Showing papers on "Cartilage published in 1984"

Specific inhibition of type I and type II collagen fibrillogenesis by the small proteoglycan of tendon.

Abstract: The small dermatan sulphate proteoglycan of bovine tendon demonstrated a unique ability to inhibit fibrillogenesis of both type I and type II collagen from bovine tendon and cartilage respectively in an assay performed in vitro. None of the other proteoglycan populations from cartilage, tendon or aorta, even those similar in size and chemical structure, had this effect. Alkali treatment of the small proteoglycan of tendon eliminated its ability to inhibit fibrillogenesis, whereas chondroitinase digestion did not. This indicates that its interaction with collagen depends on the core protein. Fibrillogenesis of pepsin-digested collagens was affected similarly, indicating that interaction with the collagen telopeptides is not involved. The results suggest that interactions between collagen and proteoglycans may be quite specific both for the type of proteoglycan and its tissue of origin.

Repair of cartilage and bones

Abstract: There are provided compositions for repairing defects of cartilage and bones. These are provided in gel form either as such, or embedded in natural or artificial bones. The gel comprises certain types of cells. These may be committed embryonal chondocytes or any kind of mesenchyme originated cells which potentially can be converted to cartilage cells, generally by the influence of chondrogenic inducing factors, in combination with fibrinogen, antiprotease and thrombin. The cells ought to be of the species to which the composition is transplanted. It is advantageous to incorporate in the gel extracellular matrix (ECM) of chondrocytes or other hormones and/or growth factors such as SM (Somatomedin=IGF-I), FGF (fibroblast growth factor), CGF (cartilage growth factor), BDGF (bone derived growth factor) or a combination of any of these.

Chondroclasts and osteoclasts at subchondral sites of erosion in the rheumatoid joint

Abstract: Histochemical and ultrastructural studies of bone-cartilage junctions from 21 rheumatoid knee joints have demonstrated the presence of both osteoclasts and chondroclasts. Significant erosions of bone and mineralized cartilage were observed in 15 specimens, and 6 showed localized erosions of unmineralized (hyaline) cartilage. Chondroclasts, defined by their close association with both mineralized and unmineralized cartilage, were morphologically and histochemically similar to osteoclasts. Our observations suggest that these multinucleate cells play a crucial role in subchondral tissue destruction, but that erosion of unmineralized cartilage is primarily the result of synovial pannus tissue.

Effects of static and cyclic compressive loading on articular cartilage plugs in vitro.

Abstract: The influence of static and intermittent stress on articular cartilage metabolism was examined in vitro. Full-thickness plugs of cartilage from femoral condyles of normal adult dogs were cultured while static or cyclic stresses were applied for 2 hours. The plugs were then incubated under atmospheric pressure for 2 hours in medium containing radioactive label, to provide measurements of net synthesis of glycosaminoglycan (GAG) or protein. As a control, cartilage from the same knee was cultured in the apparatus at atmospheric pressure. When cartilage plugs were exposed to static stress, or to cyclic stresses at a duty cycle of 60 seconds on/60 seconds off, net GAG synthesis was suppressed to 30-60% of that in controls. In contrast, when a duty cycle of 4 seconds on/11 seconds off was used, GAG synthesis was increased by 34%. The duty cycle which increased GAG synthesis did not affect protein synthesis or tissue contents of DNA, uronic acid, or water. At the cycle which suppressed GAG synthesis, protein synthesis and uronic acid content were decreased, and water content was increased. As judged by uptake of 14C-aminoisobutyric acid and 14C-xylose, the above changes in GAG synthesis do not appear to have been due to changes in diffusion of nutrient molecules through the cartilage during loading.

Pig catabolin is a form of interleukin 1. Cartilage and bone resorb, fibroblasts make prostaglandin and collagenase, and thymocyte proliferation is augmented in response to one protein.

Abstract: Homogeneous catabolin from pig leucocytes induced proteoglycan breakdown, but not collagen breakdown, in explants of articular cartilage. It augmented lectin-induced proliferation of mouse thymocytes, stimulated production of prostaglandin E2 and collagenase by fibroblasts and chondrocytes, and increased Ca2+ release from mouse calvarial explants, all at concentrations down to 50 pM. In view of these effects it was concluded that pig catabolin is a form of interleukin 1.

Histopathology of the rheumatoid lesion. Identification of cell types at sites of cartilage erosion.

