Chronic wound healing: A specific antibiofilm protein-asymmetric release system.

Chronic infection is a major cause of delayed wound-healing. It is recognized to be associated with infectious bacterial communities called biofilms. Currently used conventional antibiotics alone often reveal themselves ineffective, since they do not specifically target the wound biofilm. Here, we report a new conceptual tool aimed at overcoming this drawback: an antibiofilm drug delivery system targeting the bacterial biofilm as a whole, by inhibiting its formation and/or disrupting it once it is formed. The system consists of a micro/nanostructured poly(butylene-succinate-co-adipate) (PBSA)-based asymmetric membrane (AM) with controlled porosity. By the incorporation of hydrophilic porogen agents, polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), we were able to obtain AMs with high levels of porosity, exhibiting interconnections between pores. The PBSA-PEG membrane presented a dense upper layer with pores small enough to block bacteria penetration. Upon using such porogen agents, under dry and wet conditions, membrane's integrity and mechanical properties were maintained. Using bovine serum albumin (BSA) as a model protein, we demonstrated that protein loading and release from PBSA membranes were affected by the membrane structure (porosity) and the presence of residual porogen. Furthermore, the release curve profile consisted of a fast initial slope followed by a second slow phase approaching a plateau within 24 h. This can be highly beneficial for the promotion of wound healing. Cross-sectional confocal laser scanning microscopy (CLSM) images revealed a heterogeneous distribution of fluorescein isothiocyanate (FITC) labeled BSA throughout the entire membrane. PBSA membranes were loaded with dispersin B (DB), a specific antibiofilm matrix enzyme. Studies using a Staphylococcus epidermidis model, indicate significant efficiency in both inhibiting or dispersing preformed biofilm (up to 80 % eradication). The asymmetric PBSA membrane prepared with the PVP porogen (PBSA-PVP) displayed highest antibiofilm activity. Moreover, in vitro cytotoxicity assays using HaCaT and reconstructed human epidermis (RHE) models revealed that unloaded and DB-loaded PBSA-PVP membranes had excellent biocompatibility suitable for wound dressing applications.

Di-O-lauroyl-decitabine-lipid nanocapsules: toward extending decitabine activity.

BACKGROUND: Acute myeloid leukemia mainly affects adult patients. Complete remission for patients younger than 60 years, who are candidates for standard induction therapy, is achieved in 60%-80% of cases. However, the prognosis is still poor for older patients, who are unfit for intensive chemotherapy, and only a few therapies are available. Hypomethylating agents, such as decitabine, are approved for such patients. The current dosing regimen consists of one administration per day, for 5 days, each 4 weeks. METHODS: Here, we present the synthesis of a decitabine prodrug, combined with its encapsulation into a lipid-based nanocapsule formulation. Decitabine (C12)2 was synthetized, then loaded into nanocapsules. Its stability in phosphate buffer ans human plasma was checked. Its activity was evaluated by Cell proliferation assays and cell-cycle analysis on human erythroleukemia cells. Then its pharmacokinetics was determined on a rat model. RESULTS: Decitabine (C12)2 was obtained with a yield of 50%. Drug loading into nanocarriers of 27.45±0.05 nm was 5.8±0.5 mg/mL. The stability of decitabine was improved and its activity on leukemia cells was not altered. Finally, pharmacokinetics studies showed a prolonged mean residence time of the drug. CONCLUSION: Decitabine (C12)2 as a prodrug showed high encapsulation efficiency, a good stability in plasma with no impact on its activity on leukemia cells and improved pharmacokinetics.

Designing Biodegradable PHA-Based 3D Scaffolds with Antibiofilm Properties for Wound Dressings: Optimization of the Microstructure/Nanostructure.

One major factor inhibiting natural wound-healing processes is infection through bacterial biofilms, particularly in the case of chronic wounds. In this study, the micro/nanostructure of a wound dressing was optimized in order to obtain a more efficient antibiofilm protein-release profile for biofilm inhibition and/or detachment. A 3D substrate was developed with asymmetric polyhydroxyalkanoate (PHA) membranes to entrap Dispersin B (DB), the antibiofilm protein. The membranes were prepared using wet-induced phase separation (WIPS). By modulating the concentration and the molecular weight of the porogen polymer, polyvinylpyrrolidone (PVP), asymmetric membranes with controlled porosity were obtained. PVP was added at 10, 30, and 50% w/w, relative to the total polymer concentration. The physical and kinetic properties of the quaternary nonsolvent/solvent/PHA/PVP systems were studied and correlated with the membrane structures obtained. The results show that at high molecular weight (Mw = 360 kDa) and high PVP content (above 30%), pore size decreased and the membrane became extremely brittle with serious loss of physical integrity. This brittle effect was not observed for low molecular weight PVP (Mw = 40 kDa) at comparable contents. Whatever the molecular weight, porogen content up to 30% increased membrane surface porosity and consequently protein uptake. Above 30% porogen content, the pore size and the physical integrity/mechanical robustness both decreased. The PHA membranes were loaded with DB and their antibiofilm activity was evaluated against Staphylococcus epidermidis biofilms. When the bacterial biofilms were exposed to the DB-loaded PHA membrane, up to 33% of the S. epidermidis biofilm formation was inhibited, while 26% of the biofilm already formed was destroyed. These promising results validate our approach based on the development of bioactive-protein-loaded asymmetric membranes for antibiofilm strategies in situations where traditional antibiotic therapies are ineffective.