Single‐cell RNA Seq reveals cellular landscape‐specific characteristics and potential etiologies for adolescent idiopathic scoliosis

Abstract

Backgrounds: Abnormal vertebral growth and development have been found in adolescent idiopathic scoliosis (AIS) patients, and the proliferation and differentiation of bone development-related cells play important roles in its pathogenesis. However, a comprehensive single-cell-level differentiation roadmap in AIS has not been achieved. Methods:The present study compared the single-cell level cellular landscapes of spinal cancellous bone tissues between AIS patients and healthy subjects using high throughput single-cell RNA sequencing (scRNA-seq), which covers multiple cellular lineages including osteoblast, chondrocyte, osteoclast and related immunocytes. We constructed the differentiation trajectories of bone development-related cell lineages through pseudotime analysis, and the intercellular-communication networks between bone development-related cells and immunocytes were further developed.Results: A total of 11 distinct cell clusters were identified according to the genome-wide transcriptome profiles. t-Distributed stochastic neighbor embedding (t-SNE) analysis showed that mesenchymal stem cells (MSC) were classified into three subtypes: MSC-LOXL2, MSC-IGFBP5, and MSC-GJA1. Gene ontology (GO) analysis showed that MSC-GJA1 might possess greater osteoblast differentiation potential than the others. MSC-IGFBP5 was the specific MSC subtype observed only in AIS. There were two distinct gene expression clusters: OB-DPT and OB-OLFML2B, and the counts of osteoblasts derived from AIS was significantly less than that of non-AIS subjects. In AIS patients, MSC-IGFBP5 failed to differentiate into osteoblasts and exhibited negative regulation of cell proliferation and enhanced cell death. CPC-PCNA was found to be the specific chondrocyte progenitor cell (CPC) subtype observed only in AIS patients. The cell counts of OC-BIRC3 in AIS were less than those in controls. Pseudotime analysis suggested two possible distinct osteoclast differentiation patterns in AIS and control subjects. Monocytes in AIS mainly differentiated into OC-CRISP3.

Association of IL‑6 and MMP‑3 gene polymorphisms with adolescent idiopathic scoliosis: A systematic review and meta‑analysis

“…Thus, active measures should be taken to prevent the occurrence of AIS ( 34 , 35 ). Specific pathogenic genes of AIS remain inconclusive, and greater attention has been paid to its genetic factors, especially the relationship between candidate genes and AIS ( 36 , 37 ). In recent years, some studies on the correlation between IL-6 rs1800795, MMP-3 rs3025058 and AIS have emerged, but the conclusions are not consistent.…”

Integrated single-cell analyses decode the developmental landscape of the human fetal spine

“…Meanwhile, EPYC + HAPLN1 + fibroblasts may be the seed cells for chondrocyte formation, which highly expressed chondrogenic genes of MATN4 and SOX9 . Because previous reports performed scRNA-seq on adult spinal tissues, the mesenchymal stem cell subgroup (MSC-GJA1) that may differentiate into osteoblast and the heterogeneity of chondrocytes was revealed ( Gan et al., 2021 ; Yang et al., 2021 ). To be complementary, our results of scRNA-seq on fetal spine showed the potential key subcluster to form chondrocytes, providing new insight on chondrocyte regeneration.…”

Research progress on the regulation of bone marrow stem cells by noncoding RNAs in adolescent idiopathic scoliosis

“…Yang et al performed single‐cell analysis of patients with AIS and compared the results to those of a control group. They found that the differentiation of specific MSCs and chondrocyte progenitor cell clusters were impaired in AIS, leading to dysfunctional differentiation of osteoblasts and chondrocytes (Yang, Yang, et al, 2021). Several genes and signaling pathways are involved in the abnormal chondrogenic differentiation of BMSCs in patients with AIS.…”

“…Once cartilage and growth plate tissues are formed, Wnt signaling continues to regulate the proliferation and differentiation of growth plate chondrocytes. On the other hand, inhibiting Wnt signaling transduction can induce differentiation of MSCs into cartilage (Yang et al, 2021; Zhu et al, 2017). Zhu et al presented the results of a GWAS involving 5953 patients with AIS and 8,137 controls.…”