A highly sensitive and specific Homo1-based real-time qPCR method for quantification of human umbilical cord mesenchymal stem cells in rats.

BACKGROUND: Owing to the characteristics of easier access in vitro, low immunogenicity, and high plasticity, human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are considered as a promising cell-based drugs for clinical application. No internationally recognized technology exists to evaluate the pharmacokinetics and distribution of cell-based drugs in vivo. METHODS: We determined the human-specific gene sequence, Homo1, from differential fragments Homo sapiens mitochondrion and Rattus norvegicus mitochondrion. The expression of Homo1 was utilized to determine the distribution of UC-MSCs in the normal and diabetic nephropathy (DN) rats. RESULTS: We observed a significant correlation between the number of UC-MSCs and the expression level of Homo1. Following intravenous transplantation, the blood levels of UC-MSCs peaked at 30 min. A large amount of intravenously injected MSCs were trapped in the lungs, but the number of them decreased rapidly after 24 h. Additionally, the distribution of UC-MSCs in the kidneys of DN rats was significantly higher than that of normal rats. CONCLUSIONS: In this study, we establish a highly sensitive and specific Homo1-based real-time quantitative PCR method to quantify the distribution of human UC-MSCs in rats. The method provides guidelines for the safety research of cells in preclinical stages.

Human Umbilical Cord Mesenchymal Stem Cells Promote Macrophage PD-L1 Expression and Attenuate Acute Lung Injury in Mice.

BACKGROUND: Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) remains a serious clinical problem but has no approved pharmacotherapy. Mesenchymal stem cells (MSCs) represent an attractive therapeutic tool for tissue damage and inflammation owing to their unique immunomodulatory properties. The present study aims to explore the therapeutic effect and underlying mechanisms of human umbilical cord MSCs (UC-MSCs) in ALI mice. OBJECTIVE: In this study, we identify a novel mechanism for human umbilical cord-derived MSCs (UC-MSCs)-mediated immunomodulation through PGE2-dependent reprogramming of host macrophages to promote their PD-L1 expression. Our study suggests that UC-MSCs or primed- UC-MSCs offer new therapeutic approaches for lung inflammatory diseases. METHODS: Lipopolysaccharide (LPS)-induced ALI mice were injected with 5×105 UC-MSCs via the tail vein after 4 hours of LPS exposure. After 24 hours of UC-MSC administration, the total protein concentration and cell number in the bronchoalveolar lavage fluid (BALF) and cytokine levels in the lung tissue were measured. Lung pathological changes and macrophage infiltration after UCMSC treatment were analyzed. Moreover, in vitro co-culture experiments were performed to analyze cytokine levels of RAW264.7 cells and Jurkat T cells. RESULTS: UC-MSC treatment significantly improved LPS-induced ALI, as indicated by decreased total protein exudation concentration and cell number in BALF and reduced pathological damage in ALI mice. UC-MSCs could inhibit pro-inflammatory cytokine levels (IL-1ß, TNF-α, MCP-1, IL-2, and IFN-γ), while enhancing anti-inflammatory cytokine IL-10 expression, as well as reducing macrophage infiltration into the injured lung tissue. Importantly, UC-MSC administration increased programmed cell death protein ligand 1 (PD-L1) expression in the lung macrophages. Mechanistically, UC-MSCs upregulated cyclooxygenase-2 (COX2) expression and prostaglandin E2 (PGE2) secretion in response to LPS stimulation. UC-MSCs reduced the inflammatory cytokine levels in murine macrophage Raw264.7 through the COX2/PGE2 axis. Furthermore, UC-MSC- derived PGE2 enhanced PD-L1 expression in RAW264.7 cells, which in turn promoted programmed cell death protein 1 (PD-1) expression and reduced IL-2 and IFN-γ production in Jurkat T cells. CONCLUSION: Our results suggest that UC-MSCs attenuate ALI via PGE2-dependent reprogramming of macrophages to promote their PD-L1 expression.

Human umbilical cord-derived mesenchymal stem cells prevent the progression of early diabetic nephropathy through inhibiting inflammation and fibrosis.

