Aims. A local injection may be used as an early option in the treatment of Morton’s neuroma, and can be performed using various medications. The aim of this study was to compare the effects of injections of hyaluronic acid compared with corticosteroid in the treatment of this condition. Methods. A total of 91 patients were assessed for this trial, of whom 45 were subsequently included and randomized into two groups. One patient was lost to follow-up, leaving 22 patients (24 feet) in each group. The patients in the hyaluronic acid group were treated with three ultrasound-guided injections (one per week) of hyaluronic acid (Osteonil Plus). Those in the corticosteroid group were treated with three ultrasound-guided injections (also one per week) of triamcinolone (Triancil). The patients were evaluated before treatment and at one, three, six, and 12 months after treatment. The primary outcome measure was the visual analogue scale for pain (VAS). Secondary outcome measures included the American Orthopaedic Foot and Ankle Society (AOFAS) score, and complications. Results. Both groups showed significant improvement in VAS and AOFAS scores (p < 0.05) after 12 months. The corticosteroid group had a significantly greater reduction in VAS and increase in AOFAS scores compared with the hyaluronic acid group, at one, three, and six months, but with no significant difference at 12 months. There were no complications in the hyaluronic acid group. There were minor local complications in six patients (six feet) (25.0%) in the corticosteroid group, all with discolouration of the skin at the site of the injection. These minor complications might have been due to the three weekly injections of a relatively high dose of corticosteroid. No patient subsequently underwent excision of the neuroma. Conclusion. An ultrasound-guided corticosteroid injection showed statistically significantly better functional and pain outcomes than an ultrasound-guided injection of hyaluronic acid for the treatment of a Morton’s neuroma at many timepoints. Thus, a corticosteroid injection should be regarded as a primary option in the treatment of these patients, and the only indication for an injection of hyaluronic acid might be in patients in whom corticosteroid is contraindicated. Cite this article: Bone Joint J 2024;106-B(10):1093–1099

The Cochrane Collaboration has produced three new reviews relevant to bone and joint surgery since the publication of the last Cochrane Corner. These are relevant to a wide range of musculoskeletal specialists, and include reviews in lateral elbow pain, osteoarthritis of the big toe joint, and cervical spine injury in paediatric trauma patients.

Aims

Knee osteoarthritis (OA) is characterized by a chronic inflammatory process involving multiple cytokine pathways, leading to articular cartilage degeneration. Intra-articular therapies using pharmaceutical or autologous anti-inflammatory factors offer potential non-surgical treatment options. Autologous protein solution (APS) is one such product that uses the patient’s blood to produce a concentrate of cells and anti-inflammatory cytokines. This study evaluated the effect of a specific APS intra-articular injection (nSTRIDE) on patient-reported outcome measures compared to saline in moderate knee OA.

The August 2024 Wrist & Hand Roundup³⁶⁰ looks at: Methotrexate shows potential in reducing pain for hand osteoarthritis with synovitis; Circumferential casting versus plaster splinting in adult distal radius fractures: the CAST study findings; Surgery shows superior long-term success for Dupuytren contracture compared to needle fasciotomy and collagenase injection; Evolving trends in surgical management of wrist arthritis: a decade-long national analysis; Mid-term outcomes of three commonly used surgical reconstructions for scapholunate instability; SLAC and SNAC: what is the evidence for treatment?; Steroids for trapeziometacarpal osteoarthritis?; When is it safe to return to driving after distal radius fracture fixation? A prospective study.

