Hollow fiber membrane bioreactor consists of hollow fiber membranes parallel-assembled in an exte... more Hollow fiber membrane bioreactor consists of hollow fiber membranes parallel-assembled in an external shell, which is usually in the shape of a cylinder. The fibers are potted in the shell, thus creating a medium and a cell compartment which are separated by the membranes. Hollow fiber membranes of suitable MWCO separate cells from the medium compartment allowing the communication between the compartments through the pores of fiber wall. Depending on the pore sizes, the passage of nutrients, metabolites, and catabolites occurs and cells are retained. The principle of a hollow fiber bioreactor based on hemodialyzer modules was first described by Knazek (Knazek et al. 1972). Usually cells are cultured in suspension or attached to the outer surface of the membranes in the extracapillary space. Culture medium containing nutrients flows in the lumen of the fibers and diffuses out through the pores of the fiber wall to the cells. The metabolic species together with waste molecules produced by cells permeates back into the fibers and is removed from cell compartment (Fig. 1). As bioreactors, they are extensively used for production of biochemicals and for the development of bioartificial organs. Recently they found applications in tissue engineering applications for the development of tissue constructs, cell therapy, and the expansion and transdifferentiation of stem cells. Hollow fiber bioreactor offers several advantages for the culture and growth of adherent and suspension cells including: (i) an in vivo-like microenvironment regarding nutrient supply and metabolic waste removal as each fiber replicates a blood capillary, (ii) high surface area to volume ratio, (iii) cells can be grown to high density, (iv) cells are protected from shear stress, and (v) support of three-dimensional growth of cells for the development of tissue-engineered constructs. Different types of polymers (polyethersulfone, polysulfone, polyacrylonitrile, modified polyetheretherketone, polyamide, cellulose acetate, etc.), generally hydrophilic polymers or with moderate wettability, are used for the development of hollow fiber bioreactors in order to favor the adhesion of cells or the exchange of medium. Hydrophobic hollow fibers (e.g., polypropylene) are included in some devices for a separate oxygenation of cells (Flendrig et al. 1997). A major drawback of the hollow fiber bioreactors is represented by the mass transfer resistance due to the membrane because while it separates cells from the medium compartment, it does reduce diffusion of nutrients and oxygen to the cells. In addition, fouling due to the adsorption of plasma proteins or the
The International Journal of Artificial Organs, 2002
Oxygen is essential for the survival of isolated liver cells and its concentration is known to af... more Oxygen is essential for the survival of isolated liver cells and its concentration is known to affect their viability and function. Recent reports have also shown that ammonia is eliminated at a rate depending on its concentration and that high ammonia concentrations may be cytotoxic to rat liver cells. Nonetheless, little quantitative information on the effect of either metabolite on liver cell reaction kinetics is available although important to the design of bioreactors for bioartificial livers (BALs). In this investigation, we characterized the dependence of the rate of oxygen consumption (OCR), ammonia elimination (AER) and urea synthesis (USR) on ammonia concentration at physiological (i.e., 43 and 72 mmHg) and supra-physiological (i.e., 134 mmHg) dissolved oxygen tensions. To this purpose, isolated rat liver cells were cultured in adhesion on collagen in a continuous-flow bioreactor optimised for the kinetic characterisation of liver cell metabolic reactions. Rates of the inv...
The 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...
Comprehensive Membrane Science and Engineering, 2010
Many advances have been made in the last century to replace and restore damaged organs and tissue... more Many advances have been made in the last century to replace and restore damaged organs and tissues due to the increase of the aging population and the shortage of suitable organs for transplantation. Tissue engineering approaches based on the combination of smart biomaterials with advanced cell therapy should closely mimic and replicate the physical and biochemical milieu of the natural tissues and organs. Many efforts have been made to improve the design of natural and synthetic, resorbable and nonbiodegradable biomaterials in supporting cell adhesion, differentiation, and proliferation toward the formation of a new tissue. Micro- and nanostructured membranes have a great potential to create a biomimetic environment for cells providing them the biochemical, physical, and mechanical cues, which are necessary for the tissue formation. Tailor-made membranes are designed according to well-defined engineering criteria, taking into account the chemical composition and the physicochemical, morphological, and transport properties. These systems on the basis of their characteristics compartmentalize cells in a well-controlled microenvironment at molecular level providing a selective mass transfer of nutrients and metabolites to and from cells ensuring the system homeostasis. In this article, advances achieved in the development of liver and neuronal membrane systems as bioartificial organs and tissues were reviewed focusing on their evaluation in both the preclinical and clinical systems and their validation as in vitro platforms.
