Mycoplasma Ocular Infection in Subretinal Graft Transplantation of iPS Cells-Derived Retinal Pigment Epithelial Cells.

Purpose: To report occurrence of acute severe inflammation after surgical implantation of mycoplasma-infected induced pluripotent stem cell-derived RPE (iPS-RPE) cells into the eyes of healthy primates, and determine the immunopathological mechanisms of the inflammation. Methods: Ophthalmic allogeneic transplantation of iPS-RPE cells was performed in the subretina of major histocompatibility complex (MHC)-matched (two eyes) and MHC-mismatched (one eye) healthy cynomolgus monkeys. The clinical course after transplantation was observed using color fundus photography, fluorescence angiography, and optical coherence tomography. After the animals were killed at 1 month after surgery, eyeballs were removed and pathologically examined. Microorganisms were analyzed by PCR methods and BLAST analysis using preserved graft iPS-RPE cells and the recipients' vitreous humor. Mixed lymphocyte-RPE assay was performed on the mycoplasma-infected and noninfected iPS-RPE cells in vitro. Results: In tested eyes, abnormal findings were observed in the grafted retina 2 weeks after surgery. Here, we observed retinal vasculitis and hemorrhage, retinal detachment, and infiltration of inflammatory cells into the retina of the eyes. One month after surgery, animals were killed due to the severe immune responses observed. Using PCR methods, sequence analysis detected mycoplasma-DNA (Mycoplasma arginini species) in both the grafted RPE cells and the collected vitreous fluids of the monkeys. Mixed lymphocyte-RPE assay revealed that the infected iPS-RPE cells enhanced the proliferation of inflammatory cells in vitro. Conclusions: Transplantation of graft iPS-RPE cells contaminated with mycoplasma into the subretina caused severe ocular inflammation. Mycoplasma possesses the ability to cause immune responses in the host.

Modulation of probe-genomic DNA interaction within the confined interior of a reverse micelle: Is the bulk-like properties of water truly achieved in large reverse micelles?

The prime motivation of the present study is to explore the effect of reverse micellar confinement on the binding interaction of an anthracene-based probe 9-methyl anthroate with herring-sperm DNA. The structural modification of the genomic DNA from its native B-form to the non-native C-form and subsequently to the condensed Ψ-form as a function of the level of hydration (W0, defined as [water] / [surfactant]) of the reverse micellar core is found to reveal a remarkable regulatory role on the stability of the stacking interaction (intercalation) of the probe within the DNA helix; the interaction being progressively stabilized at higher W0. Particularly, a close perusal of the dynamical aspects of the interaction is found to be counter-intuitive to the popular notion of the properties of the confined water within the reverse micelles typically approaching bulk-like properties at sufficiently high hydration levels (W0 > 10).

Ethanol effect on gold nanoparticle aggregation state and its implication in the interaction mechanism with DNA.

The equilibria and kinetics aspects of the binding of small gold nanoparticles, AuNPs, stabilized with tiopronin to DNA in B and C conformation (B-DNA and C-DNA), has been investigated in ethanol/water mixtures using different techniques. Two modes of binding are displayed: groove binding and partial intercalation, depending on the ethanol content, [EtOH], and the molar ratio, R = CAuNPs/CDNA. Two reaction mechanisms are proposed for AuNPs/DNA interaction in each polymer conformation, and the reaction parameters are evaluated. For lower ethanol levels, ([EtOH] up to 30%), when DNA is in the B form, the simplest mechanism according to the kinetic and thermodynamic results proved to be a three-step series mechanism reaction scheme which evolves in the formation of the groove complex. In this context, solvent hydration as well as the solvent effective viscosity are the main factors that influence kinetics. In contrast, for high ethanol levels, when DNA is in a C-like conformation, the mechanism is more complex involving three parallel reactions, in which AuNPs self-aggregation plays a key role in the switch from partial intercalation to groove binding. On the whole, it is evident that AuNPs aggregation and the DNA conformation are two key factors that must be taken into account in order to control the mechanism of AuNPs/DNA interaction.

The electrostatic origin of low-hydration polymorphism in DNA.

In recent years, significant progress has been made towards uncovering the physical mechanisms of low-hydration polymorphism in double-helical DNA. The effect appears to be mechanistically similar in different biological systems, and it is due to the ability of water to form spanning H-bonded networks around biomacromolecules via a quasi-two-dimensional percolation transition. In the case of DNA, disintegration of the spanning H-bonded network leads to electrostatic condensation of DNA strands because, below the percolation threshold, water loses its high dielectric permittivity, whereas the concentration of neutralizing counterions becomes high. In this Concept article arguments propose that this simple electrostatic mechanism represents the universal origin of low-hydration polymorphism in DNA.