Giovanna Bruni

Programmable 3D silk bone marrow niche for platelet generation ex vivo and modeling of megakaryopoiesis pathologies

We present a programmable bioengineered 3-dimensional silk-based bone marrow niche tissue system that successfully mimics the physiology of human bone marrow environment allowing us to manufacture functional human platelets ex vivo. Using stem/progenitor cells, megakaryocyte function and platelet generation were recorded in response to variations in extracellular matrix components, surface topography, stiffness, coculture with endothelial cells, and shear forces. Millions of human platelets were produced and showed to be functional based on multiple activation tests. Using adult hematopoietic progenitor cells our system demonstrated the ability to reproduce key steps of thrombopoiesis, including alterations observed in diseased states. A critical feature of the system is the use of natural silk protein biomaterial allowing us to leverage its biocompatibility, nonthrombogenic features, programmable mechanical properties, and surface binding of cytokines, extracellular matrix components, and endothelial-derived proteins. This in turn offers new opportunities for the study of blood component production ex vivo and provides a superior tissue system for the study of pathologic mechanisms of human platelet production.

Drug-Excipient Compatibility Studies. Search of interaction indicators

This paper is the first one of a research project aimed to find and optimize methods by which drug-excipient compatibility can be reliably and quickly assessed.A number of experimental techniques (simultaneous TG-DSC, FT-IR spectroscopy, X-ray powder diffraction, scanning electron microscopy) have been used to investigate the compatibility between a novel tricyclic β-lactam antibiotic developed by GlaxoWellcome (now GlaxoSmithKline), GV118819x, and some commonly used excipients (poly(vinylpyrrolidone), magnesium stearate and α-lactose). Binary mixtures of two different compositions have been analyzed: drug:excipient=80:20 and 20:80 (mass/mass). Both qualitative and quantitative interaction indicators have been identified. It is shown that simultaneous thermal analysis is the best suited technique in the search of interaction indicators. With a proper selection of experimental conditions it is able to reveal the thermal changes brought about by the early stages of interaction, i.e. those occurring during the measurement on physical mixtures not previously annealed under stress conditions. Such an ability is discussed, in particular, with respect to the role of the water vapour, which has been found to be a critical parameter for all our systems.

Effect of mechanical activation on the preparation of SrTiO3 and Sr2TiO4 ceramics from the solid state system SrCO3-TiO2

Abstract By thermoanalysis (TGA and DSC) and X-ray powder diffraction it has been shown that the compounds SrTiO 3 and Sr 2 TiO 4 can be prepared by mechanical activation of, respectively, 1:1 and 2:1 SrCO 3 –TiO 2 (rutile) mixtures followed by annealing for 12 h at 800–850°C. These compounds could not be obtained by heating the physical mixtures to temperatures as high as 1000°C. Moreover, the enthalpies of the reactions leading from Sr carbonate and rutile to the formation of these compounds have been determined. By combining these data with the enthalpy of SrCO 3 decomposition, also obtained in this work, the enthalpies of formation of SrTiO 3 and Sr 2 TiO 4 have been calculated. On the contrary, no Sr 3 Ti 2 O 7 was shown to form, by the same annealing procedure, when starting from a mechanically activated mixture. DSC and XRD results agree in indicating that a mixture of Sr 2 TiO 4 and SrTiO 3 forms instead.

Drug-excipient compatibility studies by physico-chemical techniques; The case of Atenolol

We apply a range of techniques (thermal methods, microscopy, X-ray diffraction, IR spectroscopy) to characterize a drug (atenolol), several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©) and drug-excipients mixtures either as prepared, annealed, and exposed to moisture. We compare the data of the mixtures with those computed from a weighted average of similarly treated pure compounds to find evidence of drug properties modified by the interaction with the excipient. We find that thermal response is by far the most sensitive indicator of interaction while IR is the least sensitive one. Avicel© has essentially no interaction with atenolol, while MGST modifies significantly only the thermal response of the drug in the MGST-rich mixtures. PVP interacts strongly with atenolol, and this interaction appears to be mediated by the substantial amount of hydration water the excipient brings in its mixtures with a water-free drug.

