Improved Postoperative Kneeling Ability in Posterior Stabilized Total Knee Arthroplasty with Medialised Dome-Patella Resurfacing: A Retrospective Comparative Outcome Analysis.

OBJECTIVES This investigation aimed to evaluate if the modifications to prosthesis designs improve patients' clinical and functional outcomes after total knee arthroplasty (TKA), with a special focus on pain and kneeling ability. METHODS Retrospective and comparative analysis of consecutive patients who were treated with posterior stabilized TKA using two different prostheses designs (single surgeon, single vendor). Group 1 received a traditional design TKA (PFC Sigma; DePuy, Inc., Warsaw, IN) with conventional dome-patella resurfacing and group 2 received a modern design implant (Attune; DePuy, Inc., Warsaw, IN), with medialised dome-patella resurfacing. Functional outcome (range of motion: ROM) and the Oxford Knee Score (OKS) were collected preoperatively, at 4-6 weeks and 12 months following surgery. RESULTS Ninety-nine participants were included. Of these, 30 received traditional design implants, and 69 the modern design knee implants. The comparison between the two implants showed a statistically significant increased total OKS and kneeling ability in the modern design cohort at 1-year follow-up compared to the traditional design cohort (p < 0.01). In the modern design group, 53% (N=37) could kneel easily or with little difficulty, compared to 30% (N=9) in the traditional design group. No statistically significant differences in ROM or the OKS pain component were seen. CONCLUSION The incorporation of a medialized dome-patella in modern knee implant design may offer advantages over traditional designs, as seen in improved total OKS and kneeling ability at one-year follow-up. Further research with larger cohorts is needed to confirm these findings and explore the broader impact of implant design changes on patient outcomes. LEVEL OF EVIDENCE Clinical Study, Level III

Spheroid-Like Cultures for Expanding Angiopoietin Receptor-1 (aka. Tie2) Positive Cells from the Human Intervertebral Disc.

Lower back pain is a leading cause of disability worldwide. The recovery of nucleus pulposus (NP) progenitor cells (NPPCs) from the intervertebral disc (IVD) holds high promise for future cell therapy. NPPCs are positive for the angiopoietin-1 receptor (Tie2) and possess stemness capacity. However, the limited Tie2+ NPC yield has been a challenge for their use in cell-based therapy for regenerative medicine. In this study, we attempted to expand NPPCs from the whole NP cell population by spheroid-formation assay. Flow cytometry was used to quantify the percentage of NPPCs with Tie2-antibody in human primary NP cells (NPCs). Cell proliferation was assessed using the population doublings level (PDL) measurement. Synthesis and presence of extracellular matrix (ECM) from NPC spheroids were confirmed by quantitative Polymerase Chain Reaction (qPCR), immunostaining, and microscopy. Compared with monolayer, the spheroid-formation assay enriched the percentage of Tie2+ in NPCs' population from ~10% to ~36%. Moreover, the spheroid-formation assay also inhibited the proliferation of the Tie2- NPCs with nearly no PDL. After one additional passage (P) using the spheroid-formation assay, NPC spheroids presented a Tie2+ percentage even further by ~10% in the NPC population. Our study concludes that the use of a spheroid culture system could be successfully applied to the culture and expansion of tissue-specific progenitors

Effect of different cryopreservation media on human nucleus pulposus cells' viability and trilineage potential

Introduction: Low back pain (LBP) is a significant cause of disability in many countries, affecting more than half a billion people worldwide. In the past, progenitor cells have been found within the nucleus pulposus (NP) of the human intervertebral disc (IVD). However, in the context of cell therapy, little is known about the effect of cryopreservation and expansion on here called “heterogenic” human NP cells (hNPCs), and whether commercially available cryopreservation media are more efficient than “commonly used” media in terms of cell viability. Materials: In this study, hNPCs from four trauma patients (age 40.5 ± 14.3 years) and two patients with degenerated IVDs (age 24 and 46 years), undergoing spinal surgery, were collected. To isolate hNPCs, the tissue was digested with a mild two-step protocol. After subsequent expansion, hNPCs at passages 2-5 were separated and either cryo-preserved for 1 week at −150°C or differentiated into osteogenic, adipogenic, or chondrogenic lineages for 21 days. Cryopreservation was performed with five different media to compare their effect on the cell's viability and differentiation potential. Cell viability was determined with flow cytometry using propidium iodide and the trilineage differentiation potential was assessed by quantitative polymerase chain reaction and histological analysis. Results: After 1 week of cryopreservation, the hNPC's cell viability was comparable for all conditions, that is, independent of the cryopreservation medium used (82.3 ± 0.8% of cell viability). Furthermore, hNPCs from trauma patients showed some evidence for adipogenic and chondrogenic differentiation and at lower levels, this and evidence of osteogenic differentiation could be confirmed with hNPCs from degenerated discs. Moreover, cryopreservation did not affect the cell's differentiation potential in the majority of the cases tested. Conclusion: “Commonly used” cryopreservation media seem to perform just as well as commercially available media in terms of cell viability and the overall maintenance of the hNPCs trilineage differentiation potential

