The Effect of CoQ10 supplementation on ART treatment and oocyte quality in older women.

A significant problem associated with assisted reproductive technologies (ART) is recurrent treatment failure which can be attributed to the age-associated decline in oocyte quality. Co-enzyme Q10 (CoQ10) is an antioxidant and essential component of the mitochondrial electron transport chain. It is reported that de novo CoQ10 production declines with ageing and coincides with age-related decline in fertility, leading to CoQ10 supplementation being advocated to enhance response to ovarian stimulation and improve oocyte quality. CoQ10 supplementation was found to improve fertilization rates, embryo maturation rates and embryo quality when used before and during in vitro fertilization (IVF) and in vitro maturation (IVM) treatment in women aged 31 and over. Regarding oocyte quality, CoQ10 was able to reduce high rates of chromosomal abnormalities and oocyte fragmentation, as well as improve mitochondrial function. Proposed mechanisms of CoQ10 function include restoration of reactive oxygen species imbalance, preventing DNA damage and oocyte apoptosis, as well as restoration of Krebs cycle downregulation from ageing. In this literature review, we provide an overview of the use of CoQ10 in improving the success of IVF and IVM in older women, and additionally assess the impact of CoQ10 on oocyte quality and discuss potential mechanisms of action by CoQ10 on the oocyte.

Physioxia Promotes the Articular Chondrocyte-Like Phenotype in Human Chondroprogenitor-Derived Self-Organized Tissue.

INTRODUCTION: Biomaterial-based tissue engineering has not successfully reproduced the structural architecture or functional mechanical properties of native articular cartilage. In scaffold-free tissue engineering systems, cells secrete and organize the entire extracellular matrix over time in response to environmental signals such as oxygen level. In this study, we investigated the effect of oxygen on the formation of neocartilage from human-derived chondrogenic cells. MATERIALS AND METHODS: Articular chondrocytes (ACs) and articular cartilage progenitor cells (ACPs) derived from healthy human adults were guided toward cell condensation by centrifugation onto plate inserts that were uncoated or coated with either agarose or fibronectin. Neocartilage discs were cultured at hyperoxic (20%) or physioxic (5%) oxygen levels, and biochemical, biomechanical, and molecular analyses were used to compare the cartilage produced by ACs versus ACPs. RESULTS: Fibronectin-coated inserts proved optimal for growing cartilaginous discs from both cell types. In comparison with culture in hyperoxia, AC neocartilage cultured at physioxia exhibited a significant increase in chondrogenic gene expression, proteoglycan production, and mechanical properties with a concomitant decrease in collagen content. At both oxygen levels, ACP-derived neocartilage produced tissue with significantly enhanced mechanical properties and collagen content relative to AC-derived neocartilage. Both ACs and ACPs produced substantial collagen II and reduced levels of collagens I and X in physioxia relative to hyperoxia. Neocartilage from ACPs exhibited anisotropic organization characteristic of native cartilage with respect to collagen VI of the pericellular matrix when compared with AC-derived neocartilage; however, only ACs produced abundant surface-localized lubricin. DISCUSSION AND CONCLUSIONS: Guiding human-derived cells toward condensation and subsequent culture in physioxia promoted the articular cartilage tissue phenotype for ACs and ACPs. Unlike ACs, ACPs are clonable and highly expandable while retaining chondrogenicity. The ability to generate large tissues utilizing a scaffold-free approach from a single autologous progenitor cell may represent a promising source of neocartilage destined for cartilage repair.

Responses to altered oxygen tension are distinct between human stem cells of high and low chondrogenic capacity.

