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DiIorio SE, Young B, Parker JB, Griffin MF, Longaker MT. Understanding Tendon Fibroblast Biology and Heterogeneity. Biomedicines 2024; 12:859. [PMID: 38672213 PMCID: PMC11048404 DOI: 10.3390/biomedicines12040859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/06/2024] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
Tendon regeneration has emerged as an area of interest due to the challenging healing process of avascular tendon tissue. During tendon healing after injury, the formation of a fibrous scar can limit tendon strength and lead to subsequent complications. The specific biological mechanisms that cause fibrosis across different cellular subtypes within the tendon and across different tendons in the body continue to remain unknown. Herein, we review the current understanding of tendon healing, fibrosis mechanisms, and future directions for treatments. We summarize recent research on the role of fibroblasts throughout tendon healing and describe the functional and cellular heterogeneity of fibroblasts and tendons. The review notes gaps in tendon fibrosis research, with a focus on characterizing distinct fibroblast subpopulations in the tendon. We highlight new techniques in the field that can be used to enhance our understanding of complex tendon pathologies such as fibrosis. Finally, we explore bioengineering tools for tendon regeneration and discuss future areas for innovation. Exploring the heterogeneity of tendon fibroblasts on the cellular level can inform therapeutic strategies for addressing tendon fibrosis and ultimately reduce its clinical burden.
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Affiliation(s)
- Sarah E. DiIorio
- Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; (S.E.D.); (B.Y.); (J.B.P.); (M.F.G.)
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Bill Young
- Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; (S.E.D.); (B.Y.); (J.B.P.); (M.F.G.)
| | - Jennifer B. Parker
- Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; (S.E.D.); (B.Y.); (J.B.P.); (M.F.G.)
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Michelle F. Griffin
- Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; (S.E.D.); (B.Y.); (J.B.P.); (M.F.G.)
| | - Michael T. Longaker
- Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; (S.E.D.); (B.Y.); (J.B.P.); (M.F.G.)
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
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2
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Steffen D, Mienaltowski M, Baar K. Spatial gene expression in the adult rat patellar tendon. Matrix Biol Plus 2023; 19-20:100138. [PMID: 38124714 PMCID: PMC10731370 DOI: 10.1016/j.mbplus.2023.100138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/08/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023] Open
Abstract
Tendons are dense connective tissues with relatively few cells which makes studying the molecular profile of the tissue challenging. There is not a consensus on the spatial location of various cell types within a tendon, nor the accompanying transcriptional profile. In the present study, we used two male rat patellar tendon samples for sequencing-based spatial transcriptomics to determine the gene expression profile. We integrated our data with a mouse Achilles single cell dataset to predict the cell type composition of the patellar tendon as a function of location within the tissue. The spatial location of the predicated cell types suggested that there were two populations of tendon fibroblasts, one located in the tendon midsubstance, while the other localized with red blood cells, pericytes, and immune cells to the tendon peripheral connective tissue. Of the highest expressed spatially variable genes, there were multiple genes with known function in tendon: Col1a1, Col1a2, Dcn, Fmod, Sparc, and Comp. Further, a novel spatially regulated gene (AABR07000398.1) with no known function was identified. The spatial gene expression of tendon associated genes (Scx, Thbs4, Tnmd, Can, Bgn, Lum, Adamts2, Lox, Ppib, Col2a1, Col3a1, Col6a2) was also visualized. Both patellar tendon samples had similar expression patterns for all these genes. This dataset provides new spatial insights into gene expression in a healthy tendon.
