02116nas a2200193 4500008004100000245009500041210006900136260001200205520148600217653001901703100001501722700001701737700001401754700002501768700001401793700002001807700001801827856007701845 2017 eng d00aOn the adhesion-cohesion balance and oxygen consumption characteristics of liver organoids0 aadhesioncohesion balance and oxygen consumption characteristics  c03/20173 a

Liver organoids (LOs) are of interest in tissue replacement, hepatotoxicity and pathophysiological studies. However, it is still unclear what triggers LO self-assembly and what the optimal environment is for their culture. Hypothesizing that LO formation occurs as a result of a fine balance between cell-substrate adhesion and cell-cell cohesion, we used 3 cell types (hepatocytes, liver sinusoidal endothelial cells and mesenchymal stem cells) to investigate LO self-assembly on different substrates keeping the culture parameters (e.g. culture media, cell types/number) and substrate stiffness constant. As cellular spheroids may suffer from oxygen depletion in the core, we also sought to identify the optimal culture conditions for LOs in order to guarantee an adequate supply of oxygen during proliferation and differentiation. The oxygen consumption characteristics of LOs were measured using an O2 sensor and used to model the O2 concentration gradient in the organoids. We show that no LO formation occurs on highly adhesive hepatic extra-cellular matrix-based substrates, suggesting that cellular aggregation requires an optimal trade-off between the adhesiveness of a substrate and the cohesive forces between cells and that this balance is modulated by substrate mechanics. Thus, in addition to substrate stiffness, physicochemical properties, which are also critical for cell adhesion, play a role in LO self-assembly.

10aBioengineering1 aMattei, G.1 aMagliaro, C.1 aGiusti, S1 aRamachandran, S., D.1 aHeinz, S.1 aBraspenning, J.1 aAhluwalia, A. uhttp://journals.plos.org/plosone/article?id=10.1371/journal.pone.017320602269nas a2200229 4500008003900000245008800039210006900127260002700196300000700223520152800230653001901758100001801777700001401795700001401809700001801823700001401841700001501855700001401870700001401884700001701898856012401915 2014 d00aAutonomous bioreactor modules for disease models and detection of systemic toxicity0 aAutonomous bioreactor modules for disease models and detection o aPrague, Czech Republic a433 a

Advanced systems based on bioreactors and scaffolds are an essential step towards the development of more predictive and ethical alternatives to animal experiments. Size, modularity, automation, monitoring and essential design are crucial because these elements will ease the transition from old technology and accelerate their acceptance into mainstream research. Based on these requirements, the interconnected transparent sensorised “lego” bioreactors designed in our labs have been used to generate physiologically relevant disease and toxicity models which recapitulate systemic responses impossible to observe in standard cell cultures. The disease model is an interconnected bioreactor circuit with i) adipose tissue in 3D in 3 different concentrations representing normo-weight, over weight and obese body mass indices, ii) human hepatocytes on porous collagen scaffolds and iii) monolayers of human endothelial cells. High adiposity and elevated glucose levels induce systemic and endothelial inflammation in the circuit, as observed in overweight and diabetic humans (Iori et al., 2012). Using similar technology a three-tissue circuit for monitoring the absorption, distribution, metabolism and toxicity of nanoparticles was developed in the context of the EU project InLiveTox (Ucciferri et al., 2014). The results were strikingly similar to those observed in animal experiments demonstrating that the dynamic 3D in-vitro models are ethical, meaningful and economically viable replacements.

10aBioengineering1 aAhluwalia, A.1 aGiusti, S1 aSbrana, T1 aWilkinson, M.1 aMisto, A.1 aLehr, C -M1 aLiley, M.1 aHorst, S.1 aJírová, D. uhttp://175973.jxltd.asia/publications/autonomous-bioreactor-modules-disease-models-and-detection-systemic-toxicity.html02055nas a2200169 4500008004100000022001400041245009100055210006900146300001400215490000600229520154100235653001901776100001501795700001401810700001801824856004301842 2014 eng d a2227-971700aDesign Criteria for Generating Physiologically Relevant In Vitro Models in Bioreactors0 aDesign Criteria for Generating Physiologically Relevant In Vitro a548–5690 v23 a

