3D Printed polyether-ether-ketone (PEEK) has gained widespread use in clinical practice due to its excellent biocompatibility, biomechanical compatibility, and personalization. However, pre-printed PEEK implants are not without their flaws, including bioinert, optimization distortion of 3D printing digital model and prosthetic mismatching. Recent advancements in mechanical processing technology have made it possible to print bone implants with PEEK fused deposition, allowing for the construction of mechanically adaptable implants. In this study, we aimed to synthesize silanized polycitrate (PCS) via thermal polymerization and in situ graft it to PEEK surface to construct an elastomer coating for 3D printed PEEK implants (PEEK-PCS). This incorporation of PCS allows the implant to exhibit adaptive space filling ability and stress dispersal. In vivo and in vitro results, PEEK-PCS exhibited exceptional osseointegration and osteogenesis properties along with macrophage M2 phenotypic polarization, inflammatory factors reducing, promotion of osteogenic differentiation in bone marrow mesenchymal stem cells (BMSCs). Additionally, PEEK-PCS displays good autofluorescence properties in vitro and in vivo, with stable fluorescence for 14 days, suggesting potential bioimaging applications. The study confirms that PEEK in situ grafting with thermo-polymerized PCS elastomers is a viable approach for creating multifunctional (bone defect adaptation, bioimaging, immune regulation, and osseointegration) implants for bone tissue engineering

To investigate temporal changes in synovial lymphatic system (SLS) drainage function after Anterior cruciate ligament (ACL) injury, a non-invasive ACL rupture model was used to induce the PTOA phenotype without altering the SLS structure. We have created a non-invasive ACL rupture model in the right knee (single overload impact) of 12- week-old C57bl/6 male mice to mimic the ACL rupture-induced PTOA development. 70 kDa-TxRedDextran were injected into the right knee of the mice at 0, 1, 2, and 4 wks post modeling (n=5/group), and the fluorescence signal distribution and intensity were measured by the IVIS system at 1 and 6 hrs post-injection. After 24 hrs, the drainage lymph nodes and whole knee joint were harvested and subjected to ex vivo IVIS imaging and immunofluorescence detection respectively. Manual ACL rupture was induced by 12N overloaded force and validated by a front drawer test. Intraarticular clearance of TxRed-Dextran detected by the IVIS was significantly reduced at 1, and 2 wks at a level of 43% and 55% respectively but was not significantly different from baseline levels at 4 wks (89%). TxRed-Dextran signal in draining lymph nodes was significantly reduced at 1 week at the level of but not for 2 and 4 wks compared to baseline levels (week 1–29%, week 2–50%, week 4–94%). TxRed-Dextran particle was significantly enriched in the synovium at 1, 2 wks but was not significantly different from baseline levels at 4 wks rupture-post ACL rupture (Particle numbers: Sham Ctrl-34 ±14, week 1, 113 ± 17; week 2, 89 ± 13; week 4, 46 ± 18; mean ± SD). We observed the drainage function of SLS significantly decreased at 1 and 2 wks after the ACL rupture, and was slowly restored at 4 wks post-injury in a non-invasive ACL rupture model. Early impairment of SLS drainage function may lead to accumulation of inflammatory factors and promote PTOA progression

Research in orthopaedics is now moving away from permanent metallic implants, and looking towards the use of bioresorbable polymers (e.g. PLLA, PGA and related co-polymers) that, when implanted into the injured site, bioresorb as the tissue heals. However, reports of a delayed inflammatory reponse occurring in the late stages of polymer degradation has limited the wide scale use of these polymers. Few studies assess the long-term biocompatibility of these polymers and with an increasing market for bioresorbable materials it is anticipated that this will be a future issue. This work aims to develop a predictive tool that can be used to assess the delayed inflammatory response of poly(D,L-lactide-co-glycolide) (PDLGA) using in vitro tests. An elevated temperature accelerated test (47. o. C) was developed and utilitised to induce predetermined amounts of degradation in PDLGA. This was used to mimic a range of clinically relevant in vivo implantation times up to 5–6 months. All pre-degradion work was performed under sterile conditions, in PBS solution. At predetermined time intervals, indicators of late stage inflammation will be assessed using an MTT cytotoxicity assay, an inflammation antibody array and an ELISA analysis for inflammatory factors, with mouse L929 fibroblasts, RAW264.7 and primary BMDM macrophages. It is hypothosised that at the later degradation time intervals signs of inflammatory factors will be observed. The methodologies developed in this work can be applied to the optimisation of polymer degradation profiles to minimise late-stage inflammatory repsonse and identification of beneficial additives in this regard

