Publications by authors named "Ioannis Papantoniou"

Self-assembled cartilaginous microtissues provide a promising means of repairing challenging skeletal defects and connective tissues. However, despite their considerable promise in tissue engineering, the mechanical response of these engineered microtissues is not well understood. Here we examine the mechanical and viscoelastic response of progenitor cell aggregates formed from human primary periosteal cells and the resulting cartilaginous microtissues under large deformations as might be encountered in vivo.

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Article Synopsis
  • Research on multicellular spheroids like microtissues and organoids highlights their potential in tissue engineering due to enhanced interactions in 3D cell structures.
  • A new laser-assisted bioprinting technique has been developed that successfully transfers these spheroids to create larger tissue structures, demonstrating high cell viability and differentiation capability.
  • The method includes an innovative approach called LIPMO, allowing for the bioprinting of larger spheroids (up to 300 micrometers) while utilizing automated image analysis for precise selection and placement of multiple spheroids in a single printing sequence.
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Automated technologies are attractive for enhancing the robust manufacturing of tissue-engineered products for clinical translation. In this work, we present an automation strategy using a robotics platform for media changes, and imaging of cartilaginous microtissues cultured in static microwell platforms. We use an automated image analysis pipeline to extract microtissue displacements and morphological features as noninvasive quality attributes.

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Background: Clinical characteristics and outcomes of patients with transthyretin amyloidosis cardiomyopathy (ATTR-CM) vary by region, necessitating the acquisition of country-specific evidence for proper management.

Methods: This is an observational study including sequential patients presenting in the Amyloidosis Reference Center of Greece, from 01/2014 to 12/2022. ATTR-CM was diagnosed by positive scintigraphy and exclusion of light-chain amyloidosis or positive biopsy typing.

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Cartilage microtissues are promising tissue modules for bottom up biofabrication of implants leading to bone defect regeneration. Hitherto, most of the protocols for the development of these cartilaginous microtissues have been carried out in static setups, however, for achieving higher scales, dynamic process needs to be investigated. In the present study, we explored the impact of suspension culture on the cartilage microtissues in a novel stirred microbioreactor system.

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In this work a dual crosslinked network based on sodium alginate graft copolymer, bearing poly(N-isopropylacrylamide-co-N-tert-butylacrylamide) P(NIPAM-co-NtBAM) side chains was developed and examined as a shear thinning soft gelating bioink. The copolymer was found to undergo a two-step gelation mechanism; in the first step a three-dimensional (3D) network is formed through ionic interactions between the negatively ionized carboxylic groups of the alginate backbone and the positive charges of Ca divalent cations, according to the "egg-box" mechanism. The second gelation step occurs upon heating which triggers the hydrophobic association of the thermoresponsive P(NIPAM-co-NtBAM) side chains, increasing the network crosslinking density in a highly cooperative manner.

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Surface curvature both emerges from, and influences the behavior of, living objects at length scales ranging from cell membranes to single cells to tissues and organs. The relevance of surface curvature in biology is supported by numerous experimental and theoretical investigations in recent years. In this review, first, a brief introduction to the key ideas of surface curvature in the context of biological systems is given and the challenges that arise when measuring surface curvature are discussed.

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Bone fractures are one of the most common traumatic large-organ injuries and although many fractures can heal on their own, 2-12% of fractures are slow healing or do not heal (non-unions). Autologous grafts are currently used for treatment of non-unions but are associated with limited healthy bone tissue. Tissue engineered cell-based products have promise for an alternative treatment method.

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Spheroids are widely applied as building blocks for biofabrication of living tissues, where they exhibit spontaneous fusion toward an integrated structure upon contact. Tissue fusion is a fundamental biological process, but due to a lack of automated monitoring systems, the in-depth characterization of this process is still limited. Therefore, a quantitative high-throughput platform was developed to semi-automatically select doublet candidates and automatically monitor their fusion kinetics.

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CAR-T cell therapy is a promising treatment for acute leukemia and lymphoma. CAR-T cell therapies take a pioneering role in autologous gene therapy with three EMA-approved products. However, the chance of clinical success remains relatively low as the applicability of CAR-T cell therapy suffers from long, labor-intensive manufacturing and a lack of comprehensive insight into the bioprocess.

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Microvasculature is essential for the exchange of gas and nutrient for most tissues in our body. Some tissue structures such as the meniscus presents spatially confined blood vessels adjacent to non-vascularized regions. In biofabrication, mimicking the spatial distribution of such vascular components is paramount, as capillary ingrowth into non-vascularized tissues can lead to tissue matrix alterations and subsequent pathology.

