Riester, Scott M.

AbstractBackgroundAlthough racial and ethnic identities are associated with a multitude of disparate medical outcomes, surveillance of these subpopulations in the occupational clinic setting could benefit enormously from a more detailed and nuanced recognition of racial and ethnic identity.MethodsThe research group designed a brief questionnaire to capture several dimensions of this identity and collected data from patients seen for work‐related conditions in four occupational medicine clinics from May 2019 through March 2020. Responses were used to calculate the sensitivity and specificity of extant racial/ethnic identity data within our electronic health records system, and were compared to participants' self‐reported industry and occupation, coded according to North American Industry Classification System and Standard Occupational Classification System listings.ResultsOur questionnaire permitted collection of data that defined our patients' specific racial/ethnic identity with far greater detail, identified patients with multiple ethnic identities, and elicited their preferred language. Response rate was excellent (94.2%, n = 773). Non‐White participants frequently selected a racial/ethnic subcategory (78.1%–92.2%). Using our race/ethnicity data as a referent, the electronic health record (EHR) had a high specificity (>87.1%), widely variable sensitivity (11.8%–82.2%), and poorer response rates (75.1% for race, 82.5% for ethnicity, as compared to 93.8% with our questionnaire). Additional analyses revealed some industries and occupations disproportionately populated by patients of particular racial/ethnic identities.ConclusionsOur project demonstrates the usefulness of a questionnaire which more effectively identifies racial/ethnic subpopulations in an occupational medicine clinic, permitting far more detailed characterization of their occupations, industries, and diagnoses.

Abstract Background Adipose-derived mesenchymal stromal cells (AMSCs) represent attractive cellular therapeutics for treatment of various diseases including osteoarthritis and bone degeneration. Preparation and characterization of AMSCs show donor-to-donor variability that indicating that AMSCs are heterogeneous populations of cells. Cell surface markers to identify MSCs, such as CD44, CD90, and CD105, are relatively invariable among AMSCs and do not reflect the heterogeneity of AMSC populations. CD36, a multifunctional surface receptor associated with transport of oxidized low-density lipoproteins and fatty acids, is also expressed by AMSCs but this marker is considerable more variable. Therefore, we assessed whether CD36 can be used to identify subpopulations in AMSCs. Methods Clinical-grade AMSCs were isolated from patient fat biopsies, cultured under xenobiotic-free conditions using human platelet lysate and sorted by flow cytometry or magnetic cell sorting to characterize CD36 expression. CD36 enriched, CD36 depleted, and unsorted AMSCs were characterized using cellular and molecular techniques including proliferation, multilineage potential, RNA-sequencing and bioinformatics, metabolomics, and sensitivity to the CD36 inhibitor sulfosuccinimidyl oleate (SSO). Results CD36 exhibited biphasic expression on AMSCs grown in human platelet lysate. Enrichment of CD36+ AMSCs showed that CD36+ expression identifies a stable subpopulation. Transcriptomic analysis revealed enhancement of calcium transporter genes. Osteogenic differentiation of CD36+ enriched, CD36+ depleted, and unsorted AMSCs showed strikingly enhanced osteogenic calcium deposition and enhanced expression of alkaline phosphatase (ALPL) and osteoprotegrin (TNFRSF11B) in the CD36+ population. While lipid droplets were not altered, adipogenic differentiation showed upregulated gene expression of key adipogenic markers, including fatty acid-binding protein 4 (FABP4) and Adiponectin (ADIPOQ), with CD36+ enrichment. Treatment of CD36+ enriched AMSCs with the SSO showed reduced calcium deposition whereas CD36+ depleted AMSCs were unaffected. Conclusions CD36 exhibits variable expression amongst AMSCs. CD36+ enriched AMSCs are a stable subpopulation with enhanced osteogenic potential that linked to CD36 receptor function. These results may further refine production and clinical application of AMSC cellular therapeutics. Furthermore, the enhanced osteogenic potential of CD36+ AMSCs may be considered for therapeutic regeneration of bone.

An efficient musculoskeletal system depends on the precise assembly and coordinated growth and function of muscles, skeleton, and tendons. However, the mechanisms that drive integrated musculoskeletal development and coordinated growth and differentiation of each of these tissues are still being uncovered. Epigenetic modifiers have emerged as critical regulators of cell fate differentiation, but so far almost nothing is known about their roles in tendon biology. Previous studies have shown that epigenetic modifications driven by Enhancer of zeste homolog 2 (EZH2), a major histone methyltransferase, have significant roles in vertebrate development including skeletal patterning and bone formation. We now find that targeting Ezh2 through the limb mesenchyme also has significant effects on tendon and muscle patterning, likely reflecting the essential roles of early mesenchymal cues mediated by Ezh2 for coordinated patterning and development of all tissues of the musculoskeletal system. Conversely, loss of Ezh2 in the tendon cells did not disrupt overall tendon structure or collagen organization suggesting that tendon differentiation and maturation are independent of Ezh2 signaling.