Background. Infiltration is considered the first treatment option for symptomatic Morton's neuroma and can be performed with various medications. The aim of this study was to compare the effects of hyaluronic acid infiltration versus corticosteroid injection in the treatment of Morton's neuroma. Methods. A randomised clinical trial was conducted with 46 patients (50 feet) diagnosed with Morton's neuroma. After randomisation, the control group (CG) received three injections (one per week) of triamcinolone (Triancil®) guided by ultrasound, while the study group (SG) received three applications of hyaluronic acid (Osteonil Plus®). Patients were followed up for six months after the intervention. The primary outcome measure used was the Visual Pain Analog Scale (VAS). Secondary endpoints included patient-reported outcome measures using the American Orthopaedic Foot & Ankle Society (AOFAS) score and complications. Results. Both groups showed significant improvement in VAS and AOFAS scores (p < 0.001). The CG showed greater improvement than the SG in the VAS (p < 0.05) and AOFAS (p < 0.001) variables. Four patients in the CG experienced skin hypochromia at the injection site, while there were no complications in the SG. Conclusion. Ultrasound-guided hyaluronic acid infiltration in Morton's Neuroma proved to be safe, showing improvement in pain and function after six months of follow-up, without major complications, but with a significantly lower improvement when compared to corticosteroid injection. Taking into account cost implications and the potential for longer lasting improvement from viscosupplementation further medium- and long-term studies are needed

Aims. Intra-articular (IA) injection may be used when treating hip osteoarthritis (OA). Common injections include steroids, hyaluronic acid (HA), local anaesthetic, and platelet-rich plasma (PRP). Network meta-analysis allows for comparisons between two or more treatment groups and uses direct and indirect comparisons between interventions. This network meta-analysis aims to compare the efficacy of various IA injections used in the management of hip OA with a follow-up of up to six months. Methods. This systematic review and network meta-analysis used a Bayesian random-effects model to evaluate the direct and indirect comparisons among all treatment options. PubMed, Web of Science, Clinicaltrial.gov, EMBASE, MEDLINE, and the Cochrane Library were searched from inception to February 2023. Randomized controlled trials (RCTs) which evaluate the efficacy of HA, PRP, local anaesthetic, steroid, steroid+anaesthetic, HA+PRP, and physiological saline injection as a placebo, for patients with hip OA were included. Results. In this meta-analysis of 16 RCTs with a total of 1,735 participants, steroid injection was found to be significantly more effective than placebo injection on reported pain at three months, but no significant difference was observed at six months. Furthermore, steroid injection was considerably more effective than placebo injection for functional outcomes at three months, while the combination of HA+PRP injection was substantially more effective at six months. Conclusion. Evidence suggests that steroid injection is more effective than saline injection for the treatment of hip joint pain, and restoration of functional outcomes. Cite this article: Bone Joint J 2024;106-B(6):532–539

Aims. In this investigation, we administered oxidative stress to nucleus pulposus cells (NPCs), recognized DNA-damage-inducible transcript 4 (DDIT4) as a component in intervertebral disc degeneration (IVDD), and devised a hydrogel capable of conveying small interfering RNA (siRNA) to IVDD. Methods. An in vitro model for oxidative stress-induced injury in NPCs was developed to elucidate the mechanisms underlying the upregulation of DDIT4 expression, activation of the reactive oxygen species (ROS)-thioredoxin-interacting protein (TXNIP)-NLRP3 signalling pathway, and nucleus pulposus pyroptosis. Furthermore, the mechanism of action of small interfering DDIT4 (siDDIT4) on NPCs in vitro was validated. A triplex hydrogel named siDDIT4@G5-P-HA was created by adsorbing siDDIT4 onto fifth-generation polyamidoamine (PAMAM) dendrimer using van der Waals interactions, and then coating it with hyaluronic acid (HA). In addition, we established a rat puncture IVDD model to decipher the hydrogel’s mechanism in IVDD. Results. A correlation between DDIT4 expression levels and disc degeneration was shown with human nucleus pulposus and needle-punctured rat disc specimens. We confirmed that DDIT4 was responsible for activating the ROS-TXNIP-NLRP3 axis during oxidative stress-induced pyroptosis in rat nucleus pulposus in vitro. Mitochondria were damaged during oxidative stress, and DDIT4 contributed to mitochondrial damage and ROS production. In addition, siDDIT4@G5-P-HA hydrogels showed good delivery activity of siDDIT4 to NPCs. In vitro studies illustrated the potential of the siDDIT4@G5-P-HA hydrogel for alleviating IVDD in rats. Conclusion. DDIT4 is a key player in mediating pyroptosis and IVDD in NPCs through the ROS-TXNIP-NLRP3 axis. Additionally, siDDIT4@G5-P-HA hydrogel has been found to relieve IVDD in rats. Our research offers an innovative treatment option for IVDD. Cite this article: Bone Joint Res 2024;13(5):247–260

Aims

To assess the alterations in cell-specific DNA methylation associated with chondroitin sulphate response using peripheral blood collected from Kashin-Beck disease (KBD) patients before initiation of chondroitin sulphate treatment.