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Spheroids have become essential building blocks for biofabrication of functional tissues. Spheroid formats allow high cell-densities to be efficiently engineered into tissue structures closely resembling the native tissues. In this work, we explore the assembly capacity of cartilaginous spheroids (∼ 150m) in the context of endochondral bone formation.

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The mechanical microenvironment of cells has been associated with phenotypic changes that cells undergo in three-dimensional spheroid culture formats. Radial asymmetry in mechanical stress - with compression in the core and tension at the periphery - has been analyzed by representing tissue spheroids as homogeneous visco-elastic droplets under surface tension. However, the influence of the granular microstructure of tissue spheroids in the distribution of mechanical stress in tissue spheroids has not been accounted for in a generic manner.

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An increasing need toward a more efficient expansion of adherent progenitor cell types arises with the advancements of cell therapy. The use of a dynamic expansion instead of a static planar expansion could be one way to tackle the challenges of expanding adherent cells at a large scale. Microcarriers are often reported as a biomaterial for culturing cells in suspension.

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Tissue engineered constructs have the potential to respond to the unmet medical need of treating deep osteochondral defects. However, current tissue engineering strategies struggle in the attempt to create patterned constructs with biologically distinct functionality. In this work, a developmentally-inspired modular approach is proposed, whereby distinct cartilaginous organoids are used as living building blocks.

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A decade after the term developmental engineering (DE) was coined to indicate the use of developmental processes as blueprints for the design and development of engineered living implants, a myriad of proof-of-concept studies demonstrate the potential of this approach in small animal models. This review provides an overview of DE work, focusing on applications in bone regeneration. Enabling technologies allow to quantify the distance between in vitro processes and their developmental counterpart, as well as to design strategies to reduce that distance.

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Implementing a personalised feeding strategy for each individual batch of a bioprocess could significantly reduce the unnecessary costs of overfeeding the cells. This paper uses lactate measurements during the cell culture process as an indication of cell growth to adapt the feeding strategy accordingly. For this purpose, a model predictive control is used to follow this a priori determined reference trajectory of cumulative lactate.

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Stem cell expansion on 3D porous scaffolds cultured in bioreactor systems has been shown to be beneficial for maintenance of the original cell functionality in tissue engineering strategies (TE). However, the production of extracellular matrix (ECM) makes harvesting the progenitor cell population from 3D scaffolds a challenge. Medium composition plays a role in stimulating cell proliferation over extracellular matrix (ECM) production.

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In the current study, a new approach for surface modification and surface hardening of aluminum alloys is developed. The method is based on the logic of in-situ reinforcing FSP strategies. The novelty of the proposed process is the application of a bulk reinforcing metallic material instead of metallic powders.

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Clinical translation of cell-based products is hampered by their limited predictive in vivo performance. To overcome this hurdle, engineering strategies advocate to fabricate tissue products through processes that mimic development and regeneration, a strategy applicable for the healing of large bone defects, an unmet medical need. Natural fracture healing occurs through the formation of a cartilage intermediate, termed "soft callus," which is transformed into bone following a process that recapitulates developmental events.

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Background: Human mesenchymal stromal cells (hMSCs) have become attractive candidates for advanced medical cell-based therapies. An in vitro expansion step is routinely used to reach the required clinical quantities. However, this is influenced by many variables including donor characteristics, such as age and gender, and culture conditions, such as cell seeding density and available culture surface area.

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Xenogeneic-free media are required for translating advanced therapeutic medicinal products to the clinics. In addition, process efficiency is crucial for ensuring cost efficiency, especially when considering large-scale production of mesenchymal stem cells (MSCs). Human platelet lysate (HPL) has been increasingly adopted as an alternative for fetal bovine serum (FBS) for MSCs.

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Bioreactors are crucial tools for the manufacturing of living cell-based tissue engineered products. However, to reach the market successfully, higher degrees of automation, as well as a decreased footprint still need to be reached. In this study, the use of a benchtop bioreactor for in vitro perfusion culture of scaffold-based tissue engineering constructs is assessed.

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From this perspective, we discuss the different stages of development the tissue engineering (TE) field has gone through in its relatively young history. We discuss how TE is evolving from a technology-driven, science-focused field toward a patient-driven, manufacturing-focused one where patients' needs are translated into production process requirements, and subsequently into technological and biological innovations needed to meet the regulatory and clinical demands.

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In the current study, a first attempt at using aluminum flakes for the manufacture of open-cell aluminum foams with the space holder method is presented. The method involves powder mixing, compaction, leaching, and sintering processes. Saccharose particles were used as space holders, and multiple parameters were investigated to optimize the manufacturing processing route in order to produce high-quality open-cell aluminum foams with a simple, economic, and environmentally friendly method.

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