10531 Background: Osteosarcoma (OS) is a clinically challenging primary malignant bone tumor that has a high rateof local recurrence and metastasis. Disease free survival has been reported to be as low as 19% despite contemporary chemotherapy regimens and surgery. Wnt signaling is known to play a role in osteogenesis and cancer pathogenesis, therefore is a promising target for therapeutic intervention in OS. Secreted Frizzled Related Proteins (sFRPs), Dickkopf-1 (DKK1), and Sclerostin (SOST) are secreted Wnt inhibitor proteins that regulate Wnt signaling in bone. This study investigates the activity of sFRP3, DKK1, and SOST in serum from OS patients with the goal of developing therapeutic Wnt inhibitors and clinically useful biomarkers. Methods: Enzyme linked immunosorbent assayswere used to quantify sFRP3, DKK1 and SOST levels in human serum (n=40 pairs; 20 OS patients, 20 aged matched non-diseased controls). Patients were stratified into 2 age groups: >35 (n=26 pairs) and <30 (n=14 pairs) years of age. Clinical data from the medical records was correlated with experimental results. Using a Wilcoxon signed rank test, a p–value <0.05 was significant. Results: sFRP3 levels were significantly decreased in 55% (22/40) of diseased samples compared to 20% (8/40) of the non-diseased controls (p= 0.007). DKK1 levels were elevated in 40% (16/40) of OS samples compared to 30% (12/40) of the non-diseased controls (p= 0.08). SOST levels were increased in 42.5% (17/40) of diseased samples compared to 32.5% (13/40) of the non-diseased controls (p= 0.38). When stratified by age, the younger patients showed a statistically significant decrease in sFRP3 expression (p<0.001). Serum levels of sFRP3, DKK1, and SOST were not statistically significant between metastatic and non-metastatic OS. Conclusions: Serum sFRP3 levels were significantly decreased in OS patients, a difference that was even more pronounced in the pediatric strata. Since sFRP3 is differentially expressed in patient serum it has potential as a clinical biomarker for initial tumor diagnosis and early detection of recurrence. Decreased sFRP3 expression may be responsible for the up regulation of Wnt signaling in OS. Wnt inhibitors such as sFRP3 have potential as therapeutic agents in OS warranting further investigation.

Background Minnesota has an ethnically diverse labor force, with the largest number of refugees per capita in the United States. In recent years, Minnesota has been and continues to be a major site for immigrant and refugee resettlement in the United States, with a large population of both immigrant and native born Hmong, Hispanic, and East Africans. This study seeks to evaluate the injury risk among the evolving minority workforce in the Minnesota Twin Cities region. Methods A retrospective cohort study identifying work‐related injuries following pre‐employment examinations was performed using electronic health records from a large multi‐clinic occupational medicine practice. Preplacement examinations and subsequent work‐related injuries were pulled from the electronic health record using representative ICD‐10 codes for surveillance examinations and injuries. This study included patient records collected over a 2‐year period from January 1, 2015, through December, 2016. The patients in this cohort worked in a wide‐array of occupations including production, assembly, construction, law enforcement, among others. Results Hispanic minority workers were twice as likely to be injured at work compared with White workers. Hispanics were 2.89 times more likely to develop back injuries compared with non‐Hispanic workers, and 1.86 times more likely to develop upper extremity injuries involving the hand, wrist, or elbow. Conclusion Clinical practice data shows that Hispanic workers are at increased risk for work‐related injuries in Minnesota. They were especially susceptible to back and upper extremity injuries. Lower injury rates in non‐Hispanic minority workers, may be the result of injury underreporting and require further investigation.

AbstractOsteoblast differentiation is controlled by transcription factor RUNX2 which temporally activates or represses several bone‐related genes, including those encoding extracellular matrix proteins or factors that control cell‐cell, and cell‐matrix interactions. Cell‐cell communication in the many skeletal pericellular micro‐niches is critical for bone development and involves paracrine secretion of growth factors and morphogens. This paracrine signaling is in part regulated by “A Disintegrin And Metalloproteinase” (ADAM) proteins. These cell membrane‐associated metalloproteinases support proteolytic release (“shedding”) of protein ectodomains residing at the cell surface. We analyzed microarray and RNA‐sequencing data for Adam genes and show that Adam17, Adam10, and Adam9 are stimulated during BMP2 mediated induction of osteogenic differentiation and are robustly expressed in human osteoblastic cells. ADAM17, which was initially identified as a tumor necrosis factor alpha (TNFα) converting enzyme also called (TACE), regulates TNFα‐signaling pathway, which inhibits osteoblast differentiation. We demonstrate that Adam17 expression is suppressed by RUNX2 during osteoblast differentiation through the proximal Adam17 promoter region (−0.4 kb) containing two functional RUNX2 binding motifs. Adam17 downregulation during osteoblast differentiation is paralleled by increased RUNX2 expression, cytoplasmic‐nuclear translocation and enhanced binding to the Adam17 proximal promoter. Forced expression of Adam17 reduces Runx2 and Alpl expression, indicating that Adam17 may negatively modulate osteoblast differentiation. These findings suggest a novel regulatory mechanism involving a reciprocal Runx2‐Adam17 negative feedback loop to regulate progression through osteoblast differentiation. Our results suggest that RUNX2 may control paracrine signaling through regulation of ectodomain shedding at the cell surface of osteoblasts by directly suppressing Adam17 expression.