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Affiliation(s)
- Danielle Steffen
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, United States
| | - Michael Mienaltowski
- Department of Animal Science, University of California Davis, Davis, CA, United States
| | - Keith Baar
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, United States
- Physiology and Membrane Biology, University of California Davis, Davis, CA, United States
- VA Northern California Health Care System, Mather, CA 95655, United States
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3
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Szczesny SE, Corr DT. Tendon cell and tissue culture: Perspectives and recommendations. J Orthop Res 2023; 41:2093-2104. [PMID: 36794495 DOI: 10.1002/jor.25532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023]
Abstract
The wide variety of cell and tissue culture systems used to study and engineer tendons can make it difficult to choose the best approach and "optimal" culture conditions to test a given hypothesis. Therefore, a breakout session was organized at the 2022 ORS Tendon Section Meeting that focused on establishing a set of guidelines for conducting cell and tissue culture studies of tendon. This paper summarizes the outcomes of that discussion and presents recommendations for future studies. In the case of studying tendon cell behavior, cell and tissue culture systems are reductionist models in which the culture conditions should be strictly defined to approximate the in vivo condition as closely as possible. In contrast, for tissue engineering tendon replacements, the culture conditions do not need to replicate native tendon, but the outcome measures for success should be narrowly defined for the specific clinical application. Common recommendations for both applications are that researchers should perform a baseline phenotypic characterization of the cells that are ultimately used for experimentation. For models of tendon cell behavior, culture conditions should be well justified by existing literature and meticulously reported, tissue explant viability should be assessed, and comparisons to in vivo conditions should be made to determine baseline physiological relevance. For tissue engineering applications, the functional/structural/compositional outcome targets should be defined by the specific tendons they seek to replace, with key biologic and material properties prioritized for construct assessment. Lastly, when engineering tendon replacements, researchers should utilize clinically approved cGMP materials to facilitate clinical translation.
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Affiliation(s)
- Spencer E Szczesny
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Orthopaedics and Rehabilitation, Pennsylvania State University, Hershey, Pennsylvania, USA
| | - David T Corr
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
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4
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Steffen D, Avey A, Mienaltowski MJ, Baar K. The rat Achilles and patellar tendons have similar increases in mechanical properties but become transcriptionally divergent during postnatal development. J Physiol 2023; 601:3869-3884. [PMID: 37493407 DOI: 10.1113/jp284393] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 07/03/2023] [Indexed: 07/27/2023] Open
Abstract
The molecular events that drive post-natal tendon development are poorly characterized. In this study, we profiled morphological, mechanical, and transcriptional changes in the rat Achilles and patellar tendon before walking (P7), shortly after onset of walking (P14), and at motor maturity (P28). The Achilles and patellar tendons increased collagen content and mechanical strength similarly throughout post-natal development. However, at P28 the patellar tendon tended to display a higher maximal tensile load (MTL) (P = 0.0524) than the Achilles tendon, but a similar ultimate tensile strength (UTS; load relative to cross-sectional area) probably due to its increased cross-sectional area during development. The tendons started transcriptionally similar, with overlapping PCA clusters at P7 and P14, before becoming transcriptionally distinct at P28. In both tendons, there was an increase in extracellular matrix (ECM) gene expression and a concomitant decrease in cell cycle and mitochondrial gene expression. The transcriptional divergence at P28 suggested that STAT signalling was lower in the patellar tendon where MTL increased the most. Treating engineered human ligaments with the STAT inhibitor itacitinib increased collagen content and MTL. Our results suggest that during post-natal development, cellular resources are initially allocated towards cell proliferation before shifting towards extracellular matrix development following the onset of mechanical load and provide potential targets for improving tendon function. KEY POINTS: Little is known about mechanisms of post-natal tendon growth. We characterized morphological, mechanical, and transcriptional changes that occur before (P7), and early (P14) and late after (P28) rats begin to walk. From P7 to P28, the Achilles tendon increased in length, whereas the patellar tendon increased in cross-sectional area. Mechanical and material properties of the Achilles and patellar tendon increased from P7 to P28. From P7 to P28, the Achilles and patellar tendons increased expression of ECM genes and decreased mitochondrial and cell cycle gene expression. Ribosomal gene expression also significantly decreased in the Achilles and tended to decrease in the patellar tendon. At P28, STAT1 signalling tended to be lower in the patellar tendon which had grown by increasing cross-sectional area and inhibiting STAT activation in vitro improved mechanical properties in engineered human ligaments.
