Conditioned Medium Treatment for the Improvement of Functional Recovery after Spinal Cord Injury: A Meta-Analysis Study.

BACKGROUND: While there is no certain treatment for spinal cord injury (SCI), stem cellbased therapy may be an attractive alternative, but the survival and differentiation of cells in the host tissue are poor. Conditioned medium (CM) has several beneficial effects on cells. OBJECTIVE: In this meta-analysis study, we examined the effect of CM on SCI treatment. METHODS: After searching on MEDLINE, SCOPUS, EMBASE, and Web of Science, first and secondary screening were performed based on title, abstract, and full text. The data were extracted from the included studies, and meta-analysis was performed using STATA.14 software. A standardized mean difference (SMD) with a 95% confidence interval was used to report findings. Quality control and subgroup analysis were also performed. RESULTS: The results from 52 articles and 61 separate experiments showed that CM had a significantly strong effect on improving motor function after SCI (SMD = 2.58; 95% CI: 2.17 to 2.98; p < 0.001) and also analysis of data from 12 articles demonstrated that CM reduced the expression of GFAP marker (SMD = -4.16; p < 0.0001) compared to SCI group without any treatment. Subgroup analysis showed that treatment with CM of neural stem cells was better than CM of mesenchymal stem cells. It was more effective after a mild lesion than a moderate or severe one. The improvement was more pronounced with <4 weeks than >4 weeks follow-up. CONCLUSION: CM had a significant effect in improving motor function after SCI, especially in cases of mild lesions. It has been observed that if CM originates from the neural stem cells, it has a more significant effect than mesenchymal cells.

Could conditioned medium be used instead of stem cell transplantation to repair spinal cord injury in animal models? Identifying knowledge gaps.

The drawbacks of stem cell (SC) therapies have led to investigations of SC conditioned medium (CM) instead of SC transplantation in the repair of spinal cord injury (SCI). However, the effectiveness of CM in comparison with cell transplantation in SCI models remain an open and intriguing question. The focus of this review was to survey existing publications addressing this comparison. The review included articles from electronic databases Medline, Embase, Scopus, and Web of Science that included comparisons of the effects of CM versus SC transplantation and versus controls on locomotion after SCI. The search yielded 5 studies and 6 experiments. The results indicated that there was insufficient evidence to conclude that treatment with CM and source cells were equally effective (SMD = 0.12; 95% CI = -0.36 to 0.59; p = 0.07). Regarding investigations of separate effects of SCs versus CM, there currently is limited evidence on efficacy in SCI models. This highlights a notable concern affecting this field. Thus, we identified critical knowledge gaps concerning comparisons of the efficacy of therapeutic application of SC and their derived CM on functional recovery following SCI.

Retraction notice to "Noopept; a nootropic dipeptide, modulates persistent inflammation by effecting spinal microglia dependent Brain Derived Neurotropic Factor (BDNF) and pro-BDNF expression throughout apoptotic process" [Heliyon (2021) e06219].

[This retracts the article DOI: 10.1016/j.heliyon.2021.e06219.].

Noopept; a nootropic dipeptide, modulates persistent inflammation by effecting spinal microglia dependent Brain Derived Neurotropic Factor (BDNF) and pro-BDNF expression throughout apoptotic process.

There are largely unknown associations between changes in pain behavior responses during persistent peripheral inflammation and spinal cell alteration such as apoptosis. Some evidence suggests that microglia and microglia related mediators play notable roles in induction and maintenance of central nervous system pathologies and inflammatory pain. By considering those relationships and microglia related nootrophic factors, such as the Brain Derived Neurotrophic Factor (BDNF) in CNS, we attempted to assess the relationship between microglia dependent BDNF and its precursor with pain behavior through spinal cell apoptosis as well as the effect of Noopept on this relationship. Persistent peripheral inflammation was induced by a single subcutaneous injection of Complete Freund's Adjuvant (CFA) on day 0. Thermal hyperalgesia, paw edema, microglial activity, microglia dependent BDNF, pro-BDNF expression, and apoptosis were assessed in different experimental groups by confirmed behavioral and molecular methods on days 0, 7, and 21 of the study. Our findings revealed hyperalgesia and spinal cell apoptosis significantly increased during the acute phase of CFA-induced inflammation but was then followed by a decrement in the chronic phase of the study. Aligned with these variations in spinal microglial activity, microglia dependent BDNF significantly increased during the acute phase of CFA-induced inflammation. Our results also indicated that daily administration of Noopept (during 21 days of the study) not only caused a significant decrease in hyperalgesia and microglia dependent BDNF expression but also changed the apoptosis process in relation to microglia activity alteration. It appears that the administration of Noopept can decrease spinal cell apoptosis and hyperalgesia during CFA-induced inflammation due to its direct effects on microglial activity and microglia dependent BDNF and pro-BDNF expression.