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Updated: Mar 29, 2026
Real-time Visualization and Analysis of Chondrocyte Injury Due to Mechanical Loading in Fully Intact Murine Cartilage Explants
Published on: January 7, 2019
PTEN ELEVATION, AUTOPHAGY AND METABOLIC REPROGRAMMING MAY BE INDUCED IN HUMAN CHONDROCYTES DURING STEROIDS OR
O Galasso1, S Panza2, M Santoro3
1Department of Orthopaedic Surgery, Magna Graecia University, Catanzaro, Italy.
Abstract:
The exact mechanisms controlling the development and progression of osteoarthritis have not yet been clarified. Our aim was to investigate new pathomechanisms, with an emphasis on novel molecular targets that might regulate human chondrocytes in osteoarthritis. As a model for studying cell survival and metabolism, C-28/I2 and T/C-28a4 human chondrocytes were grown in complete medium, in dex-tran-coated charcoal treated medium and in serum-free medium. Healthy and osteoarthritic human cartilage samples were obtained from discarded surgical material. Cell survival, PTEN, AKT, Beclin1, AMBRA, AMPK and glucose/triglyceride metabolism were evaluated by immunoblotting and spectro-photometric assays. Starvation and steroids depletion decreased cell survival concomitantly with PTEN elevation, repression of the PI3K/AKT signaling axis and autophagy activation. These experimental conditions promoted the accumulation of glucose, decreased levels of G6PDH and resulted in differen-tial expression of OXPHOS complexes. Furthermore, they induced the expression of AMPK, reduced triglyceride levels and increased lipase activity, which was accompanied by a change in chondrocytes toward a fibroblast-like morphology. In osteoarthritic human cartilage, increased PTEN, AMPK and autophagy reflected the chondrocyte responses observed during starvation and steroids depletion. In conclusion, we defined the metabolic phenotype of human chondrocytes, in which both starvation and steroids depletion induce the activation of PTEN, AMPK and autophagy signaling, concomitant with metabolic reprogramming. Our data may aid in the development of novel in vitro models for the discovery and design of drugs or nutraceuticals capable of ameliorating the course of osteoarthritis.
Insights
Investigating osteoarthritis mechanisms, this study reveals how nutrient deprivation and steroid reduction activate PTEN, AMPK, and autophagy in chondrocytes. These changes reprogram cell metabolism, offering new targets for osteoarthritis drug discovery.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Medicine
Background:
- Osteoarthritis (OA) pathogenesis remains incompletely understood.
- Novel molecular targets regulating human chondrocytes in OA require identification.
Purpose of the Study:
- To investigate novel pathomechanisms in osteoarthritis.
- To identify molecular targets regulating human chondrocytes in OA.
Main Methods:
- Human chondrocyte cell lines (C-28/I2, T/C-28a4) were cultured under various conditions (complete, serum-free, steroid-depleted).
- Analysis of cell survival, protein expression (PTEN, AKT, Beclin1, AMBRA, AMPK), and glucose/triglyceride metabolism using immunoblotting and spectrophotometric assays.
- Evaluation of healthy and osteoarthritic human cartilage samples.
Main Results:
- Serum and steroid depletion reduced cell survival, increased PTEN and AMPK, activated autophagy, and altered glucose/lipid metabolism.
- These conditions induced a shift in chondrocyte morphology towards a fibroblast-like phenotype.
- Elevated PTEN, AMPK, and autophagy markers in osteoarthritic cartilage mirrored experimental findings.
Conclusions:
- Defined the metabolic phenotype of human chondrocytes under starvation and steroid depletion.
- Identified PTEN, AMPK, and autophagy activation as key responses.
- Findings suggest potential for developing novel in vitro models and therapeutic strategies for osteoarthritis.