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Affiliation(s)
- Danielle Steffen
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | - Alec Avey
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
| | | | - Keith Baar
- Department of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA, USA
- Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
- VA Northern California Health Care System, Mather, CA, USA
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Bautista CA, Srikumar A, Tichy ED, Qian G, Jiang X, Qin L, Mourkioti F, Dyment NA. CD206+ tendon resident macrophages and their potential crosstalk with fibroblasts and the ECM during tendon growth and maturation. Front Physiol 2023; 14:1122348. [PMID: 36909235 PMCID: PMC9992419 DOI: 10.3389/fphys.2023.1122348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/23/2023] [Indexed: 02/24/2023] Open
Abstract
Resident macrophages exist in a variety of tissues, including tendon, and play context-specific roles in their tissue of residence. In this study, we define the spatiotemporal distribution and phenotypic profile of tendon resident macrophages and their crosstalk with neighboring tendon fibroblasts and the extracellular matrix (ECM) during murine tendon development, growth, and homeostasis. Fluorescent imaging of cryosections revealed that F4/80+ tendon resident macrophages reside adjacent to Col1a1-CFP+ Scx-GFP+ fibroblasts within the tendon fascicle from embryonic development (E15.5) into adulthood (P56). Through flow cytometry and qPCR, we found that these tendon resident macrophages express several well-known macrophage markers, including Adgre1 (F4/80), Mrc1 (CD206), Lyve1, and Folr2, but not Ly-6C, and express the Csf1r-EGFP ("MacGreen") reporter. The proportion of Csf1r-EGFP+ resident macrophages in relation to the total cell number increases markedly during early postnatal growth, while the density of macrophages per mm2 remains constant during this same time frame. Interestingly, proliferation of resident macrophages is higher than adjacent fibroblasts, which likely contributes to this increase in macrophage proportion. The expression profile of tendon resident macrophages also changes with age, with increased pro-inflammatory and anti-inflammatory cytokine expression in P56 compared to P14 macrophages. In addition, the expression profile of limb tendon resident macrophages diverges from that of tail tendon resident macrophages, suggesting differential phenotypes across anatomically and functionally different tendons. As macrophages are known to communicate with adjacent fibroblasts in other tissues, we conducted ligand-receptor analysis and found potential two-way signaling between tendon fibroblasts and resident macrophages. Tendon fibroblasts express high levels of Csf1, which encodes macrophage colony stimulating factor (M-CSF) that acts on the CSF1 receptor (CSF1R) on macrophages. Importantly, Csf1r-expressing resident macrophages preferentially localize to Csf1-expressing fibroblasts, supporting the "nurturing scaffold" model for tendon macrophage patterning. Lastly, we found that tendon resident macrophages express high levels of ECM-related genes, including Mrc1 (mannose receptor), Lyve1 (hyaluronan receptor), Lair1 (type I collagen receptor), Ctss (elastase), and Mmp13 (collagenase), and internalize DQ Collagen in explant cultures. Overall, our study provides insights into the potential roles of tendon resident macrophages in regulating fibroblast phenotype and the ECM during tendon growth.
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Affiliation(s)
- Catherine A. Bautista
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of PA, Philadelphia, PA, United States
| | - Anjana Srikumar
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
| | - Elisia D. Tichy
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
| | - Grace Qian
- Department of Bioengineering, School of Engineering and Applied Science, University of PA, Philadelphia, PA, United States
| | - Xi Jiang
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
| | - Ling Qin
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
| | - Foteini Mourkioti
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of PA, Philadelphia, PA, United States
- Penn Institute for Regenerative Medicine, Musculoskeletal Program, Perelman School of Medicine, University of PA, Philadelphia, PA, United States
| | - Nathaniel A. Dyment
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of PA, Philadelphia, PA, United States
- Department of Bioengineering, School of Engineering and Applied Science, University of PA, Philadelphia, PA, United States
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6