Abstract: Histochemical and ultrastructural techniques were used to examine the cartilage—pannus junction of 49 rheumatoid joints. Whereas 24 showed relatively acellular, fibrous pannus tissue, 25 demonstrated “cellular” junctions with different cell types at sites of erosion. Macrophages and fibroblasts were commonly observed as majority cell types in most specimens, but others showed mast cells, polymorphonuclear leukocytes, dendritic, or plasma cells as the predominant cell type. Some showed local accumulations of different cell types at sites along each junction. Our findings show that the cellular composition at sites of cartilage erosion varies greatly and suggest that cells are subject to turnover and interchange.

Cartilage ultrastructure after high pressure freezing, freeze substitution, and low temperature embedding. I. Chondrocyte ultrastructure--implications for the theories of mineralization and vascular invasion.

Abstract: Electron microscopic examination of epiphyseal cartilage tissue processed by high pressure freezing, freeze substitution, and low temperature embedding revealed a substantial improvement in the preservation quality of intracellular organelles by comparison with the results obtained under conventional chemical fixation conditions. Furthermore, all cells throughout the epiphyseal plate, including the terminal chondrocyte adjacent to the region of vascular invasion, were found to be structurally integral. A zone of degenerating cells consistently observed in cartilage tissue processed under conventional chemical fixation conditions was not apparent. Hence, it would appear that cell destruction in this region occurs during chemical processing and is not a feature of cartilage tissue in the native state. Since these cells are situated in a region where tissue calcification is taking place, the implication is that the onset and progression of cartilage calcification are, at least partially, controlled by the chondrocytes themselves. The observation that the terminal cell adjacent to the zone of vascular invasion is viable has important implications in relation to the theory of vascular invasion. This may now require reconceptualization to accommodate the possibility that active cell destruction may be a precondition for vascular invasion.

Beta-tricalcium phosphate delivery system for bone morphogenetic protein.

Abstract: An aggregate of biodegradable beta-tricalcium phosphate and bone morphogenetic protein (BMP/TCP) induces the differentiation of cartilage within eight days, cartilage and woven bone within 12 days, and lamellar bone, including bone marrow, within 21 days. The yield of new bone from a 1-mg dose was more than 12 times greater from the TCP/BMP than from the BMP alone. Whether TCP acts as a slow-release delivery system, potentiates the activity of BMP, or serves to distribute BMP in a favorable three-dimensional pattern requires further investigation.

The composition of normal and osteoarthritic articular cartilage from human knee joints. With special reference to unicompartmental replacement and osteotomy of the knee

Abstract: The articular cartilage from nineteen osteoarthritic and fourteen normal control adult human knee joints was analyzed for changes in water content, proteoglycan composition and structure, glycosaminoglycan synthesis rates, and cell content. We found no significant differences between visually intact cartilage from osteoarthritic knee joints and cartilage from control joints for any of the parameters studied. In osteoarthritic specimens in which the cartilage surface was not intact the biochemical changes depended on the degree of fibrillation. Surface-fibrillated specimens had a higher water content in the surface layers but no change in the content or synthesis rate of glycosaminoglycan. Deeply fibrillated cartilage, however, had an increased water content through its full depth, and there was a decrease in both the rate of synthesis and the content of glycosaminoglycans. Clinical Relevance: The results of this study suggest that degenerative changes in osteoarthritic knees are focal in origin and that corrective osteotomy or unicompartmental joint replacement might be rational procedures for knees in which the cartilage in all of one compartment is visually intact.

Chondrocytes embedded in collagen gels maintain cartilage phenotype during long-term cultures.

Abstract: Chondrocytes isolated from sterna of 13-day-old chick embryos were cultured in vitro within collagen gels for six weeks. Under these culture conditions, chondrocytes assumed a rounded morphology, accumulated metachromatic matrix, and took on the cytological characteristics of in vivo cartilage cells. Most of the glycosaminoglycans synthesized were deposited within the collagen gels, and the rate of glycosaminoglycan synthesis was maintained over five weeks. Throughout the study, the major collagen synthesized was Type II. This cell-culture system, using collagen gels, provides chondrocytes with a suitable environment in which to accumulate synthesized matrix macromolecules and preserve their differentiated phenotype in vitro.

