Yang Yilin, Yang Mingyuan, Shi Dongliang, Chen Kai, Zhao Jian, He Shisheng, Bai Yushu, Shen Pinquan, Ni Haijian
Department of Orthopaedic Surgery The First Affiliated Hospital of Soochow University Suzhou China.
Department of Orthopaedics Changhai Hospital, Navy Medical University Shanghai China.
JOR Spine. 2021 Dec 8;4(4):e1184. doi: 10.1002/jsp2.1184. eCollection 2021 Dec.
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.
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.
A total of 11 distinct cell clusters were identified according to the genome-wide transcriptome profiles. -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.
Our single-cell analysis first revealed differences existed in the cellular states between AIS patients and healthy subjects and found the differentiation disruption of specific MSC and CPC clusters in AIS. Cell communication analysis provided the possible pathogenesis of osteoblast and chondrocyte differentiation dysfunction in AIS.
青少年特发性脊柱侧凸（AIS）患者存在椎体生长发育异常，与骨发育相关细胞的增殖和分化在其发病机制中起重要作用。然而，尚未构建出AIS中全面的单细胞水平分化图谱。
本研究使用高通量单细胞RNA测序（scRNA-seq）比较了AIS患者与健康受试者脊柱松质骨组织的单细胞水平细胞图谱，该技术涵盖多个细胞谱系，包括成骨细胞、软骨细胞、破骨细胞及相关免疫细胞。我们通过拟时间分析构建了与骨发育相关细胞谱系的分化轨迹，并进一步构建了与骨发育相关细胞和免疫细胞之间的细胞间通讯网络。
根据全基因组转录组图谱共鉴定出11个不同的细胞簇。分布随机邻域嵌入（t-SNE）分析显示间充质干细胞（MSC）可分为三个亚型：MSC-LOXL2、MSC-IGFBP5和MSC-GJA1。基因本体（GO）分析表明，MSC-GJA1可能比其他亚型具有更大的成骨细胞分化潜能。MSC-IGFBP5是仅在AIS中观察到的特定MSC亚型。存在两个不同的基因表达簇：OB-DPT和OB-OLFML2B，AIS来源的成骨细胞数量显著少于非AIS受试者。在AIS患者中，MSC-IGFBP5无法分化为成骨细胞，并表现出对细胞增殖的负调控和细胞死亡增加。CPC-PCNA被发现是仅在AIS患者中观察到的特定软骨细胞祖细胞（CPC）亚型。AIS中OC-BIRC3的细胞数量少于对照组。拟时间分析表明，AIS和对照受试者中破骨细胞可能存在两种不同的分化模式。AIS中的单核细胞主要分化为OC-CRISP3。
我们的单细胞分析首次揭示了AIS患者与健康受试者细胞状态的差异，并发现了AIS中特定MSC和CPC簇的分化破坏。细胞通讯分析提供了AIS中成骨细胞和软骨细胞分化功能障碍的可能发病机制。
