Tissue engineered organoids for neural network modelling

The increased prevalence of neurological diseases across the world has stimulated a great deal of research into the physiological and pathological brain, both at clinical and pre-clinical level. This has led to the development of many sophisticated tissue engineered neural models, presenting greater cellular complexity to better mimic the central nervous system niche environment. These have been developed with the ambition to improve pre-clinical assessment of pharma and cellular therapies, as well as better understand this tissue type and its function/dysfunction. This review covers the necessary considerations in in vitro model design, along with recent advances in 2Dculture systems, to 3D organoids and bio-artificial organs

Controlled arrangement of neuronal cells on surfaces functionalized with micro-patterned polymer brushes

Conventional in vitro cultures are useful to represent simplistic neuronal behaviour, however the lack of organisation results in random neurite spreading. To overcome this problem, control over the directionality of SH-SY5Y cells was attained, utilising photolithography to pattern the cell-repulsive anionic brush poly(potassium 3-sulfopropyl methacrylate) (PKSPMA) into tracks of 20, 40, 80 and 100 µm width. This data validates the use of PKSPMA brush coatings for long-term culture of SH-SY5Y cells, as well as providing a methodology by which the precise deposition of PKSPMA can be utilised to achieve targeted control over SH-SY5Y cells. Specifically, PKSPMA brush patterns prevented cell attachment, allowing SH-SY5Y cells to grow only on the non-coated glass (gaps of 20, 50, 75 and 100 µm width) at different cell densities (5000, 10000 and 15000 cells/cm2). This research demonstrates the importance of achieving cell directionality in vitro, whilst these simplistic models could provide new platforms to study complex neuron-neuron interactions

'Stealth' nanoparticles evade neural immune cells but also evade major brain cell populations: Implications for PEG-based neurotherapeutics

Surface engineering to control cell behavior is of high interest across the chemical engineering, drug delivery and biomaterial communities. Defined chemical strategies are necessary to tailor nanoscale protein interactions/adsorption, enabling control of cell behaviors for development of novel therapeutic strategies. Nanoparticle-based therapies benefit from such strategies but particle targeting to sites of neurological injury remains challenging due to circulatory immune clearance. As a strategy to overcome this barrier, the use of stealth coatings can reduce immune clearance and prolong circulatory times, thereby enhancing therapeutic capacity. Polyethylene glycol (PEG) is the most widely-used stealth coating and facilitates particle accumulation in the brain. However, once within the brain, the mode of handling of PEGylated particles by the resident immune cells of the brain itself (the ‘microglia’) is unknown. This is a critical question as it is well established that microglia avidly sequester nanoparticles, limiting their bioavailability and posing a major translational barrier. If PEGylation can be proved to promote evasion of microglia, then this information will be of high value in developing tailored nanoparticle-based therapies for neurological applications. Here, we have conducted the first comparative study of uptake of PEGylated particles by all the major (immune and non-immune) brain cell types. We prove for the first time that PEGylated nanoparticles evade major brain cell populations — a phenomenon which will enhance extracellular bioavailability. We demonstrate changes in protein coronas around these particles within biological media, and discuss how surface chemistry presentation may affect this process and subsequent cellular interactions

2-port Device for Segregated Cell Seeding - MASK DESIGN

This is a master mask design for a 2-port device in which two populations of cells can be cultured separately yet connected via an array of 5 um width channels.Two mask are needed: one for channels and the other for the reservoirs. </div

The need for advanced three-dimensional neural models and developing enabling technologies

Neurological and psychiatric disorders account for an increasing proportion of the global disease burden. Correspondingly the neuropharmaceutical industry has experienced a significant contraction in recent years resulting in a poor variety of therapies available to treat an expanding range of conditions. Perhaps the greatest contributor to this failure in drug-discovery is the lack of understanding of the underlying biology of the nervous system and how molecular scale events translate into macroscale pathologies. Due to the unique nature of the human nervous system commonly used model organisms are often poorly representative of human pathologies resulting in a need for the development of advanced in vitro models that are capable of faithfully modeling complex structures within the brain. In this prospective, strategies for the generation of neuronal circuits and cultivation of complex three-dimensional (3D) cultures are explored. Frequently these constructs provide valuable insights into systems and processes that are difficult to explore in vivo due to the isolated and delicate nature of neuronal tissues. New developments are required to assess the physiological functions of 3D tissues in vitro

Recent innovations in surface topography

In this review we provide a general review of current research themes where complex surface topography plays a role. Recent innovations and research possibilities have opened up using modern micro topography creation techniques. We are considering a large range of themes in limited depth in order to provide an introduction and to illustrate how broad the field is and to those already working in the area to help gain a broad perspective. Due to the breadth of scope this review will not go into much depth into any given area. This review aims to provide a comprehensive understanding and practical guidance on the modern use of micro and nano-topography to control water, adhesion, wettability, control of biological adhesion including implants, cell culture and biofouling and directional fluid transport. The broad range of functionality is highlighted in the many interfacial interactions, however, the manufacturing scale to allow these surfaces to be commonly used is still in development. In order to make it more accessible we have chosen to concentrate on open access articles to cite