Annals of transplantation : quarterly of the Polish Transplantation Society, 2001
Recent developments in tissue engineering permit to use isolated hepatocytes in a bioreactor for ... more Recent developments in tissue engineering permit to use isolated hepatocytes in a bioreactor for the creation of a bioartificial liver which supports patients suffering from acute liver failure. In this study, the authors discuss the development of a flat membrane bioreactor using pig hepatocytes for the replacement of liver functions. The flat membrane bioreactor permits a high-density hepatocyte culture under sufficient oxygenation conditions, comparable to an in vivo microenvironment. In this bioreactor, built according to the in vivo organisation of the liver, pig hepatocytes are cultured with non-parenchymal cells within an extracellular matrix between oxygen-permeable flat-sheet membranes as individual plates. The performance of the "scale-up bioreactor" was tested in vitro for 18 days in static and flux conditions. Pig hepatocytes in the bioreactor were maintained in three-dimensional co-culture with non-parenchymal cells and are reorganised in a way similar to the ...
Synthetic polymer scaffold seeded with autologous cells have a clinical translational potential. ... more Synthetic polymer scaffold seeded with autologous cells have a clinical translational potential. A rational design oriented to clinical applications must ensure an efficient mass transfer of nutrients as a function of specific metabolic rates, especially for precariously vascularized tissues grown in vitro or integrated in vivo. In this work, luminescence lifetime-based sensors were used to provide accurate, extensive and non-invasive measurements of the oxygen uptake rate for human mesenchymal stem cells (hMSCs), tracheal epithelial cells (hTEpiCs) and human chondrocytes (hCCs) within a range of 2-40% O2 partial pressure. Estimated Michaelis-Menten parameters were: V(max) = 0.099 pmol/cell⋅h and K(M) = 2.12 × 10(-7) mol/cm(3) for hMSCs, V(max) = 1.23 pmol/cell⋅h and K(M) = 2.14 × 10(-7) mol/cm(3) for hTEpiCs, V(max) = 0.515 pmol/cell⋅h and K(M) = 1.65 × 10(-7) mol/cm(3) for hCCs. Kinetics data served as an input to a preliminary computational simulation of cell culture on a poly-ethylene terephthalate (PET) tracheal scaffold obtaining an efficient mass transfer at cell density of 10(6) cell/cm(3). Oxygen concentration affected the glucose uptake and lactate production rates of cells that adapted their metabolism according to energy demand in hypoxic and normoxic conditions.
ABSTRACTBone tissue engineering typically involves the use of porous, bioresorbable scaffolds to ... more ABSTRACTBone tissue engineering typically involves the use of porous, bioresorbable scaffolds to serve as temporary, three-dimensional scaffolds to guide cell attachment, differentiation, proliferation, and subsequent tissue regeneration. In this study we developed a composite membrane scaffold by phase inversion technique by using biodegradable polyester, Polycaprolactone (PCL), with hydroxyapatite (HA) in order to develop novel controlled nanostructured biomaterials for bone tissue engineering applications.After preparation, membrane scaffolds were characterized in order to evaluate its morphological, physico-chemical and mechanical properties and then used for the cell culture.Our experimental design consists to apply the knowledge of natural bone tissue remodelling in an in vitro membrane biohybrid system. We used human mesenchymal stem cells for culture in the membrane scaffolds inducing the differentiation in osteoblasts and human monocytes to trigger osteoclastogenesis. Osteo...
ABSTRACTPolymeric membranes are widely used in biomedical field for bioartificial organs, medical... more ABSTRACTPolymeric membranes are widely used in biomedical field for bioartificial organs, medical devices and disposable clinical apparatus. Clinical utilization of blood-contacting devices requires the development of biomaterials with improved blood compatibility. The aim of this work was the exploration of a potential biocompatible membrane derived from a modified polyetheretherketone such as PEEK-WC. The surface affinity of this membrane to human plasma and plasmatic proteins such as albumin, fibrinogen and immunoglobulin G was compared to that of some commercial membranes. Changes with time of the membrane interfacial properties were evaluated by means of contact angle measurements using human protein solutions and human plasma. The extent of plasma protein adsorption on all investigated membranes was measured by comparing the behavior of the different polymer surfaces when contacting the three plasmatic proteins.