BACKGROUND: Diabetic nephropathy (DN) is one of the most serious complications of diabetes and the leading cause of end-stage chronic kidney disease. Currently, there are no effective drugs for treating DN. Therefore, novel and effective strategies to ameliorate DN at the early stage should be identified. This study aimed to explore the effectiveness and underlying mechanisms of human umbilical cord mesenchymal stem cells (UC-MSCs) in DN. METHODS: We identified the basic biological properties and examined the multilineage differentiation potential of UC-MSCs. Streptozotocin (STZ)-induced DN rats were infused with 2 × 106 UC-MSCs via the tail vein at week 6. After 2 weeks, we measured blood glucose level, levels of renal function parameters in the blood and urine, and cytokine levels in the kidney and blood, and analyzed renal pathological changes after UC-MSC treatment. We also determined the colonization of UC-MSCs in the kidney with or without STZ injection. Moreover, in vitro experiments were performed to analyze cytokine levels of renal tubular epithelial cell lines (NRK-52E, HK2) and human renal glomerular endothelial cell line (hrGECs). RESULTS: UC-MSCs significantly ameliorated functional parameters, such as 24-h urinary protein, creatinine clearance rate, serum creatinine, urea nitrogen, and renal hypertrophy index. Pathological changes in the kidney were manifested by significant reductions in renal vacuole degeneration, inflammatory cell infiltration, and renal interstitial fibrosis after UC-MSC treatment. We observed that the number of UC-MSCs recruited to the injured kidneys was increased compared with the controls. UC-MSCs apparently reduced the levels of pro-inflammatory cytokines (IL-6, IL-1ß, and TNF-α) and pro-fibrotic factor (TGF-ß) in the kidney and blood of DN rats. In vitro experiments showed that UC-MSC conditioned medium and UC-MSC-derived exosomes decreased the production of these cytokines in high glucose-injured renal tubular epithelial cells, and renal glomerular endothelial cells. Moreover, UC-MSCs secreted large amounts of growth factors including epidermal growth factor, fibroblast growth factor, hepatocyte growth factor, and vascular endothelial growth factor. CONCLUSION: UC-MSCs can effectively improve the renal function, inhibit inflammation and fibrosis, and prevent its progression in a model of diabetes-induced chronic renal injury, indicating that UC-MSCs could be a promising treatment strategy for DN.

All-trans retinoic acid improves goat oocyte nuclear maturation and reduces apoptotic cumulus cells during in vitro maturation.

All-trans retinoic acid (t-RA) is a natural component and representative physiologically active metabolite of vitamin A, having multiple physiologic functions. The objective of this study was to evaluate the effect of t-RA on goat oocyte maturation and cumulus cell apoptosis during in vitro maturation (IVM). Immature goat cumulus-oocyte complexes (COCs) were matured in vitro in the absence or presence of t-RA at concentrations of 10 nmol/L, 100 nmol/L and 1000 nmol/L. Oocyte maturation and embryo development were assessed by polar body formation and parthenogenetic activation, respectively. Oocyte survival was checked by Trypan blue staining. Apoptosis of cumulus cells was analyzed by terminal deoxynucleotidyl transferase nick end labeling staining and quantitative real-time PCR. In comparison with the control group, 100 nmol/L and 10 nmol/L t-RA significantly improved goat nuclear oocyte maturation and survival (P < 0.05). Addition of 1000 nmol/L t-RA improved nuclear maturation (P < 0.05), but had no effect on survival of goat oocytes. t-RA had no positive effect on goat parthenogenetic embryonic cleavage, blastocyst formation or total cell numbers. However, t-RA inhibits the apoptosis of cumulus cells (P < 0.01). t-RA treatment up-regulated the expression of B-cell lymphoma 2 (BCL-2), catalase (CAT) (P < 0.05) and down-regulated the expression of Caspase-8 (P < 0.05). In conclusion, t-RA has positive effects on goat oocyte nuclear maturation and reduces apoptotic cumulus cells during IVM.