Lithium Chloride Prevents Glucocorticoid-Induced Osteonecrosis of Femoral Heads and Strengthens Mesenchymal Stem Cell Activity in Rats
Glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) represents a significant clinical challenge, often leading to joint collapse and functional impairment. While GCs are indispensable for managing inflammatory and autoimmune disorders, their long-term use disrupts bone metabolism, suppresses osteogenesis, and compromises vascular integrity. Recent evidence highlights lithium’s potential to modulate mesenchymal stem cell (MSC) proliferation and osteogenic differentiation via the Wnt/β-catenin pathway. This study investigates lithium chloride’s protective effects on GC-induced ONFH and its ability to enhance MSC activity in a rat model.
Experimental Design and Methods
A rat model of ONFH was established using 30 male Sprague-Dawley rats divided into three groups: control (untreated), MP (methylprednisolone-induced ONFH), and MP + Li (MP induction with lithium chloride supplementation). The MP group received intramuscular MP injections (30 mg/kg daily for 3 days/week over 3 weeks). The MP + Li group received 0.2% lithium chloride in their feed starting 2 weeks before MP injections and continued until sacrifice. Femoral heads were analyzed 3 weeks post-modeling using micro-CT angiography, histology, and molecular assays. Bone marrow-derived MSCs were isolated to assess proliferative and osteogenic capacities.
Micro-CT and Angiographic Evaluation
Micro-CT imaging revealed severe trabecular deterioration in the MP group, including bone mineral loss and cystic degeneration. In contrast, lithium treatment (MP + Li group) significantly reduced osteonecrosis severity, with only 5 out of 20 femoral heads showing mild changes compared to 18/20 in the MP group. Trabecular parameters—bone mineral density (BMD), bone volume (BV), BV/tissue volume (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N)—were markedly higher in the MP + Li group than in the MP group (e.g., BV/TV: 25.3% vs. 12.7%, P < 0.05). Trabecular pattern factor (Tb.Pf), indicative of structural discontinuity, was lower in the MP + Li group (4.2 vs. 7.8 in MP, P < 0.05).
Angiography with Microfil perfusion demonstrated severe vascular loss in the MP group, particularly in the subchondral region. Lithium restored vessel density, with total vessel volume measuring 0.2193 mm³ in the MP + Li group versus 0.0811 mm³ in the MP group (P < 0.05). Immunohistochemical staining for CD31 further confirmed enhanced endothelial preservation in lithium-treated rats.
Histological and Molecular Analysis
Hematoxylin and eosin (H&E) staining showed extensive necrotic areas in the MP group, characterized by fragmented trabeculae and chondrocyte accumulation. The MP + Li group exhibited intact trabecular networks with minimal necrosis. Osteocalcin (OCN) expression, a marker of osteoblast activity, was robust in the control and MP + Li groups but nearly absent in the MP group, underscoring lithium’s role in preserving osteogenic function.
MSC Proliferation and Differentiation
Bone marrow-derived MSCs from the MP group displayed impaired proliferation, as shown by reduced CCK-8 absorbance values (Day 6: 0.85 vs. 1.32 in control, P < 0.01) and fewer colony-forming units (CFUs: 12 vs. 35 in control, P < 0.01). Lithium treatment restored proliferative capacity (Day 6 absorbance: 1.18; CFUs: 28).
Osteogenic differentiation assays revealed that MSCs from the MP group had diminished alkaline phosphatase (ALP) activity (0.12 U/mg protein vs. 0.45 U/mg in control, P < 0.01) and reduced mineralized nodule formation (alizarin red staining). Lithium enhanced ALP activity (0.38 U/mg) and calcium deposition, comparable to control levels. Western blotting and qRT-PCR confirmed upregulated expression of osteogenic markers—Runx2, ALP, and Collagen I—in the MP + Li group. For instance, Runx2 protein levels in the MP + Li group were 3.5-fold higher than in the MP group, while Collagen I mRNA increased by 2.8-fold (P < 0.05).
Mechanistic Insights
GCs disrupt bone homeostasis by accelerating MSC senescence, suppressing osteogenesis, and inducing adipogenesis. Lithium counteracts these effects through Wnt/β-catenin pathway activation, which promotes MSC proliferation and osteogenic differentiation while inhibiting adipogenesis. Enhanced vascularization in lithium-treated rats suggests synergistic coupling between angiogenesis and osteogenesis, possibly mediated by vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP)-9 upregulation.
Clinical Implications
This study demonstrates lithium’s dual capacity to mitigate GC-induced femoral head necrosis and rejuvenate MSC function. Lithium’s preferential accumulation in bone tissue and established safety profile in psychiatric disorders position it as a promising adjuvant therapy for preventing ONFH during long-term GC treatment. Future studies should validate these findings in larger animal models and explore optimal dosing regimens to balance efficacy and toxicity.
Conclusion
Lithium chloride significantly attenuates glucocorticoid-induced osteonecrosis of the femoral head in rats by preserving trabecular integrity, enhancing vascular perfusion, and restoring MSC proliferative and osteogenic potential. These effects are likely mediated through Wnt/β-catenin signaling activation, highlighting lithium’s therapeutic potential for bone disorders associated with GC therapy.
https://doi.org/10.1097/CM9.0000000000001530
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