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1.
Sci Rep ; 14(1): 11991, 2024 05 25.
Article in English | MEDLINE | ID: mdl-38796487

ABSTRACT

Physiochemical tissue inducers and mechanical stimulation are both efficient variables in cartilage tissue fabrication and regeneration. In the presence of biomolecules, decellularized extracellular matrix (ECM) may trigger and enhance stem cell proliferation and differentiation. Here, we investigated the controlled release of transforming growth factor beta (TGF-ß1) as an active mediator of mesenchymal stromal cells (MSCs) in a biocompatible scaffold and mechanical stimulation for cartilage tissue engineering. ECM-derived hydrogel with TGF-ß1-loaded alginate-based microspheres (MSs) was created to promote human MSC chondrogenic development. Ex vivo explants and a complicated multiaxial loading bioreactor replicated the physiological conditions. Hydrogels with/without MSs and TGF-ß1 were highly cytocompatible. MSCs in ECM-derived hydrogel containing TGF-ß1/MSs showed comparable chondrogenic gene expression levels as those hydrogels with TGF-ß1 added in culture media or those without TGF-ß1. However, constructs with TGF-ß1 directly added within the hydrogel had inferior properties under unloaded conditions. The ECM-derived hydrogel group including TGF-ß1/MSs under loading circumstances formed better cartilage matrix in an ex vivo osteochondral defect than control settings. This study demonstrates that controlled local delivery of TGF-ß1 using MSs and mechanical loading is essential for neocartilage formation by MSCs and that further optimization is needed to prevent MSC differentiation towards hypertrophy.


Subject(s)
Alginates , Bioreactors , Chondrogenesis , Hydrogels , Mesenchymal Stem Cells , Microspheres , Tissue Engineering , Alginates/chemistry , Tissue Engineering/methods , Humans , Hydrogels/chemistry , Mesenchymal Stem Cells/metabolism , Mesenchymal Stem Cells/cytology , Animals , Cartilage/metabolism , Cartilage/cytology , Tissue Scaffolds/chemistry , Decellularized Extracellular Matrix/chemistry , Transforming Growth Factor beta1/metabolism , Cell Differentiation , Cells, Cultured , Transforming Growth Factor beta/metabolism , Extracellular Matrix/metabolism
2.
Global Spine J ; 14(2_suppl): 14S-23S, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38421327

ABSTRACT

STUDY DESIGN: Methodological study for guideline development. OBJECTIVE: AO Spine Guideline for Using Osteobiologics (AO-GO) project for spine degenerative pathologies was an international, multidisciplinary collaborative initiative to identify and evaluate evidence on existing use of osteobiologics in Anterior Cervical Fusion and Decompression (ACDF). The aim was to formulate precisely defined, clinically relevant and internationally applicable guidelines ensuring evidence-based, safe and effective use of osteobiologics, considering regional preferences and cost-effectiveness. METHODS: Guideline was completed in two phases: Phase 1- evidence synthesis; Phase 2- recommendation development based on the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. In Phase 1, key questions identified by a panel of experts were addressed in a series of systematic reviews of randomized and non-randomized studies. In Phase 2, the GRADE approach was used to formulate a series of recommendations, including expert panel discussions via web calls and face-to-face meetings. DISCUSSION: AO-GO aims to bridge an important gap between evidence and use of osteobiologics in spine fusion surgeries. Owing to differences in osteobiologics preparation and functional characteristics, regulatory requirements for approval may vary, therefore it is highly likely that these products enter market without quality clinical trials. With a holistic approach the guideline aims to facilitate evidence-based, patient-oriented decision-making processes in clinical practice, thus stimulating further evidence-based studies regarding osteobiologics usage in spine surgeries. In Phase 3, the guideline will be disseminated and validated using prospectively collected clinical data in a separate effort of the AO Spine Knowledge Forum Degenerative in a global multicenter clinical study.