Osteoarthritis (OA) is a progressive and degenerative joint disease resulting in changes to articular cartilage. In focal early OA defects, autologous chondrocyte implantation (ACI) has a 2-fold failure rate due to poor graft integration and presence of inflammatory factors (e.g. Interleukin-1β). Bone marrow derived mesenchymal stem cells (MSCs) are an alternative cell source for cell-based treatments due to their chondrogenic capacity, though in vivo implantation leads to bone formation. In vivo, chondrocytes reside under an oxygen tension between 2–7% oxygen or physioxia. Physioxia enhances MSC chondrogenesis with reduced hypertrophic marker (collagen X and MMP13) expression compared to hyperoxic conditions (20% oxygen). This study sought to understand whether implantation of physioxic preconditioned MSCs improves cartilage regeneration in an early OA defect model compared to hyperoxic MSCs. Bone marrow extracted from New Zealand white rabbits (male: 5–6 months old; n = 6) was split equally for expansion under 2% (physioxia) or 20% (hyperoxia) oxygen. Chondrogenic pellets (2 × 105 cells/pellet) formed at passage 1 were cultured in the presence of TGF-β1 under their expansion conditions and measured for their wet weight and GAG content after 21 days. During bone marrow extraction, a dental drill (2.5mm diameter) was applied to medial femoral condyle on both the right and left knee and left untreated for 6 weeks. Following this period, physioxia and hyperoxia preconditioned MSCs were seeded into a hyaluronic acid (TETEC) hydrogel. Fibrous tissue was scraped and then MSC-hydrogel was injected into the right (hyperoxic MSCs) and left (physioxia MSCs) knee. Additional control rabbits with drilled defects had fibrous tissue scrapped and then left untreated without MSC-hydrogel treatment for the duration of the experiment. Rabbits were sacrificed at 6 (n = 3) and 12 (n = 3) weeks post-treatment, condyles harvested, decalcified in 10% EDTA and sectioned using a cryostat. Region of interest was identified; sections stained with Safranin-O/Fast green and evaluated for cartilage regeneration using the Sellers scoring system by three blinded observers. Physioxic culture of rabbit MSCs showed significantly shorter doubling time and greater cell numbers compared to hyperoxic culture (∗p < 0.05). Furthermore, physioxia enhanced MSC chondrogenesis via significant increases in pellet wet weight and GAG content (∗p < 0.05). Implantation of physioxic preconditioned MSCs showed significantly improved cartilage regeneration (Mean Sellers score = 7 ± 3; ∗p < 0.05) compared to hyperoxic MSCs (Sellers score = 12 ± 2) and empty defects (Sellers score = 17 ± 3). Physioxia enhances in vitro rabbit MSC chondrogenesis. Subsequent in vivo implantation of physioxia preconditioned MSCs improved cartilage regeneration in an early OA defect model compared to hyperoxic MSCs. Future studies will investigate the mechanisms for enhanced in vivo regeneration using physioxia preconditioned MSCs

Early clinical studies investigating the effects of delivery of mesenchymal stromal cells (MSCs) to degenerated intervertebral discs have shown promising results, but with an incomplete understanding of the therapeutic mechanism(s) of action. To address this, we have developed a 3D co-culture system to unravel the biological interaction between MSCs and nucleus pulposus (NP) cells. Alginate constructs were created using a biphasic configuration consisting of a cylindrical shell with an encapsulated bead. Human NP cells were seeded in monolayer or encapsulated within alginate and cultured in hypoxia with variations of pH, osmolarity and growth factors (n = 6) to replicate healthy or degenerative conditions. Wells and gels were fixed and stained for ECM content, and retrieved cells and media were analysed for ECM and inflammatory factor expression. Encapsulated hNPCs showed no migration from either alginate structure and full bead separation was achieved over 14 days, reinforcing the construct as a separable 3D co-culture method. Addition of the degenerative growth factors TNFα and IL-1β as well as the adjustment of media pH to degenerative levels (pH 6.8) caused the hNPCs to decrease in size and proliferate significantly higher than control levels. TGF-β3 addition showed higher incidence of aggrecan deposition over addition of IL-1β. Addition of FGF2 altered cell morphology and ECM deposition including formation of pseudo lamellae, indicating a phenotype shift toward annulus fibrosis cells as shown in late-stage degenerative disc disease. The data from this study will be used in future MSC:NPC co-cultures to determine immunoregulatory interactions in a degenerative environment