Aims. Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA). Methods. Mesenchymal stem/stromal cells (MSCs) were isolated from rat bone marrow (BM) and used to evaluate the impact of 29-mer on chondrogenic differentiation of BM-MSCs in culture. Knee OA was induced in rats by a single intra-articular injection of monosodium iodoacetate (MIA) in the right knees (set to day 0). The 29-mer dissolved in 5% hyaluronic acid (HA) was intra-articularly injected into right knees at day 8 and 12 after MIA injection. Subsequently, the therapeutic effect of the 29-mer/HA on OA was evaluated by the Osteoarthritis Research Society International (OARSI) histopathological scoring system and changes in hind paw weight distribution, respectively. The regeneration of chondrocytes in damaged AC was detected by dual-immunostaining of 5-bromo-2'-deoxyuridine (BrdU) and chondrogenic markers. Results. The 29-mer promoted expansion and chondrogenic differentiation of BM-MSCs cultured in different defined media. MIA injection caused chondrocyte death throughout the AC, with cartilage degeneration thereafter. The 29-mer/HA treatment induced extensive chondrocyte regeneration in the damaged AC and suppressed MIA-induced synovitis, accompanied by the recovery of cartilage matrix. Pharmacological inhibitors of PEDF receptor (PEDFR) and signal transducer and activator of transcription 3 (STAT3) signalling substantially blocked the chondrogenic promoting activity of 29-mer on the cultured BM-MSCs and injured AC. Conclusion. The 29-mer/HA formulation effectively induces chondrocyte regeneration and formation of cartilage matrix in the damaged AC. Cite this article: Bone Joint Res 2024;13(4):137–148

The fixation of articular fractures, with many small osteochondral fragments, is a challenging unmet need where a bone adhesive would be a useful adjunct to standard treatments. Whilst there are no such adhesives in current clinical use, preclinical animal models have demonstrated good healing of bone in unloaded models using an adhesive based on phosphoserine modified calcium phosphate cement (PM-CPC). An ex-vivo human bone core model has shown that this adhesive bonds freshly harvested human bone. To confirm this adhesive is capable of supporting loaded osteochondral fragments a porcine model has been developed initially ex-vivo on the path to an in-vivo study. In this model bone cores, harvested from the medial knee condyle, are glued in place with the adhesive. In-vivo adjacent pairs of bone cores would be replaced with adhesive and a control with conventional pin fixation respectively. As osteochondral bone fragments have both bone and cartilage components, this suggested a dual adhesive strategy in which components designed for each tissue type are used. This concept has been explored in an ex-vivo porcine pilot study presented herewith. At the subchondral bone level, the PM-CPC was used. At the cartilage level, a second adhesive, a methacrylated phosphoserine containing hyaluronic acid (MePHa) hydrogel designed specifically for soft tissues was applied. This is a challenging model as both adhesives have to be used simultaneously in a wet field. The pilot showed that once the subchondral component is glued in place, the PM-CPC adhesive intruding into the cartilage gap can be removed before applying the cartilage adhesive. This enabled the MePHa adhesive to be injected between the cut cartilage edges and subsequently light-cured. This two-stage gluing method is demanding and an in-vivo pilot is necessary to perfect and prove the operative technique. Acknowledgements: The human bone core project was partially financed by Innovation Fund of Västra Götaland Region, Sweden. The MePHa hydrogel work was supported by a Swiss National Fund grant # CR23I3_159301