In what case do you like reading so much? What about the type of the biomaterials for stem cell t... more In what case do you like reading so much? What about the type of the biomaterials for stem cell therapy state of art and vision for the future book? The needs to read? Well, everybody has their own reason why should read some books. Mostly, it will relate to their necessity to get knowledge from the book and want to read just to get entertainment. Novels, story book, and other entertaining books become so popular this day. Besides, the scientific books will also be the best reason to choose, especially for the students, teachers, doctors, businessman, and other professions who are fond of reading.
In tissue engineering the formation of organized and functional tissues is a very complex task: t... more In tissue engineering the formation of organized and functional tissues is a very complex task: the cellular environment requires suitable physiological conditions that, presently, can be achieved and maintained by using properly designed biomaterials that can support the viability and all specific functions of cells. The creation of the biomimetic environment can be realized by using polymeric membranes with specific physico-chemical, morphological, and transport properties on the basis of the targeted tissue or organ. Membrane can act as an instructive extracellular matrix (ECM) for cells, especially for stem cells or progenitor cells, whose differentiation is desired for their therapeutic potential and usefulness in the toxicological testing. Similar to the ECM, membrane exhibits from microscale to nanoscale of chemistry and topography and is able to provide physical, chemical, and mechanical signals to the cells, which are important for guiding their differentiation. In this chapter, the authors report on tailor-made membrane systems designed and operated according to well-defined engineering criteria and their potential use in the biofabrication of tissues and organs. Membrane surface and transport properties play a pivotal role in the proliferation and differentiation process governing mass transfer and providing instructive signals to the cells. Furthermore, membrane bioreactors, through the fluid dynamics modulation, may simulate the in vivo complex physiological environment, ensuring an adequate mass transfer of nutrients and metabolites and the molecular and mechanical regulatory signals.
New strategies aimed to surface modification of polymeric membranes are crucial to optimise cell-... more New strategies aimed to surface modification of polymeric membranes are crucial to optimise cell-biomaterial interactions in vivo and in vitro biohybrid systems. In this paper, we investigated the surface modification of Polyethersulfone (PES) membranes by plasma polymerisation of acrylic acid monomers (PES-pdAA) and by immobilization of galactonic acid through a hydrophilic "spacer arm" molecule (PES-pdAA-SA-GAL). The modification steps were characterised by high resolution X-ray photoelectron spectroscopy. The performance of modified and unmodified membranes was evaluated by assessing the expression of liver specific biotransformation functions of pig and human hepatocytes. Human liver cells cultured on PES-pdAA-SA-GAL membranes displayed an enhanced albumin production, urea synthesis and protein secretion for 24 days of culture. The immobilisation of galactose derivative units on the membrane allowed specific interactions with hepatocytes biomimicking the cellular microenvironment and produced an improvement of the long-term maintenance and differentiation of human hepatocytes.
ABSTRACT There is a growing demand for the expansion and differentiation of stem cells for cell t... more ABSTRACT There is a growing demand for the expansion and differentiation of stem cells for cell therapies, tissue engineering, and model systems for drug screening. Current methods for stem cell production are based on the use of batch tissue culture flasks, which have several drawbacks. In this paper we report on the use of a crossed hollow fiber membrane bioreactor for the expansion and differentiation of embryonic liver cells, which have been used as an alternative model of human liver progenitor cells. The bioreactor is based on two bundles of fiber (PEEK-WC HF and PES-HF) which are cross-assembled in an alternating manner. This bioreactor geometry ensures high mass exchange of nutrients and metabolites, which is important for cell proliferation and differentiation. The membrane bioreactor, thanks to its optimized fluid dynamics and mass transport and the adequate surface properties of hollow fibers, was able to guide the expansion and differentiation of liver progenitor cells in mature hepatocytes as demonstrated by their expression of liver specific functions in terms of urea synthesis, albumin production, and diazepam drug biotransformation.
