Generation of Human-Induced Pluripotent Stem Cells From Anterior Cruciate Ligament.

Human-induced pluripotent stem cells (hiPSCs) are reprogrammed somatic cells and are an excellent cell source for tissue engineering applications, disease modeling, and for understanding human development. HiPSC lines have now been generated from a diverse range of somatic cell types and have been reported to retain an epigenetic memory of their somatic origin. To date, the reprogramming of a true ligament has not been reported.

Enhanced chondrogenesis from human embryonic stem cells.

Human embryonic stem cells (hESCs) have great potential for the repair of damaged articular cartilage. We developed a serum-free 14-day protocol for hESC differentiation into chondrocyte progenitors, which surprisingly lacked strong cartilage matrix production in in vitro tests. In order to direct these progenitors to a more mature phenotype, we investigated substituting different members of the TGFβ family in the protocol.

Identification of long non-coding RNAs expressed in knee and hip osteoarthritic cartilage.

Objective: Long intergenic non-coding RNAs (lincRNAs) are emerging as key regulators in gene expression; however, little is known about the lincRNA expression changes that occur in osteoarthritis (OA). Here we aimed to define a transcriptome of lncRNAs in OA cartilage, specifically comparing the lincRNA transcriptome of knee and hip cartilage.

Method: RNA-seq was performed on nucleic acid extracted from hip cartilage from patients undergoing joint replacement surgery because of either OA (n = 10) or because of a neck of femur fracture (NOF; n = 6).

SkeletalVis: an exploration and meta-analysis data portal of cross-species skeletal transcriptomics data.

Motivation: Skeletal diseases are prevalent in society, but improved molecular understanding is required to formulate new therapeutic strategies. Large and increasing quantities of available skeletal transcriptomics experiments give the potential for mechanistic insight of both fundamental skeletal biology and skeletal disease. However, no current repository provides access to processed, readily interpretable analysis of this data.

Stratification of knee osteoarthritis: two major patient subgroups identified by genome-wide expression analysis of articular cartilage.

Introduction: Osteoarthritis (OA) is a heterogeneous and complex disease. We have used a network biology approach based on genome-wide analysis of gene expression in OA knee cartilage to seek evidence for pathogenic mechanisms that may distinguish different patient subgroups.

Methods: Results from RNA-Sequencing (RNA-Seq) were collected from intact knee cartilage at total knee replacement from 44 patients with OA, from 16 additional patients with OA and 10 control patients with non-OA.

PhenomeScape: a cytoscape app to identify differentially regulated sub-networks using known disease associations.

Unlabelled: PhenomeScape is a Cytoscape app which provides easy access to the PhenomeExpress algorithm to interpret gene expression data. PhenomeExpress integrates protein interaction networks with known phenotype to gene associations to find active sub-networks enriched in differentially expressed genes. It also incorporates cross-species phenotypes and associations to include results from animal models of disease.

Chondrocytes Derived From Mesenchymal Stromal Cells and Induced Pluripotent Cells of Patients With Familial Osteochondritis Dissecans Exhibit an Endoplasmic Reticulum Stress Response and Defective Matrix Assembly.

Unlabelled: : Familial osteochondritis dissecans (FOCD) is an inherited skeletal defect characterized by the development of large cartilage lesions in multiple joints, short stature, and early onset of severe osteoarthritis. It is associated with a heterozygous mutation in the ACAN gene, resulting in a Val-Met replacement in the C-type lectin domain of aggrecan. To understand the cellular pathogenesis of this condition, we studied the chondrogenic differentiation of patient bone marrow mesenchymal stromal cells (BM-MSCs).

Gene expression changes in damaged osteoarthritic cartilage identify a signature of non-chondrogenic and mechanical responses.

Objectives: Joint degeneration in osteoarthritis (OA) is characterised by damage and loss of articular cartilage. The pattern of loss is consistent with damage occurring only where the mechanical loading is high. We have investigated using RNA-sequencing (RNA-seq) and systems analyses the changes that occur in damaged OA cartilage by comparing it with intact cartilage from the same joint.

The development of a mature collagen network in cartilage from human bone marrow stem cells in Transwell culture.

Damaged hyaline cartilage shows a limited capacity for innate repair. Potential sources of cells to augment the clinical repair of cartilage defects include autologous chondrocytes and mesenchymal stem cells. We have reported that culture of human bone marrow mesenchymal stem cells with specific growth and differentiation factors as shallow multilayers on Transwell permeable membranes provided ideal conditions for chondrogenesis.

PhenomeExpress: a refined network analysis of expression datasets by inclusion of known disease phenotypes.

We describe a new method, PhenomeExpress, for the analysis of transcriptomic datasets to identify pathogenic disease mechanisms. Our analysis method includes input from both protein-protein interaction and phenotype similarity networks. This introduces valuable information from disease relevant phenotypes, which aids the identification of sub-networks that are significantly enriched in differentially expressed genes and are related to the disease relevant phenotypes.

Cartilage repair using human embryonic stem cell-derived chondroprogenitors.

In initial work, we developed a 14-day culture protocol under potential GMP, chemically defined conditions to generate chondroprogenitors from human embryonic stem cells (hESCs). The present study was undertaken to investigate the cartilage repair capacity of these cells. The chondrogenic protocol was optimized and validated with gene expression profiling.

