Gerardo Catapano - Academia.edu (original) (raw)

Papers by Gerardo Catapano

Frontiers in bioengineering and biotechnology, Feb 8, 2024

Biochemical Engineering Journal, May 1, 2016

Cell culture in three-dimensional hollow cylindrical porous scaffolds in radial-flow packed-bed b... more Cell culture in three-dimensional hollow cylindrical porous scaffolds in radial-flow packed-bed bioreactors (rPBBs) has advantages over static culture and axial perfusion bioreactors. Transport models of rPBBs for tissue engineering proposed thus far neglect the effect of the fluid dynamics of the bioreactor void spaces on radial flux maldistribution, although such an effect was proven important for industrial reactors. In this paper, a two-dimensional axisymmetric model is proposed for steady-state momentum transport in the three compartments of rPBBs under conditions and for construct permeability typical of tissue engineering applications. Transport in the inner hollow cavity and outer peripheral annulus is described according to Navier-Stokes equations, while Darcy-Brinkman equation is used for transport across the annular construct. Model predictions were qualitatively validated against literature data. Effects of the performance-determining dimensionless groups on radial flux distribution along the bioreactor length were investigated, and a criterion was proposed to design and operate rPBBs in which radial fluxes are uniformly distributed along the bioreactor length under conditions typical of tissue engineering. Bioreactor designs and operation meeting the criterion will avoid non-uniform development of tissue structure and functional properties.

PubMed, Sep 1, 2006

Membranes in artificial organs and scaffolds for tissue engineering are often coated with biomime... more Membranes in artificial organs and scaffolds for tissue engineering are often coated with biomimetic molecules (e.g., collagen) to improve their biocompatibility and promote primary cell adhesion and differentiation. However, animal proteins are expensive and may be contaminated with prions. Silk fibroin (SF) made by Bombyx Mori silk worms, used as a scaffold or grafted to other polymers, reportedly promotes the adhesion and growth of many human cell types. This paper describes how commercial porous membranes were physically coated with SF, and their physical-chemical properties were characterized by SEM, AFM, tensile stress analysis and dynamic contact angle measurements. The effect of the SF coating on membrane biocompatibility and resistance to bacterial colonization is also examined. The proposed technique yields SF coats of different thickness that strengthen the membranes and make their surface remarkably more wettable. The SF coat is not cytotoxic, and promotes the adhesion and proliferation of an immortalized fibroblast cell line. Similarly to collagen, SF-coated membranes also exhibit a much better resistance to the adhesion of S. epidermidis bacteria than uncoated membranes. These preliminary results suggest that SF is a feasible alternative to collagen as a biomimetic coating for 3D scaffolds for tissue engineering or bioartificial (as well as artificial) prosthesis.

