Three-Dimensional Culture of Feline Articular Chondrocytes in Alginate Microspheres

Bone marrow mesenchymal stem cells combined with calcium alginate gel modified by hTGF-β1 for the construction of tissue-engineered cartilage in three-dimensional conditions

The aim of this study was to investigate the feasibility of Ad-hTGF-β1-transfected bone marrow mesenchymal stem cells (BMMSCs) combined with calcium alginate gel for the construction of tissue-engineered cartilage under three-dimensional conditions. Rat BMMSCs were divided into three groups: the Ad-hTGF-β1 transfection group, the Ad-EGFP transfection group and the control group. The BMMSCs in the Ad-hTGF-β1 transfection group were continually grown. The compound of cell-calcium alginate gel was cultured in a constant temperature incubator. The morphology of cells was examined, and the proliferation of cells was detected by MTT assay. The results from real-time PCR showed that the average relative ratio of TGF-β1 and transcriptional coactivator with PDZ-binding motif (TAZ) in the Ad-hTGF-β1 group was comparable to that of the control group (P<0.05). Using western blotting and immunohistochemistry, strong expression of collagen II in the Ad-hTGF-β1 group was detected. The results from western blotting showed that the expression of TGF-β1 in the Ad-hTGF-β1 group was significantly increased compared with that of the other two groups. The differentiation of BMMSCs was induced by Ad-hTGF-β1 transfection into chondrocytes. TGF-β1 may promote the differentiation of BMMSCs into chondrocytes by TAZ. BMMSCs transfected by Ad-hTGF-β1 could be induced into chondrocytes. These three-dimensional conditions could preferably mimic cell growth patterns in vivo.

Development of an in vitro model of feline cartilage degradation

Osteoarthritis is the most common arthropathy of mammalian species including cats. Cartilage degradation is central to the disorder and here we present, for the first time, an in vitro model of feline cartilage degradation which will be useful for further studies in this target species. Feline articular cartilage explant cultures were maintained for 28 days and in the presence of oncostatin M with and without interleukin (IL)-17, tumour necrosis factor (TNF), IL-1alpha, or IL-1beta. Media samples and digested cartilage explants were analysed for glycosaminoglycan (GAG) and collagen content. The combination of IL-1beta and OSM, both at 20 ng/ml, was able to promote GAG release to the greatest extent at 14 days. At 28 days, all groups showed relatively high release of GAG. At 14 days, only IL-1beta and OSM in combination were associated with a statistically significant increase in collagen release over and above control tissue. IL-1beta dose-response studies showed that an IL-1beta dose of 10 ng/ml promotes a statistically significant increase in GAG breakdown when used with OSM, and higher doses of IL-1beta did not result in significantly greater response. The model demonstrated both GAG and collagen degradation and will be of use for further understanding of feline cartilage metabolism and for screening of potential structure-modifying agents to be used in cats.

Methodological models for in vitro amplification and maintenance of human articular chondrocytes from elderly patients

Articular cartilage defects, an exceedingly common problem closely correlated with advancing age, is characterized by lack of spontaneous resolution because of the limited regenerative capacity of adult articular chondrocytes. Medical and surgical therapies yield unsatisfactory short-lasting results. Recently, cultured autologous chondrocytes have been proposed as a source to promote repair of deep cartilage defects. Despite encouraging preliminary results, this approach is not yet routinely applicable in clinical practice, but for young patients. One critical points is the isolation and ex vivo expansion of large enough number of differentiated articular chondrocytes. In general, human articular chondrocytes grown in monolayer cultures tend to undergo dedifferentiation. This reversible process produces morphological changes by which cells acquire fibroblast-like features, loosing typical functional characteristics, such as the ability to synthesize type II collagen. The aim of this study was to isolate human articular chondrocytes from elderly patients and to carefully characterize their morphological, proliferative, and differentiative features. Cells were morphologically analyzed by optic and transmission electron microscopy (TEM). Production of periodic acid-schiff (PAS)-positive cellular products and of type II collagen mRNA was monitored at different cellular passages. Typical chondrocytic characteristics were also studied in a suspension culture system with cells encapsulated in alginate-polylysine-alginate (APA) membranes. Results showed that human articular chondrocytes can be expanded in monolayers for several passages, and then microencapsulated, retaining their morphological and functional characteristics. The results obtained could contribute to optimize expansion and redifferentiation sequences for applying cartilage tissue engineering in the elderly patients.