Basic Study
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Stem Cells. Feb 26, 2024; 16(2): 163-175
Published online Feb 26, 2024. doi: 10.4252/wjsc.v16.i2.163
Effects of different concentrations of nicotinamide on hematopoietic stem cells cultured in vitro
Yan Ren, Yan-Ni Cui, Hong-Wei Wang
Yan Ren, Yan-Ni Cui, The Second Clinical Medical College, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Yan Ren, Yan-Ni Cui, Hong-Wei Wang, Department of Hematology, The Second Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Hong-Wei Wang, Department of Hematology, Key Laboratory of Molecular Diagnosis and Treatment of Blood Diseases in Shanxi Province, Taiyuan 030001, Shanxi Province, China
Co-first authors: Yan Ren and Yan-Ni Cui.
Author contributions: Ren Y and Cui YN designed and coordinated the study; Ren Y performed experiments and wrote the manuscript; Cui YN acquired and analyzed the data; Wang HW contributed to ideas, supervision, review and editing; and all authors approved the final version of the article.
Supported by the Science and Technology Department of Shanxi Province, No. YDZJSX2021B009; Health Commission of Shanxi Province, No. 2021XM07; and Shanxi Provincial Department of Education, No. 2023KY380.
Institutional review board statement: This study was approved by the Second Hospital of Shanxi Medical University (Approval No. 20230055).
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: No additional data are available.
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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Hong-Wei Wang, PhD, Professor, Department of Hematology, The Second Hospital of Shanxi Medical University, No. 382 Wuyi Road, Taiyuan 030001, Shanxi Province, China. wanghw68@hotmail.com
Received: October 18, 2023
Peer-review started: October 18, 2023
First decision: December 2, 2023
Revised: December 14, 2023
Accepted: January 12, 2024
Article in press: January 12, 2024
Published online: February 26, 2024
Processing time: 130 Days and 18.6 Hours
ARTICLE HIGHLIGHTS
Research background

The in vitro expansion strategy of increasing the number of hematopoietic stem cells (HSCs) in cord blood is expected to improve its clinical efficacy. Nicotinamide (NAM) is one of the small molecules that can promote the expansion of hematopoietic stem and progenitor cells (HSPCs) ex vivo, but its mechanism of action and its effects on short-term repopulating HSCs (ST-HSCs) and long-term repopulating HSCs (LT-HSCs) have not yet been established. Revealing the dominant subgroups of NAM and elucidating the relevant mechanisms not only helps to recommend the working concentration of NAM according to demand, but also helps to reveal the signaling pathways involved in the regulation of HSC proliferation and differentiation.

Research motivation

The effects of different concentrations of NAM on proliferation and differentiation of HSCs, as well as whether it affects sirtuin 1 (SIRT1) transcription levels, have not been reported. There are various small molecule substances used for in vitro culture of HSCs (including UM171, SR1, VPA, NAM and ID8), which may affect the maintenance, proliferation, differentiation and homing of HSCs by regulating different pathways, and different molecular pathways may have synergistic effects. This study aimed to provide a theoretical basis for the future joint application of multiple small molecules by elucidating the molecular mechanism of NAM. Our work is crucial for selecting the working concentration of NAM and predicting small molecules that have a synergistic effect with NAM.

Research objectives

To evaluate the effects and mechanisms of different concentrations of NAM on HSC proliferation and differentiation.

Research methods

In this study, we added different concentrations of NAM to serum-free culture medium inoculated with CD34+ cells. We then measure the number, molecular phenotype, cycle distribution, and apoptosis of each group of cells and explore the mechanism by detecting the levels of reactive oxygen species (ROS), inflammatory factors and related gene transcription.

Research results

We evaluated the expansion efficiency of different concentrations of NAM on HSPCs, ST-HSCs as well as LT-HSCs, and the results showed that 5 mmol/L and 10 mmol/L NAM were beneficial for maintaining HSPCs, with low concentrations (5 mmol/L) of NAM being more conducive to ST-HSCs expansion, while high concentrations (10 mmol/L) of NAM had a more significant effect on promoting LT-HSCs expansion. Low concentrations of NAM can better regulate the balance between proliferation and differentiation, thereby promoting effective expansion of HSCs.

Research conclusions

Low concentration of NAM did not inhibit but upregulated the transcription of SIRT1, promoting cell proliferation by activating the SIRT1–HIF1A pathway, delaying stem cell differentiation by increasing ROS clearance, and ultimately promoting effective expansion of HSCs.

Research perspectives

Drugs that specifically target LT-HSCs or ST-HSCs may help in the development of tailored HSC grafts that either facilitate sustained blood cell reconstitution or rapidly improve blood cell counts as a bridge after anticancer radiotherapy or chemotherapy. Our findings could allow adjustment of NAM concentrations according to expansion needs and may help predict small molecules that synergistically promote expansion with NAM.