Articulating cartilage experiences a multitude of biophysical cues. Due to its primary function in distributing load with near frictionless articulation, it is clear that a major stimulus for cartilage homeostasis and regeneration is the mechanical load it experiences on a daily basis. While these effects are considered when performing in vivo studies, in vitro studies are still largely performed under static conditions. Therefore, an increasing complexity of in vitro culture models is required, with the ultimate aim to recreate the articulating joint as accurately as possible. We have for many years utilized a complex multiaxial load bioreactor capable of applying tightly regulated compression and shear loading protocols. Using this bioreactor, we have been able to demonstrate the mechanical induction of human bone marrow stromal cell (BMSC) chondrogenesis in the absence of exogenous growth factors. Building on previous bioreactor studies that demonstrated the mechanical activation of endogenous TGFβ, and subsequent chondrogenesis of human bone marrow derived MSCs, we have been further increasing the complexity of in vitro models. For example, the addition of high molecular weight hyaluronic acid, a component of synovial fluid, culture medium leads to reduced hypertrophy and increased glycosaminoglycan deposition. The ultimate aim of all of these endeavors is to identify promising materials and therapies during in vitro/ ex vivo studies, therefore reducing the numbers or candidates that are finally tested using in vivo studies. This 3R approach can improve the opportunities for success while leading to more ethically acceptable product development pathways

Biomaterials with mechanical or biological competence are ubiquitous in musculoskeletal disorders, and understanding the inflammatory response they trigger is key to guide tissue regeneration. While macrophage role has been widely investigated, immune response is regulated by other immune cells, including neutrophils, the most abundant leukocyte in human blood. As first responders to injury, infection or material implantation, neutrophils recruit other immune cells, and therefore influence the onset and resolution of chronic inflammation, and macrophage polarization. This response depends on the physical and chemical properties of the biomaterials, among other factors. In this study we report an in vitro culture model to describe the most important neutrophil functions in relation to tissue repair. We identified neutrophil survival and death, neutrophils extracellular trap formation, release of reactive oxygen species and degranulation with cytokines release as key functions and introduced a corresponding array of assays. These tests were suitable to identify clear differences in the response by neutrophils that were cultured on material of different origin, stiffness and chemical composition. Overall, substrates from biopolymers of natural origin resulted in increased survival, less neutrophil extracellular trap formation, and more reactive oxygen species production than synthetic polymers. Within the range of mechanical properties explored (storage modulus below 5 k Pa), storage modulus of covalently crosslinked hyaluronic acid hydrogels did not significantly alter neutrophils response, whereas polyvinyl alcohol gels of matching mechanical properties displayed a response indicating increased activation. Additionally, we present the effect of material stiffness, charge, coating and culture conditions in the measured neutrophils response. Further studies are needed to correlate the neutrophil response to tissue healing. By deciphering how neutrophils initiate and modulate the immune response to material implantation, we aim at introducing new principles to design immunomodulatory biomaterials for musculoskeletal disorders. Acknowledgments. This work was supported by the AO Foundation, AO CMF, grant AOCMF-21-04S

