A new concept in treatment of burn injury: controlled slow-release granulocyte-monocyte colony-stimulating factor chitosan gel system.

OBJECTIVE: The aim of the study is to investigate the effectiveness of the controlled slow-release granulocyte-monocyte colony-stimulating factor (GM-CSF) system in burn wound healing. MATERIAL AND METHODS: In vivo effect of controlled slow-release GM-CSF from chitosan gel on burn wound healing was evaluated on 18 Wistar-Albino rats, weighing between 250 and 300 g. They were randomly divided into 3 groups; (1) burned only group (n = 6), (2) burned + chitosan group (n = 6), (3) burned + chitosan + GM-CSF group (n = 6). Wound area was measured macroscopically. Hematoxylin and eosin and Masson's trichrome stained sections were evaluated for wound healing and tissue response to the polymer. RESULTS: The best healing process was observed with the controlled slow-release GM-CSF-applied group (group 3) in which the wound area was significantly narrowed. CONCLUSION: The study demonstrated the positive contribution of the single-dose controlled slow-release GM-CSF from chitosan gel on burn wound healing.

Effect of use of slow release of bone morphogenetic protein-2 and transforming growth factor-Beta-2 in a chitosan gel matrix on cranial bone graft survival in experimental cranial critical size defect model.

Bone grafts, used for providing structural integrity of cranial vault remodeling, could not always integrate with the remaining bone structures. All efforts are focused on increasing incorporation of the applied bone grafts. Allografts were covered by chitosan so that slow release of bone morphogenetic protein-2 (BMP-2) and Transforming growth factor-beta-2 (TGF-beta-2) was achieved. Two hundred forty Wistar-Albino rats were distributed equally in 8 study groups. Study groups were designed as; defect group, autograft group, allograft group, chitosan group, allograft + chitosan, TGF-beta-2 group, BMP-2 group, and TGF-Beta-2 +BMP-2 group. Bone biopsies were obtained at second, eight, and 14th weeks. Bone regeneration was evaluated by morphologic studies detecting histologic bone healing and radiologic studies detecting bone density. Histologic findings were evaluated in 2 categories; tissue response to the implant and defect healing. Additionally, scanning electron microscopy for detailed morphologic evaluation was done. Bone density of the applied scaffold and the parietal bone at the same computed tomography section were measured in Hounsfield scale and this ratio was used for densitometry evaluations. Kruskal-Wallis test was used to analyze difference among groups according to the histologic and radiologic data. Pairwise comparisons were done using Mann-Whitney U test with Bonferroni correction. P < 0.05 was considered significant. In the morphologic studies, bone regeneration in BMP-2 group was found to be compatible with bone regeneration in gold standard autograft group and even better than it within 15 days. Chitosan is a biocompatible material. TGF-Beta-2 alone is not effective enough in bone regeneration; BMP-2 alone has a positive effect in every step of bone regeneration. Combining TGF-Beta-2 with BMP-2 does not lead to a better bone regeneration than using BMP-2 alone. A synergistic effect is not obtained by using these 2 factors together.

In vitro and in vivo evaluations of PLGA microsphere vaccine formulations containing pDNA coexpressing hepatitis B surface antigen and Interleukin-2.

PURPOSE: DNA-based vaccines encoding viral antigens have been shown to elicit immune responses in animal models. In this study, a plasmid DNA (pDNA) coexpressing the middle envelope protein of hepatitis B virus (HBV) and Interleukin-2 (IL-2) was incorporated into Poly (D,L-lactic-co-glycolic acid) (PLGA) microspheres and three different formulations were investigated for their potential as a vaccine delivery system. METHODS: Emulsion solvent evaporation methods of water-in-oil-in-water (w/o/w) and oil-in-water (o/w) were used to generate three different formulations in which PLGA microspheres contained pDNA either encapsulated within or adsorbed onto the microspheres. RESULTS: In vaccine formulation A2, prepared using the (w/o/w) method, pDNA was encapsulated within the microspheres. The other two formulations (B2 and B2a) were prepared using the (o/w) method and B2 contained pDNAs encapsulated within the microspheres while B2a contained pDNAs adsorbed onto the microspheres. pDNA loading efficiencies of A2, B2 and B2a were determined to be 15%, 25% and 45%, respectively. In vitro release of pDNAs from microspheres was evaluated for a 45-day period with no conformational changes and A2 displayed slower release than that of the B2 and B2a. When mice were immunized from anterior tibialis muscle using A2, B2 and B2a formulations containing 100 microg pDNA, antibody responses were detected for 6 months in mice sera. CONCLUSIONS: Although all PLGA microsphere formulations containing pDNA elicited antibody responses by the end of the 6th month, the antibody titers were found to be higher with B2 and B2a formulations in comparison to A2 formulation and the naked pDNA in saline.

