Brain delivering RNA-based therapeutic strategies by targeting mTOR pathway for axon regeneration after central nervous system injury.

Injuries to the central nervous system (CNS) such as stroke, brain, and spinal cord trauma often result in permanent disabilities because adult CNS neurons only exhibit limited axon regeneration. The brain has a surprising intrinsic capability of recovering itself after injury. However, the hostile extrinsic microenvironment significantly hinders axon regeneration. Recent advances have indicated that the inactivation of intrinsic regenerative pathways plays a pivotal role in the failure of most adult CNS neuronal regeneration. Particularly, substantial evidence has convincingly demonstrated that the mechanistic target of rapamycin (mTOR) signaling is one of the most crucial intrinsic regenerative pathways that drive axonal regeneration and sprouting in various CNS injuries. In this review, we will discuss the recent findings and highlight the critical roles of mTOR pathway in axon regeneration in different types of CNS injury. Importantly, we will demonstrate that the reactivation of this regenerative pathway can be achieved by blocking the key mTOR signaling components such as phosphatase and tensin homolog (PTEN). Given that multiple mTOR signaling components are endogenous inhibitory factors of this pathway, we will discuss the promising potential of RNA-based therapeutics which are particularly suitable for this purpose, and the fact that they have attracted substantial attention recently after the success of coronavirus disease 2019 vaccination. To specifically tackle the blood-brain barrier issue, we will review the current technology to deliver these RNA therapeutics into the brain with a focus on nanoparticle technology. We will propose the clinical application of these RNA-mediated therapies in combination with the brain-targeted drug delivery approach against mTOR signaling components as an effective and feasible therapeutic strategy aiming to enhance axonal regeneration for functional recovery after CNS injury.

[Effect of muscle relaxants on the prognosis of neonates with congenital esophageal atresia-tracheoesophageal fistula after surgery].

OBJECTIVE: To summarize the experience in the application of muscle relaxants in the perioperative period in neonates with congenital esophageal atresia-tracheoesophageal fistula (EA-TEF). METHODS: A retrospective analysis was performed on the medical data of 58 previously untreated neonates with EA-TEF who were treated in the Neonatal Center of Beijing Children's Hospital, Capital Medical University from 2017 to 2019. The incidence rate of anastomotic leak was compared between the neonates receiving muscle relaxants for different durations after surgery (≤ 5 days and > 5 days). The correlation between the duration of postoperative use of muscle relaxants and the duration of mechanical ventilation was evaluated. RESULTS: Among the 58 neonates with EA-TEF, 44 underwent surgery, among whom 35 with type III EA-TEF underwent thoracoscopic surgery. Among these 35 neonates, 30 (86%) received muscle relaxants after surgery, with a median duration of 4.75 days, and 6 (18%) experienced anastomotic leak. There was no significant difference in the incidence rate of anastomosis leak between the ≤ 5 days and > 5 days groups (P > 0.05). The duration of postoperative invasive mechanical ventilation was positively correlated with the duration of the use of muscle relaxants (rs=0.548, P < 0.05). CONCLUSIONS: Prolonged use of muscle relaxants after surgery cannot significantly reduce the incidence of anastomotic leak, but can prolong the duration of invasive mechanical ventilation in neonates with EA-TEF. Therefore, prolonged use of muscle relaxants is not recommended after surgery.

Combined effect of honokiol and rosiglitazone on cell growth inhibition through enhanced G0/G1 phase arrest in hepatoma cells.

BACKGROUND: Honokiol, a derivative extracted from the stem and bark of Magnolia officinalis, has been reported to have anticancer effects in hepatoma cells. Recently, it was found that honokiol acted as not only a retinoid X receptor (RXR) agonist but also as a peroxisome proliferator-activated receptor gamma (PPARγ) agonist. Additionally, honokiol is capable of activating PPARγ/RXR heterodimers synergistically in the presence of rosiglitazone in 3T3-L1 adipocyte and HLE human hepatoma cells. Furthermore, synthetic PPARγ agonist thiazolidinediones exhibited growth inhibition effects in hepatoma cells through PPARγ-dependent and PPARγ-independent pathways. However, the combined effects of treatment with honokiol and PPARγ agonist are unclear in hepatoma cells. METHODS: In this study, sulforhodamine B assay, flow cytometry, and Western blot analysis were used to examine the combined effects of honokiol and PPARγ agonist (rosiglitazone) treatment on growth inhibition in SK-Hep1 and Mahlavu hepatoma cells. RESULTS: Honokiol or rosiglitazone treatment in hepatoma cells induced growth inhibition at high dose by sulforhodamine B assay. Moreover, we found that combined treatment with honokiol and rosiglitazone showed more effective growth inhibition in hepatoma cells than treatment with honokiol or rosiglitazone alone. Also, treatment with honokiol and rosiglitazone induced cell cycle arrest in the G0/G1 phase; increased p21; and decreased cyclin D1, cyclin E1, and Rb expression in SK-Hep1 hepatoma cells. CONCLUSION: Honokiol combined with rosiglitazone showed more effective growth inhibition in hepatoma cells mediated through the regulation of G0/G1 phase-related proteins p21, cyclin D1, cyclin E1, and Rb and cell cycle progression.