3.
Adv Sci (Weinh) ; 11(11): e2308478, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38113315

ABSTRACT

Discogenic pain is associated with deep nerve ingrowth in annulus fibrosus tissue (AF) of intervertebral disc (IVD). To model AF nerve ingrowth, primary bovine dorsal root ganglion (DRG) micro-scale tissue units are spatially organised around an AF explant by mild hydrodynamic forces within a collagen matrix. This results in a densely packed multicellular system mimicking the native DRG tissue morphology and a controlled AF-neuron distance. Such a multicellular organisation is essential to evolve populational-level cellular functions and in vivo-like morphologies. Pro-inflammatory cytokine-primed AF demonstrates its neurotrophic and neurotropic effects on nociceptor axons. Both effects are dependent on the AF-neuron distance underpinning the role of recapitulating inter-tissue/organ anatomical proximity when investigating their crosstalk. This is the first in vitro model studying AF nerve ingrowth by engineering mature and large animal tissues in a morphologically and physiologically relevant environment. The new approach can be used to biofabricate multi-tissue/organ models for untangling pathophysiological conditions and develop novel therapies.


Subject(s)
Intervertebral Disc Degeneration , Intervertebral Disc , Animals , Cattle , Collagen , Neurons , Ganglia, Spinal
4.
Materials (Basel) ; 16(22)2023 Nov 17.
Article in English | MEDLINE | ID: mdl-38005143

ABSTRACT

Osteochondral (OC) disorders such as osteoarthritis (OA) damage joint cartilage and subchondral bone tissue. To understand the disease, facilitate drug screening, and advance therapeutic development, in vitro models of OC tissue are essential. This study aims to create a bioprinted OC miniature construct that replicates the cartilage and bone compartments. For this purpose, two hydrogels were selected: one composed of gelatin methacrylate (GelMA) blended with nanosized hydroxyapatite (nHAp) and the other consisting of tyramine-modified hyaluronic acid (THA) to mimic bone and cartilage tissue, respectively. We characterized these hydrogels using rheological testing and assessed their cytotoxicity with live-dead assays. Subsequently, human osteoblasts (hOBs) were encapsulated in GelMA-nHAp, while micropellet chondrocytes were incorporated into THA hydrogels for bioprinting the osteochondral construct. After one week of culture, successful OC tissue generation was confirmed through RT-PCR and histology. Notably, GelMA/nHAp hydrogels exhibited a significantly higher storage modulus (G') compared to GelMA alone. Rheological temperature sweeps and printing tests determined an optimal printing temperature of 20 °C, which remained unaffected by the addition of nHAp. Cell encapsulation did not alter the storage modulus, as demonstrated by amplitude sweep tests, in either GelMA/nHAp or THA hydrogels. Cell viability assays using Ca-AM and EthD-1 staining revealed high cell viability in both GelMA/nHAp and THA hydrogels. Furthermore, RT-PCR and histological analysis confirmed the maintenance of osteogenic and chondrogenic properties in GelMA/nHAp and THA hydrogels, respectively. In conclusion, we have developed GelMA-nHAp and THA hydrogels to simulate bone and cartilage components, optimized 3D printing parameters, and ensured cell viability for bioprinting OC constructs.

5.
JOR Spine ; 6(3): e1288, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37780818
6.
JOR Spine ; 6(3): e1267, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37780827

ABSTRACT

Introduction: Mechanical overloading can trigger a degenerative-like cascade in an organ culture of intervertebral disc (IVD). Whether the overloaded IVD can influence the activation of nociceptors (i.e., the damage sensing neurons) remains unknown. The study aims to investigate the influence of overloaded IVD conditioned medium (CM) on the activation of nociceptors. Methods: In the static loading regime, force-controlled loading of 0.2 MPa for 20 h/day representing "long-term sitting and standing" was compared with a displacement-controlled loading maintaining original IVD height. In the dynamic loading regime, high-frequency-intensity loading representing degenerative "wear and tear" was compared with a lower-frequency-intensity loading. CM of differently loaded IVDs were collected to stimulate the primary bovine dorsal root ganglion (DRG) cultures. Calcium imaging (Fluo-4) and calcitonin gene-related peptide (CGRP) immunofluorescent labeling were jointly used to record the calcium flickering in CGRP(+) nociceptors. Results: Force-controlled loading led to a higher IVD cell death compared to displacement-controlled loading. Both static and dynamic overloading (force-controlled and high-frequency-intensity loadings) elevated the frequency of calcium flickering in the subsurface space of CGRP(+) nociceptors compared to their mild loading counterparts. Conclusion: In the organ culture system, IVD overloading mediated an altered IVD-nociceptor communication suggesting a biological mechanism associated with discogenic pain.