Acceleration of distraction osteogenesis with drug-releasing distractor.

OBJECTIVE: : The aim of this study was to develop an internal distractor to release a drug to the distraction site during the distraction process and to investigate whether intermittent bone morphogenetic protein 2 (BMP-2)-containing chitosan hydrogel infusion will improve radiologic and histologic parameters of distraction osteogenesis (DO) when compared with control groups. MATERIALS AND METHODS: : Experimental groups were control group (n = 6), 2-microg single-dose BMP-2-chitosan hydrogel-infused group (n = 6), and 2-microg intermittent BMP-2-containing chitosan hydrogel-infused group (n = 6). In intermittent BMP-infused group, certain amount of BMP-2 loaded chitosan hydrogel injected into the distraction gap for controlled BMP release from the chitosan with every turning of the geared rod of the distractor. Radiologic and histologic evaluation methods have been conducted. CONCLUSION: : The results of the analysis demonstrated that the newly developed distractor effectively stabilized the DO site while allowing intermittent BMP-chitosan infusion. Application of a BMP-2-chitosan hydrogel infusion to the distraction zone facilitates ossification. Intermittent infusion of BMP-2-containing chitosan hydrogel by use of a developed internal distractor increases ossification even more at the site of DO.

Effect of slow-release 5-Fluorouracil on capsule formation around silicone breast implants: an experimental study with mice.

BACKGROUND: Capsule formation around breast implants, development of tendon adhesions after tendon repair, intestinal brits after laparatomies, hypertrophic scars in skin incisions all are the results of excessive collagen synthesis to the extracellular matrix by fibroblasts. Any intervention that leads to cessation of collagen synthesis in these clinical situations may help to prevent these untoward results of wound healing. Although 5-fluorouracil (5-FU) is used mainly as a cytotoxic drug in chemotherapy protocols, it decreases cellular metabolism and blocks protein synthesis only at lower concentrations. Findings have shown that 5-FU downregulates fibroblast proliferation and differentiation in vitro. It has been used to treat fibroproliferative disorders of the eye and skin and is thought to inhibit thymidylate synthetase, blocking DNA replication. METHODS: This study used five treatment groups: (1) gelatin only, (2) silicone only, (3) silicone + gelatin, (4) silicone + gelatin containing 1 mg of 5-FU, and (5) silicone + gelatin containing 5 mg of 5-FU. The release kinetics of 5-FU from gelatin have been investigated by means of ultraviolet spectrophotometric analysis. Specimens were obtained on postoperative day 30. Gross evaluation and histopathologic examination were conducted for capsule formation and the development of inflammation. RESULTS: The silicone group had the most prominent capsule formation among all the groups. The gelatin group was second, and the silicone + gelatin group was third. As compared with the other groups, the 5-FU-containing groups had the least capsule formation. The 5-mg 5-FU-containing group had the most inflammation. The silicone + gelatin group was second in inflammation. Although the silicone, gelatin, and 1-mg 5-FU-containing groups had the same means, the results of the silicone group showed the most divergent data within the group. CONCLUSIONS: Because 5-FU loaded to a gelatin carrier for its slow release seems to prevent capsule formation around silicone blocks, it may be used to prevent capsule formation around silicone breast implants.

Chitosan microparticles containing plasmid DNA as potential oral gene delivery system.

The potential of chitosan as a polycationic gene carrier for oral administration has been explored since 1990s. Chitosan has been shown to effectively bind DNA in saline or acetic acid solution and protect DNA from nuclease degradation. In this study, pDNA (plasmid DNA) was encapsulated in chitosan microparticles. Chitosan-DNA microparticles were prepared using a complex coacervation process and stability of plasmid DNA was investigated in this complex. The chitosan-DNA microparticles could protect the encapsulated plasmid DNA from nuclease degradation. Release of pDNA from microparticles was studied in simulated gastric, simulated intestinal medium and acidic PBS (phosphate buffer saline) (pH 4.5) buffer at 37 degrees C, and released pDNA was assayed spectrophotometrically. In vitro release of pDNA from chitosan microparticles was dependent on pH, as the pH of the release medium increased release profile decreased. In in vivo-animal studies blue color was observed with X-gal (4-chloro-5-bromo-3-indolyl-beta-galactosidase) staining of histological stomach and small intestine sections after oral administration of pDNA-chitosan microparticles as an indicator of exogeneous gene expression.