Stress relaxation behavior of the transition zone in the intervertebral disc.

The stress relaxation of the TZ region, located at the interface of the Annulus Fibrosus (AF) and Nucleus Pulposus (NP) of the disc, and how its stress is relaxed compared to the adjacent regions is unknown. The current study aimed to identify the TZ stress relaxation properties under different strain magnitudes (0.2, 0.

Lumbar Total Disc Replacements for Degenerative Disc Disease: A Systematic Review of Outcomes With a Minimum of 5 years Follow-Up.

Study Design: Systematic Review.

Objectives: To systematically review the clinical outcomes, re-operation, and complication rates of lumbar TDR devices at mid-to long-term follow-up studies for the treatment of lumbar degenerative disc disease (DDD).

Methods: A systematic search was conducted on PubMed, SCOPUS, and Google Scholar to identify follow-up studies that evaluated clinical outcomes of lumbar TDR in patients with DDD.

Nanostrategy of Targeting at Embryonic Trophoblast Cells Using CuO Nanoparticles for Female Contraception.

Effective contraceptives have been comprehensively adopted by women to prevent the negative consequences of unintended pregnancy for women, families, and societies. With great contributions of traditional hormonal drugs and intrauterine devices (IUDs) to effective female contraception by inhibiting ovulation and deactivating sperm, their long-standing side effects on hormonal homeostasis and reproductive organs for females remain concerns. Herein, we proposed a nanostrategy for female contraceptives, inducing embryonic trophoblast cell death using nanoparticles to prevent embryo implantation.

An automated system for polymer wear debris analysis in total disc arthroplasty using convolution neural network.

Polymer wear debris is one of the major concerns in total joint replacements due to wear-induced biological reactions which can lead to osteolysis and joint failure. The wear-induced biological reactions depend on the wear volume, shape and size of the wear debris and their volumetric concentration. The study of wear particles is crucial in analysing the failure modes of the total joint replacements to ensure improved designs and materials are introduced for the next generation of devices.

Intervertebral disc-on-a-chip: a precision engineered toolbox for low back pain studies.

Current in vitro intervertebral disc (IVD) models do not fully recapitulate the complex mechanobiology of native tissue, and so far there is no strategy to effectively evaluate IVD regeneration. The development of a modular microfluidic on-chip model is expected to enhance the physiological relevance of experimental data leading to successful clinical outcomes.

A digitally driven manufacturing process for high resolution patterning of cell formations.

This paper presents the engineering and validation of an enabling technology that facilitates new capabilities in in vitro cell models for high-throughput screening and tissue engineering applications. This is conducted through a computerized system that allows the design and deposition of high-fidelity microscale patterned coatings that selectively alter the chemical and topographical properties of cell culturing surfaces. Significantly, compared to alternative methods for microscale surface patterning, this is a digitally controlled and automated process thereby allowing scientists to rapidly create and explore an almost infinite range of cell culture patterns.

Structure-function characterization of the transition zone in the intervertebral disc.

Understanding the structure-function relationship in the intervertebral disk (IVD) is crucial for the development of novel tissue engineering strategies to regenerate IVD and the establishment of accurate computational models for low back pain research. A large number of studies have improved our knowledge of the mechanical and structural properties of the nucleus pulposus (NP) and annulus fibrosus (AF), two of the main regions in the IVD. However, few studies have focused on the AF-NP interface (transition zone; TZ).

Isolation and characterisation of wear debris surrounding failed total ankle replacements.

Aseptic loosening and osteolysis continue to be a short- to mid-term problem for total ankle replacement (TAR) devices. The production of wear particles may contribute to poor performance, but their characteristics are not well understood. This study aimed to determine the chemical composition, size and morphology of wear particles surrounding failed TARs.

A Biomimetic Nonwoven-Reinforced Hydrogel for Spinal Cord Injury Repair.