Assembly of the respiratory mucin MUC5B: a new model for a gel-forming mucin.

Mucins are essential components in mucus gels that form protective barriers at all epithelial surfaces, but much remains unknown about their assembly, intragranular organization, and post-secretion unfurling to form mucus. MUC5B is a major polymeric mucin expressed by respiratory epithelia, and we investigated the molecular mechanisms involved during its assembly. Studies of intact polymeric MUC5B revealed a single high affinity calcium-binding site, distinct from multiple low affinity sites on each MUC5B monomer.

Generating cartilage repair from pluripotent stem cells.

The treatment of degeneration and injury of articular cartilage has been very challenging for scientists and surgeons. As an avascular and hypocellular tissue, cartilage has a very limited capacity for self-repair. Chondrocytes are the only cell type in cartilage, in which they are surrounded by the extracellular matrix that they secrete and assemble.

Fat pad-derived mesenchymal stem cells as a potential source for cell-based adipose tissue repair strategies.

Background: Mesenchymal stem cells are able to undergo adipogenic differentiation and present a possible alternative cell source for regeneration and replacement of adipose tissue. The human infrapatellar fat pad is a promising source of mesenchymal stem cells with many source advantages over from bone marrow. It is important to determine whether a potential mesenchymal stem-cell exhibits tri-lineage differentiation potential and is able to maintain its proliferation potential and cell-surface characterization on expansion in tissue culture.

Cartilage tissue engineering approaches applicable in orthopaedic surgery: the past, the present, and the future.

Tissue is frequently damaged or lost in injury and disease. There has been an increasing interest in stem cell applications and tissue engineering approaches in surgical practice to deal with damaged or lost tissue. Although there have been developments in almost all surgical disciplines, the greatest advances are being made in orthopaedics, especially in cartilage repair.

The characterisation of mesenchymal stem cells: a stem cell is not a stem cell is not a stem cell.

There has been an increasing interest in stem cell applications and tissue engineering approaches in surgical practice to deal with damaged or lost tissue. Although there have been developments in almost all surgical disciplines, the greatest advances are being made in orthopaedics. This is due to many factors including the familiarity with bone marrow derived mesenchymal stem cells.

Mesenchymal stem cells, sources of cells and differentiation potential.

Tissue is frequently damaged or lost in injury and disease. There has been an increasing interest in stem cell applications and tissue engineering approaches in surgical practice to deal with damaged or lost tissue. Tissue engineering is an exciting strategy being explored to deal with damaged or lost tissue.

Cell- and tissue-based approaches for cartilage repair.

Damage and degeneration of articular joints is a major healthcare concern, due to the association of joint disease with ageing, the current strong demographic changes in the proportion of elderly in the population, and the increased incidence of trauma in a sports-active younger population. These joints are biomechanical organs that transmit load between bones in our skeleton, and the articular cartilage forms a load-bearing surface that covers the bone within the joints. All the forces across the joints are thus transmitted through the cartilage, and it therefore makes an important biomechanical contribution to joint function.

Directed differentiation of human embryonic stem cells toward chondrocytes.

We report a chemically defined, efficient, scalable and reproducible protocol for differentiation of human embryonic stem cells (hESCs) toward chondrocytes. HESCs are directed through intermediate developmental stages using substrates of known matrix proteins and chemically defined media supplemented with exogenous growth factors. Gene expression analysis suggests that the hESCs progress through primitive streak or mesendoderm to mesoderm, before differentiating into a chondrocytic culture comprising cell aggregates.

Order within disorder: aggrecan chondroitin sulphate-attachment region provides new structural insights into protein sequences classified as disordered.

Structural investigation of proteins containing large stretches of sequences without predicted secondary structure is the focus of much increased attention. Here, we have produced an unglycosylated 30 kDa peptide from the chondroitin sulphate (CS)-attachment region of human aggrecan (CS-peptide), which was predicted to be intrinsically disordered and compared its structure with the adjacent aggrecan G3 domain. Biophysical analyses, including analytical ultracentrifugation, light scattering, and circular dichroism showed that the CS-peptide had an elongated and stiffened conformation in contrast to the globular G3 domain.

Fell-Muir lecture: cartilage 2010 - the known unknowns.

Over the past 40 years there have been giant steps forward in our understanding of cellular and molecular biology that have given us the framework by which to understand tissue organization and tissue function on a range of scales. However, although the progress has been great, the more we have discovered, the more we are aware of what we don't yet know. In this article, I would like to flag up some issues of cartilage biology, function and pathology where we still have significant ignorance.

Bone marrow-derived mesenchymal stem cells express the pericyte marker 3G5 in culture and show enhanced chondrogenesis in hypoxic conditions.

Bone marrow-derived mesenchymal stem cells are a potential source of cells for the repair of articular cartilage defects. Hypoxia has been shown to improve chondrogenesis in some cells. In this study, bone marrow-derived stem cells were characterized and the effects of hypoxia on chondrogenesis investigated.

The potential of stem cells in the treatment of knee cartilage defects.

Cartilage is frequently damaged but only shows a limited capacity for repair. There are a number of treatment strategies currently available for the repair of articular cartilage defects including abrasion chondroplasty, subchondral drilling, microfracture and mosaicplasty but these show variable results. For the younger patients, there is great interest in the potential of cell-based strategies to provide a biological replacement of damaged cartilage using autologous chondrocytes.