METHODS: By using a microarray-based global gene expression profiling system, this study aimed to decipher the underlying molecular pathways that may mediate the immunosuppressive activity of umbilical cord-derived MSCs (UC-MSCs) on activated T cells.
RESULTS: In the presence of UC-MSCs, the proliferation of activated T cells was suppressed in a dose-depended manner by cell-to-cell contact mode via an active cell-cycle arrest at the G0/G1 phase of the cell cycle. The microarray analysis revealed that particularly, IFNG, CXCL9, IL2, IL2RA and CCND3 genes were down-regulated, whereas IL11, VSIG4, GFA1, TIMP3 and BBC3 genes were up-regulated by UC-MSCs. The dysregulated gene clusters associated with immune-response-related ontologies, namely, lymphocyte proliferation or activation, apoptosis and cell cycle, were further analyzed.
CONCLUSIONS: Among the nine canonical pathways identified, three pathways (namely T-helper cell differentiation, cyclins and cell cycle regulation, and gap/tight junction signalling pathways) were highly enriched with these dysregulated genes. The pathways represent putative molecular pathways through which UC-MSCs elicit immunosuppressive activity toward activated T cells. This study provides a global snapshot of gene networks and pathways that contribute to the ability of UC-MSCs to suppress activated T cells.
METHODS: Three segments of the whole UC, each 3 cm in length, were identified anatomically as the maternal, middle and fetal segments. The hWJMSCs from the different segments were analyzed via trypan blue exclusion assay to determine the growth kinetics and cell viability, flow cytometry for immunophenotyping and immunofluorescence and reverse transcriptase polymerase chain reaction (RT-PCR) for expression of stromal cell transcriptional factors. Furthermore, the trilineage differentiation potential (osteogenic, adipogenic and chondrogenic) of these cells was also assessed.
RESULTS: hWJMSCs isolated from the maternal and fetal segments displayed greater viability and possessed a significantly higher proliferation rate compared with cells from the middle segment. Immunophenotyping revealed that hWJMSCs derived from all three segments expressed the MSC markers CD105, CD73, CD90, CD44, CD13 and CD29, as well as HLA-ABC and HLA-DR, but were negative for hematopoietic markers CD14, CD34 and CD45. Analysis of the embryonic markers showed that all three segments expressed Nanog and Oct 3/4, but only the maternal and fetal segments expressed SSEA 4 and TRA-160. Cells from all three segments were able to differentiate into chondrogenic, osteogenic and adipogenic lineages with the middle segments showing much lower differentiation potential compared with the other two segments.
CONCLUSIONS: hWJMSCs derived from the maternal and fetal segments of the UC are a good source of MSCs compared with cells from the middle segment because of their higher proliferation rate and viability. Fetal and maternal segments are the preferred cell source for bone regeneration.
METHODS: MSCs and Oh-LAAO were isolated and characterized by standard methodologies. The effects of the experimental therapies were evaluated in C57/BL6 mice. The animal study groups consisted of full-thickness uninfected and MRSA-infected wound models which received Oh-LAAO, MSCs, or both. Oh-LAAO was administered directly on the wound while MSCs were delivered via intradermal injections. The animals were housed individually with wound measurements taken on days 0, 3, and 7. Histological analyses and bacterial enumeration were performed on wound biopsies to determine the efficacy of each treatment.
RESULTS: Immunophenotyping and differentiation assays conducted on isolated MSCs indicated expression of standard cell surface markers and plasticity which corresponds to published data. Characterization of Oh-LAAO by proteomics, enzymatic, and antibacterial assays confirmed the identity, purity, and functionality of the enzyme prior to use in our subsequent studies. Individual treatments with MSCs and Oh-LAAO in the infected model resulted in reduction of MRSA load by one order of magnitude to the approximate range of 6 log10 colony-forming units (CFU) compared to untreated controls (7.3 log10 CFU). Similar wound healing and improvements in histological parameters were observed between the two groups. Co-administration of MSCs and Oh-LAAO reduced bacterial burden by approximately two orders of magnitude to 5.1 log10 CFU. Wound closure measurements and histology analysis of biopsies obtained from the combinational therapy group indicated significant enhancement in the wound healing process compared to all other groups.
CONCLUSIONS: We demonstrated that co-administration of MSCs and Oh-LAAO into a mouse model of MRSA-infected wounds exhibited a synergistic antibacterial effect which significantly reduced the bacterial count and accelerated the wound healing process.