In clinical trials, new scaffolds for regeneration after spinal cord injury (SCI) should reflect the importance of a mechanically optimised, hydrated environment. Composite scaffolds of nonwovens, self-assembling peptides (SAPs) and hydrogels offer the ability to mimic native spinal cord tissue, promote aligned tissue regeneration and tailor mechanical properties. This work studies the effects of an aligned electrospun nonwoven of P-8-enriched poly(-caprolactone) (PCL) fibres, integrated with a photo-crosslinked hydrogel of glycidylmethacrylated collagen (collagen-GMA), on neurite extension.

Elastic Fibers in the Intervertebral Disc: From Form to Function and toward Regeneration.

Despite extensive efforts over the past 40 years, there is still a significant gap in knowledge of the characteristics of elastic fibers in the intervertebral disc (IVD). More studies are required to clarify the potential contribution of elastic fibers to the IVD (healthy and diseased) function and recommend critical areas for future investigations. On the other hand, current IVD in-vitro models are not true reflections of the complex biological IVD tissue and the role of elastic fibers has often been ignored in developing relevant tissue-engineered scaffolds and realistic computational models.

ALTEN: A High-Fidelity Primary Tissue-Engineering Platform to Assess Cellular Responses Ex Vivo.

To fully investigate cellular responses to stimuli and perturbations within tissues, it is essential to replicate the complex molecular interactions within the local microenvironment of cellular niches. Here, the authors introduce Alginate-based tissue engineering (ALTEN), a biomimetic tissue platform that allows ex vivo analysis of explanted tissue biopsies. This method preserves the original characteristics of the source tissue's cellular milieu, allowing multiple and diverse cell types to be maintained over an extended period of time.

Current status and future potential of wear-resistant coatings and articulating surfaces for hip and knee implants.

Hip and knee joint replacements are common and largely successful procedures that utilise implants to restore mobility and relieve pain for patients suffering from e.g. osteoarthritis.

Mixed material wear particle isolation from periprosthetic tissue surrounding total joint replacements.

Submicron-sized wear particles are generally accepted as a potential cause of aseptic loosening when produced in sufficient volumes. With the accelerating use of increasingly wear-resistant biomaterials, identifying such particles and evaluating their biological response is becoming more challenging. Highly sensitive wear particle isolation methods have been developed but these methods cannot isolate the complete spectrum of particle types present in individual tissue samples.

Detailed mechanical characterization of the transition zone: New insight into the integration between the annulus and nucleus of the intervertebral disc.

The Nucleus Pulposus (NP) and Annulus Fibrous (AF) are two primary regions of the intervertebral disc (IVD). The interface between the AF and NP, where the gradual transition in structure and type of fibers are observed, is known as the Transition Zone (TZ). Recent structural studies have shown that the TZ contains organized fibers that appear to connect the NP to the AF.

Developing Novel Fabrication and Optimisation Strategies on Aggregation-Induced Emission Nanoprobe/Polyvinyl Alcohol Hydrogels for Bio-Applications.

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0-5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2.

Towards engineering heart tissues from bioprinted cardiac spheroids.

Currentandmodels fail to accurately recapitulate the human heart microenvironment for biomedical applications. This study explores the use of cardiac spheroids (CSs) to biofabricate advancedmodels of the human heart. CSs were created from human cardiac myocytes, fibroblasts and endothelial cells (ECs), mixed within optimal alginate/gelatin hydrogels and then bioprinted on a microelectrode plate for drug testing.

Developing a Tooth Organ Culture Model for Dental and Periodontal Regeneration Research.

In this study we have realized the need for an organ culture tooth model to simulate the tooth structure especially the tooth attachment apparatus. The importance of such a model is to open avenues for investigating regeneration of the complex tooth and tooth attachment tissues and to reduce the need for experimental animals in investigating dental materials and treatments in the future. The aim of this study was to develop a porcine tooth organ culture model and a novel bioreactor suitable for future studies of periodontal regeneration, including application of appropriate physiological loading.