Influence of extrusion-spheronization processing on the physical properties of d-Indobufen pellets containing pH adjusters

Abstractd-Indobufen pellets containing pH adjusters (acids, buffer, salt) were prepared by extrusion-spheronization technology.The interaction effect between some processing variables (feeding/agitator speeds of extruder, plate speed and residence time of spheronizer) was evaluated by comparing the basic formulation pellets with the pellets in which the soluble filler (lactose) was substituted by fumaric, tartaric and citric acids and also sodium citrate.The criteria of formulation and process evaluation were the reproducibility of the particle size distribution, the density, the hardness and morphological properties, in addition to the reproducibility of the drug dissolution rates.In all cases, the physical/technological characteristics were not influenced very much by pH adjuster incorporation, but the drug dissolution profiles showed some significant variations in the first hour. As a logical extension of this work, wet granulations with aqueous ethylcellulose and acrylic resin dispersions instead of o...

Drug-excipient compatibility studies by physico-chemical techniques; The case of Indomethacin

This work exemplifies a general method of studying the drug excipient interactions, with the aim of predicting rapidly and inexpensively the long term stability of their mixtures. We study the physico-chemical properties of a drug (indomethacin) in the solid state and in different combinations with several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©). We compare the properties of pure compounds (untreated, or moisture/temperature conditioned) with those of binary mixtures drug:excipient which underwent the same treatment. The purpose is to find indications of interactions within the mixtures, which means a potential incompatibility of the excipient. Both morphological and thermal properties are sensitive to interactions which leave mostly unmodified the IR spectra and the X-rays patterns. In particular, we find that indomethacin does interact with PVP and MGST, but is certainly compatible with Avicel©.

DEHYDRATION OF THE CYCLODEXTRINS : A MODEL SYSTEM FOR THE INTERACTIONS OF BIOMOLECULES WITH WATER

The thermodynamics of hydration of biomolecules is experimentally studied in the β‐cyclodextrin (β‐CD), which contains water molecules in a range of configurations and has been proposed as a model system for complex biomolecules. The thermal measurements point to the role of a structural transition from the hydrated β‐CD (phase I) to a ‘‘dehydrated’’ form (phase II). We show that dehydration in phase I is assisted by a ‘‘compensation mechanism’’ for which β‐CD contributes a constant amount of energy for each H2O mole. Despite the presence of different types of H2O’s, water losses in phase I are accurately described in terms of this energy and the isosteric molar enthalpy of dehydration. Moreover, in going from the fully hydrated to the fully dehydrated form, the contribution of β‐CD to dehydration is over all equal to the enthalpy of transition from phase I to phase II. Our analysis yields the changes of an enthalpy associated with the biomolecule alone as a function of the water content. In the case of β...

Research Papers: Preparation of Indobufen Pellets by Using Centrifugal Rotary Fluidized Bed Equipment Without Starting Seeds

AbstractPellets containing Indobufen as model drug were prepared by using the centrifugal-rotary fluidized bed equipment without employing non-pareil seeds.The influence of different amounts of spheronization enhancer (microcrystalline cellulose) and of different fillers (lactose, mannitol, calcium carbonate) on both processing and physical properties of the pellets were evaluated.The preparation reproducibility was also investigated. The use of 30% w/w of microcrystalline cellulose was essential to produce a good quality pellets; the incorporation of filler decreased the qualitative characteristics of the pellets.The water feeding rate proved to be an important parameter for the pellet growth.Therefore, the results showed that this technology based on the rotary fluidized bed is a promising and alternative method in producing pellets.

d-Indobufen extended-release pellets prepared by coating with aqueous polymer dispersions

AbstractA multiple units dosage form has been prepared in order to control the release of d-Indobufen, a carboxylic acid used as an inhibitor of platelet aggregation.The system consists of cores containing the active substance coated with a diffusive film and represents a classic “reservoir” system.Extrusion-spheronization was used in order to prepare the active cores. The drug release control was obtained by modifying both the core composition and the film composition characteristics.Acid and basic compounds were incorporated in the core to influence the inside microenvironment pH. Polymers chosen for the film formulation were: ethylcellulose (Aquacoat) and copolymers of acrylic esters with differing permeability characteristics (Eudragit RL/RS 30D).Technological and physical characteristics of coated pellets proved the production feasibility of an extended release multiple unit dosage form of d-Indobufen.Preliminary data of accelerated stability indicated the important role played by the thermal treatme...

The Use of β-Cyclodextrin as a Pelletization Agent in the Extrusion/ Spheronization Process

The use of beta-cyclodextrin for the preparation of pellets by the extrusion/spheronization process is described for different formulations and processing conditions. Sieve analysis and friability tests were performed to assess the physical and technological characteristics of pellets. Satisfactory products were obtained with beta-cyclodextrin contents up to 90% by weight.