Abstract. Objectives. Bone marrow aspirate concentrate (BMAC), together with fibrin glue (Tisseel, Baxter, UK) and Hyaluronic acid (HA) were used as a one-step cell therapy treating patients with ankle cartilage defects in our hospital. This therapy was proven to be safe, with patients demonstrating a significant improvement 12 months post-treatment. Enriched mesenchymal stem cells (MSCs) in BMAC are suggested inducers of cartilage regeneration, however, currently there is no point-of-care assessment for BMAC quality; especially regarding the proportion of MSCs within. This study aims to characterise the cellular component of CCR-generated BMAC using a point-of-care device, and to investigate if the total nucleated cell (TNC) count and patient age are predictive of MSC concentration. Methods. During surgery, 35ml of bone marrow aspirate (BMA) was collected from each patients’ iliac crest under anaesthesia, and BMAC was obtained via a commercial kit (Cartilage Regeneration kit, CCR, Innotec. ®. , UK). BMAC was then mixed with thrombin (B+T) for injection with HA and fibrinogen. In our study, donor-matched BMA, BMAC and B+T were obtained from consented patients (n=12, age 41 ± 16years) undergoing surgery with BMAC therapy. TNC, red blood cell (RBC) and platelet (PLT) counts were measured via a haematology analyser (ABX Micros ES 60, Horiba, UK), and the proportion of MSCs in BMA, BMAC and B+T were assessed via colony forming unit-fibroblast (CFU-F) assays. Significant differences data in matched donors were tested using Friedman test. All data were shown as mean ± SD. Results. Mean TNC counts in BMA and BMAC were not significantly different (14.0 ± 4.4 million/ml and 19.4 ± 32.9 million/ml, respectively, P>0.9999). However, TNC counts were significantly lower in B+T compared to BMAC (9.7 ± 24.5 million/ml and 19.4 ± 32.9 million/ml, respectively, P=0.0167). Similarly, PLT counts were decreased in B+T compared to BMAC (40.7 ± 30.7 million/ml and 417.5 ± 365.5 million/ml, respectively, P<0.0001), however, PLTs were significantly concentrated in BMAC compared to BMA (417.5 ± 365.5 million/ml and 114.8 ± 61.6 million/ml, respectively, P=0.0429). RBC counts were significantly decreased in BMAC and B+T compared to BMA (P=0.0322 and P<0.0001, respectively). Higher concentration of MSCs were observed in BMAC compared to BMA (0.006% ± 0.01% and 0.00007% ± 0.0001%, respectively, P=0.0176). Similar to TNCs and PLTs, the proportion of MSCs significantly decreased in B+T compared to BMAC (0.0004% ± 0.001% and 0.006% ± 0.01%, respectively, P=0.0023). Furthermore, patient age and TNC counts did not correlate with MSC concentration (Spearman's Rank test, P=0.3266 and P=0.4880, respectively). Conclusions. BMAC successfully concentrated PLTs, but BMAC preparations were highly variable. Mixing BMAC and thrombin however, as described in the CCR protocol, resulted in a dramatic reduction in TNCs, PLTs and MSCs. TNC counts and patient age could not be used to predict the MSC proportion in the BMAC based on current data. Future work aims to look at the biomolecule profile of BMAC plasma, and to correlate them to patient clinical outcomes. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Abstract. Objectives. Osteoarthritis (OA) is a complex joint disorder characterised by the loss of extracellular matrix (ECM) leading to cartilage degeneration. Changes to cartilage cell (chondrocyte) behaviour occur including cell swelling, the development of fine cytoplasmic processes and cell clustering leading to changes in cell phenotype and development of focal areas of mechanically-weak fibrocartilaginous matrix. [1]. To study the sequence of events in more detail, we have investigated the changes to in situ chondrocytes within human cartilage which has been lightly scraped and then cultured with serum. Methods. Human femoral heads were obtained with Ethical permission and consent from four female patients (mean age 74 yrs) undergoing hip arthroplasty following femoral neck fracture. Osteochondral explants of macroscopically-normal cartilage were cultured as a non-scraped control, or scraped gently six times with a scalpel blade and both maintained in culture for up to 2wks in Dulbecco's Modified Eagle's Medium (DMEM) with 25% human serum (HS). Explants were then labelled with CMFDA (5-chloromethylfluorescein-diacetate) and PI (propidium iodide) (10μM each) to identify the morphology of living or dead chondrocytes respectively. Explants were imaged using confocal microscopy and in situ chondrocyte morphology, volume and clustering assessed quantitatively within standardised regions of interest (ROI) using Imaris. ®. imaging software. Results. Within 2wks of culture with HS, chondrocyte volume increased significantly from 412±9.3µm. 3. (unscraped) at day 0 to 724±16.6 µm. 3. (scraped) [N(n) = 4(380)] (P=0.0002). Chondrocyte clustering was a prominent feature of HS culture as the percentage of clusters in the cell population increased with scraping from 4.8±1.4% to 14.9±3.9% [N(n) = 4(999)] at week 2 (P=0.0116). In addition, the % of the chondrocyte population within clusters increased from approximately 38% to 60%, and the number of cells per cluster increased significantly from 3.2±0.08 to 4±0.22 (P=0.031). The development of abnormal ‘fibroblastic-like’ chondrocyte morphology demonstrating long (>5µm) cytoplasmic processes also occurred, however the time course of this was more variable. For some samples, clustering occurred before abnormal morphology, but for others the opposite occurred. Typically, by the second week, 17±2.64% of the cell population had processes and this increased to 22±4.02% [N(n) = 4(759)] with scraping. Conclusions. Scraping the cartilage will remove surface constituents including lubricants (e.g. lubricin, hyaluronic acid, phospholipids), extracellular matrix constituents (collagen, proteoglycans – potentially the ‘lamina splendens’) and cells (chondrocytes and mesenchymal stromal cells (MSCs)). Although we do not know which of these component(s) is important, the effect is to dramatically increase the permeation of serum factors into the cartilage matrix and signal the development of cytoplasmic processes, cell clustering and swelling. It is notable that these cellular changes are similar to those occurring in early OA. [1]. This raises the interesting possibility that scraped cartilage cultured with human serum recapitulates some of the changes to in situ chondrocytes during early stages of cartilage degeneration and as such, could be a useful model for following the deleterious changes to matrix metabolism. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

