Mammalian Meckel´s cartilage is a temporary structure associated with mandible development. Notably, its elimination is not executed by apoptosis, and autophagy was suggested as the major mechanism. Simultaneous reports point to pro-apoptotic caspases as novel participants in autophagic pathways in general. The aim of this research was to find out whether activation of pro-apoptotic caspases (-2, -3, -6, -7, -8 and -9) was associated with autophagy of the Meckel´s cartilage chondrocytes. Active caspases were examined in serial histological sections of mouse mandible using immunodetection and were correlated with incidence of autophagy based on Beclin-1 expression. Caspase-2 and caspase-8 were found in Beclin-1 positive regions, whereas caspase-3, -6, -7 and -9 were not present. Caspase-8 was further correlated with Fas/FasL and HIF-1alpha, potential triggers for its activation. Some Fas and FasL positivity was observed in the chondrocytes but caspase-8 activation was found also in FasL deficient cartilage. HIF-1alpha was abundantly present in the hypertrophic chondrocytes. Taken together, caspase-8 activation in the Meckel´s cartilage was demonstrated for the first time. Caspase-8 and caspase-2 were the only pro-apoptotic caspases detected in the Beclin-1 positive segment of the cartilage. Activation of caspase-8 appears FasL/Fas independent but may be switched on by HIF-1alpha.
- MeSH
- apoptóza fyziologie MeSH
- autofagie fyziologie MeSH
- kaspasy metabolismus MeSH
- kloubní chrupavka cytologie metabolismus MeSH
- lidé MeSH
- mandibula cytologie metabolismus MeSH
- myši MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Articular cartilage has little regenerative capacity. Recently, genetic lineage tracing experiments have revealed chondrocyte progenitors at the articular surface. We further characterized these progenitors by using in vivo genetic approaches. Histone H2B-green fluorescent protein retention revealed that superficial cells divide more slowly than underlying articular chondrocytes. Clonal genetic tracing combined with immunohistochemistry revealed that superficial cells renew their number by symmetric division, express mesenchymal stem cell markers, and generate chondrocytes via both asymmetric and symmetric differentiation. Quantitative analysis of cellular kinetics, in combination with phosphotungstic acid-enhanced micro-computed tomography, showed that superficial cells generate chondrocytes and contribute to the growth and reshaping of articular cartilage. Furthermore, we found that cartilage renewal occurs as the progeny of superficial cells fully replace fetal chondrocytes during early postnatal life. Thus, superficial cells are self-renewing progenitors that are capable of maintaining their own population and fulfilling criteria of unipotent adult stem cells. Furthermore, the progeny of these cells reconstitute adult articular cartilage de novo, entirely substituting fetal chondrocytes.-Li, L., Newton, P. T., Bouderlique, T., Sejnohova, M., Zikmund, T., Kozhemyakina, E., Xie, M., Krivanek, J., Kaiser, J., Qian, H., Dyachuk, V., Lassar, A. B., Warman, M. L., Barenius, B., Adameyko, I., Chagin, A. S. Superficial cells are self-renewing chondrocyte progenitors, which form the articular cartilage in juvenile mice.
- MeSH
- chondrocyty cytologie MeSH
- chondrogeneze * MeSH
- dospělé kmenové buňky cytologie MeSH
- kloubní chrupavka cytologie fyziologie MeSH
- myši MeSH
- regenerace MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The degeneration of articular cartilage results from osteoarthritis and many other forms of severe arthritis. Current treatments for cartilage repair are less than satisfactory, and rarely restore a full function or return the tissue to its natural state. The leading strategies in the treatment are aimed at the transplantation of cells and/or the use of various biological grafts, bioactive agents, or biologically compatible implant matrices. The insertion of a crushed autologous bone graft has been reported as a possible therapy. However, the regenerative quality of the tissue was less than 70% of healthy cartilage for fragments and controls. The implantation of cycloolefin-blend 3D-cylinders with hydrogel scaffolds on their proximal parts and with the applications of type I collagen films is one of several surgical therapies. The replacement and continuous biomechanical properties of the subchondral bone play an important role in the morphology and the quality of chondrogenesis. The initial biomechanical stability of COC-blend polymer replacements in the subchondral bone contributes to the formation of a new cartilage tissue. The initial bearing capacities of the implanted tissue/replacements and vertical positions of the replacements have a principal influence upon both the quality and the quantity of new articular cartilage.
- MeSH
- analýza selhání vybavení MeSH
- chondrogeneze fyziologie MeSH
- kloubní chrupavka cytologie růst a vývoj chirurgie MeSH
- kostní náhrady terapeutické užití MeSH
- prasata MeSH
- protézy - design MeSH
- výsledek terapie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- artroskopie metody využití MeSH
- autologní transplantace metody trendy využití MeSH
- buněčná a tkáňová terapie * metody trendy využití MeSH
- chondrocyty cytologie transplantace MeSH
- instilace léků MeSH
- kloubní chrupavka * cytologie patofyziologie MeSH
- kostní dřeň * chirurgie MeSH
- kultivační techniky metody trendy využití MeSH
- lidé MeSH
- nemoci kostí chirurgie terapie MeSH
- osteoblasty cytologie transplantace MeSH
- pluripotentní kmenové buňky cytologie transplantace MeSH
- regenerativní lékařství metody trendy MeSH
- statistika jako téma MeSH
- tkáňové inženýrství metody trendy využití MeSH
- výsledky a postupy - zhodnocení (zdravotní péče) MeSH
- Check Tag
- lidé MeSH
ACI is the most widely used cell-based surgical procedure for the repair of articular cartilage defects. The method is based on in vitro chondrocyte cultivation. Two different culture conditions, rotating- wall-vessel bioreactor and static culture, were assessed by their effect on the re-differentiation potential of human articular chondrocytes seeded into a hydrogel scaffold. Gene expression analysis of the tissue-engineered construct revealed no significant difference between the tested systems.
