Progenitor cells in auricular cartilage demonstrate promising cartilage regenerative potential in 3D hydrogel culture

The reconstruction of auricular deformities is a very challenging surgical procedure that could benefit from a tissue engineering approach. Nevertheless, a major obstacle is presented by the acquisition of sufficient amounts of autologous cells to create a cartilage construct the size of the human ear. Extensively expanded chondrocytes are unable to retain their phenotype, while bone marrow-derived mesenchymal stromal cells (MSC) show endochondral terminal differentiation by formation of a calcified matrix. The identification of tissue-specific progenitor cells in auricular cartilage, which can be expanded to high numbers without loss of cartilage phenotype, has great prospects for cartilage regeneration of larger constructs. This study investigates the largely unexplored potential of auricular progenitor cells for cartilage tissue engineering in 3D hydrogels

Chondrogenic potential of chondrocytes in hyaluronic acid/PEG-based hydrogels is dependent on the hyaluronic acid concentration

Purpose: Hydrogels based on PEG and methacrylated poly(N-(2-hydroxypropyl) methacrylamide-mono/dilactate) (M10P10) are promising biomaterials for Biofabrication of cartilage constructs. Addition of hyaluronic acid (HA) to a hydrogel improves printability by increasing the viscosity. Methacrylating HA (HAMA) can ensure covalent binding in M10P10 hydrogels after UV-cross-linking. Chondrocytes can interact with HAMA via their CD44 receptor, however, the influence of HAMA on chondrogenic potential is unclear. This study aimed to evaluate the influence of different HAMA concentrations on chondrogenesis of chondrocytes in M10P10/HAMA hydrogels. Materials & Methods: Equine chondrocytes were encapsulated in M10P10 hydrogels containing different HAMA concentrations. Cylindrical constructs were cast, UV-cross-linked, and cultured in TGF-β-containing medium. Constructs were analyzed for evidence of cartilage formation. Results: Preliminary data showed an increase in glycosaminoglycan (GAG)/DNA for constructs with low HAMA concentrations (0.1-0.25%) while no differences were found for higher HAMA concentrations, compared to hydrogels without HAMA (Figure 1a). Further, constructs without or with low HAMA concentrations (0.1-0.5%) demonstrated collagen type II positive areas, while this was less pronounced in constructs with 0.5-1% HAMA (n=3, Figure 1b). Conclusion: Preliminary results indicate a dose-dependent effect of HAMA on chondrogenesis of chondrocytes: low concentrations (0.1-0.25%) increase GAG production while higher concentrations (0.5-1%) have no effect on GAG production and reduce collagen type II synthesis. Ongoing evaluations will reveal the extent of chondrogenesis and its association with HAMA concentrations in M10P10/HAMA, and the mechanism responsible for the dose-dependent effect. This study will impact the use of HAMA as viscosity enhancer to improve the printability of hydrogel

The bio in the ink: cartilage regeneration with bioprintable hydrogels and articular cartilage-derived progenitor cells

Cell-laden hydrogels are the primary building blocks for bioprinting, and, also termed bioinks, are the foundations for creating structures that can potentially recapitulate the architecture of articular cartilage. To be functional, hydrogel constructs need to unlock the regenerative capacity of encapsulated cells. The recent identification of multipotent articular cartilage-resident chondroprogenitor cells (ACPCs), which share important traits with adult stem cells, represents a new opportunity for cartilage regeneration. However, little is known about the suitability of ACPCs for tissue engineering, especially in combination with biomaterials. This study aimed to investigate the potential of ACPCs in hydrogels for cartilage regeneration and biofabrication, and to evaluate their ability for zone-specific matrix production. Gelatin methacryloyl (gelMA)-based hydrogels were used to culture ACPCs, bone marrow mesenchymal stromal cells (MSCs) and chondrocytes, and as bioinks for printing. Our data shows ACPCs outperformed chondrocytes in terms of neo-cartilage production and unlike MSCs, ACPCs had the lowest gene expression levels of hypertrophy marker collagen type X, and the highest expression of PRG4, a key factor in joint lubrication. Co-cultures of the cell types in multi-compartment hydrogels allowed generating constructs with a layered distribution of collagens and glycosaminoglycans. By combining ACPC- and MSC-laden bioinks, a bioprinted model of articular cartilage was generated, consisting of defined superficial and deep regions, each with distinct cellular and extracellular matrix composition. Taken together, these results provide important information for the use of ACPC-laden hydrogels in regenerative medicine, and pave the way to the biofabrication of 3D constructs with multiple cell types for cartilage regeneration or in vitro tissue models