ABSTRACTDegenerative disk disease of the spine is a major cause of back pain and disability. Optimization of regenerative medical therapies for degenerative disk disease requires a deep mechanistic understanding of the factors controlling the structural integrity of spinal tissues. In this investigation, we sought to identify candidate regulatory genes controlling extracellular matrix synthesis in spinal tissues. To achieve this goal we performed high throughput next generation RNA sequencing on 39 annulus fibrosus and 21 nucleus pulposus human tissue samples. Specimens were collected from patients undergoing surgical discectomy for the treatment of degenerative disk disease. Our studies identified associations between extracellular matrix genes, growth factors, and other important regulatory molecules. The fibrous matrix characteristic of annulus fibrosus was associated with expression of the growth factors platelet derived growth factor beta (PDGFB), vascular endothelial growth factor C (VEGFC), and fibroblast growth factor 9 (FGF9). Additionally we observed high expression of multiple signaling proteins involved in the NOTCH and WNT signaling cascades. Nucleus pulposus extracellular matrix related genes were associated with the expression of numerous diffusible growth factors largely associated with the transforming growth signaling cascade, including transforming factor alpha (TGFA), inhibin alpha (INHA), inhibin beta A (INHBA), bone morphogenetic proteins (BMP2, BMP6), and others. Clinical significance: this investigation provides important data on extracellular matrix gene regulatory networks in disk tissues. This information can be used to optimize pharmacologic, stem cell, and tissue engineering strategies for regeneration of the intervertebral disk and the treatment of back pain. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1356–1369, 2018.

ABSTRACTChronic low back pain is a major cause of disability and health care costs. Effective treatments are inadequate for many patients. Animal models are essential to further understanding of the pain mechanism and testing potential therapies. Currently, a number of preclinical models have been developed attempting to mimic aspects of clinical conditions that contribute to low back pain (LBP). This review focused on describing these animal models and the main behavioral tests for assessing pain in each model. Animal models of LBP can be divided into the following five categories: Discogenic LBP, radicular back pain, facet joint osteoarthritis back pain, muscle‐induced LBP, and spontaneous occurring LBP models. These models are important not only for enhancing our knowledge of how LBP is generated, but also for the development of novel therapeutic regimens to treat LBP in patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1305–1312, 2018.

ABSTRACTOsteosarcoma is the most common malignant bone tumor in children and adolescents. Metastasis and poor responsiveness to chemotherapy in osteosarcoma correlates with over‐expression of the runt‐related transcription factor RUNX2, which normally plays a key role in osteogenic lineage commitment, osteoblast differentiation, and bone formation. Furthermore, WNT/β‐catenin signaling is over‐activated in osteosarcoma and promotes tumor progression. Importantly, the WNT/β‐catenin pathway normally activates RUNX2 gene expression during osteogenic lineage commitment. Therefore, we examined whether the WNT/β‐catenin pathway controls the tumor‐related elevation of RUNX2 expression in osteosarcoma. We analyzed protein levels and nuclear localization of β‐catenin and RUNX2 in a panel of human osteosarcoma cell lines (SAOS, MG63, U2OS, HOS, G292, and 143B). In all six cell lines, β‐catenin and RUNX2 are expressed to different degrees and localized in the nucleus and/or cytoplasm. SAOS cells have the highest levels of RUNX2 protein that is localized in the nucleus, while MG63 cells have the lowest RUNX2 levels which is mostly localized in the cytoplasm. Levels of β‐catenin and RUNX2 protein are enhanced in HOS, G292, and 143B cells after treatment with the GSK3β inhibitor SB216763. Furthermore, small interfering RNA (siRNA)‐mediated depletion of β‐catenin inhibits RUNX2 expression in G292 cells. Thus, WNT/β‐catenin activation is required for RUNX2 expression in at least some osteosarcoma cell types, where RUNX2 is known to promote expression of metastasis related genes. J. Cell. Biochem. 118: 3662–3674, 2017. © 2017 Wiley Periodicals, Inc.