Biomimetic Gemcitabine-Lipid Prodrug Nanoparticles for Pancreatic Cancer.

Gemcitabine (Gem) is a key drug for pancreatic cancer, yet limited by high systemic toxicity, low bioavailability and poor pharmacokinetic profiles. To overcome these limitations, Gem prodrug amphiphiles were synthesised with oleyl, linoleyl and phytanyl chains. Self-assembly and lyotropic mesophase behaviour of these amphiphiles were examined using polarised optical microscopy and Synchrotron SAXS (SSAXS). Gem-phytanyl was found to form liquid crystalline inverse cubic mesophase. This prodrug was combined with phospholipids and cholesterol to create biomimetic Gem-lipid prodrug nanoparticles (Gem-LPNP), verified by SSAXS and cryo-TEM to form liposomes. In vitro testing of the Gem-LPNP in several pancreatic cancer cell lines showed lower toxicity than Gem. However, in a cell line-derived pancreatic cancer mouse model Gem-LPNP displayed greater tumour growth inhibition than Gem using a fraction (<6 %) of the clinical dose and without any systemic toxicity. The easy production, improved efficacy and low toxicity of Gem-LPNP represents a promising new nanomedicine for pancreatic cancer.

Biomineralization of osteoblasts on DLC coated surfaces for bone implants.

Diamond like carbon (DLC) films were deposited onto Ti6Al4V and Si wafer substrates by RF plasma enhanced chemical vapor deposition. The influence of dopants such as fluorine (F), silicon (Si), and nitrogen (N) on composition, structure, and biocompatibility was investigated. Ion scattering spectroscopy analysis revealed the presence of dopant atoms in the outer-most layers of the films. Raman studies showed that the position of the G-band shifts to higher frequencies with the fluorine and nitrogen content in the DLC film, whereas the incorporation of Si into DLC induces a decrease of the position of the G peak. The corrosion behavior was studied in simulated body fluid. A higher charge transfer resistance (Rct) was observed for the doped DLC films. The indirect cytotoxicity was performed using L929 fibroblast cells. The coated surfaces were hemocompatible when tested with red blood cells. DLC films were noncytotoxic to L929 cells over a 24 h exposure. Saos-2 osteoblast cell response to the doped and undoped DLC coated surfaces was studied in adhesion, proliferation, differentiation, and mineralization assays. The production of calcium and phosphate by cells on doped DLC, particularly, nitrogen doped DLC, was higher than that on undoped DLC.

Co-encapsulation and co-transplantation of mesenchymal stem cells reduces pericapsular fibrosis and improves encapsulated islet survival and function when allografted.

Pericapsular fibrotic overgrowth (PFO) is associated with poor survival of encapsulated islets. A strategy to combat PFO is the use of mesenchymal stem cells (MSC). MSC have anti-inflammatory properties and their potential can be enhanced by stimulation with proinflammatory cytokines. This study investigated whether co-encapsulation or co-transplantation of MSC with encapsulated islets would reduce PFO and improve graft survival. Stimulating MSC with a cytokine cocktail of IFN-γ and TNF-α enhanced their immunosuppressive potential by increasing nitric oxide production and secreting higher levels of immunomodulatory cytokines. In vitro, co-encapsulation with MSC did not affect islet viability but significantly enhanced glucose-induced insulin secretion. In vivo, normoglycemia was achieved in 100% mice receiving islets co-encapsulated with stimulated MSC as opposed to 71.4% receiving unstimulated MSC and only 9.1% receiving encapsulated islets alone. Microcapsules retrieved from both unstimulated and stimulated MSC groups had significantly less PFO with improved islet viability and function compared to encapsulated islets alone. Levels of peritoneal immunomodulatory cytokines IL-4, IL-6, IL-10 and G-CSF were significantly higher in MSC co-encapsulated groups. Similar results were obtained when encapsulated islets and MSC were co-transplanted. In summary, co-encapsulation or co-transplantation of MSC with encapsulated islets reduced PFO and improved the functional outcome of allotransplants.