In Vivo and in Vitro Stimulation of Chondrocyte Biosynthetic Activity in Early Experimental Osteoarthritis

Abstract: The biosynthesis of proteoglycans in the menisci and articular cartilages of the knee (stifle) of mature beagles was studied in the early stages of experimental osteoarthritis. The rate of proteoglycan synthesis, determined by systemic labeling in vivo at 21, 42, and 84 days after sectioning of the anterior cruciate ligament, was generally found to be 1.5-2.5-fold higher than control in articular cartilages and 3-10-fold higher than control in menisci. The medial meniscus was more stimulated than the lateral meniscus, and the medial tibial plateau under the meniscus was more stimulated than the adjacent tibial area. This area-specific stimulation suggests the involvement of mechanical factors in the cellular response. The rate of proteoglycan synthesis determined in vitro at 7, 14, and 21 days after operation was also about 2-fold higher than control in articular cartilages and about 3-fold higher in menisci. This increase in biosynthetic activity in vitro was confirmed by 35S-autoradiography and appeared to be due to general stimulation of existing chondrocytes, particularly in the middle and deep zones of the articular cartilage and throughout the meniscal cartilage. The rate of proteoglycan synthesis determined in vitro in cartilages from 2-week and 3-week sham operated joints was also increased relative to controls, suggesting that humoral as well as mechanical factors are involved in stimulating chondrocyte activity.

Neutral proteases capable of proteoglycan digesting activity in osteoarthritic and normal human articular cartilage

Abstract: Proteases have been postulated to account for the progressive disappearance of matrix proteoglycans in osteoarthritic (OA) cartilage. The digestion of endogenous proteoglycans by neutral proteases in human OA cartilage homogenates has been measured and compared with that of normal age-matched controls. Cartilage was obtained from 16 patients at the time of knee arthroplasty and from 7 accident victims. Tissue blocks were cut from the tibial plateau; part was used for histologic grading of the severity of OA and part was homogenized for the quantification of neutral metallo- and serine protease activities, based on the release of digested products from endogenous proteoglycans. Total metalloprotease activity (latent plus active forms) was elevated 3- to 10-fold in all diseased cartilage. This elevation was already significant in mild disease, but was greatest in samples of moderate to severe disease. The active form of the enzyme was highest at the center of erosions and decreased in the margins of the plateau. The digestion of proteoglycans, as distinct from their mere release from the tissue, was demonstrated by chromatography on Sepharose-CL2B and by large pore electrophoresis. Serine protease activity on proteoglycans was much lower than that of metalloprotease. The mean activity was highest in mild disease and declined in the severe disease samples, but the difference between these 2 groups and the controls was not statistically significant. The results of this study are consistent with the hypothesis that the neutral metalloproteases of cartilage are involved in the degradation of proteoglycans in osteoarthritis.

Sonographic evaluation of the cartilage of the knee.

Abstract: Real-time ultrasound was assessed as a means of evaluating osteoarthritis of the knee. The knee was maintained in complete flexion so as to expose the weight-bearing portion of the femoral condylar cartilage. After establishing the validity of the method in an excised bovine knee, 7 asymptomatic individuals, 10 arthritic patients, and several patients with other conditions were examined. The results indicated that sonography can be used to measure the thickness of the articular cartilage in man, as well as to detect changes in its surface and internal characteristics. Early changes of arthritis may be revealed in this manner.

Cartilage ultrastructure after high pressure freezing, freeze substitution, and low temperature embedding. II. Intercellular matrix ultrastructure - preservation of proteoglycans in their native state.

Abstract: The extracellular matrix of epiphyseal cartilage tissue was preserved in a state believed to resemble closely that of native tissue following processing by high pressure freezing, freeze substitution, and low temperature embedding (HPF/FS). Proteoglycans (PG) were preserved in an extended state and were apparent as a reticulum of fine filamentous threads throughout the matrix. Within this network, two morphologically discrete components were discernible and identified with the carbohydrate and protein components of PG molecules. Numerous points of contact were clearly visible between components of the PG network and cross-sectioned collagen fibrils and also between PG components and chondrocytic plasmalemmata. These observations provide direct morphological indication that such relationships may exist in native epiphyseal cartilage tissue.

Association of an extracellular protein (chondrocalcin) with the calcification of cartilage in endochondral bone formation.

