Tryfonidou leads the Horizon 2020 consortium (iPSpine; 2019–2023) bringing a transdisciplinary team of 21 partners together to address the challenges and bottlenecks of iPS-based advanced therapies towards their transition to the clinic. Here, chronic back pain due to intervertebral disc degeneration is employed as a show case. The project develops the iPS-technology and designed smart biomaterials to carry, protect and instruct the iPS cells within the degenerate disc environment. This work will be presented including ongoing activities focus on translating the developed methodology and tools towards clinically relevant animal models. The consortium optimized the protocol for the differentiated iPS-notochordal-like cells (iPS-NLCs) and shortlisted two biomaterials shortlisted based on their physicochemical, cytotoxicity, biomechanical and biocompatibility testing. Both were shown to be safe and have been tested with the progenitors of iPS-NLCs. An advanced platform (e.g., the dynamic loading bioreactor for disc tissue) was used to evaluate their performance: the biomaterials supported the iPS-NLC progenitors after injection into the degenerate disc and seem to also support their maturation towards NLCs. Furthermore, we confirmed the capacity of these cells to survive inside degenerated discs at 30 days upon injection in sheep, whereafter we continued with their evaluation at 3 months post-injection. We achieved full evaluation of the sheep spines, including biomechanical analysis using the portable spine biomechanics tester prior analysis at the macro- and microscopic, and biochemical level

Introduction. Patients (2.7M in EU) with positive cancer prognosis frequently develop metastases (≈1M) in their remaining lifetime. In 30-70% cases, metastases affect the spine, reducing the strength of the affected vertebrae. Fractures occur in ≈30% patients. Clinicians must choose between leaving the patient exposed to a high fracture risk (with dramatic consequences) and operating to stabilise the spine (exposing patients to unnecessary surgeries). Currently, surgeons rely on their sole experience. This often results in to under- or over-treatment. The standard-of-care are scoring systems (e.g. Spine Instability Neoplastic Score) based on medical images, with little consideration of the spine biomechanics, and of the structure of the vertebrae involved. Such scoring systems fail to provide clear indications in ≈60% patients. Method. The HEU-funded METASTRA project is implemented by biomechanicians, modellers, clinicians, experts in verification, validation, uncertainty quantification and certification from 15 partners across Europe. METASTRA aims to improve the stratification of patients with vertebral metastases evaluating their risk of fracture by developing dedicated reliable computational models based on Explainable Artificial Intelligence (AI) and on personalised Physiology-based biomechanical (VPH) models. Result. The METASTRA-AI model is expected to be able to stratify most patients with limited effort end cost, based on parameters extracted semi-automatically from the medical files and images. The cases which are not reliably stratified through the AI model, are examined through a more detailed and personalised biomechanical VPH model. These METASTRA numerical tools are trained through an unprecedentedly large multicentric retrospective study (2000 cases) and validated against biomechanical ex vivo experiments (120 specimens). Conclusion. The METASTRA decision support system is tested in a multicentric prospective observational study (200 patients). The METASTRA approach is expected to cut down the indeterminate diagnoses from the current 60% down to 20% of cases. METASTRA project funded by the European Union, HEU topic HLTH-2022-12-01, grant 101080135

Osteoarthritis (OA) is a painful and disabling chronic condition that constitutes a major challenge to health care worldwide. There is currently no cure for OA and the analgesic pharmaceuticals available do not offer adequate and sustained pain relief, often being associated with significant undesirable side effects. Another disease associated with degenerating joints is Intervertebral disc degeneration (IVDD) which is a leading cause of chronic back pain and loss of function. It is characterized by the loss of extracellular matrix, specifically proteoglycan and collagen, tissue dehydration, fissure development and loss of disc height, inflammation, endplate sclerosis, cell death and hyperinnervation of nociceptive nerve fibers. The adult human IVD seems incapable of intrinsic repair and there are currently no proven treatments to prevent, stop or even retard disc degeneration. Fusion is currently the most common surgical treatment of symptomatic disc disease. However, radiographic follow-up studies have revealed that many patients develop adjacent segment disc degeneration due to altered spine biomechanics. The development of safe and efficacious disease modifying OA drugs (DMOADs) that treat pain and inflammation in joints will improve our ability to control the disease. I addition, a biologic treatment of IVDD is desirable. This presentation will provide an overview of recent advances and future prospects of a multimodal biologic treatment of OA, and IVDD. We will focus on Link N, a naturally occurring peptide representing the N terminal region of link protein and the first 1–8 residues of Link N (short Link N, sLN) responsible for the biologic therapy in question

Introduction. Functional Spine Units (FSUs) play a vital role in understanding biomechanical characteristics of the spine, particularly bone fracture risk assessment. While established models focus on simulating axial compression of individual bones to assess fracture load, recent models underscore the importance of understanding fracture load within FSUs, offering a better representation of physiological conditions. Despite the limited number of FSU fracture studies, they predominantly rely on a linear material model with an annulus fibrosus Young's modulus set at 500 MPa, significantly higher than stiffness values (ca. 4 MPa) utilized in other FSU and spine section biomechanical models. Thus, this study aims to study the effect of varying annulus fibrosus stiffness on FSU fracture load, aiming to identify physiologically relevant biomechanical parameters. Method. Subject-specific geometry and material properties of bones were derived from computed tomography (CT) image data of five human cadaveric FSU specimens. The annulus fibrosus and nucleus pulposus were manually recreated and assigned linear elastic material properties. By subjecting the model to axial compression, the fracture load of the FSU was deduced from the peak of the force-displacement graph. To explore the effect of stiffness of the annulus fibrosus on simulated fracture load, we conducted a parameter study, varying stiffness values from the high 500 MPa to a more physiologically relevant 25 MPa, aiming to approximate values applied in FSU kinematic models while achieving bone fracture. Result. Significant reductions in fracture load were observed, ranging from 23% to 46%, as annulus stiffness decreased from 500MPa to 25MPa. Additionally, a discernible, gradual decline in fracture load was observed with a decrease in stiffness values. Conclusion. The stiffness of the annulus fibrosus significantly influences the simulated fracture load of an FSU. Future investigations should prioritize biomechanically accurate modeling of the intervertebral disc, ensuring alignment with experimental findings regarding FSU fracture load while maintaining biomechanical fidelity