BOA (University of Milano-Bicocca), 2016

perform their role through three main components: a biocompatible scaffold, cellular component an... more perform their role through three main components: a biocompatible scaffold, cellular component and bioactive molecules. Nanotechnology, using advanced manufacturing techniques such as conventional and unconventional lithography, allows fabricating supports with geometries, sizes and displaying physical chemical properties tuneable over different length scales. In this work we report the fabrication of scaffolds made of fibrin gel and squid pen chitin, for the regeneration of tissues. Materials and methods: Fibrin gel films are used to observe the growth of cells on random networks. Films of different thickness have been fabricated with special attention to the realization of a micro-frame that allows a simple manipulation of the structure. Such a standing fibrin scaffold prevents the artefacts arising from the interaction of the films with other surfaces. The fibrin gel clots have then been stretched to observe if the cells growth and migration is influenced by the orientation of the fibers. Fabricating a scaffold via bottom-up techniques to mimic tissues is not simple. We have chosen to adopt a top-down strategy using a scaffold manufactured by nature and composed of extremely ordered chitin fibers: squid pen. The squid's pen is a support consisting of chitin fibers transparent, biocompatible, low cost and displaying high mechanical resistance. We have changed the chemical and physical properties of the scaffold to promote cell adhesion. Both supports were functionalized with retinoic acid to obtain a support able to induce cell differentiation. We characterized the scaffolds by scanning electron microscopy and immunofluorescence technique. Results: We have fabricated two types of scaffolds and we have observed cell growth on both scaffolds. We fabricated active scaffolds able to differentiate the stem cells into neuronal cells. The ultrastructure characterization of the scaffolds is crucial for evaluating their morphology, porosity and biological efficacy. Power spectrum analyses of the images have been performed to provide the characteristic lengths of the supports. Discussion: An important goal of this work was the fabrication of 3D scaffolds with a well-defined morphology to be used as a starting point for the regeneration of portions of tissue. The realization of a fibrin scaffold, of different thickness and easy to handle fabricated under controlled spatial confinement has been demonstrated. Characterization of the fibrin network has helped us to understand how the morphology of fibrin network might affect the cell growth. We propose the squid pen as a scaffold because it is biocompatible, transparent, it withstands surgical sutures and, moreover, it is a waste material of the industrial chain. The purpose is to exploit as much as possible the original remarkable properties provided by the structure of squid pen chitin to obtain a scaffold transparent and able to support all the mechanical stress. Furthermore, in a period characterized by the necessity of producing goods by a sustainable chemistry and a green economy, finding the way for using an available natural biomass has become a must for all scientists and industrial manufacturers.

Current trends in clinical embryology, 2016

Many papers have recently reported on the in vitro culture of ovarian tissue or isolated follicle... more Many papers have recently reported on the in vitro culture of ovarian tissue or isolated follicles. Strips of ovarian tissue have been cultured to understand the mechanisms and the hormonal requirements of the activation of primordial follicles, their growth, and development of steroidogenic capacities. Isolated follicles, encapsulated in hydrogel matrices, have been cultured to study how to promote follicle development in vitro and how to exploit the reproductive potential of cryopreserved ovarian tissue of pre-pubertal girls with premature ovarian failure or of women needing immediate cancer treatment. Culture techniques have also been proposed as in vitro models to study folliculogenesis, to screen new drugs, and for toxicological studies. Many publications address the optimization of culture media and supplements provision, and of the matrices used for encapsulating ovarian tissue and follicles. Bioreactors have been proposed which are suited to the small scale of the tissue samples, varying for configuration and operation mode with the aim of enhancing and controlling transport of nutrients, oxygen and biochemical cues to tissue. The broadly differing bioreactor types and operating conditions that have been proposed suggest that the optimization of bioreactor design is often approached in empiric fashion without paying due attention to the interplay of occurring flow and mass transport phenomena and cells metabolism. In this paper, the theoretical aspects of solutes transport to cells in ovarian tissue or encapsulated follicle preparations are briefly discussed, and used for analyzing the relevant transport features of some bioreactors proposed for ovarian tissue culture. The analysis suggests that a rational and multidisciplinary approach to bioreactor design for ovarian tissue and follicle culture in vitro is highly desirable to exploit the full potential of in vitro culture techniques and to advance knowledge in the field of assisted reproduction.

WORLD SCIENTIFIC eBooks, Dec 3, 2017

Frontiers in Bioengineering and Biotechnology, Jan 10, 2020

resistance to breakthrough; the presence of surfactants in the patient's blood (e.g., lipids, alc... more resistance to breakthrough; the presence of surfactants in the patient's blood (e.g., lipids, alcohol, etc.) may significantly modify the intrinsic membrane resistance to breakthrough, more so the higher the surfactant concentration. We conclude that the requirements of ECMO devices in terms of resistance to plasma breakthrough ought to account for all these factors and not rely only on membrane maximal pore size.