BACKGROUND: Lowering oxygen from atmospheric level (hyperoxia) to the physiological level (physioxia) of articular cartilage promotes mesenchymal stem cell (MSC) chondrogenesis. However, the literature is equivocal regarding the benefits of physioxic culture on preventing hypertrophy of MSC-derived chondrocytes. Articular cartilage progenitors (ACPs) undergo chondrogenic differentiation with reduced hypertrophy marker expression in hyperoxia but have not been studied in physioxia. This study sought to delineate the effects of physioxic culture on both cell types undergoing chondrogenesis. METHODS: MSCs were isolated from human bone marrow aspirates and ACP clones were isolated from healthy human cartilage. Cells were differentiated in pellet culture in physioxia (2 % oxygen) or hyperoxia (20 % oxygen) over 14 days. Chondrogenesis was characterized by biochemical assays and gene and protein expression analysis. RESULTS: MSC preparations and ACP clones of high intrinsic chondrogenicity (termed high-GAG) produced abundant matrix in hyperoxia and physioxia. Poorly chondrogenic cells (low-GAG) demonstrated a significant fold-change matrix increase in physioxia. Both high-GAG and low-GAG groups of MSCs and ACPs significantly upregulated chondrogenic genes; however, only high-GAG groups had a concomitant decrease in hypertrophy-related genes. High-GAG MSCs upregulated many common hypoxia-responsive genes in physioxia while low-GAG cells downregulated most of these genes. In physioxia, high-GAG MSCs and ACPs produced comparable type II collagen but less type I collagen than those in hyperoxia. Type X collagen was detectable in some ACP pellets in hyperoxia but reduced or absent in physioxia. In contrast, type X collagen was detectable in all MSC preparations in hyperoxia and physioxia. CONCLUSIONS: MSC preparations and ACP clones had a wide range of chondrogenicity between donors. Physioxia significantly enhanced the chondrogenic potential of both ACPs and MSCs compared with hyperoxia, but the magnitude of response was inversely related to intrinsic chondrogenic potential. Discrepancies in the literature regarding MSC hypertrophy in physioxia can be explained by the use of low numbers of preparations of variable chondrogenicity. Physioxic differentiation of MSC preparations of high chondrogenicity significantly decreased hypertrophy-related genes but still produced type X collagen protein. Highly chondrogenic ACP clones had significantly lower hypertrophic gene levels, and there was little to no type X collagen protein in physioxia, emphasizing the potential advantage of these cells.

Evaluation of articular cartilage progenitor cells for the repair of articular defects in an equine model.

BACKGROUND: We sought to determine the effectiveness of chondroprogenitor cells derived from autologous and allogenic articular cartilage for the repair of cartilage defects in an equine model. METHODS: Cartilage defects (15 mm) were created on the medial trochlear ridge of the femur. The following experimental treatments were compared with empty-defect controls: fibrin only, autologous chondroprogenitor cells plus fibrin, and allogenic chondroprogenitor cells plus fibrin (n = 4 or 12 per treatment). Horses underwent strenuous exercise throughout the twelve-month study, and evaluations included lameness (pain) and arthroscopic, radiographic, gross, histologic, and immunohistochemical analyses. RESULTS: Arthroscopy and microscopy indicated that defects in the autologous cell group had significantly better repair tissue compared with defects in the fibrin-only and control groups. Repair tissue quality in the allogenic cell group was not superior to that in the fibrin-only group with the exception of the percentage of type-II collagen, which was greater. Radiographic changes in the allogenic cell group were poorer on average than those in the autologous cell group. Autologous cells significantly reduced central osteophyte formation compared with fibrin alone. CONCLUSIONS: On the basis of the arthroscopic, radiographic, and histologic scores, autologous cells in fibrin yielded better results than the other treatments; allogenic cells cannot be recommended at this time.

Bone marrow-derived mesenchymal stem cells become antiangiogenic when chondrogenically or osteogenically differentiated: implications for bone and cartilage tissue engineering.

Osteochondral tissue repair requires formation of vascularized bone and avascular cartilage. Mesenchymal stem cells stimulate angiogenesis both in vitro and in vivo but it is not known if these proangiogenic properties change as a result of chondrogenic or osteogenic differentiation. We investigated the angiogenic/antiangiogenic properties of equine bone marrow-derived mesenchymal stem cells (eBMSCs) before and after differentiation in vitro. Conditioned media from chondrogenic and osteogenic cell pellets and undifferentiated cells was applied to endothelial tube formation assays using Matrigel™. Additionally, the cell secretome was analysed using LC-MS/MS mass spectrometry and screened for angiogenesis and neurogenesis-related factors using protein arrays. Endothelial tube-like formation was supported by conditioned media from undifferentiated eBMSCs. Conversely, chondrogenic and osteogenic conditioned media was antiangiogenic as shown by significantly decreased length of endothelial tube-like structures and degree of branching compared to controls. Undifferentiated cells produced higher levels of angiogenesis-related proteins compared to chondrogenic and osteogenic pellets. In summary, eBMSCs produce an array of angiogenesis-related proteins and support angiogenesis in vitro via a paracrine mechanism. However, when these cells are differentiated chondrogenically or osteogenically, they produce a soluble factor(s) that inhibits angiogenesis. With respect to osteochondral tissue engineering, this may be beneficial for avascular articular cartilage formation but unfavourable for bone formation where a vascularized tissue is desired.

Evidence of a Viable Pool of Stem Cells within Human Osteoarthritic Cartilage.

