Toughening mechanisms for the attachment of architectured materials: The mechanics of the tendon enthesis.
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ABSTRACT:
SUBMITTER: Golman M
PROVIDER: S-EPMC8626067 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:On May 22, 2017, the National Institutes of Health (NIH)/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) hosted a roundtable on "Innovative Treatments for Enthesis Repair." A summary of the roundtable discussion, as well as a list of the extramural participants, can be found at https://www.niams.nih.gov/about/meetings-events/roundtables/roundtable-innovative-treatments-enthesis-repair. This paper reviews the challenges and opportunities for developing effective treatment strategies for enthesis repair that were identified at the roundtable discussion.
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Project description:The attachment of dissimilar materials is a major engineering challenge, yet this challenge is seemingly overcome in biology. This study aimed to determine how the transcription factor Scleraxis (Scx) influences the development and maturation of the tendon-to-bone attachment (enthesis). Mice with conditional knockout (cKO) for Scx (Scx(flx/-), Prx1Cre(+)) and wild-type [(WT) Scx(flx/+) or Scx(flx/flx)] littermates were killed at postnatal days 7-56 (P7-P56). Enthesis morphometry, histology, and collagen alignment were investigated throughout postnatal growth. Enthesis tensile mechanical properties were also assessed. Laser microdissection of distinct musculoskeletal tissues was performed at P7 for WT, cKO, and muscle-unloaded (botulinum toxin A treated) attachments for quantitative PCR. cKO mice were smaller, with altered bone shape and impaired enthesis morphology, morphometry, and organization. Structural alterations led to altered mechanical properties; cKO entheses demonstrated reduced strength and stiffness. In P7 attachments, cKO mice had reduced expression of transforming growth factor (TGF) superfamily genes in fibrocartilage compared with WT mice. In conclusion, deletion of Scx led to impairments in enthesis structure, which translated into impaired functional (i.e., mechanical) outcomes. These changes may be driven by transient signaling cues from mechanical loading and growth factors.
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Project description:Our studies used scRNA-seq analysis to get a full map of transcriptional profiles of enthesis cells and also a seprate Gli1-lineage enthesis stem cells. By harvesting enthesis cells from different development stages for scRNA-seq analysis, we revealed enthesis cell heterogeneity and identified six cell sub-populations using scRNA-seq. We infered cell differentiation trajectories for enthesis stem cells differentiating into mineralizing chondrocytes. A gene regulatory network analysis combined fluorescent in situ hybridization were then used to identify a number of transcription factors coordinating tenogenesis, chondrogenesis, and osteogenesis to form an enthesis with spatially graded mineralization.To further define the enthesis stem cell population, enthesis Gli1-lineage cells were isolated and their transcriptomes were characterized at single cell resolution. These specific Gli1-responsive cells had a linear trajectory and a capacity of chondrogenesis and osteogenesis. The full characterization of transcriptional landscape of tendon enthesis stem cells demonstrates a promising therapeutic strategies using this cell source for enthesis regeneration.
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