Evaluation of Acridine Orange Derivatives as DNA-Targeted Radiopharmaceuticals for Auger Therapy: Influence of the Radionuclide and Distance to DNA

A new family of ^99mTc(I)- tricarbonyl complexes and ¹²⁵I-heteroaromatic compounds bearing an acridine orange (AO) DNA targeting unit was evaluated for Auger therapy. Characterization of the DNA interaction, performed with the non-radioactive Re and ¹²⁷I congeners, confirmed that all compounds act as DNA intercalators. Both classes of compounds induce double strand breaks (DSB) in plasmid DNA but the extent of DNA damage is strongly dependent on the linker between the Auger emitter (^99mTc or ¹²⁵I) and the AO moiety. The in vitro evaluation was complemented with molecular docking studies and Monte Carlo simulations of the energy deposited at the nanometric scale, which corroborated the experimental data. Two of the tested compounds, ¹²⁵I-C₅ and ^99mTc-C₃, place the corresponding radionuclide at similar distances to DNA and produce comparable DSB yields in plasmid and cellular DNA. These results provide the first evidence that ^99mTc can induce DNA damage with similar efficiency to that of ¹²⁵I, when both are positioned at comparable distances to the double helix. Furthermore, the high nuclear retention of ^99mTc-C₃ in tumoral cells suggests that ^99mTc-labelled AO derivatives are more promising for the design of Auger-emitting radiopharmaceuticals than the ¹²⁵I-labelled congeners.

Biomimetic fibroblast-loaded artificial dermis with "sandwich" structure and designed gradient pore sizes promotes wound healing by favoring granulation tissue formation and wound re-epithelialization

The structure of dermal scaffolds greatly affects the engineered tissue's functions and the activities of seeded cells. Current strategies of dermal scaffold design tend to yield a homogeneous architecture with a uniform pore size. However, the structures of the human dermis are not homogeneous in terms of either interstitial spaces or architecture at different dermal depths. In the present study, a biomimetic fibroblasts-loaded artificial dermis composed of three-layer scaffolds with different pore sizes was prepared. The three-layer scaffolds, which look similar to a sandwich, mimic the natural structures of the human dermis, which has comparatively larger pores in the outer layers and smaller pores in the middle layer. The fibroblasts-loaded artificial dermis were shown to favor wound healing by promoting granulation tissue formation and wound re-epithelialization, as determined by a histological study and Western blotting. Our data indicated that the biomimetic fibroblasts-loaded artificial dermis with "Sandwich" structure and designed gradient pore sizes may hold promise as tissue-engineered dermis.

STATEMENT OF SIGNIFICANCE

Pore size effect on wound healing had been extensively studied. However, it is still not well understood whether dermal scaffolds with a uniform pore size are better than that with varied pore sizes, which are similar to human dermis as determined by our previous work. In our study, we demonstrated that the "sandwich" collagen scaffolds mimicking the natural structures of the human dermis significantly promoted wound healing compared with the "Homogeneous" scaffolds with a uniform pore size. These results may be helpful in the design of dermal scaffolds.