In this paper, we discuss the basic design requirements for the development of physiologically meaningful in vitro systems comprising cells, scaffolds and bioreactors, through a bottom up approach. Very simple micro- and milli-fluidic geometries are first used to illustrate the concepts, followed by a real device case-study. At each step, the fluidic and mass transport parameters in biological tissue design are considered, starting from basic questions such as the minimum number of cells and cell density required to represent a physiological system and the conditions necessary to ensure an adequate nutrient supply to tissues. At the next level, we consider the use of three-dimensional scaffolds, which are employed both for regenerative medicine applications and for the study of cells in environments which better recapitulate the physiological milieu. Here, the driving need is the rate of oxygen supply which must be maintained at an appropriate level to ensure cell viability throughout the thickness of a scaffold. Scaffold and bioreactor design are both critical in defining the oxygen profile in a cell construct and are considered together. We also discuss the oxygen-shear stress trade-off by considering the levels of mechanical stress required for hepatocytes, which are the limiting cell type in a multi-organ model. Similar considerations are also made for glucose consumption in cell constructs. Finally, the allometric approach for generating multi-tissue systemic models using bioreactors is described.

10aBioengineering1 aMattei, G.1 aGiusti, S1 aAhluwalia, A. uhttp://www.mdpi.com/2227-9717/2/3/548/01235nas a2200169 4500008003900000245010200039210006900141260002200210520060000232653001900832100001600851700001400867700001800881700001800899700001800917856013000935 2014 d00aFluid dynamics in porous scaffolds stimulated with cyclic squeeze pressure in the S2PR bioreactor0 aFluid dynamics in porous scaffolds stimulated with cyclic squeez aPavia, 25-27 June3 a

In cardiac tissue engineering, the use of bioreactors is fundamental for applying controlled mechanical stimuli on the cells and recreate a physiological environment for cardiomyocytes cultures. This work is focused on an innovative Sensorized Squeeze PRessure (S2PR) bioreactor, able to apply a periodic contactless hydrodynamic pressures on 3D porous constructs. The fluid-dynamic environment inside the bioreactor was fully characterized using computational models, focusing on the pressures and fluid velocity profiles generated in the porous scaffold during the cyclic stimulation.

10aBioengineering1 aFerroni, M.1 aGiusti, S1 aSpatafora, G.1 aBoschetti, F.1 aAhluwalia, A. uhttp://175973.jxltd.asia/publications/fluid-dynamics-porous-scaffolds-stimulated-cyclic-squeeze-pressure-s2pr-bioreactor.html00545nas a2200157 4500008003900000245010200039210006900141300001300210653001900223100001600242700001400258700001800272700001800290700001800308856006100326 2014 d00aFluid dynamics in porous scaffolds stimulated with cyclic squeeze pressure in the S2PR bioreactor0 aFluid dynamics in porous scaffolds stimulated with cyclic squeez a363–6810aBioengineering1 aFerroni, M.1 aGiusti, S1 aSpatafora, G.1 aBoschetti, F.1 aAhluwalia, A. uhttp://amsacta.unibo.it/4085/1/ProceedingsİCMMB2014.pdf02631nas a2200181 4500008003900000245010200039210006900141260003600210300000800246520196600254653001902220100001402239700001402253700001902267700001802286700001802304856012702322 2014 d00aMulti-organ-on-plate system for in-vitro studies of intestinal drug absorption and hepatotoxicity0 aMultiorganonplate system for invitro studies of intestinal drug  aEgmond aan Zee, The Netherlands a1073 a

More meaningful in-vitro models which simulate the physiological conditions of native tissue are becoming essential in the pharmaceutical field, for early and rapid screening of drug candidates. Here, we describe a multi-organ-on-plate system based on single and double flow mini bioreactor modules for dynamic in-vitro studies of intestinal drug absorption, drug metabolism and more relevant toxicity studies. The double flow module for membrane culture was firstly characterized using computational fluid dynamic models and measurements of pressure gradients, in order to indentify the optimal flow rates for maximizing the passage of solutes through the membrane. Then, cell culture experiments were performed with fully differentiated Caco-2 cells seeded on the semi-permeable membrane as a dynamic model of the intestinal epithelium, connected to a single flow chamber with metabolically competent human upcyte® hepatocytes (Medicyte GmbH, Germany) seeded on a 3D collagen cryogel. First we assessed the role of flow in modulating the passage of compounds across the epithelial barrier. Then toxicity tests were performed by administering different concentrations of hepatotoxic compounds (i.e. Diclofenac, Nimesulide, industrial nanoparticles) in the apical compartment of the MB, compared the data with cell cultures in transwells. Our results show: i) the presence of flow significantly increases translocation of all molecules tested across the membrane, ii) flow conditioned Caco-2 cells are more permeable to small hydrophilic compounds, despite having high TEER values iii) although they display higher levels of phenotypic markers (tight junctions, albumin expression etc), cells in the system are more susceptible to drug induced toxicity. In conclusion, the multi-organ-on-plate system predicts drug adsorption and toxicity better than traditional cell cultures and could be used to reduce, refine and eventually replace animal tests.

