Project description:The anterior cruciate ligament (ACL) is an essential stabilizer of the tibiofemoral articulation. ACL tears often lead to functional instability and are associated with an increased risk for osteoarthritis. The healing potential of the injured ACL is poorly understood and is considered to be limited. Transcriptome-wide expression profiles of 24 human ACL remnants recovered at the time of surgical reconstruction were analyzed utilizing the Agilent human 8x60K microarray platform. Gene ontology was performed on differentially expressed transcripts based on time-from-injury (acute, <3 months; intermediate, 3-12 months; chronic, >12 months). A subset of transcripts was validated via microfluidic digital polymerase-chain-reaction. Expression of periostin, a highly differentially expressed transcript, was tested by immunohistochemistry. Numerous transcripts covering important functional classifications were differentially expressed by time-from-injury. In acute tears, processes representing angiogenesis were repressed while those representing stem-cell differentiation were elevated. In intermediate tears, processes representing stem-cell proliferation concomitant with cellular component organization/cellular localization were elevated. In chronic tears, processes denoting myosin filament organization were elevated while those representing cellular component organization/cell localization and extracellular matrix organization were repressed. Expression levels of periostin were down-regulated in chronic tears compared to acute (42-fold) and intermediate (29-fold) tears. Immunohistochemistry confirmed a decline in periostin expression in tissues from chronic tears. These findings suggest an initial attempt of the injured ACL to repair, which declines with time-from-injury. These findings have implications for efforts to repair the ACL and may be relevant for reconstruction of the ACL. The functional role of periostin in ACL injuries, and the potential implication for surgical treatment, warrants further investigation. Total RNA obtained frominjured anterior cruciate ligament (ACL) tissues from pateints undergoing ACL surgery.
Project description:Injury to anterior cruciate ligament (ACL) is common in young individuals and a frequent cause of functional instability and early onset of osteoarthritis. The healing potential of an injured ACL is known to decay over time. The molecular origin of this healing deficiency largely remains elusive but plausibly involves gene transcripts associated with tissue healing. To explore this possibility, we set out to identify transcript expression differences in injured ACL remnants recovered at the time of surgical reconstruction, via microarray (n=24) and RNA-seq (n=8) technologies in transcriptome profiling. We found that time-from-injury was an important determinant of changes in gene expression signatures predominately resulting in repression of several biological processes as identified by gene ontology. The most interesting observation was a time-dependent decline in the gene transcripts as well as the biological processes common to both microarray and RNA-seq analyses. Compared to acute tears, in chronic several important biological processes were namely extracellular matrix organization, angiogenesis, cell adhesion, wound healing, mesenchyme transition, and response to hypoxia. Furthermore, the cross-platform concordance in terms of differentially expressed transcripts or enriched pathways was linearly correlated (r=0.64). Microfluidic digital PCR confirmed the expression of selected differentially expressed transcripts. These intriguing findings suggest an initial attempt of the injured ACL to repair, which drops with time. These findings have implications for efforts to repair the ACL and may be relevant for its reconstruction. These findings also emphasize the utility of differentially expressed transcripts as prognostic biomarkers in patients with ACL injury. Examination of transcript expression differences by time-from-injury in anterior cruciate ligament
Project description:The anterior cruciate ligament (ACL) is an essential stabilizer of the tibiofemoral articulation. ACL tears often lead to functional instability and are associated with an increased risk for osteoarthritis. The healing potential of the injured ACL is poorly understood and is considered to be limited. Transcriptome-wide expression profiles of 24 human ACL remnants recovered at the time of surgical reconstruction were analyzed utilizing the Agilent human 8x60K microarray platform. Gene ontology was performed on differentially expressed transcripts based on time-from-injury (acute, <3 months; intermediate, 3-12 months; chronic, >12 months). A subset of transcripts was validated via microfluidic digital polymerase-chain-reaction. Expression of periostin, a highly differentially expressed transcript, was tested by immunohistochemistry. Numerous transcripts covering important functional classifications were differentially expressed by time-from-injury. In acute tears, processes representing angiogenesis were repressed while those representing stem-cell differentiation were elevated. In intermediate tears, processes representing stem-cell proliferation concomitant with cellular component organization/cellular localization were elevated. In chronic tears, processes denoting myosin filament organization were elevated while those representing cellular component organization/cell localization and extracellular matrix organization were repressed. Expression levels of periostin were down-regulated in chronic tears compared to acute (42-fold) and intermediate (29-fold) tears. Immunohistochemistry confirmed a decline in periostin expression in tissues from chronic tears. These findings suggest an initial attempt of the injured ACL to repair, which declines with time-from-injury. These findings have implications for efforts to repair the ACL and may be relevant for reconstruction of the ACL. The functional role of periostin in ACL injuries, and the potential implication for surgical treatment, warrants further investigation.