OBJECTIVES: Osteoarthritis (OA) is a debilitating disease affecting more than 4 million people in the United Kingdom. Despite its prevalence, there is no successful cell-based therapy currently used to treat patients whose cartilage is deemed irrecoverable. The present study aimed to isolate stem cells from tibial plateaux cartilage obtained from patients who underwent total knee replacements for OA and investigate their stem cell characteristics. DESIGN: Clonally derived cell lines were selected using a differential adhesion assay to fibronectin and expanded in monolayer culture. Colony forming efficiencies and growth kinetics were investigated. The potential for tri-lineage differentiation into chondrogenic, osteogenic, and adipogenic phenotypes were analyzed using histological stains, immunocytochemistry, and reverse transcriptase polymerase chain reaction. RESULTS: Colony forming cells were successfully isolated from osteoarthritic cartilage and extensively expanded in monolayer culture. Colony forming efficiencies were consistently below 0.1%. Clonal cell lines were expanded beyond 40 population doublings but disparities were observed in the number of population doublings per day. Clonally derived cell lines also demonstrated in vitro multilineage potential via successful differentiation into chondrogenic, osteogenic, and adipogenic lineages. However, variation in the degree of differentiation was observed between these clonal cell lines. CONCLUSIONS: A viable pool of cells with stem cell characteristics have been identified within human osteoarthritic cartilage. Variation in the degree of differentiation suggests the possibility of further subpopulations of cells. The identification of this stem cell population highlights the reparative potential of these cells in osteoarthritic cartilage, which could be further exploited to aid the field of regenerative medicine.

The comparison of equine articular cartilage progenitor cells and bone marrow-derived stromal cells as potential cell sources for cartilage repair in the horse.

A chondrocyte progenitor population isolated from the surface zone of articular cartilage presents a promising cell source for cell-based cartilage repair. In this study, equine articular cartilage progenitor cells (ACPCs) and equine bone marrow-derived stromal cells (BMSCs) were compared as potential cell sources for repair. Clonally derived BMSCs and ACPCs demonstrated expression of the cell fate selector gene, Notch-1, and the putative stem cell markers STRO-1, CD90 and CD166. Chondrogenic induction revealed positive labelling for collagen type II and aggrecan. Collagen type X was not detected in ACPC pellets but was observed in all BMSC pellets. In addition, it was observed that BMSCs labelled for Runx2 and matrilin-1 antibodies, whereas ACPC labelling was significantly less or absent. For both cell types, osteogenic induction revealed positive von Kossa staining in addition to positive labelling for osteocalcin. Adipogenic induction revealed a positive result via oil red O staining in both cell types. ACPCs and BMSCs have demonstrated functional equivalence in their multipotent differentiation capacity. Chondrogenic induction of BMSCs resulted in a hypertrophic cartilage (endochondral) phenotype, which can limit cartilage repair as the tissue can undergo mineralisation. ACPCs may therefore be considered superior to BMSCs in producing cartilage capable of functional repair.

Identification and clonal characterisation of a progenitor cell sub-population in normal human articular cartilage.

BACKGROUND: Articular cartilage displays a poor repair capacity. The aim of cell-based therapies for cartilage defects is to repair damaged joint surfaces with a functional replacement tissue. Currently, chondrocytes removed from a healthy region of the cartilage are used but they are unable to retain their phenotype in expanded culture. The resulting repair tissue is fibrocartilaginous rather than hyaline, potentially compromising long-term repair. Mesenchymal stem cells, particularly bone marrow stromal cells (BMSC), are of interest for cartilage repair due to their inherent replicative potential. However, chondrocyte differentiated BMSCs display an endochondral phenotype, that is, can terminally differentiate and form a calcified matrix, leading to failure in long-term defect repair. Here, we investigate the isolation and characterisation of a human cartilage progenitor population that is resident within permanent adult articular cartilage. METHODS AND FINDINGS: Human articular cartilage samples were digested and clonal populations isolated using a differential adhesion assay to fibronectin. Clonal cell lines were expanded in growth media to high population doublings and karyotype analysis performed. We present data to show that this cell population demonstrates a restricted differential potential during chondrogenic induction in a 3D pellet culture system. Furthermore, evidence of high telomerase activity and maintenance of telomere length, characteristic of a mesenchymal stem cell population, were observed in this clonal cell population. Lastly, as proof of principle, we carried out a pilot repair study in a goat in vivo model demonstrating the ability of goat cartilage progenitors to form a cartilage-like repair tissue in a chondral defect. CONCLUSIONS: In conclusion, we propose that we have identified and characterised a novel cartilage progenitor population resident in human articular cartilage which will greatly benefit future cell-based cartilage repair therapies due to its ability to maintain chondrogenicity upon extensive expansion unlike full-depth chondrocytes that lose this ability at only seven population doublings.