Hollow fiber membrane bioreactor consists of hollow fiber membranes parallel-assembled in an exte... more Hollow fiber membrane bioreactor consists of hollow fiber membranes parallel-assembled in an external shell, which is usually in the shape of a cylinder. The fibers are potted in the shell, thus creating a medium and a cell compartment which are separated by the membranes. Hollow fiber membranes of suitable MWCO separate cells from the medium compartment allowing the communication between the compartments through the pores of fiber wall. Depending on the pore sizes, the passage of nutrients, metabolites, and catabolites occurs and cells are retained. The principle of a hollow fiber bioreactor based on hemodialyzer modules was first described by Knazek (Knazek et al. 1972). Usually cells are cultured in suspension or attached to the outer surface of the membranes in the extracapillary space. Culture medium containing nutrients flows in the lumen of the fibers and diffuses out through the pores of the fiber wall to the cells. The metabolic species together with waste molecules produced by cells permeates back into the fibers and is removed from cell compartment (Fig. 1). As bioreactors, they are extensively used for production of biochemicals and for the development of bioartificial organs. Recently they found applications in tissue engineering applications for the development of tissue constructs, cell therapy, and the expansion and transdifferentiation of stem cells. Hollow fiber bioreactor offers several advantages for the culture and growth of adherent and suspension cells including: (i) an in vivo-like microenvironment regarding nutrient supply and metabolic waste removal as each fiber replicates a blood capillary, (ii) high surface area to volume ratio, (iii) cells can be grown to high density, (iv) cells are protected from shear stress, and (v) support of three-dimensional growth of cells for the development of tissue-engineered constructs. Different types of polymers (polyethersulfone, polysulfone, polyacrylonitrile, modified polyetheretherketone, polyamide, cellulose acetate, etc.), generally hydrophilic polymers or with moderate wettability, are used for the development of hollow fiber bioreactors in order to favor the adhesion of cells or the exchange of medium. Hydrophobic hollow fibers (e.g., polypropylene) are included in some devices for a separate oxygenation of cells (Flendrig et al. 1997). A major drawback of the hollow fiber bioreactors is represented by the mass transfer resistance due to the membrane because while it separates cells from the medium compartment, it does reduce diffusion of nutrients and oxygen to the cells. In addition, fouling due to the adsorption of plasma proteins or the
The International Journal of Artificial Organs, 2002
Oxygen is essential for the survival of isolated liver cells and its concentration is known to af... more Oxygen is essential for the survival of isolated liver cells and its concentration is known to affect their viability and function. Recent reports have also shown that ammonia is eliminated at a rate depending on its concentration and that high ammonia concentrations may be cytotoxic to rat liver cells. Nonetheless, little quantitative information on the effect of either metabolite on liver cell reaction kinetics is available although important to the design of bioreactors for bioartificial livers (BALs). In this investigation, we characterized the dependence of the rate of oxygen consumption (OCR), ammonia elimination (AER) and urea synthesis (USR) on ammonia concentration at physiological (i.e., 43 and 72 mmHg) and supra-physiological (i.e., 134 mmHg) dissolved oxygen tensions. To this purpose, isolated rat liver cells were cultured in adhesion on collagen in a continuous-flow bioreactor optimised for the kinetic characterisation of liver cell metabolic reactions. Rates of the inv...
The 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...
Comprehensive Membrane Science and Engineering, 2010
Many advances have been made in the last century to replace and restore damaged organs and tissue... more Many advances have been made in the last century to replace and restore damaged organs and tissues due to the increase of the aging population and the shortage of suitable organs for transplantation. Tissue engineering approaches based on the combination of smart biomaterials with advanced cell therapy should closely mimic and replicate the physical and biochemical milieu of the natural tissues and organs. Many efforts have been made to improve the design of natural and synthetic, resorbable and nonbiodegradable biomaterials in supporting cell adhesion, differentiation, and proliferation toward the formation of a new tissue. Micro- and nanostructured membranes have a great potential to create a biomimetic environment for cells providing them the biochemical, physical, and mechanical cues, which are necessary for the tissue formation. Tailor-made membranes are designed according to well-defined engineering criteria, taking into account the chemical composition and the physicochemical, morphological, and transport properties. These systems on the basis of their characteristics compartmentalize cells in a well-controlled microenvironment at molecular level providing a selective mass transfer of nutrients and metabolites to and from cells ensuring the system homeostasis. In this article, advances achieved in the development of liver and neuronal membrane systems as bioartificial organs and tissues were reviewed focusing on their evaluation in both the preclinical and clinical systems and their validation as in vitro platforms.
