Single-cell RNA sequencing of human non-hematopoietic bone marrow cells reveals a unique set of inter-species conserved biomarkers for native mesenchymal stromal cells.

BACKGROUND: Native bone marrow (BM) mesenchymal stem/stromal cells (BM-MSCs) participate in generating and shaping the skeleton and BM throughout the lifespan. Moreover, BM-MSCs regulate hematopoiesis by contributing to the hematopoietic stem cell niche in providing critical cytokines, chemokines and extracellular matrix components. However, BM-MSCs contain a heterogeneous cell population that remains ill-defined. Although studies on the taxonomy of native BM-MSCs in mice have just started to emerge, the taxonomy of native human BM-MSCs remains unelucidated. METHODS: By using single-cell RNA sequencing (scRNA-seq), we aimed to define a proper taxonomy for native human BM non-hematopoietic subsets including endothelial cells (ECs) and mural cells (MCs) but with a focal point on MSCs. To this end, transcriptomic scRNA-seq data were generated from 5 distinct BM donors and were analyzed together with other transcriptomic data and with computational biology analyses at different levels to identify, characterize and classify distinct native cell subsets with relevant biomarkers. RESULTS: We could ascribe novel specific biomarkers to ECs, MCs and MSCs. Unlike ECs and MCs, MSCs exhibited an adipogenic transcriptomic pattern while co-expressing genes related to hematopoiesis support and multilineage commitment potential. Furthermore, by a comparative analysis of scRNA-seq of BM cells from humans and mice, we identified core genes conserved in both species. Notably, we identified MARCKS, CXCL12, PDGFRA, and LEPR together with adipogenic factors as archetypal biomarkers of native MSCs within BM. In addition, our data suggest some complex gene nodes regulating critical biological functions of native BM-MSCs together with a preferential commitment toward an adipocyte lineage. CONCLUSIONS: Overall, our taxonomy for native BM non-hematopoietic compartment provides an explicit depiction of gene expression in human ECs, MCs and MSCs at single-cell resolution. This analysis helps enhance our understanding of the phenotype and the complexity of biological functions of native human BM-MSCs.

Simple foot an ankle value: a simple evaluation correlated to the existing PROMs.

PURPOSE: The SFAV (Simple Foot and Ankle Value) consists in asking patients how they rate their joint function on the day of the examination, as a percentage of that of a normal joint (0-100% scale with 100% being normal). The main objective was to validate the SFAV by determining its correlation with validated foot and ankle function scores. METHODS: This was a prospective study. 90 patients were included in three groups: patients 16 to 54 years old with an acute or subacute ankle pathology (foot/ankle trauma patient group), patients more than 55 years old with ankle or foot osteoarthritis (foot/ankle degeneration patient group), and adults of any age without foot or ankle pathology (control group). A self-administered questionnaire with the American Orthopedic Foot and Ankle Society, The European Foot and Ankle Society, the Foot and Ankle Outcome Score, the Visual Analogic Scale, and the SFAV was given at three different timepoints (enrollment, preoperative visit, and 6-month postoperative visit) to the patients. The validity of the SFAV was investigated by determining its correlation with the existing foot and ankle PROMs using Spearman's correlation; test-retest reliability, the responsiveness to change, and the discriminative ability of the SFAV were also analyzed. The significance threshold was set at 0.05. RESULTS: The SFAV was significantly correlated with the AOFAS, EFAS, and FAOS at all tested time points, with all p values below 0.033. SFAV scoring was reliable over time, as p values resulting from the comparison between initial and preoperative SFAV were all above the significance threshold. SFAV scoring was responsive to change, based on the comparison between pre- and postoperative SFAV (p < 0.05). Like for the AOFAS, EFAS, and FAOS, SFAV provides good discrimination between a healthy subject and a patient. The control group scores and initial consultation scores of the pooled patient's groups were statistically correlated (p < 0.05). CONCLUSION: The SFAV is a valid outcome measure correlated with the AOFAS, EFAS, FAOS, and VAS. LEVEL OF EVIDENCE: Level of evidence III.

Toll-like receptor 4 selective inhibition in medullar microenvironment alters multiple myeloma cell growth.