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Disser NP, Piacentini AN, De Micheli AJ, Schonk MM, Yao VJH, Deng XH, Oliver DJ, Rodeo SA. Achilles Tendons Display Region-Specific Transcriptomic Signatures Associated With Distinct Mechanical Properties. Am J Sports Med 2022; 50:3866-3874. [PMID: 36305762 DOI: 10.1177/03635465221128589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Previous studies have examined the transcriptomes and mechanical properties of whole tendons in different regions of the body. However, less is known about these characteristics within a single tendon. PURPOSE To develop a regional transcriptomic atlas and evaluate the region-specific mechanical properties of Achilles tendons. STUDY DESIGN Descriptive laboratory study. METHODS Achilles tendons from 2-month-old male Sprague Dawley rats were used. Tendons were isolated and divided into proximal, middle, and distal thirds for RNA sequencing (n = 5). For mechanical testing, the Achilles muscle-tendon-calcaneus unit was mounted in a custom-designed materials testing system with the unit clamped over the musculotendinous junction (MTJ) and the calcaneus secured at 90° of dorsiflexion (n = 9). Tendons were stretched to 20 N at a constant speed of 0.0167 mm/s. Cross-sectional area, strain, stress, and Young modulus were determined in each tendon region. RESULTS An open-access, interactive transcriptional atlas was generated that revealed distinct gene expression signatures in each tendon region. The proximal and distal regions had the largest differences in gene expression, with 2596 genes significantly differentially regulated at least 1.5-fold (q < .01). The proximal tendon displayed increased expression of genes resembling a tendon phenotype and increased expression of nerve cell markers. The distal region displayed increases in genes involved in extracellular matrix synthesis and remodeling, immune cell regulation, and a phenotype similar to cartilage and bone. There was a 3.72-fold increase in Young modulus from the proximal to middle region (P < .01) and an additional 1.34-fold increase from the middle to distal region (P = .027). CONCLUSION Within a single tendon, there are region-specific transcriptomic signatures and mechanical properties, and there is likely a gradient in the biological and functional phenotype from the proximal origin at the MTJ to the distal insertion at the enthesis. CLINICAL RELEVANCE These findings improve our understanding of the underlying biological heterogeneity of tendon tissue and will help inform the future targeted use of regenerative medicine and tissue engineering strategies for patients with tendon disorders.
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Affiliation(s)
- Nathaniel P Disser
- Hospital for Special Surgery, New York, New York, USA.,McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | | | - Andrea J De Micheli
- Hospital for Special Surgery, New York, New York, USA.,Department of Oncology of the Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
| | | | - Vincent J H Yao
- Hospital for Special Surgery, New York, New York, USA.,Sophie Davis Biomedical Education Program at CUNY School of Medicine, New York, New York, USA
| | | | - David J Oliver
- Hospital for Special Surgery, New York, New York, USA.,The David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, New York, USA
| | - Scott A Rodeo
- Hospital for Special Surgery, New York, New York, USA
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7
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Omoto T, Yimiti D, Sanada Y, Toriyama M, Ding C, Hayashi Y, Ikuta Y, Nakasa T, Ishikawa M, Sano M, Lee M, Akimoto T, Shukunami C, Miyaki S, Adachi N. Tendon-Specific Dicer Deficient Mice Exhibit Hypoplastic Tendon Through the Downregulation of Tendon-Related Genes and MicroRNAs. Front Cell Dev Biol 2022; 10:898428. [PMID: 35784484 PMCID: PMC9241168 DOI: 10.3389/fcell.2022.898428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/23/2022] [Indexed: 12/17/2022] Open
Abstract
Tendon is a fibrous connective tissue, that is, transmitting the forces that permit body movement. However, tendon/ligament biology is still not fully understood and especially, the role of miRNAs in tendon/ligament is sparse and uncharacterized in in vivo models. The objectives of this study were to address the function of DICER using mice with tendon/ligament-specific deletion of Dicer (Dicer conditional knockout; cKO), and to identify key miRNAs in tendon/ligament. Dicer cKO mice exhibited hypoplastic tendons through structurally abnormal collagen fibrils with downregulation of tendon-related genes. The fragility of tendon did not significantly affect the tensile strength of tendon in Dicer cKO mice, but they showed larger dorsiflexion angle in gait compared with Control mice. We identified two miRNAs, miR-135a and miR-1247, which were highly expressed in the Achilles tendon of Control mice and were downregulated in the Achilles tendon of Dicer cKO mice compared with Control mice. miR-135a mimic increased the expression of tendon-related genes in injured Achilles tendon-derived fibroblasts. In this study, Dicer cKO mice exhibited immature tendons in which collagen fibrils have small diameter with the downregulation of tendon-related genes such as transcriptional factor, extracellular matrix, and miRNAs. Thus, DICER plays an important role in tendon maturation, and miR-135a may have the potential to become key miRNA for tendon maturation and healing.