Theriogenology, Mar 1, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

International Journal of Artificial Organs, 2004

Collagen is often used in bioartificial livers as a biomimetic coating to promote liver cell adhe... more Collagen is often used in bioartificial livers as a biomimetic coating to promote liver cell adhesion and differentiation. Animal proteins are expensive and expose the host to risks of crossspecies infection due to contamination with prions. Silk fibroin (SF) is a biocompatible protein produced by Bombyx mori silk worms and possibly an alternative to collagen. We prepared SFcollagen blend films with different SF content adherent to the bottom of standard tissue culture dishes, and characterized their surface morphology by SEM, their wettability and examined them for their capacity to support rat liver cell adhesion and metabolism. Cell metabolism was characterized by estimating the rate at which cells eliminated ammonia and synthesized urea for up to 48h of culture. SF-containing films were smooth, clear and more wettable than collagen. Cells readily adhered, formed junctions and small size aggregates on all films. As many cells adhered on SF as on collagen films. Cell adhesion to high collagen content blend films could not be reliably estimated because cells dwelt in the large cavities in the film. The effect of SF on cell metabolism differed with the investigated metabolic pathway. However, cells on SF-containing films eliminated ammonia and synthesized urea at rates generally comparable to, for urea synthesis at times higher than, that of cells on collagen. These results suggest that silk fibroin is a suitable substratum for liver cell attachment and culture, and a potential alternative to collagen as a biomimetic coating.

International Journal of Artificial Organs, Dec 1, 2009

Journal of Membrane Science, Sep 1, 1990

Membrane bioreactors have been extensively used both in the medical and the industrial field. Whe... more Membrane bioreactors have been extensively used both in the medical and the industrial field. When cells are entrapped in the reactor shell, experimental evidence shows the existence of convective fluxes through the reactor shell side. Nevertheless, solute transport to and from the immobilized cells has been mostly assumed to occur by diffusion only. This paper reports on the authors' ex vivo and in vitro experimental work with a hybrid bioartificial membrane pancreas (HBMP), in which porcine islets of Langerhans were segregated in the shell side of a hollow fibre module. The purpose of the paper is to outline the important role played by convective fluxes in determining reactor performance, in particular when the HBMP is used in vivo. Hydraulic parameters estimated from ex vivo experiments, where the HBMP was implanted as an arterio-venous shunt between the aorta and vena cava in Landrace pigs, show that convection contributes to solute transport to and from the shell as much as diffusion. Kinetic parameters for insulin delivery by the islets were estimated from in vitro experiments at various feed flow rates. A distributed parameter model, taking into account radial convective fluxes in the reactor shell side, is also proposed for a better description of mass transfer and kinetic phenomena occurring in this kind of bioreactor.

Journal of Membrane Science, Aug 1, 2014

ABSTRACT Polymeric membranes used in bioreactors for bioartificial livers are generally chosen fo... more ABSTRACT Polymeric membranes used in bioreactors for bioartificial livers are generally chosen for their transport and separation properties to provide liver cells with adequate nutrients supply and avoid rejection. Possible effects of membrane surface properties on cell metabolism are generally given little consideration. The reported effects of membrane surface wettability on adherent liver cells are qualitative and inconsistent, possibly due to the variation of other surface properties and the culture in Petri dishes, often at confluence, under uncontrolled time- and space-varying metabolite concentrations. In this investigation, rat liver cells were cultured in sub-confluent adhesion on model membranes hydrophilized by physical treatment featuring varying surface wettability in a continuous-flow recycle bioreactor. Bioreactor optimization permitted to culture cells at uniform and measurable pericellular concentrations of metabolic substrates, and to challenge them with controlled increasing ammonia concentrations. Membrane surface wettability was characterized in terms of water sorption, dynamic contact angle, and oxygen content by XPS. The kinetics of oxygen consumption, ammonia elimination and urea synthesis of cells adherent on membranes with increasing wettability was characterized at increasing ammonia concentrations. Cells exhibited increasingly better metabolic functions on membranes with increasing surface wettability. Metabolic reaction rate differences were increasingly more evident at increasing ammonia concentrations. Membrane surface wettability appeared to mainly affect cell capacity to respond to the ammonia challenge.