Towards Tissue-Specific Stem Cell Therapy for the Intervertebral Disc: PPARδ Agonist Increases the Yield of Human Nucleus Pulposus Progenitor Cells in Expansion

(1) Background: Low back pain (LBP) is often associated with intervertebral disc degeneration (IVDD). Autochthonous progenitor cells isolated from the center, i.e., the nucleus pulposus, of the IVD (so-called nucleus pulposus progenitor cells (NPPCs)) could be a future cell source for therapy. The NPPCs were also identified to be positive for the angiopoietin-1 receptor (Tie2). Similar to hematopoietic stem cells, Tie2 might be involved in peroxisome proliferator-activated receptor delta (PPARδ) agonist-induced self-renewal regulation. The purpose of this study was to investigate whether a PPARδ agonist (GW501516) increases the Tie2+ NPPCs’ yield within the heterogeneous nucleus pulposus cell (NPC) population. (2) Methods: Primary NPCs were treated with 10 µM of GW501516 for eight days. Mitochondrial mass was determined by microscopy, using mitotracker red dye, and the relative gene expression was quantified by qPCR, using extracellular matrix and mitophagy-related genes. (3) The NPC’s group treated with the PPARδ agonist showed a significant increase of the Tie2+ NPCs yield from ~7% in passage 1 to ~50% in passage two, compared to the NPCs vehicle-treated group. Furthermore, no significant differences were found among treatment and control, using qPCR and mitotracker deep red. (4) Conclusion: PPARδ agonist could help to increase the Tie2+ NPCs yield during NPC expansion

Assessing lower extremity loading during activities of daily living using continuous-scale physical functional performance 10 and wireless sensor insoles: a comparative study between younger and older adults.

PURPOSE This study aims to investigate the lower extremity loading during activities of daily living (ADLs) using the Continuous Scale of Physical Functional Performance (CS-PFP 10) test and wireless sensor insoles in healthy volunteers. METHODS In this study, 42 participants were recruited, consisting of 21 healthy older adults (mean age 69.6 ± 4.6 years) and 21 younger healthy adults (mean age 23.6 ± 1.8 years). The performance of the subjects during ADLs was assessed using the CS-PFP 10 test, which comprised 10 tasks. The lower extremity loading was measured using wireless sensor insoles (OpenGo, Moticon, Munich, Germany) during the CS-PFP 10 test, which enabled the measurement of ground reaction forces, including the mean and maximum total forces during the stance phase, expressed in units of body weight (BW). RESULTS The total CS-PFP 10 score was significantly lower in older participants compared to the younger group (mean total score of 57.1 ± 9.0 compared to 78.2 ± 5.4, respectively). No significant differences in the mean total forces were found between older and young participants. The highest maximum total forces were observed during the tasks 'endurance walk' (young: 1.97 ± 0.34 BW, old: 1.70 ± 0.43 BW) and 'climbing stairs' (young: 1.65 ± 0.36 BW, old: 1.52 ± 0.28 BW). Only in the endurance walk, older participants showed a significantly higher maximum total force (p < 0.001). CONCLUSION The use of wireless sensor insoles in a laboratory setting can effectively measure the load on the lower extremities during ADLs. These findings could offer valuable insights for developing tailored recommendations for patients with partial weight-bearing restrictions

Gender authorship trends in spine research publications - Research across different countries from 1976 to 2020.

•Gender trends in authorship showed an increase in female authors from 1976 to 2020.•In 2020, Europe had the highest and Asia the lowest proportion of female authors.•The Netherlands had the highest proportion of women and Japan the lowest

Effect of glucose depletion and fructose administration during chondrogenic commitment in human bone marrow-derived stem cells.

BACKGROUND Bone marrow mesenchymal stromal cells (BMSCs) are promising for therapeutic use in cartilage repair, because of their capacity to differentiate into chondrocytes. Often, in vitro differentiation protocols employ the use of high amount of glucose, which does not reflect cartilage physiology. For this reason, we investigated how different concentrations of glucose can affect the chondrogenic differentiation of BMSCs in cell culture pellets. Additionally, we investigated how fructose could influence the chondrogenic differentiation in vitro. METHODS BMSC were isolated from six donors and cultured in DMEM containing glucose at either 25 mM (HG), 5.5 mM (LG) or 1 mM (LLG), and 1% non-essential amino acids, 1% ITS+, in the presence of 100 nM dexamethasone, 50 µg/ml ascorbic acid-2 phosphate and 10 ng/ml TGF-β1. To investigate the effect of different metabolic substrates, other groups were exposed to additional 25 mM fructose. The media were replaced every second day until day 21 when all the pellets were harvested for further analyses. Biochemical analysis for glycosaminoglycans into pellets and released in medium was performed using the DMMB method. Expression of GLUT3 and GLUT5 was assayed by qPCR and validated using FACS analysis and immunofluorescence in monolayer cultures. Chondrogenic differentiation was further confirmed by qPCR analysis of COL2A1, COL1A1, COL10A1, ACAN, RUNX2, SOX9, SP7, MMP13, and PPARG, normalized on RPLP0. Type 2 collagen expression was subsequently validated by immunofluorescence analysis. RESULTS We show for the first time the presence of fructose transporter GLUT5 in BMSC and its regulation during chondrogenic commitment. Additionally, decreasing glucose concentration during chondrogenesis dramatically decreased the yield of differentiation. However, the use of fructose alone or together with low glucose concentrations does not limit cell differentiation, but on the contrary it might help in maintaining a stable chondrogenic phenotype comparable with the standard culture conditions (high glucose). CONCLUSION This study provides evidence that BMSC express GLUT5 and differentially regulate GLUT3 in the presence of glucose variation. This study gives a better comprehension of BMSCs sugar use during chondrogenesis