Project description:The hamstring tendon is used as autograft in surgical reconstruction of tears of the anterior cruciate ligament. The rate of re-rupture after surgery is higher in younger patients. The aim of the study was to identify molecular mechanisms that underlie the greater susceptibility of tendon from younger people to tear.
Project description:Patients with anterior cruciate ligament (ACL) tears have a significantly increased risk for developing knee osteoarthritis. These injuries often result in a knee effusion in response to the injury. Early changes in these effusions could be informative regarding initial steps in the development of post traumatic osteoarthritis. The purpose of this study was to test the hypothesis that the proteomics of knee synovial fluid changes over time following ACL injury.
Project description:36 Yucatan minipigs underwent anterior cruciate ligament (ACL) transection and were randomly assigned in equal numbers to no further treatment, reconstruction or ligament repair. Cartilage was harvested at 1 and 4 weeks post-operatively and histology and RNA-sequencing performed. The generated data served to identify the molecular pathophysiology present in early post-traumatic osteoarthritis (PTOA), as well as differences between surgical treatments.
Project description:36 Yucatan minipigs underwent anterior cruciate ligament (ACL) transection and were randomly assigned in equal numbers to no further treatment, reconstruction or ligament repair. Peri-meniscal synovium was harvested at 1 and 4 weeks post-operatively and histology and RNA-sequencing performed. The generated data served to identify the molecular pathophysiology present in inflamed synovium during the early development of post-traumatic osteoarthritis (PTOA), as well as differences between surgical treatments.
Project description:Injury to anterior cruciate ligament (ACL) is common in young individuals and a frequent cause of functional instability and early onset of osteoarthritis. The healing potential of an injured ACL is known to decay over time. The molecular origin of this healing deficiency largely remains elusive but plausibly involves gene transcripts associated with tissue healing. To explore this possibility, we set out to identify transcript expression differences in injured ACL remnants recovered at the time of surgical reconstruction, via microarray (n=24) and RNA-seq (n=8) technologies in transcriptome profiling. We found that time-from-injury was an important determinant of changes in gene expression signatures predominately resulting in repression of several biological processes as identified by gene ontology. The most interesting observation was a time-dependent decline in the gene transcripts as well as the biological processes common to both microarray and RNA-seq analyses. Compared to acute tears, in chronic several important biological processes were namely extracellular matrix organization, angiogenesis, cell adhesion, wound healing, mesenchyme transition, and response to hypoxia. Furthermore, the cross-platform concordance in terms of differentially expressed transcripts or enriched pathways was linearly correlated (r=0.64). Microfluidic digital PCR confirmed the expression of selected differentially expressed transcripts. These intriguing findings suggest an initial attempt of the injured ACL to repair, which drops with time. These findings have implications for efforts to repair the ACL and may be relevant for its reconstruction. These findings also emphasize the utility of differentially expressed transcripts as prognostic biomarkers in patients with ACL injury.
Project description:Anterior cruciate ligament (ACL) tears occur in isolation or in combination with other intra-articular injuries such as meniscus tears. The impact of injury pattern on the molecular biology of the injured ACL is unknown. Here, we tested the hypothesis that the biological response of the ACL to injury varies based on the presence or absence of concomitant meniscus tear. RNA-seq analysis was performed on 28 ACL tears remnants (12 isolated, 16 combined). 16,654 transcripts were differentially-expressed between isolated and combined injury groups at false-discovery-rate of 0.05. Due to the large number of differentially expressed transcripts, we undertook an Ensembl approach to discover features that acted as hub-genes that did not necessarily have large fold-changes or high statistical significance, but instead had high biological significance. Our data revealed a negatively-correlated turquoise-module containing 5960 transcripts (down-regulated in combined injury) and a positively-correlated blue-module containing 2260 transcripts (up-regulated in combined injury). TNS1, MEF2D, NOTCH3, SOGA1, and MLXIP were highly-connected hub-genes in the turquoise-module and SCN2A, CSMD3, LRC44, USH2A, and LRP1B were critical hub-genes in the blue-module. Transcripts in the turquoise-module were associated with biological-adhesion, actin-filament organization, cell-junction assembly, and cell-matrix adhesion. The blue-module transcripts were enriched for neuron-migration and exocytosis-regulation. These findings indicate a loss of healing and gain of neurogenic signaling in combined ACL and meniscus tears, suggesting they have diminished potential for repair. The biological response of the ACL to injury could have implications for the healing potential of the ligament and the long-term health of the knee.