ABSTRACT
The present study describes the production of hyaluronan based porous microparticles by a semi-continuous gas anti-solvent (GAS) precipitation process to be used as a growth factor delivery system for in vivo treatment of ulcers. Operative process conditions, such as pressure, nozzle diameter and HYAFF11 solution concentrations, were adjusted to optimize particle production in terms of morphology and size. Scanning electron microscopy (SEM) and light scattering demonstrated that porous nano-structured particles with a size of 300 and 900 nm had a high specific surface suitable for absorption of growth factors from the aqueous environment within the polymeric matrix. Water acted as a plasticizer, enhancing growth factor absorption. Water contents within the HYAFF11 matrix were analyzed by differential scanning calorimetry (DSC). The absorption process was developed using fluorescence dyes and growth factors. Immunohistochemical analysis confirmed the high efficiency of absorption of growth factor and a mathematical model was generated to quantify and qualify the in vitro kinetics of growth factor release within the polymeric matrix. In vivo experiments were performed with the aim to optimize timed and focal release of PDGF to promote optimal tissue repair and regeneration of full-thickness wounds.
Subject(s)
Biocompatible Materials/chemistry , Growth Substances/administration & dosage , Hyaluronic Acid/chemistry , Nanoparticles/chemistry , Nanoparticles/therapeutic use , Skin Ulcer/therapy , Absorption , Animals , Male , Materials Testing , Microscopy, Electron, Scanning , Nanoparticles/ultrastructure , Nanotechnology/instrumentation , Platelet-Derived Growth Factor/administration & dosage , Rats , Rats, Wistar , Skin Ulcer/drug therapy , Skin Ulcer/pathology , Tissue Scaffolds , Transforming Growth Factor beta/administration & dosage , Water/chemistry , Wound Healing/drug effectsABSTRACT
In this study we coated a new biocompatible, nanostructured titanium alloy, Ti13Nb13Zr, with a thin layer of hydroxyapatite nanocrystals and we investigated the response of human bone-marrow-derived mesenchymal cells. The coating was realized using a slightly supersaturated CaP solution, which provokes a fast deposition of nanocrystalline hydroxyapatite. A thin layer of deposition is appreciable on the etched Ti13Nb13Zr substrates after just 1.5 h soaking in the CaP solution, and it reaches a thickness of 1-2 mum after 3 h soaking. The coating seems thinner than that deposited on Ti6Al4V, which was examined for comparison, likely because of the different roughness profiles of the two etched alloys, and it is constituted of elongated HA nanocrystals, with a mean length of about 100 nm. Mesenchymal stem cells were seeded onto coated and uncoated Ti alloys and cultured for up to 35 days. Cell morphology, proliferation and differentiation were evaluated. The cells display good adhesion and proliferation on the uncoated substrates, whereas the presence of hydroxyapatite coating slightly reduces cell proliferation and induces differentiation of MSCs towards a phenotypic osteoblastic lineage, in agreement with the increase of the expression of osteopontin, osteonectin and collagen type I, evaluated by means of rt-PCR. Type I collagen expression is higher in Ti13Nb13Zr MSC culture compared to Ti6Al4V, standing for a more efficient extracellular matrix deposition.
Subject(s)
Coated Materials, Biocompatible/chemistry , Durapatite/chemistry , Mesenchymal Stem Cells/cytology , Nanoparticles/chemistry , Titanium/chemistry , Alloys/chemistry , Base Sequence , Bone Marrow Cells/cytology , Bone Marrow Cells/metabolism , Cell Adhesion , Cell Culture Techniques/methods , Cell Differentiation , Cell Proliferation , Collagen Type I/genetics , DNA Primers/genetics , Gene Expression , Humans , Materials Testing , Mesenchymal Stem Cells/metabolism , Microscopy, Electron, Scanning , Osteoblasts/cytology , Osteoblasts/metabolism , Osteonectin/genetics , Osteopontin/geneticsSubject(s)
Aeromonas , Gram-Negative Bacterial Infections/diagnosis , Neutropenia/microbiology , Sepsis/microbiology , Acute Disease , Aged , Amikacin/administration & dosage , Anti-Bacterial Agents/administration & dosage , Anti-Infective Agents/administration & dosage , Ciprofloxacin/administration & dosage , Female , Gram-Negative Bacterial Infections/drug therapy , Gram-Negative Bacterial Infections/etiology , Humans , Leukemia, Myeloid/complications , Leukemia, Myeloid/microbiology , Leukemia, Myeloid/pathology , Neutropenia/etiology , Neutropenia/pathology , Sepsis/drug therapy , Sepsis/etiologyABSTRACT
The authors describe an unusual case of bacterial endocarditis. A very rare etiologic agent, Erysipelothrix rhusiopathiae, was isolated. The patient was not fisherman or butcher and he did ot other risky job. Moreover the disease had an atypical course.
