Published online May 26, 2022. doi: 10.4252/wjsc.v14.i5.347
Peer-review started: January 28, 2022
First decision: March 11, 2022
Revised: March 25, 2022
Accepted: May 8, 2022
Article in press: May 8, 2022
Published online: May 26, 2022
Processing time: 118 Days and 1.8 Hours
Exposure to high doses of ionizing radiation is known to cause acute radiation syndrome, such as damage to hematopoietic, gastrointestinal, and neurovascular systems depending on the dose. To avoid acute radiation syndrome, regenerative therapy will be a good therapeutic option. Therefore, stem cell therapy may be one of the promising candidates to ameliorate acute radiation syndrome because of its regenerative and damage sensing potential.
Stem cells isolated from Wharton’s jelly of the umbilical cord are a unique source of mesenchymal stromal/stem cells (MSCs), which have been reported to be safe when administered to recipients without inducing any adverse effects or teratoma formation. Recently, we reported that human Wharton’s jelly-MSCs (hWJ-MSCs) and their conditioned medium (CM) have significant therapeutic radioprotective potential in lethally irradiated mice. These findings motivated us to identify a unique feature of hWJ-MSCs over other sources of stem cells for the understanding of its radioprotective mechanism and deciphering the role of the granulocyte-colony stimulating factor (G-CSF) present in hWJ-MSC-CM.
The main objective was to understand the radioprotective mechanism of soluble factors secreted by hWJ-MSCs and identification of their unique genes.
Propidium iodide staining, endogenous spleen colony-forming assay, and survival study were carried out for radioprotection studies. Homeostasis-driven proliferation assay was performed for in vivo lymphocyte proliferation measurement. Neutralization of G-CSF with anti-G-CSF was done to investigate the role of G-CSF in therapeutic radioprotection. Analysis of RNAseq data was performed to find the unique genes of WJ-MSCs by comparing them with bone marrow mesenchymal stem cells, embryonic stem cells, and human fibroblasts. Gene enrichment analysis and protein-protein interaction network were used for pathway analysis.
Co-culture of irradiated murine splenic lymphocytes with WJ-MSCs offered significant radioprotection to lymphocytes. WJ-MSC transplantation increased the homeostasis-driven proliferation of the lymphocytes. Neutralization of WJ-MSC-CM with G-CSF antibody abolished therapeutic radioprotection. Transcriptome analysis showed that WJ-MSCs share several common genes with bone marrow MSCs and embryonic stem cells and express a high level of unique genes such as interleukin (IL)1-α, IL1-β, IL-6, CXCL3, CXCL5, CXCL8, CXCL2, CCL2, FLT-1, and IL-33. It was also observed that WJ-MSCs preferentially modulated several cellular pathways and processes that are responsible for the repair and regeneration of damaged tissues compared to other sources of stem cells. Cytokine-based network analysis showed that most of the radiosensitive tissues have a more complex network for the elevated cytokines.
This study showed the role of cytokine G-CSF present in WJ-MSC-CM in eliciting therapeutic radioprotection. Systemic infusion of WJ-MSC-CM may have significant potential for treating accidental radiation exposed victims.
WJ-MSC-CM holds significant therapeutic radioprotective ability and has translational potential for its use during radiation accidents.