10aBioengineering1 aGiusti, S1 aSbrana, T1 aGiacopelli, D.1 aDi Patria, V.1 aAhluwalia, A. uhttp://175973.jxltd.asia/publications/multi-organ-plate-system-vitro-studies-intestinal-drug-absorption-and-hepatotoxicity02063nas a2200193 4500008003900000245010100039210006900140260002700209300001100236520139000247653001901637100001401656700001501670700001401685700001801699700001501717700001401732856012301746 2014 d00aThe need of innovative technologies for new 3D relevant in-vitro models and the answer of Ivtech0 aneed of innovative technologies for new 3D relevant invitro mode aPrague, Czech Republic a45–63 a

New relevant in-vitro models are priorities in pharmaco-toxicology, cosmetic and food research to reduce the animal tests. Therefore, invivo models show ethical issues, are not time and cost effective and are progressively showing scientific limitations: for instance they fail in detection of pathogens that are species specific (Mazzoleni et al., 2009). The search of more relevant pre-clinical models forced the researcher to move from 2D to 3D in-vitro models in order to maintain the phenotype of cells (Lovit et al., 2013; Mattei et al., 2014). Even if the significant progress in material science, the metabolic requirement of 3D tissues is higher than a 2D culture and the scaffold is a limitation in nutrients transport. Dynamic cell culture chambers are then required to assure the gas/nutrient supply, waste elimination, mechanical stimulation of cells, study of cross talk between different tissues and real time monitoring of cells. Nowadays the only systems that meet all these specifications are the Ivtech technologies. Ivtech is an innovative Italian start-up that grows up to solve the needs of in-vitro experts, offering and customizing several type of transparent, dynamic and modular cell culture systems, organizing workshops and training. The goal is to expand the 3D approach and permits a significant evolution towards highly relevant in-vitro models.

10aBioengineering1 aSbrana, T1 aMattei, G.1 aGiusti, S1 aAhluwalia, A.1 aDagmar, J.1 aHorst, S. uhttp://175973.jxltd.asia/publications/need-innovative-technologies-new-3d-relevant-vitro-models-and-answer-ivtech.html02045nas a2200205 4500008004100000022001400041245010800055210006900163520140900232653001901641100001401660700001401674700001601688700001801704700001901722700001501741700001701756700001801773856004801791 2014 eng d a1860-731400aA novel dual-flow bioreactor simulates increased fluorescein permeability in epithelial tissue barriers0 anovel dualflow bioreactor simulates increased fluorescein permea3 a

Permeability studies across epithelial barriers are of primary importance in drug delivery as well as in toxicology. However, traditional in vitro models do not adequately mimic the dynamic environment of physiological barriers. Here, we describe a novel two-chamber modular bioreactor for dynamic in vitro studies of epithelial cells. The fluid dynamic environment of the bioreactor was characterized using computational fluid dynamic models and measurements of pressure gradients for different combinations of flow rates in the apical and basal chambers. Cell culture experiments were then performed with fully differentiated Caco-2 cells as a model of the intestinal epithelium, comparing the effect of media flow applied in the bioreactor with traditional static transwells. The flow increases barrier integrity and tight junction expression of Caco-2 cells with respect to the static controls. Fluorescein permeability increased threefold in the dynamic system, indicating that the stimulus induced by flow increases transport across the barrier, closely mimicking the in vivo situation. The results are of interest for studying the influence of mechanical stimuli on cells, and underline the importance of developing more physiologically relevant in vitro tissue models. The bioreactor can be used to study drug delivery, chemical, or nanomaterial toxicity and to engineer barrier tissues.