Abstract: We examined bovine fetal epiphyseal and growth plate cartilages by immunofluorescence microscopy and immunoelectron microscopy using monospecific antibodies to a newly discovered cartilage-matrix calcium-binding protein that we now call chondrocalcin. Chondrocalcin was evenly distributed at relatively low concentration in resting fetal epiphyseal cartilage. In growth plate cartilage, it was absent from the extracellular matrix in the zone of proliferating chondrocytes but was present in intracellular vacuoles in proliferating, maturing and upper hypertrophic chondrocytes. The protein then disappeared from the lower hypertrophic chondrocytes and appeared in the adjoining extracellular matrix, where it was selectively concentrated in the longitudinal septa in precisely the same location where amorphous mineral was deposited in large amounts as demonstrated by von Kossa staining and electron microscopy. Mineral then spread out from these "nucleation sites" to occupy much of the surrounding matrix. Matrix vesicles were identified in this calcifying matrix but they bore no observable morphological relationship to these major sites of calcification where chondrocalcin was concentrated. Since chondrocalcin is a calcium-binding protein and has a strong affinity for hydroxyapatite, these observations suggest that chondrocalcin may play a fundamental role in the creation of nucleation sites for the calcification of cartilage matrix in endochondral bone formation.

Mast cells at sites of cartilage erosion in the rheumatoid joint.

Abstract: Cartilage-pannus junctions of the rheumatoid lesion have been examined by histochemical and ultrastructural techniques in an attempt to identify the cells responsible for cartilage degradation. Mast cells have been identified at sites of cartilage erosion in 3 specimens of rheumatoid joint. It is known that mast cells participate in immunological reactions, produce the vasoactive and proteinase-modulating agents histamine and heparin as well as their own degradative proteinases. The close association of mast cells with sites of cartilage erosion suggests they may play an important role in the pathophysiology of joint destruction in rheumatoid arthritis.

In vitro transformation of mesenchymal cells derived from embryonic muscle into cartilage in response to extracellular matrix components of bone.

Abstract: Subcutaneous implantation of demineralized diaphyseal bone matrix into rats induces cartilage and bone formation in vivo. When minced skeletal muscle is cultured on hemicylinders of demineralized bone in vitro, mesenchymal cells are transformed into chondrocytes. In the present investigation, the potential of extracellular matrix components of bone to trigger cartilage differentiation in vitro was examined. Extraction of bone hemicylinders with 6 M guanidine X HCl resulted in the absence of chondrogenesis in vitro and endochondral bone formation in vivo. Biologically inactive hemicylinders of bone were then reconstituted with the guanidine extract and also with partially purified components extracted from bone matrix and bioassayed. Reconstitution completely restored the ability to elicit chondrogenesis in vitro and endochondral bone differentiation in vivo. Reconstitution of the whole guanidine extract on Millipore filters coated with gels of tendon collagen (type I) and subsequent culture with minced skeletal muscle also resulted in cartilage induction in vitro. These observations show that the extracellular matrix of bone is a repository of factors that govern local cartilage and bone differentiation.

Benign exostoses and exostotic chondrosarcomas: evaluation of cartilage thickness by CT.

Abstract: Computed tomograms of 16 benign exostoses and 15 exostotic chondrosarcomas were generally accurate in delineating anatomy for purposes of planning surgery, but they were inaccurate in the detection and measurement of the cartilage caps of the lesions. CT studies of 14 of the benign exostoses failed to show any cartilage cap, although the maximum cartilage thickness of these 14 lesions ranged from 0.1 to 2.5 cm pathologically. CT did demonstrate thick cartilage in 14 of the 15 chondrosarcomas, but the CT measurements of maximum thickness often were imprecise. Altogether, 15 CT studies failed to show any cartilage cap; 14 of these lesions were benign. CT did not reliably detect cartilage caps less than 2.5 cm in maximum thickness, and CT measurement of cartilage thickness was imprecise when the cartilage was 1.5 to 2.5 cm thick. For this reason, CT did not solve the difficult problem of distinguishing between benign exostoses with relatively thick cartilage caps and exostotic chondrosarcomas with relatively...

Connective Tissue Matrix

Abstract: Dynamic Aspects of Connective Tissue Structure and Function D.W.L.Hukins - The Role of the Extracellular Matrix in Development J.B.L.Bard - Solute Transport in Articular Cartilage and Interverterbral Disc J.P.G.Urban - Poroelastic Finite Element Models for Soft Tissue Structures B.R.Simon - Electromechanical and Physiological Regulation of Cartilage Strength and Metabolism A.J.Grodzinsky & E.H.Frank - The Structure and Function of Intramuscular Connective Tissue P.P.Purslow & V.C.Duance - Physicochemical Properties of Vascular Elastin C.P.Winlove & K.H.Parker - Structural Basis of Dilation of the Cervix R.M.Aspden - MR Imaging of Tissue Degeneration D.S.Hickey et al - Tissue Repair with the Aid of Carbon Fibre R.J.Minns - Index

