@article {2204, title = {Smart Sensing Scaffolds}, journal = {Smart Membranes and Sensors: Synthesis, Characterization, and Applications}, year = {2014}, pages = {337}, keywords = {Bioengineering}, author = {C. De Maria and Whulanza, Y. and G. Vozzi and A. Ahluwalia} } @article {2284, title = {Squeeze pressure bioreactor: a hydrodynamic bioreactor for noncontact stimulation of cartilage constructs}, journal = {Tissue engineering. Part C, Methods}, volume = {17}, year = {2011}, pages = {757{\textendash}64}, abstract = {

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.

}, keywords = {Bioengineering}, issn = {1937-3392}, doi = {10.1089/ten.TEC.2011.0002}, url = {http://online.liebertpub.com/doi/abs/10.1089/ten.tec.2011.0002 http://www.ncbi.nlm.nih.gov/pubmed/21410315}, author = {C. De Maria and S. Giusti and D. Mazzei and A. Crawford and A. Ahluwalia} } @inbook {2285, title = {The Squeeze Pressure Bioreactor: Design and Modelling of a Non-Contact Device for Mechanical Stimulation of Tissue Engineered Constructs}, booktitle = {Bioreactors: Design, Properties and Applications}, year = {2011}, pages = {199{\textendash}214}, publisher = {Nova Science Publishers, Inc.}, organization = {Nova Science Publishers, Inc.}, address = {Hauppauge NY}, abstract = {

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.

}, keywords = {Bioengineering}, url = {https://www.novapublishers.com/catalog/product\_info.php?products\_id=22653}, author = {S. Giusti and A. Ahluwalia and C. De Maria}, editor = {Antolli, P. G. and Z. Liu} } @article {1488, title = {Substrate stiffness influences high resolution printing of living cells with an ink-jet system}, journal = {Journal of bioscience and bioengineering}, volume = {112}, year = {2011}, pages = {79{\textendash}85}, abstract = {

The adaptation of inkjet printing technology for the realisation of controlled micro- and nano-scaled biological structures is of great potential in tissue and biomaterial engineering. In this paper we present the Olivetti BioJet system and its applications in tissue engineering and cell printing. BioJet, which employs a thermal inkjet cartridge, was used to print biomolecules and living cells. It is well known that high stresses and forces are developed during the inkjet printing process. When printing living particles (i.e., cell suspensions) the mechanical loading profile can dramatically damage the processed cells. Therefore computational models were developed to predict the velocity profile and the mechanical load acting on a droplet during the printing process. The model was used to investigate the role of the stiffness of the deposition substrate during droplet impact and compared with experimental investigations on cell viability after printing on different materials. The computational model and the experimental results confirm that impact forces are highly dependent on the deposition substrate and that soft and viscous surfaces can reduce the forces acting on the droplet, preventing cell damage. These results have high relevance for cell bioprinting; substrates should be designed to have a good compromise between substrate stiffness to conserve spatial patterning without droplet coalescence but soft enough to absorb the kinetic energy of droplets in order to maintain cell viability.

}, keywords = {Bioengineering}, issn = {1347-4421}, doi = {10.1016/j.jbiosc.2011.03.019}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21497548}, author = {Tirella, A and Vozzi, F. and C. De Maria and G. Vozzi and Sandri, T and Sassano, D and Cognolato, L and A. Ahluwalia} }