Influence of Angiopoietin Treatment with Hypoxia and Normoxia on Human Intervertebral Disc Progenitor Cell’s Proliferation, Metabolic Activity, and Phenotype

Increasing evidence implicates intervertebral disc (IVD) degeneration as a major contributor to low back pain. In addition to a series of pathogenic processes, degenerated IVDs become vascularized in contrast to healthy IVDs. In this context, angiopoietin (Ang) plays a crucial role and is involved in cytokine recruitment, and anabolic and catabolic reactions within the extracellular matrix (ECM). Over the last decade, a progenitor cell population has been described in the nucleus pulposus (NP) of the IVD to be positive for the Tie2 marker (also known as Ang-1 receptor). In this study, we investigated the influence of Ang-1 and Ang-2 on human NP cell (Tie2+, Tie2- or mixed) populations isolated from trauma patients during 7 days in normoxia (21% O2) or hypoxia (≤ 5% O2). At the end of the process, the proliferation and metabolic activity of the NP cells were analyzed. Additionally, the relative gene expression of NP-related markers was evaluated. NP cells showed a higher proliferation depending on the Ang treatment. Moreover, the study revealed higher NP cell metabolism when cultured in hypoxia. Additionally, the relative gene expression followed, with an increase linked to the oxygen level and Ang concentration. Our study comparing different NP cell populations may be the start of new approaches for the treatment of IVD degeneration

In Vitro Characterization of a Tissue Renin-Angiotensin System in Human Nucleus Pulposus Cells.

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

Mimicking the Intervertebral Disc Microenvironment for Expansion of Nucleus Pulposus Progenitor Cells in a Context of Cell Therapy

INTRODUCTION: Low back pain (LBP) is a global health concern that affects as many as 75–80% of people during their lifetime. Although the causes of LBP are multifactorial, increasing evidence implicates intervertebral disc (IVD) degeneration as a major contributor. In this respect, tissue-specific progenitors may play a crucial role in tissue regeneration, as these cells are perfectly adapted to their niche. Recently, the progenitor cell population was described in the nucleus pulposus (NP) of the IVD. These cells, positive for the Tie2 marker, have self-renewal capacity and in vitro multipotency potential. However, extremely low numbers of the NP progenitors limit the feasibility of cell therapy strategies. Here, we study the influence of the culture method and of the microenvironment on the human NP progenitors and their differentiation potential in vitro. METHODS:Cells were obtained from human NP tissue from trauma patients undergoing spinal surgery. Briefly, after mild overnight digestion, the NP tissue cells were cultured in 2D (monolayer) or 3D (alginate beads) conditions with medium supplemented in ascorbic acid. After 2 weeks, cells from 2D or 3D culture were expanded on fibronectin-coating flasks with medium supplemented in FGF-2 to mimic the native microenvironment of NP cells. Subsequently, expanded NP cells were then characterized by cytometry (CD105, CD90, CD73, CD45, CD34, and Tie2) and tri-lineage differentiation, which was analyzed by qPCR and histology. RESULTS: Cytometry analysis, after 2D- or 3D-expansion showed the presence of 0.1 % and 78.2 % of Tie2+ NP progenitors, respectively. Concerning the chondrogenic differentiation assay, the detection of glycosaminoglycans in the culture medium was drastically increased for 3D-expanded cells (11-fold) vs 2D-expanded cells. Moreover, the relative gene expression of collagen type 2 and aggrecan was also increased (600-fold and 2-fold, respectively). Regarding osteogenic differentiation assay, relative gene expression for osteopontin increased for 3D- (150-fold) vs 2D-expanded cells. However, no difference was observed between 2D and 3D expansion for the adipogenic differentiation assay. DISCUSSION & CONCLUSIONS: The present study shows that 3D expansion of NP cells better preserves the progenitor's cells population and increases the chondrogenic and osteogenic differentiation potential compared to 2D expansion. This project not only has a scientific impact by evaluating the role of native physiological niches on the functionality of NP progenitors but could also lead to an innovative clinical approach with cell therapy for IVD regeneration and repair. Acknowledgments: Financial support was received from iPSpine H2020 project #825925