10aBioengineering1 aGiusti, S1 aSbrana, T1 aLa Marca, M1 aDi Patria, V.1 aMartinucci, V.1 aTirella, A1 aDomenici, C.1 aAhluwalia, A. uhttp://www.ncbi.nlm.nih.gov/pubmed/2475686900623nas a2200205 4500008003900000245009600039210006900135300001100204490001400215653001900229100001400248700001300262700001600275700001500291700001500306700001500321700001500336700001800351856004800369 2014 d00aSensorized Squeeze Pressure Bioreactor For mechanical modulation of cardiomyocyte phenotype0 aSensorized Squeeze Pressure Bioreactor For mechanical modulation a67–80 v8 Suppl 110aBioengineering1 aGiusti, S1 aVozzi, F1 aPagliari, F1 aTirella, A1 aMazzei, D.1 aCabiati, M1 adel Ry, S.1 aAhluwalia, A. uhttp://www.ncbi.nlm.nih.gov/pubmed/2491268601220nas a2200229 4500008004100000022001300041245007100054210006900125300001400194490000700208520056900215653001900784100001400803700001600817700001300833700001500846700001500861700001500876700001500891700001800906856006600924 2013 eng d a1877705800aSQPR 3.0: A Sensorized Bioreactor for Modulating Cardiac Phenotype0 aSQPR 30 A Sensorized Bioreactor for Modulating Cardiac Phenotype a219–2250 v593 a

In cardiac tissue engineering, the use of bioreactors is fundamental for applying controlled mechanical stimuli on cells and recreate a physiological environment for cardiomyocyte cultures. This work is focused on the design of a sensorized Squeeze Pressure bioreactor (SQPR 3.0) able to apply a periodic contactless hydrodynamic pressure on tissue constructs. This system was then tested with H2c9, a murine cardiomyoblast cell line, to investigate the effect of different stimulation times (2h, 24h, 30h) on cell shape and cardiotypic marker expression.

10aBioengineering1 aGiusti, S1 aPagliari, F1 aVozzi, F1 aTirella, A1 aMazzei, D.1 aCabiati, M1 adel Ry, S.1 aAhluwalia, A. uhttp://linkinghub.elsevier.com/retrieve/pii/S187770581301028X02093nas a2200205 4500008003900000245006300039210006000102260002000162520144900182653001901631653001601650653002401666100001501690700001801705700001701723700001701740700001401757700001601771856010001787 2012 d00aA multi-stimuli environment for cardiac tissue engineering0 amultistimuli environment for cardiac tissue engineering aVienna, Austria3 a

The identification of the ideal cell source to generate cardiac tissue able to integrate into the host myocardium and with the contractile system is crucial for cardiac engineering. Amongst different cell sources so far proposed, human adult Cardiac Progenitor Cells (hCPCs) show the ability to proliferate and differentiate toward cardiac lineages when grown in appropriate microenvironmental conditions. It is widely accepted that conventional 2D cultures may provide a physiological environment for growing cells. For this reason the need to have an engineered microenvironment, matching physiological requirements, is crucial. A 3D context with spatial and time varying distribution of regulatory factors using mechanically matched scaffolds and bioreactors could represent an in vitro cell culture model being able to more closely reflects the in vivo conditions. In the present study, the possibility of using biocompatible and biodegradable scaffolds of collagen based or derivatives hydrogels in combination with Linneg/Sca-1pos hCPCs gathered from human heart biopsies was investigated. Bio-constructs were placed in the low shear, high flow MCmB (MultiCompartment modular Bioreactor) and the combined effects of dynamic culture conditions and 3D scaffolds on cell morphology and differentiation were studied in order to investigate the possibility of fabricating stem cell-derived cardiac patches to replace infarcted tissue.

