Proteomics Analysis of the Protective Effect of Polydeoxyribonucleotide Extracted from Sea Cucumber (Apostichopus japonicus) Sperm in a Hydrogen Peroxide-Induced RAW264.7 Cell Injury Model.

Sea cucumber viscera contain various naturally occurring active substances, but they are often underutilized during sea cucumber processing. Polydeoxyribonucleotide (PDRN) is an adenosine A2A receptor agonist that activates the A2A receptor to produce various biological effects. Currently, most studies on the activity of PDRN have focused on its anti-inflammatory, anti-apoptotic, and tissue repair properties, yet relatively few studies have investigated its antioxidant activity. In this study, we reported for the first time that PDRN was extracted from the sperm of Apostichopus japonicus (AJS-PDRN), and we evaluated its antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and hydroxyl radical scavenging assays. An in vitro injury model was established using H2O2-induced oxidative damage in RAW264.7 cells, and we investigated the protective effect of AJS-PDRN on these cells. Additionally, we explored the potential mechanism by which AJS-PDRN protects RAW264.7 cells from damage using iTRAQ proteomics analysis. The results showed that AJS-PDRN possessed excellent antioxidant activity and could significantly scavenge DPPH, ABTS, and hydroxyl radicals. In vitro antioxidant assays demonstrated that AJS-PDRN was cytoprotective and significantly enhanced the antioxidant capacity of RAW264.7 cells. The results of GO enrichment and KEGG pathway analysis indicate that the protective effects of AJS-PDRN pretreatment on RAW264.7 cells are primarily achieved through the regulation of immune and inflammatory responses, modulation of the extracellular matrix and signal transduction pathways, promotion of membrane repair, and enhancement of cellular antioxidant capacity. The results of a protein-protein interaction (PPI) network analysis indicate that AJS-PDRN reduces cellular oxidative damage by upregulating the expression of intracellular selenoprotein family members. In summary, our findings reveal that AJS-PDRN mitigates H2O2-induced oxidative damage through multiple pathways, underscoring its significant potential in the prevention and treatment of diseases caused by oxidative stress.

Immunomodulatory effects of mesenchymal stem cells in a rat corneal allograft rejection model.

Mesenchymal stem cells (MSCs) are promising candidates for immunomodulatory therapy that are currently being tested in several organ transplant rejection models. In this study, we tested the immunomodulatory effects of MSC injection in a rat model of corneal allograft rejection. MSCs were isolated and cultured from bone marrow of Wistar rats. A rat corneal allograft rejection model was established using Wistar rats as donors and Lewis rats as recipients. Lewis rats were randomly separated into 12 groups and treated with MSCs alone or MSCs combined with Cyclosporin A (CsA) at different doses. In MSC-treated rats, the T cell response to ConA was evaluated, Th1/Th2 cytokines produced by T lymphocytes were measured, and the number of CD4+CD25+Foxp3+ regulatory T cells (Treg) was assessed. Results demonstrated that postoperative injection of MSCs prolonged graft survival time. MSCs significantly inhibited proliferation of pathogenic T cells in vitro and prevented T cell response in vivo (p < 0.05). Postoperative injection also reduced Th1 pro-inflammatory cytokines and elevated IL-4 cytokine secretion from T lymphocytes derived from cornea-transplanted rats. In addition, Tregs were upregulated by MSC treatment. Unexpectedly, the application of MSCs combined with low dose CsA therapy (1 mg/kg) accelerated graft rejection compared with postoperative MSC therapy alone. However, when 2 mg/kg CsA was given together with MSCs, graft survival was significantly prolonged. These results suggested that MSCs could exert therapeutic effect against corneal allograft rejection, and further investigation of combined MSC and CsA treatment be required as opposite effects were observed depending on CsA dose.

[Investigation of the role of mesenchymal stem cells on keratoplasty rejection].

