Injectable deferoxamine nanoparticles loaded chitosan-hyaluronic acid coacervate hydrogel for therapeutic angiogenesis.

In this study, an injectable chitosan-hyaluronic acid (CS-HA) based hydrogel was designed incorporating pro-angiogenic molecule, deferoxamine loaded PLGA nanoparticles (DFO NPs), for enhancing angiogenesis. DFO-NPs were prepared by double emulsion solvent diffusion technique and characterized for their physicochemical properties. The DLS and SEM analysis showed an average particle size of 220±71nm with spherical morphology and the encapsulation efficiency was found to be 30±5%. An ECM mimicking chitosan-hyaluronic acid (CS-HA) coacervate hydrogel was prepared. Both free DFO and DFO NPs were entrapped into the prepared CS-HA composite hydrogel. The hydrogels were characterized by SEM, FTIR and Rheology. Addition of DFO NPs did not affect the injectablility and flowability of developed hydrogels. In vitro DFO release from the prepared composite hydrogels showed controlled release over a period of 10days. Both the hydrogel systems showed excellent cyto-compatability and good cell proliferation for rASCs as well as HUVECs. The DFO and DFO NPs loaded composite hydrogels revealed effective tube formation in comparison with control hydrogels without DFO and DFO NPs. The in vivo angiogenic evaluation of the free DFO and DFO NPs (0.025%w/w) loaded composite hydrogels were studied by injecting the developed hydrogel subcutaneously into mice for 2-4 weeks. The DFO NPs loaded composite hydrogel had enhanced neovascularization when compared to control gels. Thus, the developed DFO NPs loaded composite hydrogel could potentially be used for therapeutic angiogenesis.

Osteointegration of titanium implant is sensitive to specific nanostructure morphology.

An important aspect of orthopedic implant integration is the enhancement of functional activity of osteoblasts at the tissue-implant interface without any fibrous tissue intervention. Nanostructured implant surfaces are known to enhance osteoblast activity. Previously, we have reported a simple hydrothermal method for the fabrication of non-periodic nanostructures (nanoscaffold, nanoleaves and nanoneedles) on titanium implants showing good biocompatibility and a distinct osteoblast response in vitro in terms of osteoblast adhesion to the surface. In the present work, these nanostructures have been evaluated for their detailed in vitro cellular response as well as in vivo osteointegration. Our studies showed that a specific surface nanomorphology, viz. nanoleaves, which is a network of vertically aligned, non-periodic, leaf-like structures with thickness in the nanoscale, provided a distinct increase in osteoblast cell proliferation, alkaline phosphatase (ALP) activity and collagen synthesis compared to several other types of nanomorphology, such as nanotubes, nanoscaffold and nanoneedles (rods). Gene expression analysis of ALP, osteocalcin, collagen, decorin and Runx2 showed ~20- to 40-fold up-regulation on the leaf-like topography. Cytoskeletal arrangement studies on this substrate again revealed a unique response with favorable intracellular protein expressions of vinculin, FAK and src. In vivo osteointegration study over 12 weeks on rat model (Sprague-Dawley) showed early-stage bone formation (60% bone contact by week 2 and ~85% by week 8, p<0.01) in the leaf-like nanopattern, without any inflammatory cytokine production.