10aBioengineering10aBioreactors10aDynamic 3D Cultures1 aTirella, A1 aAhluwalia, A.1 aDi Nardo, P.1 aGaudiello, E1 aGiusti, S1 aPagliari, F uhttp://175973.jxltd.asia/publications/multi-stimuli-environment-cardiac-tissue-engineering.html02043nas a2200169 4500008003900000245008600039210006900125260001800194300000800212490001400220520152500234653001901759100001401778700001501792700001801807856004801825 2012 d00aReal Time and In-Situ control of environmental parameters in a modular bioreactor0 aReal Time and InSitu control of environmental parameters in a mo aVien, Austria a3310 v6 Suppl 13 a

Many researchers now recognize the importance of the external environment in which cells are cultured for cell function and differentiation. Most of the systems able to apply physiological-like stimuli also need a classical incubator or a specifically designed system to control the environmental parameters at some distance from the cells. Here, a standalone platform for cell, tissue and organ culture is described. The SUITE (Supervising Unit for In-vitro Testing) system can control local environmental variables like pH, temperature and hydrostatic pressure over long periods, to provide the optimal environment for cells outside the classical incubator and also to apply mechanical and chemical stimuli to simulate the physiological milieu. The SUITE platform is used with Multi-Compartmental modular Bioreactors (MCmB) to perform dynamic cultures of hepatocytes as in-vitro liver model. Preliminary tests demonstrated the capability of the system to maintain the target parameters for more than 72 h generating different hydrostatic pressures (20–30–40–50 mmHg). Then, two bioreactors were connected in series and cultured for 24 h in the SUITE platform with hydrostatic pressures of 20–30–40 mmHg. Static and dynamic controls were placed in the classical humidified incubator at 37°C, 5% CO2. The results show that cell function is enhanced in SUITE at up to 30 mmHg of hydrostatic pressure, as confirmed by viability, metabolic function and morphological analysis.

10aBioengineering1 aGiusti, S1 aMazzei, D.1 aAhluwalia, A. uhttp://www.ncbi.nlm.nih.gov/pubmed/2294175300551nas a2200181 4500008003900000245008400039210006900123300000800192490001400200653001900214100001400233700001500247700001300262700001300275700001500288700001800303856004800321 2012 d00aReplicating the 3D cardiomyocyte environment in the squeeze pressure bioreactor0 aReplicating the 3D cardiomyocyte environment in the squeeze pres a3410 v6 Suppl 110aBioengineering1 aGiusti, S1 aTirella, A1 aGalli, E1 aVozzi, F1 aCabiati, M1 aAhluwalia, A. uhttp://www.ncbi.nlm.nih.gov/pubmed/2294175300555nas a2200157 4500008003900000245007500039210006900114653001900183100001400202700001500216700001300231700001300244700001500257700001800272856010700290 2012 d00aReplicating the cardiac environment in the Squeeze Pressure Bioreactor0 aReplicating the cardiac environment in the Squeeze Pressure Bior10aBioengineering1 aGiusti, S1 aTirella, A1 aGalli, E1 aVozzi, F1 aCabiati, M1 aAhluwalia, A. uhttp://175973.jxltd.asia/publications/replicating-cardiac-environment-squeeze-pressure-bioreactor.html03567nas a2200205 4500008004100000022002200041245010600063210006900169260003300238300001400271520283400285653001903119100001503138700001403153700001403167700001803181700001703199700001703216856012803233 2011 eng d a978-1-62100-164-500aMulti-Compartmental Modular Bioreactor as Innovative System for Dynamic Cell Cultures and Co-Cultures0 aMultiCompartmental Modular Bioreactor as Innovative System for D bNova Science Publishers, Inc a159 - 1783 a

