Neurodegenerative diseases that include Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Huntington's disease (HD), and multiple sclerosis (MS), arise due to numerous causes like protein accumulation and autoimmunity, characterized by neurologic depletion which lead to incapacity in normal physiological function such as thinking and movement in these patients. Glial cells perform a critical role in protective neuronal function; in the case of neuroinflammation, glial cell dysfunction can promote the development of neurodegenerative diseases. MiRNA participates in gene regulation and plays a vital role in many biological processes in the body; in the central nervous system (CNS), it can play an essential part in neural maturation and differentiation. In neurodegenerative diseases, miRNA dysregulation occurs, enhancing the development of these diseases. In this review, we discuss neurodegenerative diseases (Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS)) and how miRNA is preserved as a diagnostic biomarker or therapeutic agent in these disorders. Finally, we highlighted miRNA as therapy.

Background: Amyotrophic lateral sclerosis (ALS) is an incurable disease. There are no defined valid biomarkers for evaluating therapeutic outcomes of this disease. Numerous approaches have been made to meet this impact. Stem cells, one of these approaches, that might give various hopeful results that can be interpreted as a treatment for ALS This study aims to evaluate Mesenchymal Stem Cell (MSC) therapy as a promising novel treatment modality by estimating some parameters, such as immunological and biochemical factors. Methods: This study course involved 15 confirmed patients with ALS and was designed as an open-label, one-arm retrospective study to evaluate potential diagnostic biomarkers of repeated infusions of autologous bone marrow-derived mesenchymal stem cells (BM-MSC) administered at a dose of 1×106cells/kg BW with 1-month interval, in equal amounts in both intravenous (IV) and intrathecal (IT) simultaneously, by various biochemical and immunological parameters were evaluated during the three-month follow-up period. Results: Our study indicated that in the case of Immunological biomarkers ,Tumor Necrosis Factor-alpha (TNF-α) levels in the Cerebrospinal fluid (CSF) showed a significant decrease at month three after transplantation compared to levels at month zero, and the P-value was (P<0.01). No statistically significant changes were observed for other immunological and biochemical parameters and P-value (P>0.05). Conclusions: These results can indicate the benefit of stem cell transfusion in patients with ALS and suggest some diagnostic biomarkers. Several studies are required to approve these results.

Background: Since there is no cure for amyotrophic lateral sclerosis (ALS) currently, it is very important for searching diagnostic biomarkers and novel treatments to reduce the severity of this disease; one of these treatment approaches is stem cell transplantation. This study aims to evaluate the safety and efficacy of repeated transplantation of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in patients with ALS by analyzing molecular data. Methods: In this single-centre, open-label, phase II clinical trial, retrospective study, fifteen confirmed ALS patients entered the study based on defined inclusion and exclusion criteria and underwent repeated stem cell transplantation (3 times BM-MSCs transplantation (1×10^6) , MSC/Kg BW per injection) concurrently intrathecally (IT) and intravenously (IV), with one-month interval). Clinical assessment of molecular investigation by evaluating specific microRNAs expression (Mir206, 133a-3p, 338-3p) in the patient's serum and Cerebra spinal fluid (CSF) samples were done three times during the 3-month follow-up. Statistical analysis includes paired T-test or Wilcoxon signed ranks. Results: No serious adverse effects were reported following stem cell transplantation. Besides, the mentioned microRNA expression slightly increased but still non-significant (P>0.05). Conclusions: Although Our study demonstrated non-signifying results. However, the still increasing of these MircRNAs in serum and CSF overall, can indicate that repeated transplantation of BM-MSCs was a safe procedure in ALS patients, leading to delay in disease progression and improvement in clinical symptoms. Future studies are needed to confirm these results.