Bone marrow (BM) mesenchymal stromal cells (MSCs) are abnormal in multiple myeloma (MM) and play a critical role by promoting growth, survival, and drug resistance of MM cells. We observed higher Toll-like receptor 4 (TLR4) gene expression in MM MSCs than in MSCs from healthy donors. At the clinical level, we highlighted that TLR4 expression in MM MSCs evolves in parallel with the disease stage. Thus, we reasoned that the TLR4 axis is pivotal in MM by increasing the protumor activity of MSCs. Challenging primary MSCs with TLR4 agonists increased the expression of CD54 and interleukin-6 (IL-6), 2 factors directly implicated in MM MSC-MM cell crosstalk. Then, we evaluated the therapeutic efficacy of a TLR4 antagonist combined or not with conventional treatment in vitro with MSC-MM cell coculture and in vivo with the Vk*MYC mouse model. Selective inhibition of TLR4 specifically reduced the MM MSC ability to support the growth of MM cells in an IL-6-dependent manner and delayed the development of MM in the Vk*MYC mouse model by altering the early disease phase in vivo. For the first time, we demonstrate that specific targeting of the pathological BM microenvironment via TLR4 signaling could be an innovative approach to alter MM pathology development.

Pediatric Simple Knee Value: a simple patient-reported outcome measure for the knee.

PURPOSE: The pediatric Simple Knee Value (pedi-SKV) is an outcome score in which paediatric patients are asked 'How would you rate your knee today as a percentage of normal (0% to 100% scale with 100% being normal)?'. The primary aim of this study was to validate the pedi-SKV by measuring its correlation with validated knee function scores used most often in paediatric orthopaedics. METHODS: This prospective study was conducted at a teaching hospital to evaluate the pedi-SKV's validity. A total of 44 paediatric patients (ten to 15 years old), were enrolled prior to anterior cruciate ligament reconstruction as well as 17 healthy controls. A survey form consisting of the Lysholm, International Knee Documentation Committee Pediatric Form (Pedi-IKDC) and pedi-SKV was given to subjects twice (enrolment and six months postoperatively). The criterion validity of the pedi-SKV was determined by correlating it to existing knee functional scores. Responsiveness to change was evaluated by comparing the pedi-SKV scores before and after surgery (enrolment visit and six-month postoperative visit). Discriminative ability was evaluated by comparing the pedi-SKV distribution in patients versus controls. RESULTS: There was a strong and significant correlation between the pedi-SKV and the Lysholm and Pedi-IKDC (p < 0.0001). The pedi-SKV had a good responsiveness to change (p < 0.0001 for the pedi-SKV before versus six months postoperatively). Like the other knee-specific functional sores (p < 0.0001), the pedi-SKV was able to distinguish between patients and controls (p < 0.0001). CONCLUSION: The pedi-SKV is a valid outcome measure that is strongly correlated with the Lysholm and Pedi-IKDC. This is a novel simple score that can be used by physicians in their daily practice. LEVEL OF EVIDENCE: II.

A retrospective comparison of central and posterior hinge joints in 53 total knee arthroplasties.

INTRODUCTION: The number of hinged total knee arthroplasty (HTKA) procedures is constantly increasing. There are two hinge types: central (CHTKA) and posterior (PHTKA). The primary purpose of the study was to compare implant survival in patients with CHTKA versus PHTKA. The secondary purpose was to analyse the radiological and clinical results of the implants. HYPOTHESIS: There is no difference between the two groups. MATERIALS AND METHODS: This study involved 53 patients who received a HTKA for either primary, trauma or revision surgery, of these 32 were in the CHTKA group and 21 in the PHTKA group, with a mean age of 69 years (38-89). The exclusion criteria were: etiology of sepsis, incomplete records and refusal to use data. The revision rate, with the replacement of prosthetic components, was the primary endpoint. The secondary outcomes were: mobility, complications, VAS, IKS, Devane, Charnley and Oxford knee scores, and radiological progression. RESULTS: The mean follow-up was 51 months (1-139). At 60 months, overall survival rate of the HTKA was 81%, with a confidence interval (CI) of 95% (71-93.2), and there was no difference between CHTKA and PHTKA, 77.7% (95% CI, 63.3-95.4) versus 85.7% (95% CI, 72-100), p=0.625, respectively. Flexion was 101°±15 (80-140) for CHTKA versus 98°±12 (30-130) for PHTKA, p=0.006. VAS was 0.5±16 (0-6) for CHTKA versus 1.6±14 (0-4) for PHTKA, p=0.000008. The IKS was 103±39 (15-180) for CHTKA versus 81±51 (9-200) for PHTKA, p=0.03. There were no differences in either radiological progression, complications or other functional scores. DISCUSSION: No significant difference was observed between the survival of CHTKA and PHTKA. CHTKA had better flexion, reduced VAS and increased IKS. Surgeons should be aware of these findings and apply careful consideration to their choice of hinge. LEVEL OF EVIDENCE: IV; retrospective single-centre study.

Simple Knee Value: a simple evaluation correlated to existing knee PROMs.