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Affiliation(s)
- Takenori Omoto
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Dilimulati Yimiti
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yohei Sanada
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Medical Center for Translational and Clinical Research, Hiroshima University Hospital, Hiroshima, Japan
| | - Minoru Toriyama
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Chenyang Ding
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yuta Hayashi
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of Musculoskeletal Traumatology and Reconstructive Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Yasunari Ikuta
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tomoyuki Nakasa
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Medical Center for Translational and Clinical Research, Hiroshima University Hospital, Hiroshima, Japan
| | - Masakazu Ishikawa
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of Artificial Joints and Biomaterials, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Masayuki Sano
- Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Minjung Lee
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | | | - Chisa Shukunami
- Department of Molecular Biology and Biochemistry, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Shigeru Miyaki
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Medical Center for Translational and Clinical Research, Hiroshima University Hospital, Hiroshima, Japan
- *Correspondence: Shigeru Miyaki,
| | - Nobuo Adachi
- Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
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8
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Nichols AEC, Muscat SN, Miller SE, Green LJ, Richards MS, Loiselle AE. Impact of isolation method on cellular activation and presence of specific tendon cell subpopulations during in vitro culture. FASEB J 2021; 35:e21733. [PMID: 34160846 DOI: 10.1096/fj.202100405r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/26/2021] [Accepted: 06/01/2021] [Indexed: 11/11/2022]
Abstract
Tendon injuries are common and heal poorly, due in part to a lack of understanding of fundamental tendon cell biology. A major impediment to the study of tendon cells is the absence of robust, well-characterized in vitro models. Unlike other tissue systems, current tendon cell models do not account for how differences in isolation methodology may affect the activation state of tendon cells or the presence of various tendon cell subpopulations. The objective of this study was to characterize how common isolation methods affect the behavior, fate, and lineage composition of tendon cell cultures. Tendon cells isolated by explant exhibited reduced proliferative capacity, decreased expression of tendon marker genes, and increased expression of genes associated with fibroblast activation compared to digested cells. Consistently, explanted cells also displayed an increased propensity to differentiate to myofibroblasts compared to digested cells. Explanted cultures from multiple different tendons were substantially enriched for the presence of scleraxis-lineage (Scx-lin+) cells compared to digested cultures, while the overall percentage of S100a4-lineage (S100a4-lin+) cells was dependent on both isolation method and tendon of origin. Neither isolation methods preserved the ratios of Scx-lin+ or S100a4-lin+ to non-lineage cells seen in tendons in vivo. Combined, these data indicate that further refinement of in vitro cultures models is required in order to more accurately understand the effects of various stimuli on tendon cell behavior. Statement of clinical significance: The development of informed in vitro tendon cell models will facilitate enhanced screening of potential therapeutic candidates to improve tendon healing.
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Affiliation(s)
- Anne E C Nichols
- Center for Musculoskeletal Research, Department of Orthopaedics & Rehabilitation, University of Rochester Medical Center, Rochester, NY, USA
| | - Samantha N Muscat
- Center for Musculoskeletal Research, Department of Orthopaedics & Rehabilitation, University of Rochester Medical Center, Rochester, NY, USA
| | - Sarah E Miller
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Luke J Green
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Michael S Richards
- Department of Biomedical Engineering, Rochester Institute of Technology, Rochester, NY, USA
| | - Alayna E Loiselle
- Center for Musculoskeletal Research, Department of Orthopaedics & Rehabilitation, University of Rochester Medical Center, Rochester, NY, USA
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9
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Abstract
The transcriptional regulators underlying induction and differentiation of dense connective tissues such as tendon and related fibrocartilaginous tissues (meniscus and annulus fibrosus) remain largely unknown. Using an iterative approach informed by developmental cues and single cell RNA sequencing (scRNA-seq), we establish directed differentiation models to generate tendon and fibrocartilage cells from mouse embryonic stem cells (mESCs) by activation of TGFβ and hedgehog pathways, achieving 90% induction efficiency. Transcriptional signatures of the mESC-derived cells recapitulate embryonic tendon and fibrocartilage signatures from the mouse tail. scRNA-seq further identify retinoic acid signaling as a critical regulator of cell fate switch between TGFβ-induced tendon and fibrocartilage lineages. Trajectory analysis by RNA sequencing define transcriptional modules underlying tendon and fibrocartilage fate induction and identify molecules associated with lineage-specific differentiation. Finally, we successfully generate 3-dimensional engineered tissues using these differentiation protocols and show activation of mechanotransduction markers with dynamic tensile loading. These findings provide a serum-free approach to generate tendon and fibrocartilage cells and tissues at high efficiency for modeling development and disease.
