Hyaluronic acid-based interpenetrating network hydrogel as a cell carrier for nucleus pulposus repair.

Hyaluronic acid (HA) is a key component of the intervertebral disc (IVD) that is widely investigated as an IVD biomaterial. One persisting challenge is introducing materials capable of supporting cell encapsulation and function, yet with sufficient mechanical stability. In this study, a hybrid interpenetrating polymer network (IPN) was produced as a non-covalent hydrogel, based on a covalently cross-linked HA (HA-BDDE) and HA-poly(N-isopropylacrylamide) (HA-pNIPAM).

In Vitro Model to Investigate Communication between Dorsal Root Ganglion and Spinal Cord Glia.

Chronic discogenic back pain is associated with increased inflammatory cytokine levels that can influence the proximal peripheral nervous system, namely the dorsal root ganglion (DRG). However, transition to chronic pain is widely thought to involve glial activation in the spinal cord. In this study, an in vitro model was used to evaluate the communication between DRG and spinal cord glia.

Coaxial micro-extrusion of a calcium phosphate ink with aqueous solvents improves printing stability, structure fidelity and mechanical properties.

Micro-extrusion-based 3D printing of complex geometrical and porous calcium phosphate (CaP) can improve treatment of bone defects through the production of personalized bone substitutes. However, achieving printing and post-printing shape stabilities for the efficient fabrication and application of rapid hardening protocol are still challenging. In this work, the coaxial printing of a self-setting CaP cement with water and ethanol mixtures aiming to increase the ink yield stress upon extrusion and the stability of fabricated structures was explored.

Hypoxic stress enhances extension and branching of dorsal root ganglion neuronal outgrowth.

Unlabelled: It has been shown that painful intervertebral discs (IVDs) were associated with a deeper innervation. However, the effect of the disc's degenerative microenvironment on neuronal outgrowth remains largely unknown. The focus of this study was to determine the influence of hypoxia on dorsal root ganglion (DRG) neurite outgrowth.

Direct and Intervertebral Disc-Mediated Sensitization of Dorsal Root Ganglion Neurons by Hypoxia and Low pH.

Objective: Ischemia-related risk factors are consistently correlated with discogenic pain, but it remains unclear how the ischemia-associated hypoxia and acidosis influence the peripheral sensory nervous system, namely the dorsal root ganglion (DRG), either directly or indirectly via intervertebral disc (IVD) mediation.

Methods: Bovine tail IVD organ cultures were preconditioned in different hypoxic and/or acidic conditions for 3 days to collect the conditioned medium (CM). The DRG-derived ND7/23 cells were either treated by the IVD CM or directly stimulated by hypoxic and/or acidic conditions.

Fibrin-Hyaluronic Acid Hydrogel (RegenoGel) with Fibroblast Growth Factor-18 for In Vitro 3D Culture of Human and Bovine Nucleus Pulposus Cells.

We investigated the effects of a fibrin-hyaluronic acid hydrogel (FBG-HA) and fibroblast growth factor 18 (FGF-18) for nucleus pulposus (NP) regeneration. Healthy bovine ( = 4) and human degenerated NP cells ( = 4) were cultured for 14 days in FBG-HA hydrogel with FGF-18 (∆51-mutant or wild-type) in the culture medium. Gene expression, DNA content, and glycosaminoglycan (GAG) synthesis were evaluated on day 7 and 14.

Intervertebral disc organ culture for the investigation of disc pathology and regeneration - benefits, limitations, and future directions of bioreactors.

Low back pain is the leading cause of disability worldwide and in many patients the source of pain can be attributed to pathological changes within the intervertebral disc (IVD). As present treatment options fail to address the underlying biological problem, novel therapies are currently subject to intense research. The physiologic IVD microenvironment features a highly complex interaction of biochemical and mechanical factors influencing cell metabolism and extracellular matrix turnover and is therefore difficult to simulate for research purposes on IVD pathology.

Isolation of high-quality RNA from intervertebral disc tissue via pronase predigestion and tissue pulverization.

The isolation of high-quality RNA from the intervertebral disc and especially from the nucleus pulposus is challenging due to the low cellularity and high proteoglycan content of this tissue. In this study, we report a simple modification of the standard guanidinium thiocyanate-phenol-chloroform extraction method, which involves enzymatic predigestion of the tissue prior to standard RNA isolation. Yield, purity and integrity of RNA isolated from bovine nucleus pulposus, inner annulus fibrosus and outer annulus fibrosus were compared among complete matrix digestion, predigestion and pulverization, pulverization alone, and pulverization followed by on-column purification.

Intervertebral disc response to stem cell treatment is conditioned by disc state and cell carrier: An study.

and studies evidenced that mesenchymal stem cells (MSCs) contribute to intervertebral disc (IVD) regeneration by differentiation towards the disc phenotype and matrix synthesis and/or by paracrine signalling to endogenous cells, thereby promoting a healthier disc phenotype in degenerative discs. The aim of this study was to investigate IVD response to human MSC (hMSC) treatment based on the disc degenerative state and hMSC carrier. Bovine caudal IVDs with endplates were cultured in a bioreactor under simulated physiological (0.

Ageing affects chondroitin sulfates and their synthetic enzymes in the intervertebral disc.

