Immunophenotyping of Synovial Tissue in Adolescents Undergoing ACL Reconstruction: What Is the Role of Synovial Inflammation in Arthrofibrosis?

Background: Loss of motion and arthrofibrosis after anterior cruciate ligament (ACL) reconstruction (ACLR) can be devastating complications for athletes. The cellular and molecular pathogenesis of arthrofibrosis is poorly understood, limiting prevention and treatment options. Synovial inflammation may contribute to post-ACLR arthrofibrosis.

Harmonization and standardization of nucleus pulposus cell extraction and culture methods.

Background: In vitro studies using nucleus pulposus (NP) cells are commonly used to investigate disc cell biology and pathogenesis, or to aid in the development of new therapies. However, lab-to-lab variability jeopardizes the much-needed progress in the field. Here, an international group of spine scientists collaborated to standardize extraction and expansion techniques for NP cells to reduce variability, improve comparability between labs and improve utilization of funding and resources.

Orthopaedic Implant Coatings: Recent Approaches and Clinical Translation.

Despite improved surgical techniques and prophylactic procedures, orthopaedic implant-associated infections remain high with complications that can lead to devastating outcomes for the patient. Implant coatings and associated surface modification techniques represent a promising means to prevent infections. Various approaches have emerged to address the challenges associated with implant infections, such as antibacterial resistance, biofilm prevention, and appropriate efficacy kinetics.

Promoting Bone Formation and Healing in Segmental Defects Through Ectopic Induced Membrane.

We aimed to determine whether addition of an in vivo ectopic induced membrane (EM) to the Masquelet Technique enhanced angiogenesis and bone formation in a segmental defect. After generating and stabilizing a diaphyseal femur defect, 10 rats received a polymethylmethacrylate (PMMA) spacer within the defect (control); 10 received another PMMA spacer implanted subcutaneously (EM). We removed the spacers and added autograft; the excised EM was added to their autograft (EM group).

Verteporfin treatment controls morphology, phenotype, and global gene expression for cells of the human nucleus pulposus.

Cells of the nucleus pulposus (NP) are essential contributors to extracellular matrix synthesis and function of the intervertebral disc. With age and degeneration, the NP becomes stiffer and more dehydrated, which is associated with a loss of phenotype and biosynthetic function for its resident NP cells. Also, with aging, the NP cell undergoes substantial morphological changes from a rounded shape with pronounced vacuoles in the neonate and juvenile, to one that is more flattened and spread with a loss of vacuoles.

Mechanosensitive transcriptional coactivators MRTF-A and YAP/TAZ regulate nucleus pulposus cell phenotype through cell shape.

Cells of the adult nucleus pulposus (NP) are critically important in maintaining overall disc health and function. NP cells reside in a soft, gelatinous matrix that dehydrates and becomes increasingly fibrotic with age. Such changes result in physical cues of matrix stiffness that may be potent regulators of NP cell phenotype and may contribute to a transition toward a senescent and fibroblastic NP cell with a limited capacity for repair.

Mechanotransduction and cell biomechanics of the intervertebral disc.

Mechanical loading of the intervertebral disc (IVD) initiates cell-mediated remodeling events that contribute to disc degeneration. Cells of the IVD, nucleus pulposus (NP) and anulus fibrosus (AF), will exhibit various responses to different mechanical stimuli which appear to be highly dependent on loading type, magnitude, duration, and anatomic zone of cell origin. Cells of the NP, the innermost region of the disc, exhibit an anabolic response to low-moderate magnitudes of static compression, osmotic pressure, or hydrostatic pressure, while higher magnitudes promote a catabolic response marked by increased protease expression and activity.

Regulation of human nucleus pulposus cells by peptide-coupled substrates.

Unlabelled: Nucleus pulposus (NP) cells are derived from the notochord and differ from neighboring cells of the intervertebral disc in phenotypic marker expression and morphology. Adult human NP cells lose this phenotype and morphology with age in a pattern that contributes to progressive disc degeneration and pathology. Select laminin-mimetic peptide ligands and substrate stiffnesses were examined for their ability to regulate human NP cell phenotype and biosynthesis through the expression of NP-specific markers aggrecan, N-cadherin, collagen types I and II, and GLUT1.

In vitro response of macrophage polarization to a keratin biomaterial.

Macrophage response to biomaterials is emerging as a major focus in tissue repair and wound healing. Macrophages are able to differentiate into two distinct states, eliciting divergent effects. The M1 phenotype is considered pro-inflammatory and up-regulates activity related to tissue destruction, whereas the M2 phenotype is considered anti-inflammatory and supports tissue remodeling.