7.
Mater Today Bio ; 22: 100775, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37674778

ABSTRACT

Herein we show an accessible technique based on Faraday waves that assist the rapid assembly of osteoinductive ß-Tricalcium phosphate (ß-TCP) particles as well as human osteoblast pre-assembled in spheroids. The hydrodynamic forces originating at 'seabed' of the assembly chamber can be used to tightly aggregate inorganic and biological entities at packing densities that resemble those of native tissues. Additionally, following a layer-by-layer assembly procedure, centimeter scaled osteoinductive three-dimensional and cellularized constructs have been fabricated. We showed that the intimate connection between biological building blocks is essential in engineering living system able of localized mineral deposition. Our results demonstrate, for the first time, the possibility to obtain three-dimensional cellularized and acellularized anisotropic constructs using Faraday waves.

8.
JOR Spine ; 6(2): e1271, 2023 Jun.
Article in English | MEDLINE | ID: mdl-37361326
9.
Eur Spine J ; 32(6): 2048-2058, 2023 06.
Article in English | MEDLINE | ID: mdl-37071156

ABSTRACT

PURPOSE: This study aims to analyze the effect of pro-inflammatory cytokine-stimulated human annulus fibrosus cells (hAFCs) on the sensitization of dorsal root ganglion (DRG) cells. We further hypothesized that celecoxib (cxb) could inhibit hAFCs-induced DRG sensitization. METHODS: hAFCs from spinal trauma patients were stimulated with TNF-α or IL-1ß. Cxb was added on day 2. On day 4, the expression of pro-inflammatory and neurotrophic genes was evaluated using RT-qPCR. Levels of prostaglandin E2 (PGE-2), IL-8, and IL-6 were measured in the conditioned medium (CM) using ELISA. hAFCs CM was then applied to stimulate the DRG cell line (ND7/23) for 6 days. Then, calcium imaging (Fluo4) was performed to evaluate DRG cell sensitization. Both spontaneous and bradykinin-stimulated (0.5 µM) calcium responses were analyzed. The effects on primary bovine DRG cell culture were performed in parallel to the DRG cell line model. RESULTS: IL-1ß stimulation significantly enhanced the release of PGE-2 in hAFCs CM, while this increase was completely suppressed by 10 µM cxb. hAFCs revealed elevated IL-6 and IL-8 release following TNF-α and IL-1ß treatment, though cxb did not alter this. The effect of hAFCs CM on DRG cell sensitization was influenced by adding cxb to hAFCs; both the DRG cell line and primary bovine DRG nociceptors showed a lower sensitivity to bradykinin stimulation. CONCLUSION: Cxb can inhibit PGE-2 production in hAFCs in an IL-1ß-induced pro-inflammatory in vitro environment. The cxb applied to the hAFCs also reduces the sensitization of DRG nociceptors that are stimulated by the hAFCs CM.


Subject(s)
Annulus Fibrosus , Humans , Animals , Cattle , Interleukin-1beta/pharmacology , Celecoxib/pharmacology , Nociceptors , Tumor Necrosis Factor-alpha , Interleukin-6 , Bradykinin/pharmacology , Calcium/pharmacology , Interleukin-8/pharmacology , Cells, Cultured , Ganglia, Spinal
10.
JOR Spine ; 6(1): e1255, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36994460
11.
JOR Spine ; 6(1): e1230, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36994457