Synthesis and characterization of cDNA encoding a cartilage-specific short collagen

Abstract: Hyaline cartilage contains a unique set of collagenous proteins. Type II collagen is the most abundant, constituting about 85% of the total cartilage collagen. In addition, several minor collagenous components have been described. To study the structure and developmental regulation of chondrocyte-specific collagens, we have constructed a cDNA library from embryonic chicken sternal cartilage mRNA. We report here on the isolation and characterization of a 3200 base-pair-long cDNA that codes for a collagenous polypeptide of unusual structure in that the total length of the molecule is only about half of pro alpha 1(II) collagen chains. The mRNA for this polypeptide is considerably smaller than mRNA encoding the pro alpha chains of interstitial collagens. In addition, the peptide encoded by the cDNA appears to contain at least three domains with triple-helical potential separated by short, noncollagenous peptides. Between the three collagenous domains are several cysteinyl residues.

Experimental arthritis induced by intraarticular injection of allogenic cartilaginous particles into rabbit knees.

Abstract: Human synovial fluid often contains small cartilaginous "wear particles" Previous in vitro experiments have indicated the potential involvement of these particles in the pathophysiology of arthritis To determine whether this potential is realized under the conditions existing within joints, standard suspensions of lapine articular cartilage were injected intraarticularly into the knee joints of rabbits Thrice-weekly injections of 1 mg allogenic cartilage produced an inflammatory arthritis, accompanied by a marked cellular effusion, in all rabbits within 5 months The synovium became hyperplastic, discolored, and infiltrated with mononuclear inflammatory cells Embedded particles of the injected material were seen in histologic preparations of these synovia Organ cultures of such synovia produced 4 to 5 times more collagenase, plasminogen activator, "Pz-peptidase," neutral and acid azocaseinase, and beta-glucuronidase than did cultures of synovia from control knees injected with saline Furthermore, the articular cartilage of knees injected with cartilaginous particles showed elevated intrinsic collagenolytic activity Histologic examination of the articular cartilage revealed an attendant loss of metachromasy, resulting in friability, pitting, and discoloring of the cartilage Preliminary immunoassays failed to demonstrate a systemic immune response to the injected material

A Continuum Theory and an Experiment for the Ion-Induced Swelling Behavior of Articular Cartilage

Abstract: Swelling of normal bovine articular cartilage equilibrated in NaCl solutions was dimensionally measured in thin strips of tissue. The ion-induced strains show that free swelling of articular cartilage is anisotropic and inhomogeneous. For the molar concentrations used, contraction increased linearly with concentration, defining a "coefficient of chemical contraction" (alpha c). Isometrically constrained specimens registered a rise in tensile force followed by stress relaxation. An extension of the biphasic theory incorporating this ion-induced strain is proposed. This theory can describe the equilibrium anisotropic swelling behavior of cartilage and explain the transient force history observed in the isometric experiment.

Biomechanical and biochemical properties of dog cartilage in experimentally induced osteoarthritis.

Abstract: The finding of other investigators that increased water content is often associated with signs of a torn collagen network in human osteoarthritic (OA) cartilage led to this study. In the Pond-Nuki model of post-traumatic OA experimental but not control femoral condylar cartilage showed evidence of breakdown and stiffening of collagen network as assessed by measurement of swelling properties and indentation behaviour respectively. These changes in the unstable knees occurred despite lack of erosion of that surface cartilage ascertained from carbon black mapping and history. The stiffening rather than softening change was therefore attributed to cartilage oedema of the middle and deep certilagenous zones, wherein breakdown of collagen network has been postulated to occur. Because of insignificant reduction of total hexuronate in these cartilages, a proteoglycan (PG) profile of sedimentation coefficients for aggregate (PGA) and subunit species (PGS) was analysed to see if collagen network changes in the dog preceded PG alteration. Despite minimal histological changes our results confirmed previous findings in the tibial plateau cartilage in this model, that PGA was reduced in size and PGS increased in amount. Slight enzymatic breakdown of PGs, or altered synthesis due to cellular responses to either the injury directly or to synovial inflammation, seems necessary to explain such changes in the absence of cartilage erosion.

Process of adapting soluble bone protein for use in stimulating osteoinduction

Abstract: A method for treating implants such as biodegradable masses, xenogenic bony implants, allografts and prosthetic devices with soluble bone protein to enhance or stimulate new cartilage and/or bone formation. Substrate immobilization or surface coating techniques retard diffusion of the soluble bone protein away from the implant site so that cartilage and bone growth is initiated.