The use of lumbar fusion procedures in the USA and Europe has rapidly increased over the last decade and a large number of these procedures involve the use of bone grafts. Despite of technical progress of spinal surgery and operative materials the risk of vertebral fusion failure occurs in 5 – 35 % of cases. Autografting has been considered the gold standard for bone graft procedures. However, the harvesting from the iliac crest can be associated with short and long-term morbidity in up to 22 % of cases. Main goal of this experimental study was to compare newly developed hybrid biodegradable nanocomposit porous implant (HBNPI) against bone craft from iliac crest as a new and better alternative for lumbar interbody fusion. 24 male pigs 4 months old weighting around 40 Kg were included in our study. These pigs were divided into two study groups depending on fusion method. Group A – 12 pigs underwent lateral lumbal interbody fusion (L2/3) with implantation of iliac crest bonegraft. Group B - 12 pigs underwent lateral lumbal interbody fusion (L2/3) with newly developed HBNPI. Each group were divided into two subgroups from these 6 spines were harvested 8 weeks (subgroup A1, B1) and 6 spines 16 weeks (group A2, B2) after surgery. After sacrifice, the lumbar spines were taking out and micro-CT, biomechanical testing and histomorphological analysis in all groups were performed to evaluate a quality of intervertebral fusion. As controls (group N), 6 cadaveric intact lumbar spines underwent biomechanical, micro-CT and histological testing. All 24 animals recovered from general anesthesia without unusual events. The operations lasted between 50–90 minutes (mean 70) in Group A and between 35–72 minutes (mean 43) in Group B. All of the pigs from group A could stand up and were mobile within 20 hours (range 7–20). When bone graft harvesting was not necessary (group B) this time was shortened, ranging from 1 – 1,5 hour. All pigs from Group A were limping on the first postoperative day. No limping animal was observed in group B. Total body weight of the pigs increased from 37 kg (range 36–40) at the start to 85 (range 80–89) at sacrifice. Biomechanics evaluation shows that extension flexural stiffness values are statistically significantly different between A2 (16 weeks post-implant) and A1 (8 weeks post-implant). Group A2 achieves higher values than Group A1, which is attributed to the adhesion of the implant to the surrounding vertebrae. Similarly, this also applies to groups B2 and B1. The flexural stiffness at group B2 extension is statistically significantly higher than the A2 group and also than the native N group. Biomechanical evaluation supports findings on micro-CT and histological specimens, where both adjacent vertebrae are completely fused in groups B2, unlike in group A2, where there is no or incomplete fusion. Newly developed HBNPI represents new possibility how to do intervertebral fusion, and simultaneous become chance how to improve and accelerate bone healing process against standard procedures

The causes of spine disease are often biomechanical ones (e.g. disc degeneration, vertebral fracture). Currently, a deep investigation of the spine biomechanics is missing, due to the high complexity of the spine system (Fung 1980, Brandolini, Cristofolini et al. 2014): vertebrae and intervertebral discs. Recently, the Digital Image Correlation allowed measuring in vitrothe displacement and strain on the surface of soft and hard tissues, upon a specific non-invasive preparation of their surface with a speckle pattern (Palanca, Tozzi et al. 2016). The aim of this explorative work was to evaluate the deformation on spine segments, being able to distinguish between hard and soft tissue in the elastic regime and up to fracture. Segment of four vertebrae were extracted from porcine spines. All ligaments and muscles were removed, without damaging the spine segment (vertebrae and intervertebral discs). A suitable non-conventional white-on-black speckle pattern was prepared on the surface with airbrush airgun to track the movements of the specimen with DIC (Lionello, Sirieix et al. 2014). The endplates of the extreme vertebrae were potted in poly-methyl-methacrylate. The spine segments were tested in pure axial loading with cycles of increasing magnitude, up to fialure. A commercial 3D-DIC (Dantec Dynamics, Denmark) was used. In the present configuration, it allowed a resolution of 30 micrometers. It was used to measure the displacements and strains in a full-field and contactless way on the frontal surface of the spine segments. DIC allowed measuring with success the displacement and strain during the entire test, in the elastic regime and up to failure. The displacements and strains could be measured on the entire specimen, both in the vertebrae (hard tissue) and in the intervertebral discs (soft tissue). The axial strain evaluated prior to failure was close to 10’000 microstrain on the vertebral body surface and exceed 70’000 microstrain on the intervertebral discs, where failure was localized. The pattern, prepared in a dedicated way showed its suitability for both the bone and the disc. The evaluated failure strains were in agreement with the literature (Bayraktar, Morgan et al. 2004) (Spera, Genovese et al. 2011). To the authors' best knowledge, this kind of measurement including strain on soft and hard tissue simultaneously has never been performed before. This work showed the capability of DIC in providing full-field measures on the surface with complex geometry, such as the spine. The assertion of these potentialities could open the way to further application of DIC to study the behaviour of human spines, including improvement of spinal fixation devices