The ultrastructural organization of elastic fibers at the interface of the nucleus and annulus of the intervertebral disk.

There has been no study to describe the ultrastructural organization of elastic fibers at the interface of the nucleus pulposus and annulus fibrosus of the intervertebral disk (IVD), a region called the transition zone (TZ). A previously developed digestion technique was optimized to eliminate cells and non-elastin ECM components except for the elastic fibers from the anterolateral (AL) and posterolateral (PL) regions of the TZ in ovine IVDs. Not previously reported, the current study identified a complex elastic fiber network across the TZ for both AL and PL regions.

Advanced Strategies for the Regeneration of Lumbar Disc Annulus Fibrosus.

Damage to the annulus fibrosus (AF), the outer region of the intervertebral disc (IVD), results in an undesirable condition that may accelerate IVD degeneration causing low back pain. Despite intense research interest, attempts to regenerate the IVD have failed so far and no effective strategy has translated into a successful clinical outcome. Of particular significance, the failure of strategies to repair the AF has been a major drawback in the regeneration of IVD and nucleus replacement.

Elastic fibers: The missing key to improve engineering concepts for reconstruction of the Nucleus Pulposus in the intervertebral disc.

The increasing prevalence of low back pain has imposed a heavy economic burden on global healthcare systems. Intense research activities have been performed for the regeneration of the Nucleus Pulposus (NP) of the IVD; however, tissue-engineered scaffolds have failed to capture the multi-scale structural hierarchy of the native tissue. The current study revealed for the first time, that elastic fibers form a network across the NP consisting of straight and thick parallel fibers that were interconnected by wavy fine fibers and strands.

Neural cell responses to wear debris from metal-on-metal total disc replacements.

Purpose: Total disc replacements, comprising all-metal articulations, are compromised by wear and particle production. Metallic wear debris and ions trigger a range of biological responses including inflammation, genotoxicity, cytotoxicity, hypersensitivity and pseudotumour formation, therefore we hypothesise that, due to proximity to the spinal cord, glial cells may be adversely affected.

Methods: Clinically relevant cobalt chrome (CoCr) and stainless steel (SS) wear particles were generated using a six-station pin-on-plate wear simulator.

Biological Impact of Silicon Nitride for Orthopaedic Applications: Role of Particle Size, Surface Composition and Donor Variation.

The adverse biological impact of orthopaedic wear debris currently limits the long-term safety of human joint replacement devices. We investigated the role of particle size, surface composition and donor variation in influencing the biological impact of silicon nitride as a bioceramic for orthopaedic applications. Silicon nitride particles were compared to the other commonly used orthopaedic biomaterials (e.

Concentration and size distribution data of silicon nitride nanoparticles measured using nanoparticle tracking analysis.

This article refers to the paper "A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates" (Lal et al., 2016) [1] and describes the concentration and size distribution data of silicon nitride nanoparticles measured using nanoparticle tracking analysis (NTA). A NanoSight LM10 instrument was used to capture the video data of silicon nitride nanoparticles moving under Brownian motion in the water.

Evaluation of a new methodology to simulate damage and wear of polyethylene hip replacements subjected to edge loading in hip simulator testing.

Wear and fatigue of polyethylene acetabular cups have been reported to play a role in the failure of total hip replacements. Hip simulator testing under a wide range of clinically relevant loading conditions is important. Edge loading of hip replacements can occur following impingement under extreme activities and can also occur during normal gait, where there is an offset deficiency and/or joint laxity.

The Biologic Response to Polyetheretherketone (PEEK) Wear Particles in Total Joint Replacement: A Systematic Review.

Background: Polyetheretherketone (PEEK) and its composites are polymers resistant to fatigue strain, radiologically transparent, and have mechanical properties suitable for a range of orthopaedic applications. In bulk form, PEEK composites are generally accepted as biocompatible. In particulate form, however, the biologic response relevant to joint replacement devices remains unclear.