Accumulation of Fat Not Responsible for Femoral Head Necrosis, Revealed by Single-Cell RNA Sequencing: A Preliminary Study

Abstract

The etiology of osteonecrosis of the femoral head (ONFH) is not yet fully understood. However, ONFH is a common disease with high morbidity, and approximately one-third of cases are caused by glucocorticoids. We performed single-cell RNA sequencing of bone marrow to explore the effect of glucocorticoid on ONFH. Bone marrow samples of the proximal femur were extracted from four participants during total hip arthroplasty, including two participants diagnosed with ONFH for systemic lupus erythematosus (SLE) treated with glucocorticoids (the case group) and two participants with femoral neck fracture (the control group). Unbiased transcriptome-wide single-cell RNA sequencing analysis and computational analyses were performed. Seventeen molecularly defined cell types were identified in the studied samples, including significantly dysregulated neutrophils and B cells in the case group. Additionally, fatty acid synthesis and aerobic oxidation were repressed, while fatty acid beta-oxidation was enhanced. Our results also preliminarily clarified the roles of the inflammatory response, substance metabolism, vascular injury, angiogenesis, cell proliferation, apoptosis, and dysregulated coagulation and fibrinolysis in glucocorticoid-induced ONFH. Notably, we list the pathways that were markedly altered in glucocorticoid-induced ONFH with SLE compared with femoral head fracture, as well as their common genes, which are potential early therapeutic targets. Our results provide new insights into the mechanism of glucocorticoid-induced ONFH and present potential clues for effective and functional manipulation of human glucocorticoid-induced ONFH, which could improve patient outcomes.

Bioinformatic analysis of related immune cell infiltration and key genes in the progression of osteonecrosis of the femoral head

“…Jiang et al's revelation of a close association between resting Mast cells and macrophages in ankylosing spondylitis combined with ONFH further substantiates our findings (38). Moreover, Wang et al's single-cell sequencing study, revealing a significant reduction in neutrophils and monocytes in ONFH patients, emphasizes the intricate relationship between ONFH and the dysregulation of immune cell ratios (39). Crucially, we observed a close correlation between APOD and dysregulated immune cells.…”

Carboxypeptidase M modulates BMSCs osteogenesis–adipogenesis via the MAPK/ERK pathway: An integrated single‐cell and bulk transcriptomic study

“…To date, three scRNA-seq datasets of the femoral head have been published. 11,20,21 For this study, we specifically selected five samples representing cases of osteoporosis or osteopenia. Despite the prevalence of osteonecrosis samples in the aforementioned dataset, due to potential cell loss in necrotic regions which might mask unique anatomical features and amplify transcriptomic signatures from other areas, we utilized osteoarthritis (OA) sample data as the control.…”

“…Given the accessibility of femoral heads discarded during joint replacement surgeries, along with their intact tissue structure and high cellular viability, these samples serve as an appropriate resource for single‐cell transcriptomic studies of the bone marrow niche. To date, three scRNA‐seq datasets of the femoral head have been published 11,20,21 . For this study, we specifically selected five samples representing cases of osteoporosis or osteopenia.…”

17 variants interaction of Wnt/β-catenin pathway associated with development of osteonecrosis of femoral head in Chinese Han population

“…Fat accumulation is often observed in the lesion bone marrow cavity of ONFH in the animal experiments as well as the clinical studies 39 , 40 . Here, we clearly showed not only the increase of serum LDLc, LDLc/HDLc and the decrease of HDLc but also the rise of PCT, MPV, and PDW parameters of ONFH patients, which at the first time provided forceful evidence that there were simultaneous lipid metabolic disorders and coagulation disturbance in the same research system of focusing on the roles of 17 variants in Wnt/β-catenin pathway in ONFH development.…”