OBJECTIVE: To investigate the effect of mesenchymal stem cells (MSC) on keratoplasty rejection in a rat mode. METHODS: MSC from bone marrow of Wistar rats was cultured. Corneas of Wistar rats (donors) were transplanted to Lewis rats (recipients). Transplanted rats were randomly divided into A, B, C three groups. Rats in group B were injected with MSC suspended in PBS via the tail vein continually for three days before the surgery, while rats in group C accepted similar MSC transplantation after the surgery. The rats in group A were given the same volume of PBS. Grafts were scored for corneal transparency, edema and extent of neovascularization by slit lamp observation. Expressions of CD(4), CD(8), CD(25) and CD(45) in corneas 10 days after transplantation were examined by immunohistochemistry. RESULTS: The survival time of the corneal grafts in group C [(9.9 ± 0.69) d] was significantly prolonged compared with that of the group A and group B [(11.83 ± 0.54), (16.89 ± 1.91) d] (F = 5.732, P = 0.001, 0.019). Expression level of CD(4), CD(8), CD(25) of the corneal grafts in group C was lower than that of group A and group B (t = 2.477, 2.359, 2.445, P = 0.024, 0.042, 0.030). CONCLUSION: Post-operative injection of MSCs could inhibit keratoplasty rejection and prolong the corneal allografts survival in a rat model.

Mesenchymal stem cells ameliorate experimental autoimmune uveoretinitis by comprehensive modulation of systemic autoimmunity.

PURPOSE: The authors studied the therapeutic effect of rat mesenchymal stem cells (MSCs) on experimental autoimmune uveoretinitis (EAU) induced in rats by peptide 1169-1191 of the interphotoreceptor retinoid-binding protein (IRBP). METHODS: The authors intravenously injected syngeneic (isolated from Lewis rats) or allogeneic (isolated from Wistar rats) MSCs into IRBP-induced EAU Lewis rats, either before disease onset (simultaneous with immunization, preventive protocol) or at different time points after disease onset (therapeutic protocol). T-cell response to IRBP 1169-1191 from MSC-treated rats was evaluated, Th1/Th2/Th17 cytokines produced by lymphocytes were measured, and CD4(+)CD25(+) regulatory T cells (Treg) were detected. RESULTS: MSC administration before disease onset not only strikingly reduced the severity of EAU, it also delayed the onset of the disease. MSC administration was also effective after disease onset and at the peak of disease, but not after disease stabilization. Clinical efficacy for all treatments was consistent with reduced cellular infiltrates and milder uveal and retinal impairment. T-cell response to IRBP 1169-1191 from MSC-treated rats was inhibited. MSCs significantly decreased the production of IFN-γ and IL-17 and increased the production of IL-10 of T lymphocytes from EAU rats either in vivo or in vitro. Allogeneic and syngeneic MSCs showed a similar immunosuppression potential with regard to clinical effect, T cell proliferation, and cytokine secretion, and MSC therapy upregulated Treg cells. CONCLUSIONS: These data suggest that the immunoregulatory properties of MSCs effectively interfere with the autoimmune attack in the course of EAU through the comprehensive modulation of systemic autoimmunity.

Role of mesenchymal stem cells in immunological rejection of organ transplantation.

The discovery that Mesenchymal Stem Cells (MSCs) can strongly inhibit T cell proliferation in vitro and in vivo and exert similar inhibitory effects on B cells, dendritic cells, and natural killer cells has highlighted the potential for clinical translation of these cells as a new class of stem cell therapy for autoimmune disease, organ transplantation and treatment of graft-versus-host disease (GVHD). Even though the mechanism underlying these immunosuppressive effects of MSCs has not been clearly defined, their immunosuppressive properties are already being exploited in the clinical setting. Most of these early clinical studies are investigating the effect of MSCs in suppressing GVHD after allogenenic hematopoietic stem cell transplantation (HSCT). Additional studies, mostly in animal models, are being conducted in solid organ transplantation, such as: heart, renal, liver and skin. While the early results of these studies are conflicting, the potential for clinical benefit remains high and further studies are warranted in order to discover the best methods and settings for consistent clinical results. MSCs have opened a series of opportunities for researchers in the areas of transplantation and autoimmune disease. While it is important not to overestimate the potential therapeutic effects of MSCs, and well-designed preclinical trials should be done before clinical use.