The depletion of chondroitin sulfates (CSs) within the intervertebral disc (IVD) during degenerative disc disease (DDD) results in a decrease in tissue hydration, a loss of fluid movement, cell apoptosis, a loss of nerve growth inhibition and ultimately, the loss of disc function. To date, little is known with regards to the structure and content of chondroitin sulfates (CSs) during IVD ageing. The behavior of glycosaminoglycans (GAGs), specifically CSs, as well as xylosyltransferase I (XT-I) and glucuronyltransferase I (GT-I), two key enzymes involved in CS synthesis as a primer of glycosaminoglycan (GAG) chain elongation and GAG synthesis in the nucleus pulposus (NP), respectively, were evaluated in a bovine ageing IVD model.

Relevance of bioreactors and whole tissue cultures for the translation of new therapies to humans.

The purpose of this review is to provide a brief overview of bioreactor-based culture systems as alternatives to conventional two- and three-dimensional counterparts. The role, challenges, and future aspirations of bioreactors in the musculoskeletal field (e.g.

Self-Healing Dynamic Hydrogel as Injectable Shock-Absorbing Artificial Nucleus Pulposus.

The intervertebral discs (IVDs) provide unique flexibility to the spine and exceptional shock absorbing properties under impact. The inner core of the IVD, the nucleus pulposus (NP) is responsible for this adaptive behavior. Herein, we evaluate an injectable, self-healing dynamic hydrogel (DH) based on gold(I)-thiolate/disulfide (Au-S/SS) exchange as NP replacement in a spine motion segment model.

Roughness gradients on zirconia for rapid screening of cell-surface interactions: Fabrication, characterization and application.

Roughness is one of the key parameters for successful osseointegration of dental implants. The understanding of how roughness affects cell response is thus crucial to improve implant performance. Surface gradients, which allow rapid and systematic investigations of cell-surface interactions, have the potential to facilitate this task.

Development of an ex vivo cavity model to study repair strategies in loaded intervertebral discs.

Purpose: The aim of this study was to compare two approaches for the delivery of biomaterials to partially nucleotomised intervertebral discs in whole organ culture under loading. Such models can help to bridge the gap between in vitro and in vivo studies by assessing (1) suitability of biomaterial delivery and defect closure methods, (2) effect of mechanical loading and (3) tissue response.

Methods: Mechanical performance of bovine discs filled with a hyaluronan-based thermoreversible hydrogel delivered through the annulus fibrosus (AF) or the bony endplate (EP) was evaluated under cyclic axial loading in a bioreactor.

A Nucleotomy Model with Intact Annulus Fibrosus to Test Intervertebral Disc Regeneration Strategies.

Introduction: New cells/hydrogel-based treatments for intervertebral disc (IVD) regeneration need to be tested on animal models before clinical translation. Ovine IVD represents a good model but does not allow the injection of a significant volume into intact IVD. The aim of this study was to compare different methods to create a cavity into ovine nucleus pulposus (NP) by enzymatic digestion (E), mechanical nucleotomy (N), or a combining technique (E+N), as a model to study IVD regeneration strategies with intact annulus fibrosus (AF) in functional spinal units (FSUs) in vitro.

Potential and limitations of intervertebral disc endogenous repair.

Intervertebral disc (IVD) disorders, especially degenerative disc disease, reduce the quality of life, and are short of effective therapy. A new direction for treatment of chronic tissue and organ diseases is to promote regeneration by harnessing endogenous repair mechanisms. In this review, we discuss the potential of endogenous repair in the IVD, the recent findings on endogenous IVD progenitor cells, and stem cell niches involved in IVD endogenous repair.

Multivalent dendrimers presenting spatially controlled clusters of binding epitopes in thermoresponsive hyaluronan hydrogels.

The controlled presentation of biofunctionality is of key importance for hydrogel applications in cell-based regenerative medicine. Here, a versatile approach was demonstrated to present clustered binding epitopes in an injectable, thermoresponsive hydrogel. Well-defined multivalent dendrimers bearing four integrin binding sequences and an azido moiety were covalently grafted to propargylamine-derived hyaluronic acid (Hyal-pa) using copper-catalyzed alkyne-azide cycloaddition (CuAAC), and then combined with pN-modified hyaluronan (Hyal-pN).

The effect of hyaluronan-based delivery of stromal cell-derived factor-1 on the recruitment of MSCs in degenerating intervertebral discs.

Intervertebral disc (IVD) degeneration is the leading cause of low back pain and disability in the active population. Transplantation of mesenchymal stem cells (MSCs) in a hydrogel carrier can induce regenerative effects in degenerated IVDs. Moreover, it was found that degenerative discs release chemoattractants effective in MSC recruitment.

Biomimetic fibrin-hyaluronan hydrogels for nucleus pulposus regeneration.

Aim: To develop a biomimetic polymeric injectable hydrogel that can support nucleus pulposus (NP) regeneration.

Materials & Methods: Natural polymer-based hydrogels were synthesized using fibrinogen (FBG) and hyaluronic acid (HA), conjugated by a novel two-step procedure. Bovine NP cells were cultured in FBG-HA conjugate-based 3D beads in vitro and in a nucleotomized organ culture model.