Biochemical and metabolic abnormalities in normal and osteoarthritic human articular cartilage.

Abstract: Incorporation of radioactive precursors into macromolecules was studied with human normal and osteoarthritic articular cartilage organ culture. Analysis of the salt extracted matrix components separated by cesium chloride buoyant density gradient centrifugation showed an increase in the specific activities of all gradient fractions prepared from the osteoarthritic cartilage. Further analysis of these fractions showed the osteoarthritic cartilage contained 5 times as much sulfate incorporated into proteoglycans, and an even greater amount of 3H-glucosamine incorporated into material sedimenting to the middle of the gradient. Greater than half of this radioactive middle fraction appears to be hyaluronate, as judged by the position it elutes from a DEAE column and its susceptibility to hyaluronidase digestion. This study supports earlier findings showing increased rates of macromolecular synthesis in osteoarthritis, and in addition, an even greater synthetic rate for hyaluronic acid is demonstrated.

Demineralized bone-matrix-induced osteogenesis.

Abstract: A review of the literature on bone formation induced by demineralized bone and dentin indicates that: there is considerable interest in the biology and applied science of osteoinduction; the technology has been developed, but it varies in detail from one laboratory to another because of specific and individual objectives; and the accumulated evidence supports the concept of cartilage and bone cell differentiation induced by a unique bone morphogenetic protein (BMP).

Bone morphogenetic protein-induced cartilage development in tissue culture.

Abstract: Outgrowths of mesenchyme-type cells from explants of allogeneic rat muscle onto a substratum of bone matrix containing bone morphogenetic protein (BMP) differentiate into cartilage. When BMP is chemically extracted from the bone matrix, the explanted cells develop only into fibrous tissue. When exogenous bovine BMP is introduced into the culture medium, either as a microsuspension or as a layer of particles between the matrix and the muscle cell tissue, cartilage develops at the interface between the matrix and the mesenchymal cell outgrowth. The chondrogenetic response is induced by as little as 2 micrograms of BMP; the optimum dose is 10 micrograms/40 mg (wet weight) of explant. The endogenous BMP equivalent for a comparable chondrogenetic response is about 0.6 micrograms/mg of allogeneic matrix. The minimum time for transfer of BMP to mesenchymal cell receptors is 1.0 hour, adequate time is 2.5 hours, and optimum time is approximately 5.0 hours. Measured in terms of incorporation of 3H-thymidine into DNA and of 35S sulfate into glycosaminoglycan, there is a latent period of one to three days preceeding the differentiation of mesenchyme-type cells into cartilage. During this latent period BMP-modulated mesenchymal cells disaggregate, migrate, reaggregate, and proliferate on new surfaces and constitute the morphogenetic phase of bone development. By the fourth day cells simultaneously undergo mitotic division, synthesize extracellular cartilage matrix, and establish the cytodifferentiation phase of development.

Studies on cryopreservation of articular cartilage chondrocytes.

Abstract: We used cartilage cells isolated from bovine articular cartilage in experiments to: (1) determine the toxicity of cryopreservatives (glycerol and dimethyl sulphoxide) on chondrocytes, (2) evaluate methods of freezing chondrocytes to maximize viability after freezing, and (3) examine the biosynthetic activity of frozen and thawed chondrocytes in culture. Results showed that the toxicity of cryopreservatives to chondrocytes is dependent on the time and temperature of exposure as well as on the concentration of the cryopreservative. Maximum viability was obtained by a two-stage freezing procedure using a slow cooling period initially, with equilibration of the cells at -40 degrees Celsius before further rapid freezing to -80 degrees Celsius. After seventy-two hours in culture, chondrocytes that had been frozen using this protocol synthesized products that appeared by column chromatography to form proteoglycan aggregates. Clinical Relevance: One of the reasons for failure of frozen osteochondral allografts is the deterioration of joint function after transplantation due to degeneration of the articular cartilage. An important factor in the survival of these cartilage grafts may be preservation of the viability of the chondrocytes during storage and maintenance of the cell's ability to function following storage. In this study we evaluated the ability to store chondrocytes in a frozen state with the aid of cryopreservatives. The results confirmed that chondrocytes will survive freezing and remain capable of functioning in the same manner as fresh chondrocytes. This suggests that chondrocytes in articular cartilage should be able to survive freezing. The pursuit of methods of preserving articular cartilage by freezing appears to be warranted.