The October 2023 Sports Roundup³⁶⁰ looks at: Extensor mechanism disruption in the treatment of dislocated and multiligament knee injuries; Treatment of knee osteoarthritis with injection of stem cells; Corticosteroid injection plus exercise or exercise alone as adjuvants for patients with plantar fasciitis?; Generalized joint hypermobility and a second ACL injury?; The VISA-A ((sedentary) questionnaire for Achilles tendinopathy?.

Abstract. Introduction. The effectiveness of single intra-articular injections of polyacrylamide hydrogel (iPAAG) and hyaluronic acid (HA) was compared in subgroups of participants from an RCT based on baseline age, BMI or Kellgren-Lawrence (KL) grade. Methodology. 239 participants were randomised to 6 mL iPAAG (Arthrosamid; n=119) or 6 mL HA (Synvisc-One; n=120). Participants continued analgesics (except 48 hours prior to visits) and non-pharmacological therapy. Topical therapies and intra-articular corticosteroids were not allowed. Pre-specified subgroup analyses (age: <70 years, ≥70 years; BMI: normal, overweight, obese; KL grade: 2, 3, 4, 2–3) of change from baseline in WOMAC pain subscale at 52 weeks were based on the least squares means for the treatment-by-week interaction effect using a mixed model for repeated measurement with a restricted maximum likelihood-based approach. Results. Across all patients, change from baseline in WOMAC pain subscale in the iPAAG group was non-inferior to HA at 26 weeks and approached superiority (p=0.0572) at 52 weeks. Treatment differences for change from baseline in WOMAC pain subscale in favour of iPAAG over HA were statistically significant for the age <70 years (p=0.019), BMI normal (p=0.011) and KL grade 2–3 (p=0.033) subgroups. Treatment differences for all other subgroups favoured iPAAG, except for KL grade 4 which favoured HA, without reaching statistical significance. Conclusion. iPAAG approached superiority to HA across all participants at 52weeks, but demonstrated statistical superiority in participants with normal BMI, participants <70 years old or participants with KL score 2–3. iPAAG represents a useful alternative to HA for the treatment of knee OA

The August 2023 Foot & Ankle Roundup. 360. looks at: Achilles tendon rupture: surgery or conservative treatment for the high-demand patient?; First ray amputation in diabetic patients; Survival of ankle arthroplasty in the UK; First metatarsophalangeal joint fusion and flat foot correction; Intra-articular corticosteroid injections with or without hyaluronic acid in the management of subtalar osteoarthritis; Factors associated with nonunion of post-traumatic subtalar arthrodesis; The Mayo Prosthetic Joint Infection Risk Score for total ankle arthroplasty

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by progressive cartilage degradation, synovial membrane inflammation, osteophyte formation, and subchondral bone sclerosis. Pathological changes in cartilage and subchondral bone are the main processes in OA. In recent decades, many studies have demonstrated that activin-like kinase 3 (ALK3), a bone morphogenetic protein receptor, is essential for cartilage formation, osteogenesis, and postnatal skeletal development. Although the role of bone morphogenetic protein (BMP) signalling in articular cartilage and bone has been extensively studied, many new discoveries have been made in recent years around ALK3 targets in articular cartilage, subchondral bone, and the interaction between the two, broadening the original knowledge of the relationship between ALK3 and OA. In this review, we focus on the roles of ALK3 in OA, including cartilage and subchondral bone and related cells. It may be helpful to seek more efficient drugs or treatments for OA based on ALK3 signalling in future.

