Published online Jul 26, 2023. doi: 10.4252/wjsc.v15.i7.751
Peer-review started: April 8, 2023
First decision: April 25, 2023
Revised: May 15, 2023
Accepted: June 6, 2023
Article in press: June 6, 2023
Published online: July 26, 2023
Processing time: 107 Days and 21.8 Hours
Zinc (Zn) is the second most abundant trace element after Fe, present in the human body. It is frequently reported in association with cell growth and proliferation, and its deficiency is considered to be a major disease contributing factor.
Trace elements are required to be supplemented in culturing media that will help to promote proliferation, cell division, and cellular growth, which will result in in vitro expansion of mesenchymal stem cells (MSCs) to achieve a desired number of cells for therapeutic dose.
In the present study, we aimed to determine the effect of Zn on in vitro growth and proliferation of human umbilical cord (hUC)-derived MSCs.
hUC-MSCs were isolated from human umbilical cord tissue and characterized based on immunocytochemistry, immunophenotyping, and tri-lineage differentiation. The impact of Zn on cytotoxicity and proliferation was determined by MTT and Alamar blue assay. To determine the effect of Zn on population doubling time (PDT), hUC-MSCs were cultured in media with and without Zn for several passages. An in vitro scratch assay was performed to analyze the effect of Zn on the wound healing and migration capability of hUC-MSCs. A cell adhesion assay was used to test the surface adhesiveness of hUC-MSCs. Transcriptional analysis of genes involved in the cell cycle, proliferation, migration, and self-renewal of hUC-MSCs was performed by quantitative real-time polymerase chain reaction. The protein expression of Lin28, a pluripotency marker, was analyzed by immunocytochemistry.
Zn at lower concentrations enhanced the rate of proliferation but at higher concentrations (> 100 µM), showed concentration dependent cytotoxicity in hUC-MSCs. hUC-MSCs treated with Zn exhibited a significantly greater healing and migration rate compared to untreated cells. Zn also increased the cell adhesion rate, and colony forming efficiency (CFE). In addition, Zn upregulated the expression of genes involved in the cell cycle (CDC20, CDK1, CCNA2, CDCA2), proliferation (TGFβ1, GDF5, hypoxia-inducible factor 1α), migration (CXCR4, VCAM1, VEGF-A), and self-renewal (OCT4, SOX2, NANOG) of hUC-MSCs. Expression of Lin28 protein was significantly increased in cells treated with Zn.
Our findings suggest that zinc enhances the proliferation rate of hUC-MSCs decreasing the PDT, and maintaining the CFE. Zn also enhances the cell adhesion, migration, and self-renewal of hUC-MSCs. These results highlight the essential role of Zn in cell growth and development.
Zinc at lower concentrations supported cell growth, division, and proliferation of MSCs while maintaining the MSC-specific characteristics, including pluripotency, migration, and cell adhesion. This will lead to produce large number of MSCs required for in vivo implanation in shorter period of time.