Biomineralisation with Saos-2 bone cells on TiSiN sputtered Ti alloys.

Surface modifications of metallic implants are important in order to protect the underlying metals from the harsh corrosive environment inside the human body and to minimize the losses caused by wear. Recently, researches are carried out in developing bioactive surfaces on metallic implants, which supports the growth and proliferation of cells on to these surfaces. Titanium silicon nitride (TiSiN) hard nanocomposites thin films were fabricated on Ti alloys (Ti-6Al-4V) by pulsed direct current (DC) reactive magnetron sputtering. The films were characterized for its microstructural and electrochemical behavior. The higher charge transfer resistance (Rct) and positive shift in Ecorr value of TiSiN/Ti alloys than the bare Ti-alloys indicates a better corrosion resistance offered by the TiSiN thin films to the underlying substrates. The biological response to TiSiN/Ti alloys and control bare Ti-alloys was measured in vitro using cell-based assays with two main outcomes. Firstly, neither the Ti alloy nor the TiSiN thin film was cytotoxic to cells. Secondly, the TiSiN thin film promoted differentiation of human bone cells above the bare control Ti alloy as measured by alkaline phosphatase and calcium production. TiSiN thin films provide better corrosion resistance and protect the underlying metal from the corrosive environment. The thin film surface is both biocompatible and bioactive as indicated from the cytotoxicity and biomineralization studies.

Coencapsulation of Target Effector Cells With Mesenchymal Stem Cells Reduces Pericapsular Fibrosis and Improves Graft Survival in a Xenotransplanted Animal Model.

Pericapsular fibrotic overgrowth (PFO) is a problem that thwarts full implementation of cellular replacement therapies involving encapsulation in an immunoprotective material, such as for the treatment of diabetes. Mesenchymal stem cells (MSCs) have inherent anti-inflammatory properties. We postulated that coencapsulation of MSCs with the target cells would reduce PFO. A hepatoinsulinoma cell line (HUH7) was used to model human target cells and was coencapsulated with either human or mouse MSCs at different ratios in alginate microcapsules. Viability of encapsulated cells was assessed in vitro and xenografted either intraperitoneally or subcutaneously into C57BL/6 mice. Graft retrieval was performed at 3 weeks posttransplantation and assessed for PFO. Coencapsulation of human MSCs (hMSCs) or mouse MSCs (mMSCs) with HUH7 at different ratios did not alter cell viability in vitro. In vivo data from intraperitoneal infusions showed that PFO for HUH7 cells coencapsulated with hMSCs and mMSCs in a ratio of 1:1 was significantly reduced by ∼30% and ∼35%, respectively, compared to HUH7 encapsulated alone. PFO for HUH7 cells was reduced by ∼51% when the ratio of mMSC/HUH7 was increased to 2:1. Implanting the microcapsules subcutaneously rather than intraperitoneally substantially reduced PFO in all treatment groups, which was most significant in the mMSC/HUH7 2:1 group with a ∼53% reduction in PFO compared with HUH7 alone. Despite the reduced PFO reaction to the individual microcapsules implanted subcutaneously, all microcapsule treatment groups were contained in a vascularized fibrotic pouch at 3 weeks. The presence of MSCs in microcapsules retrieved from these fibrotic pouches improved graft survival with significantly higher cell viabilities of 83.1 ± 0.6% and 79.1 ± 0.8% seen with microcapsules containing mMSC/HUH7 at 2:1 and 1:1 ratios, respectively, compared to HUH7 alone (51.5 ± 0.7%) transplanted subcutaneously. This study showed that coencapsulation of MSCs with target cells has a dose-dependent effect on reducing PFO and improving graft survival when implanted either intraperitoneally or subcutaneously in a stringent xenotransplantation setting.