Traumatic acute or chronic tendon injuries are a wide clinical problem in modern society, resulting in important economic burden to the health system and poor quality of life in patients. Due to the low cellularity and vascularity of tendon tissue the repair process is slow and inefficient, resulting in mechanically, structurally, and functionally inferior tissue. Tissue engineering and regenerative medicine are promising alternatives to the natural healing process for tendon repair, especially in the reconstruction of large damaged tissues. The aim of TRITONE project is to develop a smart, bioactive implantable 3D printed scaffold, able to reproduce the structural and functional properties of human tendon, using FDA approved materials and starting from MSC and their precursor, MPC cell mixtures from human donors. Total cohort selected in the last 12 months was divided in group 1 (N=20) of subjects with tendon injury and group 2 (N=20) of healthy subject. Groups were profiled and age and gender matched. Inclusion criteria were age>18 years and presence of informed consent. Ongoing pregnancy, antihypertensive treatment, cardiovascular diseases, ongoing treatment with anti-aggregants, acetylsalicylic-acid or lithium and age<18 years were exclusion criteria. Firstly, we defined clinical, biological, nutritional life style and genetic profile of the cohort. The deficiency of certain nutrients and sex hormonal differences were correlated with tendon-injured patients. It was established the optimal amount of MPC/MSC human cell (collected from different patients during femoral neck osteotomy). Finally, most suitable biomaterials for tendon regeneration and polymer tendon-like structure were identified. Hyaluronic acid, chemical surface and soft-molecular imprinting (SOFT-MI) was used to functionalize the scaffold. These preliminary results are promising. It will be necessary to enroll many more patients to identify genetic status connected with the onset of tendinopathy. The functional and structural characterization of smart bioactive tendon in dynamic environment will represent the next project step

The extracellular matrix (ECM)-based biomaterials provide a platform to mimic the disc microenvironment in facilitating stem cell transplantation for tissue regeneration. However, little is known about in vitro preconditioning human umbilical cord Wharton Jelly-derived mesenchymal stem cells (MSCs) on 3D hyaluronic acid (HA)/type II collagen (COLII) hydrogel for nucleus pulposus (NP) phenotype and pain modulation. We developed a tuneable 3D HA/COLII by fabricating HA/COLII hydrogel at 2 mg/ml COLII and various weight ratios of HA:COLII, 1:9 and 4.5:9. The hydrogel was characterized for degradability, stability, and swelling capacity. The viability of hWJ-MSC encapsulated on hydrogel supplemented with TGF-β3 was assessed. The implantation of HA/COLII hydrogel was done in surgically induced disc injury model of pain in the rat tail. The general health status in rats was monitored. The nociceptive behaviour in rats was performed for mechanical allodynia using von Frey test. The HA/COLII 4.5:9 hydrogel showed higher swelling capacity than weight ratio 1:9, suggesting that a higher amount of HA can absorb a large amount of water. Both HA/COLII 4.5:9 and 1:9 hydrogel formulations had a similar degradation profile, stable to the hydrolytic process. The hWJ-MSC-encapsulated on hydrogel marked higher cell viability with round morphology shape of cells in vitro. The surgically induced disc injury in the rat tail evoked mechanical allodynia, without affecting general health status in rats. The implantation of HA/COLII 1:9 hydrogel was observed to slightly alleviate injury-induced mechanical allodynia. Fine-tuning HA/COLII-based hydrogel provides the optimal swelling capacity, stability, degradability, and non-cytotoxic, mimicking the 3D NP niche in guiding hWJ-MSCs towards NP phenotype. The HA/COLII hydrogel could be employed as an advanced cell delivery system in facilitating stem cell transplantation for intervertebral disc regeneration targeting pain