Rijenbemesting: kansen, nieuwe producten en technieken : tussenrapportage 2012

In opdracht van het MMM voeren PRI, PPO en Altic in 2012 t/m 2014 nieuw onderzoek uit naar rijenbemesting. Nagegaan wordt in welke mate rijenbemesting de efficiëntie van de toegediende meststof verhoogd. Ook wordt nagegaan op welke bodems rijenbemesting met name voordelen biedt. In 2012 zijn veldproeven uitgevoerd in consumptieaardappel op centrale zeeklei (Lelystad) en zuidoostelijk zand (Vredepeel) en in zaaiui op zuidwestelijke zeeklei (Westmaas)

A Stimuli-Responsive Nanocomposite for 3D Anisotropic Cell-Guidance and Magnetic Soft Robotics

Stimuli-responsive materials have the potential to enable the generation of new bioinspired devices with unique physicochemical properties and cell-instructive ability. Enhancing biocompatibility while simplifying the production methodologies, as well as enabling the creation of complex constructs, i.e., via 3D (bio)printing technologies, remains key challenge in the field. Here, a novel method is presented to biofabricate cellularized anisotropic hybrid hydrogel through a mild and biocompatible process driven by multiple external stimuli: magnetic field, temperature, and light. A low-intensity magnetic field is used to align mosaic iron oxide nanoparticles (IOPs) into filaments with tunable size within a gelatin methacryloyl matrix. Cells seeded on top or embedded within the hydrogel align to the same axes of the IOPs filaments. Furthermore, in 3D, C2C12 skeletal myoblasts differentiate toward myotubes even in the absence of differentiation media. 3D printing of the nanocomposite hydrogel is achieved and creation of complex heterogeneous structures that respond to magnetic field is demonstrated. By combining the advanced, stimuli-responsive hydrogel with the architectural control provided by bioprinting technologies, 3D constructs can also be created that, although inspired by nature, express functionalities beyond those of native tissue, which have important application in soft robotics, bioactuators, and bionic devices

Fog interception by Ball moss (<i>Tillandsia recurvata</i>)

Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. <i>Tillandsia recurvata</i> is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by <i>T. recurvata</i> was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (<i>C</i>_min) was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for <i>T. recurvata</i> in a xeric scrub to calculate the depth of water intercepted by rain. <i>T. recurvata</i> contributed 20 % to the rain interception capacity of their shrub hosts: <i>Acacia farnesiana</i> and <i>Prosopis laevigata</i> and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in <i>T. recurvata</i> is not only relevant for CO₂ but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, <i>p</i> = 0.048). The storage capacity of <i>T. recurvata</i> leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h⁻¹ to reach saturation conditions when fog was applied

