Low dose naloxone mitigates opioid tolerance and dependence and restores mesenchymal stem cell function for cell therapy in addiction.

The increasing prevalence of treatment-resistant diseases has driven researchers to investigate advanced medical approaches, including stem cell-based therapies. Morphine, commonly used for pain relief, is associated with high addiction potential. It has been established that µ, δ, and κ opioid receptors are present in bone marrow mesenchymal stem cells (BMSCs), suggesting that morphine may compromise the efficacy of stem cell therapy in addicted individuals. However, the impact of morphine on the biological characteristics of BMSCs remains poorly understood. Therefore, this study aims to evaluate the morphine effects on the properties of BMSCs in morphine-dependent rats and assess the potential of low-dose naloxone (LDN) in counteracting the adverse effects. Animals were randomly devided into four experimental groups (n = 7) including the morphine treatment group (10 mg/kg), LDN treatment group (10 µg/kg), Combination group (MOR + NXL) (10 mg/kg + 10 µg/kg), and the control group (normal saline). All subcutaneous administrations were every 12 h for 7 consecutive days. After chronic morphine addiction, behavioral tests were conducted to assess opioid tolerance and dependence in different groups. Rats were then euthanized, and BMSCs were isolated. Subsequently, cell survival, migration, and the expression of homing markers, including C-X-C chemokine receptor type 4 (CXCR4), matrix metalloproteinase-2 (MMP-2), and Very Late Antigen-4 (VLA4), were analyzed. Additionally, antioxidant markers and TNFα and IL-10 levels were measured in the conditioned medium. Morphine administration significantly reduced the body weight (P < 0.05). However, this weight loss was not observed in morphine co-administered with LDN. LDN also blocked morphine-induced analgesic tolerance and dependence. Afterward, isolated BMSCs from morphine-dependent rats exhibited significantly reduced cell survival, migration, and prolonged doubling time compared to other groups (P < 0.05). Additionally, levels of TNFα, IL-10, and malondialdehyde (MDA), a marker of lipid peroxidation, were significantly higher in the morphine group than in the other groups. Moreover, the protein expressions of CXCR4, VLA4, and MMP-2 were downregulated in the morphine-treated group. Notably, LDN co-treatment preserved survival, lowered doubling time, MDA, and TNFα levels, and restored the homing markers. Given the negative effects of morphine on the key properties of BMSCs, it can be concluded that individuals addicted to morphine may be suboptimal candidates for cell therapy. However, adjunctive LDN treatment could restore these effects and improve therapeutic outcomes.