ABSTRACT

Animal models have been invaluable in the identification of molecular events occurring in and contributing to intervertebral disc (IVD) degeneration and important therapeutic targets have been identified. Some outstanding animal models (murine, ovine, chondrodystrophoid canine) have been identified with their own strengths and weaknesses. The llama/alpaca, horse and kangaroo have emerged as new large species for IVD studies, and only time will tell if they will surpass the utility of existing models. The complexity of IVD degeneration poses difficulties in the selection of the most appropriate molecular target of many potential candidates, to focus on in the formulation of strategies to effect disc repair and regeneration. It may well be that many therapeutic objectives should be targeted simultaneously to effect a favorable outcome in human IVD degeneration. Use of animal models in isolation will not allow resolution of this complex issue and a paradigm shift and adoption of new methodologies is required to provide the next step forward in the determination of an effective repairative strategy for the IVD. AI has improved the accuracy and assessment of spinal imaging supporting clinical diagnostics and research efforts to better understand IVD degeneration and its treatment. Implementation of AI in the evaluation of histology data has improved the usefulness of a popular murine IVD model and could also be used in an ovine histopathological grading scheme that has been used to quantify degenerative IVD changes and stem cell mediated regeneration. These models are also attractive candidates for the evaluation of novel anti-oxidant compounds that counter inflammatory conditions in degenerate IVDs and promote IVD regeneration. Some of these compounds also have pain-relieving properties. AI has facilitated development of facial recognition pain assessment in animal IVD models offering the possibility of correlating the potential pain alleviating properties of some of these compounds with IVD regeneration.

12.
JOR Spine ; 6(1): e1228, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36994461

ABSTRACT

Introduction: Cell transplantation shows promising results for intervertebral disc (IVD) repair, however, contemporary strategies present concerns regarding needle puncture damage, cell retention, and straining the limited nutrient availability. Mesenchymal stromal cell (MSC) homing is a natural mechanism of long-distance cellular migration to sites of damage and regeneration. Previous ex vivo studies have confirmed the potential of MSC to migrate over the endplate and enhance IVD-matrix production. In this study, we aimed to exploit this mechanism to engender IVD repair in a rat disc degeneration model. Methods: Female Sprague Dawley rats were subjected to coccygeal disc degeneration through nucleus pulposus (NP) aspiration. In part 1; MSC or saline was transplanted into the vertebrae neighboring healthy or degenerative IVD subjected to irradiation or left untouched, and the ability to maintain the IVD integrity for 2 and 4 weeks was assessed by disc height index (DHI) and histology. For part 2, ubiquitously GFP expressing MSC were transplanted either intradiscally or vertebrally, and regenerative outcomes were compared at days 1, 5, and 14 post-transplantation. Moreover, the homing potential from vertebrae to IVD of the GFP+ MSC was assessed through cryosection mediated immunohistochemistry. Results: Part 1 of the study revealed significantly improved maintenance of DHI for IVD vertebrally receiving MSC. Moreover, histological observations revealed a trend of IVD integrity maintenance. Part 2 of the study highlighted the enhanced DHI and matrix integrity for discs receiving MSC vertebrally compared with intradiscal injection. Moreover, GFP rates highlighted MSC migration and integration in the IVD at similar rates as the intradiscally treated cohort. Conclusion: Vertebrally transplanted MSC had a beneficial effect on the degenerative cascade in their neighboring IVD, and thus potentially present an alternative administration strategy. Further investigation will be needed to determine the long-term effects, elucidate the role of cellular homing versus paracrine signaling, and validate our observations on a large animal model.

