Modulation of mesenchymal stem cell genotype and phenotype by extracellular matrix proteins.

Aim: To investigate the effect of extracellular matrix (ECM) proteins on characteristics of mesenchymal stem cells (MSCs) and tendon-derived cells (TDCs).

Materials And Methods: MSCs and TDCs, cultured in a monolayer (2D) or hydrogels (3D), with or without ECM protein supplementation, and on a non-viable native tendon (NNT) matrix were assayed for adhesion, proliferation, gene expression, and integrin expression.

Results: MSCs exhibited a fibroblastic, spindle-shaped morphology on 2D matrices except in the presence of fibronectin.

Exposure of a tendon extracellular matrix to synovial fluid triggers endogenous and engrafted cell death: A mechanism for failed healing of intrathecal tendon injuries.

Aim: The purpose of this study was to investigate the effect of normal synovial fluid (SF) on exposed endogenous tendon-derived cells (TDCs) and engrafted mesenchymal stem cells (MSCs) within the tendon extracellular matrix.

Methods: Explants from equine superficial digital flexor (extra-synovial) and deep digital flexor tendons (DDFTs) from the compressed, intra-synovial and the tensile, extra-synovial regions were cultured in allogeneic or autologous SF-media. Human hamstring explants were cultured in allogeneic SF.

Mineralization of the Equine Palmar/Plantar Annular Ligament Treated by Surgical Resection.

Objective: To document the clinical presentation, diagnosis, and surgical treatment of mineralization of the equine palmar/plantar annular ligament (PAL).

Study Design: Retrospective study.

Animals: Ponies (n=7).

Influence of commonly used pharmaceutical agents on equine bone marrow-derived mesenchymal stem cell viability.

Reason For Performing Study: To provide evidence to support recommendations regarding the co-administration of drugs with mesenchymal stem cell (MSC) therapy.

Objectives: To determine the influence of sedatives, local anaesthetic and corticosteroids on MSC viability and proliferation, in comparison to somatic cells derived from tendon (TDCs).

Study Design: In vitro cell culture.

The current 'state of play' of regenerative medicine in horses: what the horse can tell the human.

The horse is an attractive model for many human age-related degenerative diseases of the musculoskeletal system because it is a large animal species that both ages and exercises, and develops naturally occurring injuries with many similarities to the human counterpart. It therefore represents an ideal species to use as a 'proving ground' for new therapies, most notably regenerative medicine. Regenerative techniques using cell-based therapies for the treatment of equine musculoskeletal disease have been in use for over a decade.

Viability of equine mesenchymal stem cells during transport and implantation.

Introduction: Autologous mesenchymal stem cell (MSC) injection into naturally-occurring equine tendon injuries has been shown to be safe and efficacious and protocols inform translation of the technique into humans. Efficient transfer of cells from the laboratory into tissue requires well-validated transport and implantation techniques.

Methods: Cell viability in a range of media was determined over 72 hours and after injection through a 19G, 21G or 23G needle.

Equine mesenchymal stromal cells and embryo-derived stem cells are immune privileged in vitro.

Introduction: Autologous mesenchymal stem cells (MSCs) are an attractive concept in regenerative medicine, but their mechanism of action remains poorly defined. No immune response is reported after in vivo injection of allogeneic equine MSCs or embryo-derived stem cells (ESCs) into the equine tendon, which may be due to the cells' immune-privileged properties. This study further investigates these properties to determine their potential for clinical application in other tissues.

Mesenchymal stem cells modulate release of matrix proteins from tendon surfaces in vitro: a potential beneficial therapeutic effect.

Aim: Injury of tendons contained within a synovial environment, such as joint, bursa or tendon sheath, frequently fails to heal and releases matrix proteins into the synovial fluid, driving inflammation. This study investigated the effectiveness of cells to seal tendon surfaces and provoke matrix synthesis as a possible effective injectable therapy.

Materials & Methods: Equine flexor tendon explants were cultured overnight in suspensions of bone marrow and synovium-derived mesenchymal stems cells and, as controls, two sources of fibroblasts, derived from tendon and skin, which adhered to the explants.

Biomarkers of cartilage turnover. Part 1: Markers of collagen degradation and synthesis.

Type II collagen is a major component of articular cartilage and its breakdown is a key feature of osteoarthritis. Products of cartilage collagen metabolism can be detected in the blood, synovial fluid and urine. Several biomarker assays have been developed which can be used to measure the synthesis and degradation of collagen, and therefore provide information regarding cartilage turnover.

Biomarkers of cartilage turnover. Part 2: Non-collagenous markers.

Osteoarthritis (OA) results in the destruction and breakdown of articular cartilage matrix. Breakdown of the cartilage proteoglycan component results in the generation of constituent fragments that can be detected in the blood, synovial fluid or urine. Non-collagenous, non-proteoglycan components of cartilage can also be detected following their release as a result of turnover and disease.

MMP-mediated collagen breakdown induced by activated protein C in equine cartilage is reduced by corticosteroids.

The plasma serine protease activated protein C (APC) is synthesized by human chondrocytes at sites of pathological cartilage fibrillation. APC levels are increased in osteoarthritis (OA) synovial fluid, and in vitro APC has been shown to synergize with interleukin-1beta (IL-1) to promote degradation from ovine cartilage. A model of equine cartilage degradation was established and used to explore corticosteroid activities.

MT3-MMP (MMP-16) is downregulated by in vitro cytokine stimulation of cartilage, but unaltered in naturally occurring equine osteoarthritis and osteochondrosis.

Matrix degradation by metalloproteinases is considered a key feature in the loss of articular cartilage seen in many joint diseases. Membrane-type matrix metalloproteinase-3 (MT3-MMP) expression is elevated in human cartilage in end-stage osteoarthritis. We investigated whether MT3-MMP is similarly regulated in cartilage in two naturally occurring arthropathies in vivo and whether proinflammatory cytokines regulate its expression in vitro.

Chondrocytes harvested from osteochondritis dissecans cartilage are able to undergo limited in vitro chondrogenesis despite having perturbations of cell phenotype in vivo.

Our objective was to characterize the variation in gene expression for key genes associated with chondrogenic phenotype of osteochondrosis (OC)-affected and normal chondrocytes, and to identify whether OC chondrocytes can redifferentiate and regain a phenotype similar to normal chondrocytes if appropriate chondrogenic signals are given. Equine articular cartilage removed at surgery to treat clinically significant OC lesions was collected (n = 10), and the gene expression evaluated and compared to aged-matched normal samples (n = 10). Cartilage was harvested from normal (n = 4) and OC (n = 3) joints from horses at necropsy.