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Affiliation(s)
- Deepak A Kaji
- Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Angela M Montero
- Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Roosheel Patel
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Alice H Huang
- Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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10
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Huang Z, Yin Z, Xu J, Fei Y, Heng BC, Jiang X, Chen W, Shen W. Tendon Stem/Progenitor Cell Subpopulations and Their Implications in Tendon Biology. Front Cell Dev Biol 2021; 9:631272. [PMID: 33681210 PMCID: PMC7930382 DOI: 10.3389/fcell.2021.631272] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 01/27/2021] [Indexed: 12/28/2022] Open
Abstract
Tendon harbors a cell population that possesses stem cell characteristics such as clonogenicity, multipotency and self-renewal capacity, commonly referred to as tendon stem/progenitor cells (TSPCs). Various techniques have been employed to study how TSPCs are implicated in tendon development, homeostasis and healing. Recent advances in single-cell analysis have enabled much progress in identifying and characterizing distinct subpopulations of TSPCs, which provides a more comprehensive view of TSPCs function in tendon biology. Understanding the mechanisms of physiological and pathological processes regulated by TSPCs, especially a particular subpopulation, would greatly benefit treatment of diseased tendons. Here, we summarize the current scientific literature on the various subpopulations of TSPCs, and discuss how TSPCs can contribute to tissue homeostasis and pathogenesis, as well as examine the key modulatory signaling pathways that determine stem/progenitor cell state. A better understanding of the roles that TSPCs play in tendon biology may facilitate the development of novel treatment strategies for tendon diseases.
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Affiliation(s)
- Zizhan Huang
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Orthopedics Research Institute, Zhejiang University, Hangzhou, China.,Institute of Sports Medicine, Zhejiang University, Hangzhou, China
| | - Zi Yin
- Institute of Sports Medicine, Zhejiang University, Hangzhou, China.,Dr. Li Dak Sum and Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China.,China Orthopedic Regenerative Medicine (CORMed), Hangzhou, China
| | - Jialu Xu
- Department of Infectious Diseases, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yang Fei
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Orthopedics Research Institute, Zhejiang University, Hangzhou, China.,Institute of Sports Medicine, Zhejiang University, Hangzhou, China
| | - Boon Chin Heng
- School of Stomatology, Peking University, Beijing, China
| | - Xuesheng Jiang
- Department of Orthopedic Surgery, Huzhou Hospital, Zhejiang University, Huzhou, China
| | - Weishan Chen
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Orthopedics Research Institute, Zhejiang University, Hangzhou, China
| | - Weiliang Shen
- Department of Orthopedic Surgery, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.,Orthopedics Research Institute, Zhejiang University, Hangzhou, China.,Institute of Sports Medicine, Zhejiang University, Hangzhou, China.,Dr. Li Dak Sum and Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, China.,China Orthopedic Regenerative Medicine (CORMed), Hangzhou, China
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11
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Abstract
The identification of a gain-of-function mutation in CACNA1C as the cause of Timothy syndrome, a rare disorder characterized by cardiac arrhythmias and syndactyly, highlighted roles for the L-type voltage-gated Ca2+ channel CaV1.2 in nonexcitable cells. Previous studies in cells and animal models had suggested that several voltage-gated Ca2+ channels (VGCCs) regulated critical signaling events in various cell types that are not expected to support action potentials, but definitive data were lacking. VGCCs occupy a special position among ion channels, uniquely able to translate membrane excitability into the cytoplasmic Ca2+ changes that underlie the cellular responses to electrical activity. Yet how these channels function in cells not firing action potentials and what the consequences of their actions are in nonexcitable cells remain critical questions. The development of new animal and cellular models and the emergence of large data sets and unbiased genome screens have added to our understanding of the unanticipated roles for VGCCs in nonexcitable cells. Here, we review current knowledge of VGCC regulation and function in nonexcitable tissues and cells, with the goal of providing a platform for continued investigation.