In this chapter, the design, fabrication process and preliminary tests of a Multi- Compartmental Modular Bioreactor used as a system for dynamic cell cultures and co-cultures is described. Although the microwell (MW) plate has become a standard in cell culture, the complexity of the physiological environment is not replicated in petri dishes or microplates. All cells are exquisitely sensitive to their micro-environment which is rich with cues from other cells and from mechanical stimuli due to flow, perfusion and movement. Microwells do not offer any form of dynamic chemical or physical stimulus to cells, such as concentration gradients, flow, pressure or mechanical stress. This is a major limitation in experiments investigating cellular responses in-vitro since the complex interplay of mechanical and biochemical factors is absent. Most researchers and industry have started to accept that classical in vitro experiments offer poor predictive value or mechanistic understanding and are shifting their interests to new technologies such as bioreactors. For this reason, a large number of bioreactor systems for cell culture have been recently designed and described. With the purpose of developing cell culture models to establish a physiological-like interaction between different cell types, a novel Multi-Compartmental Modular Bioreactor (MCmB)was realized. The modular chamber was designed with shape and dimensions similar to the 24-MultiWell allowing an easy transfer of microwell protocols. The MCmB consists of a cell culture chamber made of bio-compatible silicon polymer, with excellent self-sealing proprieties, transparency and flexibility. The modular chambers can be also connected together in series or in parallel as desired, in order to allow cell-cell cross-talk or replicate in vitro models of metabolism or diseases using allometric design principles. In this chapter we describe the bioreactor design process starting from a finite-element method (FEM) model, developed in order to study the shear stress and the oxygen concentration at the cell surface. A further version of the MCmB is also described, in which a semipermeable membrane is placed into the bioreactor allowing to create a double-chamber system (MCmB-dc) for biological barriers simulation like for example lung or intestine. Allometric methods for designing in-vitro organ models using combinations of different cell types or tissues cultured in different chambers are also presented. Allometric laws mathematically correlate non linear quantities such as organ mass, blood flow, blood retention time and metabolic rate. Using these laws the modules can be assembled in various configurations enabling organ and system physiology to be recapitulated in vitro. Preliminary experiments using the modules are also described.

10aBioengineering1 aMazzei, D.1 aGiusti, S1 aSbrana, T1 aAhluwalia, A.1 aAntolli, P G1 aLiu, Zhiming uhttp://175973.jxltd.asia/publications/multi-compartmental-modular-bioreactor-innovative-system-dynamic-cell-cultures-and-co01878nas a2200193 4500008004100000022001400041245011000055210006900165300001300234490000700247520121900254653001901473100001701492700001401509700001501523700001701538700001801555856011101573 2011 eng d a1937-339200aSqueeze pressure bioreactor: a hydrodynamic bioreactor for noncontact stimulation of cartilage constructs0 aSqueeze pressure bioreactor a hydrodynamic bioreactor for noncon a757–640 v173 a

A novel squeeze pressure bioreactor for noncontact hydrodynamic stimulation of cartilage is described. The bioreactor is based on a small piston that moves up and down, perpendicular to a tissue construct, in a fluid-filled chamber. Fluid displaced by the piston generates a pressure wave and shear stress as it moves across the sample, simulating the dynamic environment of a mobile joint. The fluid dynamics inside the squeeze pressure bioreactor was modeled using analytical and computational methods to simulate the mechanical stimuli imposed on a construct. In particular, the pressure, velocity field, and wall shear stress generated on the surface of the construct were analyzed using the theory of hydrodynamic lubrication, which describes the flow of an incompressible fluid between two surfaces in relative motion. Both the models and in-situ pressure measurements in the bioreactor demonstrate that controlled cyclic stresses of up to 10 kPa can be applied to tissue constructs. Initial tests on three-dimensional scaffolds seeded with chondrocytes show that glycosaminoglycan production is increased with regard to controls after 24 and 48 h of cyclic noncontact stimulation in the bioreactor.

10aBioengineering1 aDe Maria, C.1 aGiusti, S1 aMazzei, D.1 aCrawford, A.1 aAhluwalia, A. uhttp://online.liebertpub.com/doi/abs/10.1089/ten.tec.2011.0002 http://www.ncbi.nlm.nih.gov/pubmed/2141031504733nas a2200181 4500008004100000245014100041210006900182260004800251300001400299520406100313653001904374100001404393700001804407700001704425700001704442700001204459856008004471 2011 eng d00aThe Squeeze Pressure Bioreactor: Design and Modelling of a Non-Contact Device for Mechanical Stimulation of Tissue Engineered Constructs0 aSqueeze Pressure Bioreactor Design and Modelling of a NonContact aHauppauge NYbNova Science Publishers, Inc. a199–2143 a

