Supramolecular polypseudorotaxane gels for controlled delivery of rAAV vectors in human mesenchymal stem cells for regenerative medicine

The aim of this work was to investigate, for the first time, the possibility of using supramolecular polypseudorotaxane gels as scaffolds that can durably deliver rAAV vectors for applications in cartilage regeneration. Dispersions of Pluronic (R) F68 (PF68) or Tetronic (R) 908 (T908) containing either hyaluronic acid (HA) or chondroitin sulfate (CS) were prepared in PBS. Then, alpha-cyclodextrin (alpha CD) was added to some dispersions to form polypseudorotaxane gels. Polysaccharides and alpha CD reinforced the viscoelasticity of the gels, which could withstand autoclaving without changes. In vitro release of rAAV vectors and subsequent transduction of human mesenchymal stem cells (hMSCs) by rAAV vectors from the release medium and from gels in direct contact with the cells were investigated. Compared with free vectors, the gels provided higher levels of transgene expression. CS (or HA)/PF68/alpha CD gels rapidly released rAAV vectors while CS (or HA)/T908/alpha CD gels provided sustained release probably due to different interactions with the viral vectors. Incorporation of aCD into CS (or HA)/PF68 gels resulted on higher rAAV concentrations and sustained levels of transgene expression over time. HA increased the bioactivity and cytocompatibility of the gels, especially those based on T908. Overall, combining rAAV gene transfer with polypseudorotaxane gels may provide new, promising tools for human tissue engineering and regenerative medicine strategies. (C) 2017 Elsevier B.V. All rights reserved.