Human umbilical-cord mesenchymal stem cells (hUCMSCs) are a safe and convenient source of MSCs and have shown beneficial effects in neonatal infection and sepsis animal models. However, the factors leading to improved outcomes are still unclear. The aim of this study was to investigate the antibacterial effect and regulation of antimicrobial resistance of hUCMSCs. We separated imipenem-resistant Pseudomonas aeruginosa (PA) from neonates and incubated it with hUCMSCs as well as their culture medium. Assessment of direct inhibition of bacterial growth was done by counting CFUs. The concentration of antibacterial peptides in the culture medium of hUCMSCs was measured. Standard PA was inoculated with a sub-inhibitory concentration of imipenem with and without hUCMSC conditioned medium and antimicrobial peptides. The sensitivity to imipenem was detected until PA showed resistance to imipenem. Outer membrane protein (OprD2) mRNA expression in PA before and after the induction of imipenem resistance was analysed. We found that HUCMSCs possessed direct antimicrobial properties against bacteria and could alleviate antibiotic resistance via reserving OprD2 expression in PA.

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The frequency of hearing loss-associated gene mutation was higher in NICU.There were hearing loss-associated gene mutations in the NICU, suggesting this mutation may complicate with perinatal high-risk factors.

Biofilm formation is easily found in patients suffered from ventilator-associated pneumonia (VAP) in neonatal intensive care unit (NICU) and makes the VAP infections not only harder to be treated but easier to relapse. In order to find some novel ways to inhibit biofilm formation, this study describe a previously unrecognized role for the human umbilical cord mesenchymal stem cells (hUCMSCs). In addition to multiple differentiation, hUCMSCs have the ability to prevent the biofilms formation in vitro by secreting antibacterial peptides (LL-37 and hBD-2). This occurred while P. aeruginosa PA27853 and hUCMSCs were cocultured, and the filtrated medium, which was the supernatant containing antibacterial peptides (5.9 ng/ml of LL-37, 1.77 ng/ml of hBD-2), and inhibited the growth of the bacterial biofilm on the surface of tracheal tube (2.5#, for preterm infant). Using microarrays, we were able to demonstrate that the antibacterial peptides from hUCMSC affected biofilm formation by downregulating the gene-encoded polysaccharide biosynthesis protein. In addition, in order to find out the most suitable concentration of hUCMSCs, P. aeruginosa was cocultured with eight-level concentrations of hUCMSCs, and we found that the concentration of LL-37 was positively correlated with the concentration of hUCMSCs. Meanwhile, the concentration of LL-37 became stable while the hUCMSC concentration reaches higher than 5 × 10 6   cells / ml . But the concentration of hBD-2 had no significant correlation with hUCMSCs. The collection of these stem cells is not only limited by ethics but also reduces host rejection. This makes it possible to use autologous hUCMSCs to treat neonatal VAP.