susceptibility to fractures. Distinctive environmental bone marrow conditions appear to support the development and maintenance of the unbalance between bone resorption and bone formation; these complex bone marrow circumstances would be reflected in the fluid surrounding bone marrow cells. The content of regulatory molecules in the extracellular fluid from the human bone marrow is practically unknown. Since the content of cytokines such as adiponectin, leptin, osteoprogeterin (OPG), soluble receptor activator of nuclear factor kappaB ligand (s-RANKL), tumor necrosis factor alpha, and interleukin 6 (IL-6) may elicit conditions promoting or sustaining osteoporosis, in this work we compared the concentrations of the above-mentioned cytokines and also the level of the soluble receptors for both IL-6 and leptin in the extracellular fluid from the bone marrow of nonosteoporotic and osteoporotic human donors. A supernatant fluid (bone marrow supernatant fluid [BMSF]) was obtained after spinning the aspirated bone marrow samples; donors were classified as nonosteoporotic or osteoporotic after dual-energy X-ray absorptiometry (DXA) measuring. Specific commercially available kits were used for all measurements. The cytokines' concentration in BMSF showed differently among nonosteoporotic and osteoporotic women; this last group was characterized by higher content of proinflammatory and adipogenic cytokines. Also, osteoporotic BMSF differentiated by decreased leptin bioavailability, suggesting that insufficient leptin action may distinguish the osteoporotic bone marrow.

[Adipogenesis and osteoporosis]. / Adipogénesis y osteoporosis.

Mesenchymal stem cells (MSCs) found in bone marrow stroma, are able to differentiate into osteoblasts and adipocytes, among other cellphenotypes. In normal bone marrow balance osteoblastic an adipocytes cell differentiation favour bone formation, while in osteoporosis there is an increased adipocytes content. Since osteoblasts and adipocytes originate from a common MSC precursor cell, here we discuss whether quantitative and qualitative stem cell defects may be the cause of alterations in the number and function of differentiated cells. This review analyzes some conditions that contribute to different osteogenic/adipogenic potentials in human bone marrow MSCs obtained from control and osteoporotic postmenopausal women. We analyze the protective effect exerted by locally generated factors like estradiol and leptin on MSCs differentiation, because altered bioavailability of these factors may play a role in osteoporosis. Osteoporotic MSCs (o-MSCs) are characterized by increased adipogenic potential as compared to control cells. Leptin exerted a direct protective action against adiposeness only in control cells. In contrast, leptin action on o-MSCs is hampered, suggesting that inadequate leptin action may be associated to lipid accumulation in bone marrow.

Adipogénesis y osteoporosis: [revisión] / Adipogenesis and osteoporosis: [review]

Mesenchymal stem cells (MSCs) found in bone marrow stroma, are able to differentiate into osteoblasts and adipocytes, among other cellphenotypes. In normal bone marrow balance osteoblastic an adipocytes cell differentiation favour bone formation, while in osteoporosis there is an increased adipocytes content. Since osteoblasts and adipocytes originate from a common MSC precursor cell, here we discuss whether quantitative and qualitative stem cell defects may be the cause of alterations in the number and function of differentiated cells. This review analyzes some conditions that contribute to different osteogenic/adipogenic potentials in human bone marrow MSCs obtained from control and osteoporotic postmenopausal women. We analyze the protective effect exerted by locally generated factors like estradiol and leptin on MSCs differentiation, because altered bioavailability of these factors may play a role in osteoporosis. Osteoporotic MSCs (o-MSCs) are characterized by increased adipogenic potential as compared to control cells. Leptin exerted a direct protective action against adiposeness only in control cells. In contrast, leptin action on o-MSCs is hampered, suggesting that inadequate leptin action may be associated to lipid accumulation in bone marrow.