A gap-filling, regenerative implant for open-wedge osteotomy

Introduction: In patients suffering from unilateral osteoarthritis in the knee, an osteotomy can provide symptomatic relief and postpone the need for replacement of the joint. Nevertheless, open-wedge osteotomies (OWOs) around the knee joint face several challenges like postoperative pain and bone nonunion. Objectives: In this study, the aim was to design, fabricate, and evaluate a gap-filling implant for OWO using an osteoinductive and degradable biomaterial. Methods: Design of porous wedge-shaped implants was based on computed tomography scans of cadaveric legs. Implants were 3-dimensionally printed using a magnesium strontium phosphate-polycaprolactone (MgPSr-PCL) biomaterial ink. Standardized scaffolds with different inter-fiber spacing (IFS) were mechanically characterized and osteoinductive properties of the biomaterial were assessed in vitro. Finally, human-sized implants with different heights (5 mm, 10 mm, 15 mm) were designed and fabricated for ex vivo implantation during 3 OWO procedures in human cadaveric legs. Results: Implants printed with an interior of IFS-1.0 resulted in scaffolds that maintained top and bottom porosity, while the interior of the implant exhibited significant mechanical stability. Bone marrow concentrate and culture expanded mesenchymal stromal cells attached to the MgPSr-PCL material and proliferated over 21 days in culture. The production of osteogenic markers alkaline phosphatase activity, calcium, and osteocalcin was promoted in all culture conditions, independent of osteogenic induction medium. Finally, 3 OWO procedures were planned and fabricated wedges were implanted ex vivo during the procedures. A small fraction of one side of the wedges was resected to assure fit into the proximal biplanar osteotomy gap. Preplanned wedge heights were maintained after implantation as measured by micro-computed tomography. Conclusion: To conclude, personalized implants for implantation in OWOs were successfully designed and manufactured. The implant material supported osteogenesis of mesenchymal stromal cells and bone marrow concentrate in vitro and full-size implants were successfully implemented into the surgical procedure without compromising preplanned wedge height.</p

Кіноніми Кіровоградщини: особливості вибору кличок та способи їх творення

Стаття присвячена вивченню особливостей української кінонімії. Основну увагу зосереджено на дослідженні процесу номінації та способів словотворення кличок собак. Окремо розглянуто офіційні назви тварин, які мають родослівну.Статья посвящена изучению особенностей украинской кинонимии. Основное внимание сосредоточено на изучении процесса номинации и способах словообразования кличек собак. Отдельно рассмотрены официальные названия собак, имеющих родословную.The article is devoted to the research of the peculiarities of Ukrainian cynonymy. Most attention is taid to the research of the process of nomination and to the ways of formation of dogs' names. Special consideration is given to the official names of the animals with genealogy

Biofabricating the vascular tree in engineered bone tissue

The development of tissue engineering strategies for treatment of large bone defects has become increasingly relevant, given the growing demand for bone substitutes. Native bone is composed of a dense vascular network necessary for the regulation of bone development, regeneration and homeostasis. A major obstacle in fabricating living, clinically relevant-sized bone mimics (1-10 cm3) is the limited supply of nutrients, including oxygen to the core of the construct. Therefore, strategies to support vascularization are pivotal for the development of tissue engineered bone constructs. Creating a functional bone construct integrated with a vascular network, capable of delivering the necessary nutrients for optimal tissue development is imperative for translation into the clinics. The vascular system is composed of a complex network that runs throughout the body in a tree-like hierarchical branching fashion. A significant challenge for tissue engineering approaches lies in mimicking the intricate, multi-scale structures consisting of larger vessels (macro-vessels) which interconnect with multiple sprouting vessels (microvessels) in a closed network. The advent of biofabrication has enabled complex, out of plane channels to be generated and has laid the groundwork for the creation of multi-scale vasculature in recent years. This review highlights the key state-of-the-art achievements for the development of vascular networks of varying scales in the field of biofabrication with a particular focus for its application in developing a functional tissue engineered bone construct. Statement of significance: There is a growing need for bone substitutes to overcome the limited supply of patient-derived bone. Bone tissue engineering aims to overcome this by combining stem cells with scaffolds to restore missing bone. The current bottleneck in upscaling is the lack of an integrated vascular network, required for the delivery of nutrients to cells. 3D bioprinting techniques has enabled the creation of complex hollow structures of varying dimensions that resemble native blood vessels. The convergence of multiple materials, cell types and fabrication approaches, opens the possibility of developing clinically-relevant sized vascularized bone constructs. This review provides an up-to-date insight of the technologies currently available for the generation of complex vascular networks, with a focus on their application in bone tissue engineering