Annals of transplantation : quarterly of the Polish Transplantation Society, 2001
Recent developments in tissue engineering permit to use isolated hepatocytes in a bioreactor for ... more Recent developments in tissue engineering permit to use isolated hepatocytes in a bioreactor for the creation of a bioartificial liver which supports patients suffering from acute liver failure. In this study, the authors discuss the development of a flat membrane bioreactor using pig hepatocytes for the replacement of liver functions. The flat membrane bioreactor permits a high-density hepatocyte culture under sufficient oxygenation conditions, comparable to an in vivo microenvironment. In this bioreactor, built according to the in vivo organisation of the liver, pig hepatocytes are cultured with non-parenchymal cells within an extracellular matrix between oxygen-permeable flat-sheet membranes as individual plates. The performance of the "scale-up bioreactor" was tested in vitro for 18 days in static and flux conditions. Pig hepatocytes in the bioreactor were maintained in three-dimensional co-culture with non-parenchymal cells and are reorganised in a way similar to the ...
Synthetic polymer scaffold seeded with autologous cells have a clinical translational potential. ... more Synthetic polymer scaffold seeded with autologous cells have a clinical translational potential. A rational design oriented to clinical applications must ensure an efficient mass transfer of nutrients as a function of specific metabolic rates, especially for precariously vascularized tissues grown in vitro or integrated in vivo. In this work, luminescence lifetime-based sensors were used to provide accurate, extensive and non-invasive measurements of the oxygen uptake rate for human mesenchymal stem cells (hMSCs), tracheal epithelial cells (hTEpiCs) and human chondrocytes (hCCs) within a range of 2-40% O2 partial pressure. Estimated Michaelis-Menten parameters were: V(max) = 0.099 pmol/cell⋅h and K(M) = 2.12 × 10(-7) mol/cm(3) for hMSCs, V(max) = 1.23 pmol/cell⋅h and K(M) = 2.14 × 10(-7) mol/cm(3) for hTEpiCs, V(max) = 0.515 pmol/cell⋅h and K(M) = 1.65 × 10(-7) mol/cm(3) for hCCs. Kinetics data served as an input to a preliminary computational simulation of cell culture on a poly-ethylene terephthalate (PET) tracheal scaffold obtaining an efficient mass transfer at cell density of 10(6) cell/cm(3). Oxygen concentration affected the glucose uptake and lactate production rates of cells that adapted their metabolism according to energy demand in hypoxic and normoxic conditions.
ABSTRACTBone tissue engineering typically involves the use of porous, bioresorbable scaffolds to ... more ABSTRACTBone tissue engineering typically involves the use of porous, bioresorbable scaffolds to serve as temporary, three-dimensional scaffolds to guide cell attachment, differentiation, proliferation, and subsequent tissue regeneration. In this study we developed a composite membrane scaffold by phase inversion technique by using biodegradable polyester, Polycaprolactone (PCL), with hydroxyapatite (HA) in order to develop novel controlled nanostructured biomaterials for bone tissue engineering applications.After preparation, membrane scaffolds were characterized in order to evaluate its morphological, physico-chemical and mechanical properties and then used for the cell culture.Our experimental design consists to apply the knowledge of natural bone tissue remodelling in an in vitro membrane biohybrid system. We used human mesenchymal stem cells for culture in the membrane scaffolds inducing the differentiation in osteoblasts and human monocytes to trigger osteoclastogenesis. Osteo...
ABSTRACTPolymeric membranes are widely used in biomedical field for bioartificial organs, medical... more ABSTRACTPolymeric membranes are widely used in biomedical field for bioartificial organs, medical devices and disposable clinical apparatus. Clinical utilization of blood-contacting devices requires the development of biomaterials with improved blood compatibility. The aim of this work was the exploration of a potential biocompatible membrane derived from a modified polyetheretherketone such as PEEK-WC. The surface affinity of this membrane to human plasma and plasmatic proteins such as albumin, fibrinogen and immunoglobulin G was compared to that of some commercial membranes. Changes with time of the membrane interfacial properties were evaluated by means of contact angle measurements using human protein solutions and human plasma. The extent of plasma protein adsorption on all investigated membranes was measured by comparing the behavior of the different polymer surfaces when contacting the three plasmatic proteins.
