Wang Zun, Li Xiaohua, Yang Junxiao, Gong Yun, Zhang Huixi, Qiu Xiang, Liu Ying, Zhou Cui, Chen Yu, Greenbaum Jonathan, Cheng Liang, Hu Yihe, Xie Jie, Yang Xucheng, Li Yusheng, Schiller Martin R, Chen Yiping, Tan Lijun, Tang Si-Yuan, Shen Hui, Xiao Hong-Mei, Deng Hong-Wen
Xiangya School of Nursing, Central South University, Changsha, 410013, China; Laboratory of Molecular and Statistical Genetics, College of Life Sciences, Human Normal University, Changsha, 410081, China.
Tulane Center for Biomedical Informatics and Genomics, School of Medicine, Tulane University, New Orleans, 70112, USA.
Int J Biol Sci. 2021 Oct 11;17(15):4192-4206. doi: 10.7150/ijbs.61950. eCollection 2021.
Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stromal cells that have a critical role in the maintenance of skeletal tissues such as bone, cartilage, and the fat in bone marrow. In addition to providing microenvironmental support for hematopoietic processes, BM-MSCs can differentiate into various mesodermal lineages including osteoblast/osteocyte, chondrocyte, and adipocyte that are crucial for bone metabolism. While BM-MSCs have high cell-to-cell heterogeneity in gene expression, the cell subtypes that contribute to this heterogeneity in humans have not been characterized. To investigate the transcriptional diversity of BM-MSCs, we applied single-cell RNA sequencing (scRNA-seq) on freshly isolated CD271 BM-derived mononuclear cells (BM-MNCs) from two human subjects. We successfully identified LEPRCD45 BM-MSCs within the CD271 BM-MNC population, and further codified the BM-MSCs into distinct subpopulations corresponding to the osteogenic, chondrogenic, and adipogenic differentiation trajectories, as well as terminal-stage quiescent cells. Biological functional annotations of the transcriptomes suggest that osteoblast precursors induce angiogenesis coupled with osteogenesis, and chondrocyte precursors have the potential to differentiate into myocytes. We also discovered transcripts for several clusters of differentiation (CD) markers that were either highly expressed (e.g., CD167b, CD91, CD130 and CD118) or absent (e.g., CD74, CD217, CD148 and CD68) in BM-MSCs, representing potential novel markers for human BM-MSC purification. This study is the first systematic dissection of human BM-MSCs cell subtypes at the single-cell resolution, revealing an insight into the extent of their cellular heterogeneity and roles in maintaining bone homeostasis.
骨髓间充质干细胞（BM-MSCs）是多能基质细胞，在维持骨骼组织（如骨、软骨和骨髓中的脂肪）方面发挥着关键作用。除了为造血过程提供微环境支持外，BM-MSCs还可分化为各种中胚层谱系细胞，包括对骨代谢至关重要的成骨细胞/骨细胞、软骨细胞和脂肪细胞。虽然BM-MSCs在基因表达上具有高度的细胞间异质性，但导致人类这种异质性的细胞亚型尚未得到表征。为了研究BM-MSCs的转录多样性，我们对从两名人类受试者新鲜分离的CD271骨髓来源的单核细胞（BM-MNCs）进行了单细胞RNA测序（scRNA-seq）。我们在CD271 BM-MNC群体中成功鉴定出LEPRCD45 BM-MSCs，并进一步将BM-MSCs编码为对应成骨、软骨生成和脂肪生成分化轨迹以及终末期静止细胞的不同亚群。转录组的生物学功能注释表明，成骨细胞前体诱导血管生成并伴有成骨作用，软骨细胞前体具有分化为肌细胞的潜力。我们还发现了几种分化簇（CD）标志物的转录本，这些标志物在BM-MSCs中要么高表达（如CD167b、CD91、CD130和CD118），要么缺失（如CD74、CD217、CD148和CD68），它们代表了人类BM-MSC纯化的潜在新型标志物。这项研究首次在单细胞分辨率下对人类BM-MSCs细胞亚型进行了系统剖析，揭示了它们细胞异质性的程度及其在维持骨稳态中的作用。