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Affiliation(s)
- Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY 10021, USA;
| | - Maiko Matsui
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY 10021, USA;
| | - Chike Cao
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY 10021, USA;
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12
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Tsai SL, Nödl MT, Galloway JL. Bringing tendon biology to heel: Leveraging mechanisms of tendon development, healing, and regeneration to advance therapeutic strategies. Dev Dyn 2020; 250:393-413. [PMID: 33169466 DOI: 10.1002/dvdy.269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 12/11/2022] Open
Abstract
Tendons are specialized matrix-rich connective tissues that transmit forces from muscle to bone and are essential for movement. As tissues that frequently transfer large mechanical loads, tendons are commonly injured in patients of all ages. Following injury, mammalian tendons heal poorly through a slow process that forms disorganized fibrotic scar tissue with inferior biomechanical function. Current treatments are limited and patients can be left with a weaker tendon that is likely to rerupture and an increased chance of developing degenerative conditions. More effective, alternative treatments are needed. However, our current understanding of tendon biology remains limited. Here, we emphasize why expanding our knowledge of tendon development, healing, and regeneration is imperative for advancing tendon regenerative medicine. We provide a comprehensive review of the current mechanisms governing tendon development and healing and further highlight recent work in regenerative tendon models including the neonatal mouse and zebrafish. Importantly, we discuss how present and future discoveries can be applied to both augment current treatments and design novel strategies to treat tendon injuries.
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Affiliation(s)
- Stephanie L Tsai
- Center for Regenerative Medicine, Department of Orthopedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Marie-Therese Nödl
- Center for Regenerative Medicine, Department of Orthopedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Jenna L Galloway
- Center for Regenerative Medicine, Department of Orthopedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
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13
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De Micheli AJ, Swanson JB, Disser NP, Martinez LM, Walker NR, Oliver DJ, Cosgrove BD, Mendias CL. Single-cell transcriptomic analysis identifies extensive heterogeneity in the cellular composition of mouse Achilles tendons. Am J Physiol Cell Physiol 2020; 319:C885-C894. [PMID: 32877217 DOI: 10.1152/ajpcell.00372.2020] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Tendon is a dense connective tissue that stores and transmits forces between muscles and bones. Cellular heterogeneity is increasingly recognized as an important factor in the biological basis of tissue homeostasis and disease, yet little is known about the diversity of cell types that populate tendon. To address this, we determined the heterogeneity of cell populations within mouse Achilles tendons using single-cell RNA sequencing. In assembling a transcriptomic atlas of Achilles tendons, we identified 11 distinct types of cells, including three previously undescribed populations of tendon fibroblasts. Prior studies have indicated that pericytes, which are found in the vasculature of tendons, could serve as a potential source of progenitor cells for adult tendon fibroblasts. Using trajectory inference analysis, we provide additional support for the notion that pericytes are likely to be at least one of the progenitor cell populations for the fibroblasts that compose adult tendons. We also modeled cell-cell interactions and identified previously undescribed ligand-receptor signaling interactions involved in tendon homeostasis. Our novel and interactive tendon atlas highlights previously underappreciated heterogeneity between and within tendon cell populations. The atlas also serves as a resource to further the understanding of tendon extracellular matrix assembly and maintenance and in the design of therapies for tendinopathies.