13.
J Orthop Translat ; 38: 106-116, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36381242

ABSTRACT

Background: Osteoarthritis (OA) is the most common degenerative joint disease, mainly affecting the elderly worldwide, for which the drug treatment remains a major challenge. Low-grade inflammation plays a pivotal role in OA onset and progression. Exploration of notable anti-inflammatory and disease-modifying drugs on human samples could facilitate the evaluation of therapeutic strategies for OA. Methods: The anti-inflammatory drug 5-aminosalicylic acid (5-ASA) is a first-line drug for ulcerative colitis (UC), however no study has explored the effects of 5-ASA on articular chondrocytes. In this work, both in vitro (chondrocyte pellets) and ex vivo (osteochondral explants) human inflammatory OA models were applied to evaluate the effects of 5-ASA. Results: In the inflammatory pellet model, 5-ASA remarkably downregulated the gene expression of interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2) while upregulating proteoglycan 4 (PRG4) and cartilage oligomeric matrix protein (COMP) gene expression. Total glycosaminoglycan (GAG) synthesis by pellets was markedly increased in 5-ASA-treated groups compared with the inflammatory group. In conditioned medium, inflammatory mediators (IL-8, nitric oxide) were markedly inhibited upon 5-ASA treatment. Moreover, histological staining showed 5-ASA retained proteoglycan content and inhibited degradation of extracellular matrix (ECM) core components, aggrecan (ACAN) and collagen type II (COL2). In the inflammatory explant model, 5-ASA mitigated signs of OA development by reducing inflammatory mediators and GAG loss. Conclusions: These findings suggest that 5-ASA has anti-inflammatory and pro-anabolic effects on human chondrocyte pellet and osteochondral explant inflammatory OA models. The translational potential of this article: Disease-modifying OA drugs are an unmet clinical need for the treatment of OA. Our study explored and demonstrated the anti-inflammatory and protective effects of 5-ASA on in vitro and ex vivo human inflammatory OA models, showing its translational potential for OA treatment.

14.
Methods Mol Biol ; 2598: 115-121, 2023.
Article in English | MEDLINE | ID: mdl-36355288

ABSTRACT

The 1,9-dimethylmethylene blue (DMMB) assay enables the detection of sulfated glycosaminoglycans (sGAGs). This assay can be used to quickly quantify the sGAG content in a large number of samples using spectrophotometry. While this widespread assay appears straightforward, there are certain pitfalls that need to be considered.


Subject(s)
Glycosaminoglycans , Methylene Blue , Spectrophotometry
15.
Global Spine J ; 13(7): 1894-1908, 2023 Sep.
Article in English | MEDLINE | ID: mdl-34870488

ABSTRACT

OBJECTIVE: Resource allocation to research activities is challenging and there is limited evidence to justify decisions. Members of AO Spine were surveyed to understand the research practices and needs of spine surgeons worldwide. METHODS: An 84-item survey was distributed to the AO Spine community in September of 2020. Respondent demographics and insights regarding research registries, training and education, mentorship, grants and financial support, and future directions were collected. Responses were anonymous and compared among regions. RESULTS: A total of 333 spine surgeons representing all geographic regions responded; 52.3% were affiliated with an academic/university hospital, 91.0% conducted clinical research, and 60.9% had 5+ years of research experience. There was heterogeneity among research practices and needs across regions. North American respondents had more research experience (P = .023), began conducting research early on (P < .001), had an undergraduate science degree (P < .001), and were more likely to have access to a research coordinator or support staff (P = .042) compared to other regions. While all regions expressed having the same challenges in conducting research, Latin America, and Middle East/Northern Africa respondents were less encouraged to do research (P < .001). Despite regional differences, there was global support for research registries and research training and education. CONCLUSION: To advance spine care worldwide, spine societies should establish guidelines, conduct studies on pain management, and support predictive analytic modeling. Tailoring local/regional programs according to regional needs is advised. These results can assist spine societies in developing long-term research strategies and provide justified rationale to governments and funding agencies.

