Osteoporosis, the most common metabolic bone disease, increases with age and is characterized by low bone mass and disrupted bone microarchitecture, leading to increased bone fragility. It arises from an imbalance between bone resorption by osteoclasts and bone formation by osteoblasts. Osteoblasts originate from mesenchymal stem cells (MSCs) in the bone marrow.
Current osteoporosis treatments include antiresorptive drugs like bisphosphonates and denosumab, which reduce bone resorption but do not promote bone formation. Teriparatide (TPTD) is one of the few osteoanabolic drugs that stimulate bone formation. TPTD’s effect on bones depends on dosing: intermittent dosing has an anabolic effect, while continuous dosing increases bone resorption. Although TPTD treatment is more effective than bisphosphonates, fractures still occur. Therefore, therapy effectiveness is crucial, and research shows that it varies among individuals, which remains unexplained. This variability is likely due to epigenetic factors, including non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs).
This doctoral thesis aimed to investigate the role of ncRNAs in bone remodeling and their connection to the osteoanabolic effects of TPTD. For the first time, we performed a transcriptomic analysis of MSCs treated with TPTD, revealing differences in the expression of miRNAs, lncRNAs, mRNAs, and circRNAs. Through bioinformatic analysis, we identified key miRNAs and signaling pathways involved in TPTD’s effects, including pathways regulating stem cell pluripotency, the Hippo pathway, and the TGF-β pathway. We demonstrated that selected miRNAs have potential as early biological markers of response to TPTD treatment. Finally, functional analyses highlighted 3 miRNAs (hsa-miR-375-3p, hsa-miR-20b-5p, hsa-miR-31-3p) that promote osteogenesis and 3 miRNAs (hsa-miR-133a-3p, hsa-miR-31-3p, hsa-miR-363-3p) that inhibit MSC adipogenesis. Our findings deepen the understanding of TPTD's molecular mechanisms, which could lead to personalized osteoporosis treatment.
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