Letter to the Editor
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World J Stem Cells. Apr 26, 2022; 14(4): 314-317
Published online Apr 26, 2022. doi: 10.4252/wjsc.v14.i4.314
Skinny people serum factors promote the differentiation of multipotent stem cells into brown adipose tissue
Yuan-Long Gu, Wei Shen, Zhi-Peng Li, Bo Zhou, Zi-Jun Lin, Lian-Ping He
Yuan-Long Gu, Department of Interventional Oncology, Municipal Hospital Affiliated to Taizhou University, Taizhou 318000, Zhejiang Province, China
Wei Shen, Zhi-Peng Li, Bo Zhou, Zi-Jun Lin, Lian-Ping He, School of Medicine Taizhou University, Taizhou University, Taizhou 318000, Zhejiang Province, China
Author contributions: Shen W and Li ZP conceptualization, formal analysis; Zhou B, Li ZP and He LP writing of the original draft; Gu YL is responsible for writing, reviewing, and editing; all authors participated in drafting the manuscript and all have read, contributed to, and approved the final version of the manuscript.
Conflict-of-interest statement: Each author has reviewed the statement by the Baishideng Publishing Group on conflict of interest, and each author states that there is no commercial, professional, or personal conflict of interest relevant to the study and hereby attests that it complies with the principles of publishing ethics.
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: Yuan-Long Gu, MD, Resident, Department of Interventional Oncology, Municipal Hospital Affiliated to Taizhou University, No. 381 Zhongshan East Road, Jiaojiang District, Taizhou 318000, Zhejiang Province, China. ylgu@tzc.edu.cn
Received: December 12, 2021
Peer-review started: December 12, 2021
First decision: January 12, 2022
Revised: January 21, 2022
Accepted: March 16, 2022
Article in press: March 16, 2022
Published online: April 26, 2022
Abstract

The original study by Alessio et al reported that skinny people (SP) serum can promote the formation of brown adipocytes, but not the differentiation of white adipocytes. This finding may explain why SP do not often become obese, despite consuming more calories than the body needs. More importantly, they demonstrated that circulating factors in SP serum can promote the expression of UCP-1 protein, thereby reducing fat accumulation. In this study, only male serum samples were evaluated to avoid the interference of sex hormones in experiments, but adult males also synthesize estrogen, which is produced by the cells of the testes. At the same time, adult females secrete androgens, and females synthesize androgens that are mainly produced by the adrenal cortex. We believe that the approach of excluding sex hormone interference by sex selection alone may be flawed, so we comment on the article and debate the statistical analysis of the article.

Keywords: Androgen, Cytokine, Estrogen, Gender, Multipotent stem cell, Obesity

Core Tip: Both men and women secrete estrogens and androgens. In females, androgens are mainly derived from the sites of the zona fasciculata and the zona reticularis in the adrenal cortex. In males, estrogens are produced by surrounding tissues, such as the skin, through the conversion of testosterone. Sex hormones in the serum can affect the differentiation and the stereotype of multipotent stem cells.