Feng XD, Zhu JQ, Zhou JH, Lin FY, Feng B, Shi XW, Pan QL, Yu J, Li LJ, Cao HC. Hypoxia-inducible factor-1α–mediated upregulation of CD99 promotes the proliferation of placental mesenchymal stem cells by regulating ERK1/2. World J Stem Cells 2021; 13(4): 317-330 [PMID: 33959221 DOI: 10.4252/wjsc.v13.i4.317]
Corresponding Author of This Article
Hong-Cui Cao, MD, PhD, Professor, State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, No. 79 Qingchun Road, Hangzhou 310003, Zhejiang Province, China. hccao@zju.edu.cn
Research Domain of This Article
Cell Biology
Article-Type of This Article
Basic Study
Open-Access Policy of This Article
This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Xu-Dong Feng, Jia-Qi Zhu, Jia-Hang Zhou, Fei-Yan Lin, Bing Feng, Xiao-Wei Shi, Qiao-Ling Pan, Jiong Yu, Lan-Juan Li, Hong-Cui Cao, State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, Zhejiang Province, China
Author contributions: Feng XD contributed to the experimental design, cellular and molecular biology experiments, and manuscript writing; Zhu JQ, Zhou JH and Lin FY contributed to the cellular experiment; Feng B and Shi XW joined in the molecular biology experiment; Feng XD, Pan QL and Yu J participated in analysis, interpretation of data and manuscript writing; Li LJ and Cao HC participated in the conception, design, study supervision, and manuscript writing; all authors reviewed and approved the final version of the manuscript.
Supported byStem Cell and Translational Research from the National Key Research and Development Program of China, No. 2020YFA0113003; and National Natural Science Foundation of China, No. 81971756.
Institutional review board statement: The study was reviewed and approved by the Research Ethics Committee of The First Affiliated Hospital, College of Medicine, Zhejiang University Institutional Review Board (Approval No. 2013-272).
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
Data sharing statement: The data used to support the findings of this study are available from the corresponding authors upon request.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Hong-Cui Cao, MD, PhD, Professor, State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, No. 79 Qingchun Road, Hangzhou 310003, Zhejiang Province, China. hccao@zju.edu.cn
Received: February 1, 2021 Peer-review started: February 1, 2021 First decision: February 28, 2021 Revised: March 11, 2021 Accepted: March 29, 2021 Article in press: March 29, 2021 Published online: April 26, 2021 Processing time: 80 Days and 6.7 Hours
ARTICLE HIGHLIGHTS
Research background
Mesenchymal stem cells (MSCs) are in a physiologically hypoxic microenvironment in the body, while the expansion of MSCs before cell therapy is typically performed at a 20%-21% oxygen level. Thus, investigators have become increasingly aware of the effects of oxygen levels on MSCs biology and are investigating the natural niche of those cells in vitro for more detailed results.
Research motivation
Although some researches have focused on the effect of hypoxia on MSCs, the underlying mechanisms remain unclear. Thus, this study concentrated on the mechanism of MSC proliferation.
Research objectives
In this study, we aimed to explore the effect of hypoxia on the proliferation capacity of human placenta-derived MSCs (hP-MSCs) and to elucidate underlying mechanisms.
Research methods
Hypoxic (2.5% oxygen) incubation was used to simulate the hypoxic microenvironment. Cell counting kit-8, 5-ethynyl-20-deoxyuridine incorporation assays, and flow cytometry assay were performed to evaluate the proliferation rate and the cell cycle profile of hP-MSCs. Additionally, proliferation-related and MAPK/ERK signaling pathway-related proteins were evaluated by western blotting and immunofluorescence assays. Small interfering RNA-mediated hypoxia-inducible factor 1α (HIF-1α) or CD99 knockdown in hP-MSCs, luciferase reporter assays, and the ERK1/2 signaling inhibitor PD98059 were used to elucidate the regulatory network of hypoxia on hP-MSCs proliferation.
Research results
Hypoxic culture enhanced the proliferation capacity of hP-MSCs by modulating cell cycle progression. Western blotting assay results further confirmed that hP-MSCs cultured under hypoxia exhibited increased cyclin E1, cyclin-dependent kinase 2, and cyclin A2 expression and decreased p21 expression. In addition, CD99 expression was directly regulated by HIF-1α under hypoxia. Also, CD99-specific small interfering RNAs or the ERK1/2 signaling inhibitor PD98059 abrogated the hypoxia-induced increase of cell proliferation, which further confirmed the influence of HIF-1α/CD99/ERK axis on hP-MSC proliferation.
Research conclusions
Hypoxia promoted hP-MSC proliferation in vitro in a manner dependent on the HIF-1α/CD99/ERK axis. In detail, CD99 activated pathways that transport ERK1/2 to the nucleus, resulting in increased activity of cell cycle-associated proteins.
Research perspectives
This study contributes to the understanding of MSC biology, especially the effect of hypoxia on MSC proliferation capacity.