Clinical trials are underway to elucidate a successful MSC-based therapy for the repair and regeneration of intervertebral disc (IVD) tissue. Currently, there is a lack of knowledge surrounding the relationship between naïve MSCs and the inflammatory microenvironment of the degenerate disc. To inform a phase II clinical trial, this study tests the hypothesis that cytokines, IL-1ß and TNFα regulate the expression of neuropeptides and neurotrophic factors from MSCs, thus exacerbating pain in those patients that have the presence of sensory nerve fibres within the IVD. Patient-matched MSCs derived from bone marrow (BM) or adipose (AD) tissue were stimulated with IL-1β (10ng/ml) or TNFα (10ng/ml) for 48 hours in either 21% or 5% O2. qRT-PCR was performed to assess expression of trophic factors involved in the survival or nerves (NGF & BDNF), blood vessels (VEGF) as well as pain related peptides (SP & CGRP) and inflammatory factors. Conditioned culture medium was analysed using ELISAs to identify secretion of soluble factors. IL-1β did not regulate neurotrophic factor expression from BM-MSCs under normoxic or hypoxic conditions. However, TNFα increased NGF, BDNF, SP and CGRP under normoxic conditions. In ADMSCs, VEGF was increased following IL-1β and TNFα stimulation; with TNFα also increasing NGF and CGRP under normoxic conditions. When exposed to hypoxia, the trophic effect of TNFα on human BM-MSCs was reduced. Overall this data suggests a role for priming or pre-stimulation of naïve MSCs prior to implantation to prevent exacerbation of pain from sensory nerve fibres

Aims

This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation.

Objectives

The aim of this study was to investigate the role of miR-126 in the development of osteoarthritis, as well as the potential molecular mechanisms involved, in order to provide a theoretical basis for osteoarthritis treatment and a novel perspective for clinical therapy.

Objectives

This study aimed to examine the effects of SRT1720, a potent SIRT1 activator, on osteoarthritis (OA) progression using an experimental OA model.

Objectives

We have observed clinical cases where bone is formed in the overlaying muscle covering surgically created bone defects treated with a hydroxyapatite/calcium sulphate biomaterial. Our objective was to investigate the osteoinductive potential of the biomaterial and to determine if growth factors secreted from local bone cells induce osteoblastic differentiation of muscle cells.

Previous research has shown an increase in chromosomal aberrations in patients with worn implants. The type of aberration depended on the type of metal alloy in the prosthesis. We have investigated the metal-specific difference in the level of DNA damage (DNA stand breaks and alkali labile sites) induced by culturing human fibroblasts in synovial fluid retrieved at revision arthroplasty.

All six samples from revision cobalt-chromium metal-on-metal and four of six samples from cobalt-chromium metal-on-polyethylene prostheses caused DNA damage. By contrast, none of six samples from revision stainless-steel metal-on-polyethylene prostheses caused significant damage. Samples of cobalt-chromium alloy left to corrode in phosphate-buffered saline also caused DNA damage and this depended on a synergistic effect between the cobalt and chromium ions.

Our results further emphasise that epidemiological studies of orthopaedic implants should take account of the type of metal alloy used.

Platelet-leucocyte gel (PLG), a new biotechnological blood product, has hitherto been used primarily to treat chronic ulcers and to promote soft-tissue and bone regeneration in a wide range of medical fields. In this study, the antimicrobial efficacy of PLG against Staphylococcus aureus (ATCC 25923) was investigated in a rabbit model of osteomyelitis. Autologous PLG was injected into the tibial canal after inoculation with Staph. aureus. The prophylactic efficacy of PLG was evaluated by microbiological, radiological and histological examination. Animal groups included a treatment group that received systemic cefazolin and a control group that received no treatment.

Treatment with PLG or cefazolin significantly reduced radiological and histological severity scores compared to the control group. This result was confirmed by a significant reduction in the infection rate and the number of viable bacteria. Although not comparable to cefazolin, PLG exhibited antimicrobial efficacy in vivo and therefore represents a novel strategy to prevent bone infection in humans.