Journal of Membrane Science, Jun 1, 1986

ABSTRACT

International Journal of Artificial Organs, Apr 1, 1996

The treatment of patients with hepatic failure by means of hybrid liver support devices using pri... more The treatment of patients with hepatic failure by means of hybrid liver support devices using primary xenogeneic hepatocytes is currently hindered by the rapid loss of cell metabolic functions. Similarly to what happens with other mammalian cells, accumulation of cataboJites in the neighborhood of cultured hepatocytes might significantly affect their viability and functions. In this paper, we investigated the effects of high concentrations of catabolites, such as ammonia and lactic acid, on the viability and functions of rat hepatocytes cultured on collagen coated Petri dishes. The effects on hepatocyte functions were established with respect to their ability to synthesize urea and to eliminate ammonia. Indeed, high catabolite concentrations effected both hepatocyte viability and functions. The number of viable hepatocytes decreased with increasing ammonia concentrations in the culture medium. High ammonia concentrations had also both an inhibitory and a toxic effect on hepatocyte functions. In fact, the hepatocytes synthesized urea and eliminated ammonia at rates that decreased with increasing ammonia concentrations. Similarly, high lactic acid concentrations were toxic to the cells and also inhibited their synthetic functions.

Principles and practice, 2009

International Journal of Artificial Organs, 1996

The treatment of fulminant hepatic failure with a bioartificial liver support device relies on th... more The treatment of fulminant hepatic failure with a bioartificial liver support device relies on the possibility of replacing the detoxification and synthetic functions of the injured liver for as long as needed for patient recovery. In spite of progress in cell culture techniques, the effective use of isolated hepatocytes in liver support devices is currently hampered by a lack of information on the metabolic factors limiting long term hepatocyte culture. In this paper, we report our investigation on the effects of oxygen transport resistances on the viability and functions of isolated rat hepatocytes cultured on collagen coated Petri dishes. Detoxification and synthetic functions of the hepatocytes were studied with respect to ammonia and phenolsulphonphthalein elimination and urea synthesis. Lower resistances to oxygen transport favored hepatocyte survival. The isolated hepatocytes synthesized urea at rates that decreased as the resistance to oxygen transport increased. The rate at which urea was synthesized also decreased during the culture. Neither PSP, nor ammonia elimination rate was greatly affected by increasing oxygen transport resistances and remained rather constant up to a week of culture.

PubMed, Oct 16, 2003

In the pharmaceutical industry, the integrity of sterile filters is critical to ensure sterility ... more In the pharmaceutical industry, the integrity of sterile filters is critical to ensure sterility of filtered products. Filter integrity is frequently tested by measuring gas diffusion across water-contacting hydrophobic or hydrophilic membranes with the same automated test devices. Constant device accuracy over the whole range of possible operating conditions is an especially important requirement, as set by the GMP regulations for product critical devices. In this paper, we investigate the accuracy of gas diffusion rate and water intrusion rate estimates provided by a batch-operated and a refilling, continuous-flow commercial automated test device used both for diffusive flow tests and water intrusion tests. Tests were performed on custom-designed model filter systems and full-scale filters over a broad range of gas diffusive flow rates and upstream gas volumes. Neither tested device provided accurate measurements of gas diffusion rate when a small gas diffusion flow was measured out of a very large upstream volume. The batch-operated device provided measurements of gas diffusion rates (either gas diffusion or water intrusion rate) with an accuracy that strongly depends on the gas diffusion rate and on the gas volume upstream from the membrane. Gas diffusion rate measurements were particularly biased in diffusive flow tests of filters with less than 500 mL gas upstream volume. Gas diffusion rates were underestimated by as much as -14.5% in diffusive flow tests and -25% in water intrusion tests. The refilling, continuous flow device generally provided consistent and accurate gas diffusion rate and water intrusion rate measurements within less than 5% of the reference value, practically independent of the gas diffusion flow rate and upstream volume value. A serious bias was only noted in diffusion flow tests at very high upstream volumes and low gas diffusion rate. The results reported in this paper show the importance of qualifying the automated test devices used to assess sterile filter integrity.