PURPOSE: The Simple Knee Value (SKV) is an outcome score in which patients are asked to grade their knee function as a percentage of that of a normal knee. The primary aim of this study was to validate the SKV by measuring its correlation with existing knee-related PROMs. METHODS: This was a prospective study conducted at a teaching hospital to assess the SKV's validity. The study enrolled 47 young patients (16-54 years old), 49 older patients (≥ 55 years) and 30 healthy controls. A paper questionnaire consisting of the Lysholm, IKDC, KOOS, WOMAC and SKV was given to subjects three times (enrolment, 1-month preoperative visit and 6 months postoperative visit). The criterion validity of the SKV was determined by correlating it to existing knee PROMs using the Spearman correlation coefficient (S). SKV test-retest reliability was assessed by the intraclass correlation coefficient (ICC) between two time points (initial consultation at enrolment and preoperative visit, reflecting the same clinical condition). Responsiveness to change was determined by comparing the SKV scores before and after surgery (enrolment consultation and 6 months postoperative). Discriminative ability was determined by comparing the SKV distribution in patients and controls. RESULTS: There was a strong and significant correlation between the SKV and the gold standard Lysholm, IKDC, KOOS and WOMAC in the younger patients and the older patients (p < 0.0001). The reliability between the SKV at the initial consultation and before surgery was excellent (ICC 0.862, 95% CI 0.765; 0.921) in the younger patients, and moderate (ICC 0.506, 95% CI 0.265; 0.688) in the older patients. The SKV was responsive to change in both patient groups (p < 0.0001 for the SKV before versus 6 months after surgery). Like the other knee-specific PROMs (p < 0.0001), the SKV was able to distinguish between patients and controls (p < 0.0001). CONCLUSIONS: The SKV is valid as it is significantly correlated to existing knee PROMs. It is also reliable, responsive to change and discriminating. Its simplicity gives it many advantages and it can be used by physicians in their daily practice. LEVEL OF EVIDENCE: Level II.

Does augmented core decompression decrease the rate of collapse and improve survival of femoral head avascular necrosis? Case-control study comparing 184 augmented core decompressions to 79 standard core decompressions with a minimum 2 years' follow-up.

INTRODUCTION: Avascular necrosis of the femoral head often progresses to femoral head collapse if not treated. Conservative treatment yields highly variable results and is not standardised, mainly because it is typically evaluated in small patient populations. This led us to conduct a large retrospective comparative study with the goals of 1) analysing survival and functional outcomes, 2) looking for differences in survival between core decompression techniques (standard versus augmented), and 3) studying the risk factors for femoral head collapse and revision by arthroplasty. HYPOTHESIS: Core decompression limits the number of patients who suffer femoral head collapse requiring arthroplasty at 2 years' follow-up. METHODS: This multicentre, comparative, retrospective study analysed 330 patient records (1975-2016) where at least 2 years' follow-up was available. Sixty-two patients were excluded from the analysis: 5 had a stage III with collapse, 5 were lost to follow-up, 2 died within 24 months of the procedure and 50 had incomplete data. The study included 263 patients with a mean age of 42 years (15.7-70). In the Ficat classification, there were 51 cases of stage I necrosis, 186 cases of stage II and 22 cases of stage II with crescent sign (transition stage). The Kerboull angle on radiographs was between 5° and 20° in 40 patients, between 20° and 40° in 107 patients, between 40° and 60° in 52 patients and more than 60° in 29 patients. A standard core decompression was done in 79 patients and an augmented one in 184 patients. The more severe AVN cases (stage II) were more likely to be treated by augmented CD (160/184 patients, 87%) than by standard CD (48/79 patients, 61%) (p<0.001). RESULTS: In the 263 patients, the overall survival (no arthroplasty at 2 years) was 73% (196/263). At 2 years, the survival rate (without arthroplasty) was 71% (56/79) in the standard CD group versus 76% (140/184) in the augmented CD group. This difference was significant when adjusted for Ficat stage and Kerboull angle [HR=0.457, 95% CI (0.247-0.844) (p=0.012)]. When the survival data was adjusted to the Ficat stage, augmented CD was better than standard CD with 10-year survival of 58.1% vs. 57.9% (p=0.0082). More than 30% necrosis volume increased the risk of failure [HR=3.291 95%CI (1.494-7.248) (p=0.0031)]. Also, a Kerboull angle above 60° increased the risk of failure [HR=3.148 95%CI (1.346-7.5) (p=0.0083)]. CONCLUSION: After 2 years, CD for non-collapsed femoral head AVN prevents collapse and revision to arthroplasty in 73% of cases (196/268). Augmented CD improves the 2-year survival and the long-term survival after adjusting for preoperative characteristics (Kerboullangle and Ficat stage). The risk of collapse and need for arthroplasty is greater in patients with 30% necrosis volume on MRI and Kerboull angle above 60°. LEVEL OF EVIDENCE: III; retrospective case-control study.