In what case do you like reading so much? What about the type of the biomaterials for stem cell t... more In what case do you like reading so much? What about the type of the biomaterials for stem cell therapy state of art and vision for the future book? The needs to read? Well, everybody has their own reason why should read some books. Mostly, it will relate to their necessity to get knowledge from the book and want to read just to get entertainment. Novels, story book, and other entertaining books become so popular this day. Besides, the scientific books will also be the best reason to choose, especially for the students, teachers, doctors, businessman, and other professions who are fond of reading.
In tissue engineering the formation of organized and functional tissues is a very complex task: t... more In tissue engineering the formation of organized and functional tissues is a very complex task: the cellular environment requires suitable physiological conditions that, presently, can be achieved and maintained by using properly designed biomaterials that can support the viability and all specific functions of cells. The creation of the biomimetic environment can be realized by using polymeric membranes with specific physico-chemical, morphological, and transport properties on the basis of the targeted tissue or organ. Membrane can act as an instructive extracellular matrix (ECM) for cells, especially for stem cells or progenitor cells, whose differentiation is desired for their therapeutic potential and usefulness in the toxicological testing. Similar to the ECM, membrane exhibits from microscale to nanoscale of chemistry and topography and is able to provide physical, chemical, and mechanical signals to the cells, which are important for guiding their differentiation. In this chapter, the authors report on tailor-made membrane systems designed and operated according to well-defined engineering criteria and their potential use in the biofabrication of tissues and organs. Membrane surface and transport properties play a pivotal role in the proliferation and differentiation process governing mass transfer and providing instructive signals to the cells. Furthermore, membrane bioreactors, through the fluid dynamics modulation, may simulate the in vivo complex physiological environment, ensuring an adequate mass transfer of nutrients and metabolites and the molecular and mechanical regulatory signals.
New strategies aimed to surface modification of polymeric membranes are crucial to optimise cell-... more New strategies aimed to surface modification of polymeric membranes are crucial to optimise cell-biomaterial interactions in vivo and in vitro biohybrid systems. In this paper, we investigated the surface modification of Polyethersulfone (PES) membranes by plasma polymerisation of acrylic acid monomers (PES-pdAA) and by immobilization of galactonic acid through a hydrophilic "spacer arm" molecule (PES-pdAA-SA-GAL). The modification steps were characterised by high resolution X-ray photoelectron spectroscopy. The performance of modified and unmodified membranes was evaluated by assessing the expression of liver specific biotransformation functions of pig and human hepatocytes. Human liver cells cultured on PES-pdAA-SA-GAL membranes displayed an enhanced albumin production, urea synthesis and protein secretion for 24 days of culture. The immobilisation of galactose derivative units on the membrane allowed specific interactions with hepatocytes biomimicking the cellular microenvironment and produced an improvement of the long-term maintenance and differentiation of human hepatocytes.
ABSTRACT There is a growing demand for the expansion and differentiation of stem cells for cell t... more ABSTRACT There is a growing demand for the expansion and differentiation of stem cells for cell therapies, tissue engineering, and model systems for drug screening. Current methods for stem cell production are based on the use of batch tissue culture flasks, which have several drawbacks. In this paper we report on the use of a crossed hollow fiber membrane bioreactor for the expansion and differentiation of embryonic liver cells, which have been used as an alternative model of human liver progenitor cells. The bioreactor is based on two bundles of fiber (PEEK-WC HF and PES-HF) which are cross-assembled in an alternating manner. This bioreactor geometry ensures high mass exchange of nutrients and metabolites, which is important for cell proliferation and differentiation. The membrane bioreactor, thanks to its optimized fluid dynamics and mass transport and the adequate surface properties of hollow fibers, was able to guide the expansion and differentiation of liver progenitor cells in mature hepatocytes as demonstrated by their expression of liver specific functions in terms of urea synthesis, albumin production, and diazepam drug biotransformation.
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