16.
Cells ; 11(21)2022 10 28.
Article in English | MEDLINE | ID: mdl-36359814

ABSTRACT

Low back pain is a clinically highly relevant musculoskeletal burden and is associated with inflammatory as well as degenerative processes of the intervertebral disc. However, the pathophysiology and cellular pathways contributing to this devastating condition are still poorly understood. Based on previous evidence, we hypothesize that tissue renin-angiotensin system (tRAS) components, including the SARS-CoV-2 entry receptor angiotensin-converting enzyme 2 (ACE2), are present in human nucleus pulposus (NP) cells and associated with inflammatory and degenerative processes. Experiments were performed with NP cells from four human donors. The existence of angiotensin II, angiotensin II type 1 receptor (AGTR1), AGTR2, MAS-receptor (MasR), and ACE2 in human NP cells was validated with immunofluorescent staining and gene expression analysis. Hereafter, the cell viability was assessed after adding agonists and antagonists of the target receptors as well as angiotensin II in different concentrations for up to 48 h of exposure. A TNF-α-induced inflammatory in vitro model was employed to assess the impact of angiotensin II addition and the stimulation or inhibition of the tRAS receptors on inflammation, tissue remodeling, expression of tRAS markers, and the release of nitric oxide (NO) into the medium. Furthermore, protein levels of IL-6, IL-8, IL-10, and intracellular as well as secreted angiotensin II were assessed after exposing the cells to the substances, and inducible nitric oxide synthase (iNOS) levels were evaluated by utilizing Western blot. The existence of tRAS receptors and angiotensin II were validated in human NP cells. The addition of angiotensin II only showed a mild impact on gene expression markers. However, there was a significant increase in NO secreted by the cells. The gene expression ratios of pro-inflammatory/anti-inflammatory cytokines IL-6/IL-10, IL-8/IL-10, and TNF-α/IL-10 were positively correlated with the AGTR1/AGTR2 and AGTR1/MAS1 ratios, respectively. The stimulation of the AGTR2 MAS-receptor and the inhibition of the AGTR1 receptor revealed beneficial effects on the gene expression of inflammatory and tissue remodeling markers. This finding was also present at the protein level. The current data showed that tRAS components are expressed in human NP cells and are associated with inflammatory and degenerative processes. Further characterization of the associated pathways is warranted. The findings indicate that tRAS modulation might be a novel therapeutic approach to intervertebral disc disease.


Subject(s)
Nucleus Pulposus , Renin-Angiotensin System , Humans , Angiotensin II/metabolism , Angiotensin-Converting Enzyme 2 , Interleukin-10/metabolism , Interleukin-6/metabolism , Interleukin-8/metabolism , Nucleus Pulposus/cytology , Nucleus Pulposus/metabolism , Receptor, Angiotensin, Type 1/metabolism , Tumor Necrosis Factor-alpha/metabolism
17.
JOR Spine ; 5(3): e1226, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36203861
18.
JOR Spine ; 5(3): e1215, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36203866

ABSTRACT

Background: During the intervertebral disc (IVD) degeneration process, initial degenerative events occur at the extracellular matrix level, with the appearance of neoepitope peptides formed by the cleavage of aggrecan and collagen. This study aims to elucidate the spatial and temporal alterations of aggrecan and collagen neoepitope level during IVD degeneration. Methods: Bovine caudal IVDs were cultured under four different conditions to mimic different degenerative situations. Samples cultured after 1- or 8-days were collected for analysis. Human IVD samples were obtained from patients diagnosed with lumbar disc herniation (LDH) or adolescent idiopathic scoliosis (AIS). After immunohistochemical (IHC) staining of Aggrecanase Cleaved C-terminus Aggrecan Neoepitope (NB100), MMP Cleaved C-terminus Aggrecan Neoepitope (MMPCC), Collagen Type 1α1 1/4 fragment (C1α1) and Collagenase Cleaved Type I and II Collagen Neoepitope (C1,2C), staining optical density (OD)/area in extracellular matrix (OECM) and pericellular zone (OPCZ) were analyzed. Conditioned media of the bovine IVD was collected to measure protein level of inflammatory cytokines and C1,2C. Results: For the bovine IVD sections, the aggrecan MMPCC neoepitope was accumulated in nucleus pulposus (NP) and cartilage endplate (EP) regions following mechanical overload in the one strike model after long-term culture; as for the TNF-α induced degeneration, the OECM and OPCZ of collagen C1,2C neoepitope was significantly increased in the outer AF region after long-term culture; moreover, the C1,2C was only detected in conditioned medium from TNF-α injection + Degenerative loading group after 8 days of culture. LDH patients showed higher MMPCC OECM in NP and higher C1,2C OECM in AF region compared with AIS patients. Conclusions: In summary, aggrecan and collagen neoepitope profiles showed degeneration induction trigger- and region-specific differences in the IVD organ culture models. Different IVD degeneration types are correlated with specific neoepitope expression profiles. These neoepitopes may be helpful as biomarkers of ECM degradation in early IVD degeneration and indicators of different degeneration phenotypes.