Diseases of hyaline cartilage represent one of the major health problems, especially in industrialized countries with high life expectancy. The erosion of the articulating surfaces of joints, known as osteoarthritis, currently affects more than 200 million citizens worldwide, and more than 50% of the patients need or will need a surgical treatment. Articular cartilage is a three dimensional avascular tissue, which covers the ends of all synovial joints. During normal daily function, articular cartilage can be repeatedly subjected to forces up to several time body weight, but it is able to provide articulating joints with a nearly frictionless motion. Despite its tremendously important function, articular cartilage has limited capacity for auto regeneration after degenerative and rheumatic diseases, like arthritis, as well as traumatic injuries. Cartilage problems are a huge and still unsolved medical issue, which therefore represents one of the most important tissue engineering targets requiring high quality products as fast as possible. For this reason, the possibility to recreate in vitro cartilage substitutes as a real alternative to total joint replacement represents an increasing and hopeful market, in which many research groups are still working. At the moment, one of the main findings in invitro cartilage studies is the importance of the role of mechanical stimuli and dynamic loads for the chondrocytes growth and differentiation. Several studies using cartilage explants or chondrocytes seeded in 3D scaffolds have shown that mechanical compressive loads affect the cells metabolic activity and their matrix production. In order to simulate the in vivo environment, the use of bioreactors is becoming fundamental: bioreactors can provide the chemical and mechanical signals that optimize tissue development. Furthermore, bioreactors could be an important instrument to reduce the cost of clinical studies, used as in vitro predictors of in vivo performance. In this way,the use of bioreactors can reduce animal studies, helping the scientists to focus their attention in the right direction before starting pre-clinical studies, which are usually more expensive than preliminary research. In the past few years, several systems for the application of different mechanical stimuli to chondrocytes have been developed. Most of these can generate biomechanical-like forces such as the direct compression, tensile and shear forces, or hydrostatic pressure, in order to stimulate the articular chondrocyctes to increase their matrix production. Generally, the most important requirements that a culture system has to satisfy are high reliability and usability, perfect sterility, easy control of all the important culture parameters and low cost. In this work, a new system, inspired by the synovial environment of mobile joints and able to apply an innovative type of stimulation on articular chondrocytes is described and modeled. The SQPR (SQueeze PRessure) bioreactor chamber is designed to impose a cyclic hydrodynamic pressure on cell cultures, constructs or tissues slices. The basic principle of this new system is the generation of a localized contact less overpressure on articular chondrocytes, using a simple vertical piston movement. This kind of stimulation is particularly useful for neo-tissue or fresh-constructs, in which cells require a dynamic environment to maintain their differentiate state, but at the same time do not tolerate direct compression or high shear stress. When the piston moves down, a controlled hydrodynamic overpressure and a shear stress is generated over the cell surface, stimulating the chondrocytes to improve their matrix production. The fluid dynamics inside the SQPR bioreactor is illustrated from an analytical and numerical point of view. We show how these models can predict the pressure, velocity field and wall shear stress generated on the cell surface of the construct. The bioreactor design is presented in detail and validation tests on chondrocytes are described.

10aBioengineering1 aGiusti, S1 aAhluwalia, A.1 aDe Maria, C.1 aAntolli, P G1 aLiu, Z. uhttps://www.novapublishers.com/catalog/product\_info.php?products\_id=2265301654nas a2200193 4500008004100000245009200041210006900133260000800202300001400210490000800224520099800232653001901230653001601249100001501265700002001280700001401300700001801314856012801332 2010 eng d00aA low shear stress modular bioreactor for connected cell culture under high flow rates.0 alow shear stress modular bioreactor for connected cell culture u cMay a127–1370 v1063 a

A generic "system on a plate" modular multicompartmental bioreactor array which enables microwell protocols to be transferred directly to the bioreactor modules, without redesign of cell culture experiments or protocols is described. The modular bioreactors are simple to assemble and use and can be easily compared with standard controls since cell numbers and medium volumes are quite similar. Starting from fluid dynamic and mass transport considerations, a modular bioreactor chamber was first modeled and then fabricated using "milli-molding," a technique adapted from soft lithography. After confirming that the shear stress was extremely low in the system in the range of useful flow rates, the bioreactor chambers were tested using hepatocytes. The results show that the bioreactor chambers can increase or maintain cell viability and function when the flow rates are below 500 microL/min, corresponding to wall shear stresses of 10(-5) Pa or less at the cell culture surface.

10aBioengineering10aBioreactors1 aMazzei, D.1 aGuzzardi, M. A.1 aGiusti, S1 aAhluwalia, A. uhttp://175973.jxltd.asia/publications/low-shear-stress-modular-bioreactor-connected-cell-culture-under-high-flow-rates.html