- MeSH
- agrekany metabolismus MeSH
- bioreaktory MeSH
- buněčná diferenciace genetika MeSH
- buněčné kultury MeSH
- chondrocyty cytologie metabolismus transplantace MeSH
- exprese genu MeSH
- kloubní chrupavka cytologie metabolismus MeSH
- kolagen typ II metabolismus MeSH
- kolagen typu I metabolismus MeSH
- kultivované buňky MeSH
- lidé MeSH
- PEG-DMA hydrogel MeSH
- tkáňové inženýrství metody MeSH
- tkáňové podpůrné struktury MeSH
- versikany metabolismus MeSH
- Check Tag
- lidé MeSH
The aim of our study was to evaluate the occurrence of chondrocytes containing alpha-smooth muscle actin in human normal and diseased cartilage. Immunohistochemistry using monoclonal antibodies for alpha-smooth actin, muscle-specific actin, S-100 protein, CD 34, and desmin was performed on samples of human articular cartilage obtained at autopsy following sudden death, during total hip and knee replacement for osteoarthritis, or after femoral neck fracture in patients without symptoms of osteoarthritis. Moreover, the layers of residual cartilage from chondral posttraumatic defects obtained during preoperative arthroscopy and of newly formed cartilage after autologous-chondrocyte transplantation (Hyalograft C) obtained during second-look arthroscopy were also examined by immunohistochemistry and RT PCR. Our study showed that a significant percentage of articular chondrocytes express alpha-smooth muscle actin in healthy, diseased, and regenerated articular cartilage. Alpha-actin positive chondrocytes (18%) were observed predominantly in the upper zone of normal articular cartilage. By contrast, only approximately 10% of cartilage cells in the deep region stained for this contractile actin isoform. Actin-positive chondrocytes (myochondrocytes) are formed predominantly in response to injury to the osteoarthrotic cartilage, at sites of defective healing, and in newly formed cartilage after autologous chondrocyte transplantation. Fibrocartilage is present in some of these conditions, and it is known that this tissue contains chondrocytes with actin. The presence of myochondrocytes in the surface layer of normal articular cartilage indicates that this region probably plays an important role in maintaining cartilage integrity. Myochondrocytes may utilize the contractile actin isoform in manipulating the extracellular matrix of articular cartilage. It is also possible that actin-containing chondrocytes have a higher potential for regeneration in contrast to chondrocytes that do not contain this contractile material in their cytoplasm.
- MeSH
- aktiny biosyntéza MeSH
- antigeny CD34 biosyntéza MeSH
- chondrocyty metabolismus transplantace MeSH
- desmin biosyntéza MeSH
- dospělí MeSH
- imunohistochemie MeSH
- kloubní chrupavka cytologie metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- osteoartróza metabolismus MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- proteiny S100 biosyntéza MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
Změny mikrostruktury kloubní chrupavky jsou významným morfologickým korelátem patologic - kých procesů. Nezbytným předpokladem úspěšné detekce jejich prvotních příznaků je vedle užití vhodných technik i detailní znalost stavby jednotlivých vrstev chrupavky. V literatuře se vyskytují nesrovnalosti v popisu povrchové chondrální membrány (lamina splendens) i v orientaci kolagen- ních fibril probíhajících v podpovrchové vrstvě a jejich zakončení v lamina splendens. Vyšetřovali jsme podpovrchovou vrstvu prasečí kolenní chrupavky se zaměřením na lamina splendens. Pro orientaci v celé tloušťce kloubní chrupavky jsme preparáty barvené na kolagen studovali v polari- začním mikroskopu; průběh jednotlivých fibril a jejich orientace jsou patrné v transmisním elek- tronovém mikroskopu. Jasně odlišitelná lamina splendens se v polarizačním mikroskopu jeví jako homogenní nebuněčná vrstva; v transmisním elektronovém mikroskopu je jemně zrnitá s přítom- ností různě uspořádaných fibril. Výsledný model je použit k popisu změn povrchu kloubn í chrupav- ky po experimentálně vyvolané fisuře (split line).
Microstructural changes of the joint cartilage are a significant morphological correlate of patholo- gical process. Successful detection of their primary symptoms requires both detailed knowledge of structure of particular cartilage layers and the use of suitable histological techniques. In the literature there are fundamental discrepancies in the description of the superficial chondral membrane (lamina splendens) as well as in the orientation of collagen fibrils running in the horizontal layer and their attachment in the lamina splendens. We investigated the horizontal layer of the hog knee cartilage with respect to the lamina splendens. For orientation in the whole thickness of the joint cartilage, sections stained for collagen were studied under the polarization microscope; the course and the orientation of particular fibrils are apparent in the transmission electron microscope. The clearly distinct lamina splendens appears as a homogeneous acellular layer under the polarization microscope, being finely granular with fibrils running in all directions parallel to the articular surface in the transmission electron microscope. The resultant model is used for the description of articular cartilage surface changes after experimentally introduced fissures (split line).