19.
ACS Biomater Sci Eng ; 8(9): 3969-3976, 2022 09 12.
Article in English | MEDLINE | ID: mdl-35977717

ABSTRACT

A new generation of bioreactors with integrated six degrees of freedom (6 DOF) aims to mimic more accurately the natural intervertebral disc (IVD) load. We developed and validated in a biological and mechanical study a specimen holder and corresponding ex vivo IVD organ model according to the bioreactor requirements for multiaxial loading and a long-term IVD culture. IVD height changes and cell viability were compared between the 6 DOF model and the standard 1 DOF model throughout the 3 weeks of cyclic compressive loading in the uniaxial bioreactor. Furthermore, the 6 DOF model and holder were loaded for 9 days in the multiaxial bioreactor under development using the same conditions, and the IVDs were evaluated for cell viability. The interface of the IVD model and specimen holder, enhanced with fixation screws onto the bone, was tested in compression, torsion, lateral bending, and tension. Additionally, critical motions such as tension and bending were assessed for a combination of side screws and top screws or side screws and adhesive. The 6 DOF model loaded in the uniaxial bioreactor maintained similar cell viability in the IVD regions as the 1 DOF model. The viability was high after 2 weeks throughout the whole IVD and reduced by more than 30% in the inner annulus fibrous after 3 weeks. Similarly, the IVDs remained highly viabile when cultured in the multiaxial bioreactor. In both models, IVD height changes after loading were in the range of typical physiological conditions. When differently directed motions were applied, the holder-IVD interface remained stable under hyper-physiological loading levels using a side screw approach in compression and torsion and the combination of side and top screws in tension and bending. We thus conclude that the developed holding system is mechanically reliable and biologically compatible for application in a new generation of multiaxial bioreactors.


Subject(s)
Intervertebral Disc , Bioreactors , Intervertebral Disc/physiology , Organ Culture Techniques
20.
Medicina (Kaunas) ; 58(8)2022 Jul 26.
Article in English | MEDLINE | ID: mdl-35893113

ABSTRACT

Background and Objectives: Commonly being the first step in trauma routine imaging, up to 67% fractures are missed on plain radiographs of the thoracolumbar (TL) spine. The aim of this study was to develop a deep learning model that detects traumatic fractures on sagittal radiographs of the TL spine. Identifying vertebral fractures in simple radiographic projections would have a significant clinical and financial impact, especially for low- and middle-income countries where computed tomography (CT) and magnetic resonance imaging (MRI) are not readily available and could help select patients that need second level imaging, thus improving the cost-effectiveness. Materials and Methods: Imaging studies (radiographs, CT, and/or MRI) of 151 patients were used. An expert group of three spinal surgeons reviewed all available images to confirm presence and type of fractures. In total, 630 single vertebra images were extracted from the sagittal radiographs of the 151 patients-302 exhibiting a vertebral body fracture, and 328 exhibiting no fracture. Following augmentation, these single vertebra images were used to train, validate, and comparatively test two deep learning convolutional neural network models, namely ResNet18 and VGG16. A heatmap analysis was then conducted to better understand the predictions of each model. Results: ResNet18 demonstrated a better performance, achieving higher sensitivity (91%), specificity (89%), and accuracy (88%) compared to VGG16 (90%, 83%, 86%). In 81% of the cases, the "warm zone" in the heatmaps correlated with the findings, suggestive of fracture within the vertebral body seen in the imaging studies. Vertebras T12 to L2 were the most frequently involved, accounting for 48% of the fractures. A4, A3, and A1 were the most frequent fracture types according to the AO Spine Classification. Conclusions: ResNet18 could accurately identify the traumatic vertebral fractures on the TL sagittal radiographs. In most cases, the model based its prediction on the same areas that human expert classifiers used to determine the presence of a fracture.


Subject(s)
Spinal Fractures , Thoracic Vertebrae , Artificial Intelligence , Humans , Lumbar Vertebrae/injuries , Radiography , Retrospective Studies , Spinal Fractures/diagnostic imaging , Spinal Fractures/surgery , Thoracic Vertebrae/diagnostic imaging , Thoracic Vertebrae/injuries
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