Human umbilical cord mesenchymal stem cells reverse depression in rats induced by chronic unpredictable mild stress combined with lipopolysaccharide

BACKGROUND

Inflammation and oxidative stress are considered crucial to the pathogenesis of depression. Rat models of depression can be created by combined treatments of chronic unpredictable mild stress (CUMS) and lipopolysaccharide (LPS). Behaviors associated with depression could be improved by treatment with mesenchymal stem cells (MSCs) owing to immunomodulatory functions of the cells. Therapeutic potentials of the MSCs to reverse pro-inflammatory cytokines, proteins, and metabolites were identified by transcriptomic, proteomic, and metabolomic analysis, respectively.

METHODS

A depression model was established in male SD rats by 2 weeks of CUMS combined with LPS. The models were verified by behavioral tests, namely SPT, OFT, EPM, and qRT-PCR for pro-inflammatory cytokines. Such depressed rats were administered human umbilical cord MSCs (hUC-MSCs) via the tail vein once a week for 2 and 4 weeks. The homing capacity was confirmed by detection of the fluorescent dye on day 7 after the hUC-MSCs were labeled with CM-Dil and administered. The expression of GFAP in astrocytes serves as a biomarker of CNS disorders and IBA1 in microglia serves as a marker of microglia activation were detected by immunohistochemistry at 2 and 4 weeks after final administration of hUC-MSCs. At the same time, transcriptomics of rat hippocampal tissue, proteomic and metabolomic analysis of the serum from the normal, depressed, and treated rats were also compared.

RESULTS

Reliable models of rat depression were successfully induced by treatments of CUMS combined with LPS. Rat depression behaviors, pro-inflammatory cytokines, and morphological disorders of the hippocampus associated with depression were reversed in 4 weeks by hUC-MSC treatment. hUC-MSCs could reach the hippocampus CA1 region through the blood circulation on day 7 after administration owing to the disruption of blood brain barrier (BBB) by microglial activation from depression. Differentiations of whole-genome expression, protein, and metabolite profiles between the normal and depression-modeled rats, which were analyzed by transcriptomic, proteomics, and metabolomics, further verified the high association with depression behaviors.

CONCLUSIONS

Rat depression can be reversed or recovered by treatment with hUC-MSCs.