Acrylamide-based hydrogels with distinct osteogenic and chondrogenic differentiation potential

Regeneration solutions for the osteochondral interface depth are limited, where multi-material implants have the potential to delaminate affecting the regeneration process and impacting the final integrity of tissue interface. Here we explore regionally mixed hydrogel networks, presenting distinct chemical features to determine their compatibility in supporting osteogenic or chondrogenic cell behaviour and differentiation. Poly(N-isopropylacrylamide) (pNIPAM) and poly(N-tert-butylacrylamide) (pNTBAM) hydrogels were assessed in terms of their chemical differences, mechanical strength, internal architecture, porosity and capacity to support cell viability, migration, and differentiation. pNTBAM polymerized with a Young’s modulus of up to 371 ± 31 kPa compared to the more flexible pNIPAM, 16.5 ± 0.6 kPa. Viability testing revealed biocompatibility of both hydrogels with significantly increased cell numbers observed in pNTBAM (500 ± 95 viable cells/mm2) than in pNIPAM (60 ± 3 viable cells/mm2) (P ≤ 0.05). Mineralization determined through alkaline phosphatase (ALP) activity, calcium ion and annexin A2 markers of mineralization) and osteogenic behaviour (collagen I expression) were supported in both hydrogels, but to a greater extent in pNTBAM. pNTBAM supported significantly elevated levels of chondrogenic markers as evidenced by collagen II and glycosaminoglycan expression in comparison to little or no evidence in pNIPAM (P ≤ 0.05). In conclusion, structurally similar, chemically distinct, acrylamide hydrogels display variable capacities in supporting osteochondral cell behaviours. These systems demonstrate spatial control of cell interaction through simple changes in monomer chemistry. Fine control over chemical presentation during the fabrication of biomaterial implants could lead to greater efficacy and targeted regeneration of semi-complex tissues.</p

Tissue engineering of the retina: from organoids to microfluidic chips

Despite advancements in tissue engineering, challenges remain for fabricating functional tissues that incorporate essential features including vasculature and complex cellular organisation. Monitoring of engineered tissues also raises difficulties, particularly when cell population maturity is inherent to function. Microfluidic, or lab-on-a-chip, platforms address the complexity issues of conventional 3D models regarding cell numbers and functional connectivity. Regulation of biochemical/biomechanical conditions can create dynamic structures, providing microenvironments that permit tissue formation while quantifying biological processes at a single cell level. Retinal organoids provide relevant cell numbers to mimic in vivo spatiotemporal development, where conventional culture approaches fail. Modern bio-fabrication techniques allow for retinal organoids to be combined with microfluidic devices to create anato-physiologically accurate structures or ‘ retina-on-a-chip’ devices that could revolution ocular sciences. Here we present a focussed review of retinal tissue engineering, examining the challenges and how some of these have been overcome using organoids, microfluidics, and bioprinting technologies

Supplementary information files for Fourier transform infrared spectroscopy as a non-destructive method for analysing herbarium specimens

Supplementary files for article Fourier transform infrared spectroscopy as a non-destructive method for analysing herbarium specimensDried plant specimens stored in herbaria are an untapped treasure chest of information on environmental conditions, plant evolution and change over many hundreds of years. Owing to their delicate nature and irreplaceability, there is limited access for analysis to these sensitive samples, particularly where chemical data are obtained using destructive techniques. Fourier transform infrared (FTIR) spectroscopy is a chemical analysis technique which can be applied non-destructively to understand chemical bonding information and, therefore, functional groups within the sample. This provides the potential for understanding geographical, spatial and species-specific variation in plant biochemistry. Here, we demonstrate the use of mid-FTIR microspectroscopy for the chemical analysis of Drosera rotundifolia herbarium specimens, which were collected 100 years apart from different locations. Principal component and hierarchical clustering analysis enabled differentiation between three main regions on the plant (lamina, tentacle stalk and tentacle head), and between the different specimens. Lipids and protein spectral regions were particularly sensitive differentiators of plant tissues. Differences between the different sets of specimens were smaller. This study demonstrates that relevant information can be extracted from herbarium specimens using FTIR, with little impact on the specimens. FTIR, therefore, has the potential to be a powerful tool to unlock historic information within herbaria.</p

Modification of the surface nanotopography of implant devices: A translational perspective

There is an increasing need for the development of superior, safe, and more sophisticated implants, especially as our society historically has been moving towards an increasingly aging population. Currently, most research is being focused on the next generation of advanced medical implants, that are not only biocompatible but have modified surfaces that direct specific immunomodulation at cellular level. While there is a plethora of information on cell-surface interaction and how surfaces can be nanofabricated at research level, less is known about how the academic knowledge has been translated into clinical trials and commercial technologies. In this review, we provide a clinical translational perspective on the use of controlled physical surface modification of medical implants, presenting an analysis of data acquired from clinical trials and commercial products. We also evaluate the state-of-the-art of nanofabrication techniques that are being applied for implant surface modification at a clinical level. Finally, we identify some current challenges in the field, including the need of more advanced nanopatterning techniques, the comparatively small number of clinical trials and comment on future avenues to be explored for a successful clinical translation