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Affiliation(s)
- Andrea J De Micheli
- Hospital for Special Surgery, New York, New York.,Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York
| | | | | | | | - Nicholas R Walker
- Hospital for Special Surgery, New York, New York.,Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
| | | | - Benjamin D Cosgrove
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York
| | - Christopher L Mendias
- Hospital for Special Surgery, New York, New York.,Department of Physiology and Biophysics, Weill Cornell Medical College, New York, New York
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14
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Disser NP, De Micheli AJ, Schonk MM, Konnaris MA, Piacentini AN, Edon DL, Toresdahl BG, Rodeo SA, Casey EK, Mendias CL. Musculoskeletal Consequences of COVID-19. J Bone Joint Surg Am 2020; 102:1197-1204. [PMID: 32675661 PMCID: PMC7508274 DOI: 10.2106/jbjs.20.00847] [Citation(s) in RCA: 205] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Coronavirus disease 2019 (COVID-19) is an emerging pandemic disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the majority of patients who become infected with SARS-CoV-2 are asymptomatic or have mild symptoms, some patients develop severe symptoms that can permanently detract from their quality of life. SARS-CoV-2 is closely related to SARS-CoV-1, which causes severe acute respiratory syndrome (SARS). Both viruses infect the respiratory system, and there are direct and indirect effects of this infection on multiple organ systems, including the musculoskeletal system. Epidemiological data from the SARS pandemic of 2002 to 2004 identified myalgias, muscle dysfunction, osteoporosis, and osteonecrosis as common sequelae in patients with moderate and severe forms of this disease. Early studies have indicated that there is also considerable musculoskeletal dysfunction in some patients with COVID-19, although long-term follow-up studies have not yet been conducted. The purpose of this article was to summarize the known musculoskeletal pathologies in patients with SARS or COVID-19 and to combine this with computational modeling and biochemical signaling studies to predict musculoskeletal cellular targets and long-term consequences of the SARS-CoV-2 infection.
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Affiliation(s)
| | - Andrea J. De Micheli
- Hospital for Special Surgery, New York, NY
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY
| | | | | | | | | | | | | | | | - Christopher L. Mendias
- Hospital for Special Surgery, New York, NY
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY
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15
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Gumucio JP, Schonk MM, Kharaz YA, Comerford E, Mendias CL. Scleraxis is required for the growth of adult tendons in response to mechanical loading. JCI Insight 2020; 5:138295. [PMID: 32463804 DOI: 10.1172/jci.insight.138295] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/20/2020] [Indexed: 12/13/2022] Open
Abstract
Scleraxis is a basic helix-loop-helix transcription factor that plays a central role in promoting tenocyte proliferation and matrix synthesis during embryonic tendon development. However, the role of scleraxis in the growth and adaptation of adult tendons is not known. We hypothesized that scleraxis is required for tendon growth in response to mechanical loading and that scleraxis promotes the specification of progenitor cells into tenocytes. We conditionally deleted scleraxis in adult mice using a tamoxifen-inducible Cre-recombinase expressed from the Rosa26 locus (ScxΔ) and then induced tendon growth in Scx+ and ScxΔ adult mice via plantaris tendon mechanical overload. Compared with the WT Scx+ group, ScxΔ mice demonstrated blunted tendon growth. Transcriptional and proteomic analyses revealed significant reductions in cell proliferation, protein synthesis, and extracellular matrix genes and proteins. Our results indicate that scleraxis is required for mechanically stimulated adult tendon growth by causing the commitment of CD146+ pericytes into the tenogenic lineage and by promoting the initial expansion of newly committed tenocytes and the production of extracellular matrix proteins.
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Affiliation(s)
- Jonathan P Gumucio
- Department of Molecular & Integrative Physiology and.,Department of Orthopaedic Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Yalda A Kharaz
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, and Medical Research Council Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing, University of Liverpool, Liverpool, United Kingdom
| | - Eithne Comerford
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, and Medical Research Council Versus Arthritis Centre for Integrated Research into Musculoskeletal Ageing, University of Liverpool, Liverpool, United Kingdom
| | - Christopher L Mendias
- Department of Molecular & Integrative Physiology and.,Department of Orthopaedic Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Hospital for Special Surgery, New York, New York, USA.,Department of Physiology & Biophysics, Weill Cornell Medical College, New York, New York, USA
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