MicroRNAs (miRNAs) are a class of small noncoding RNAs, which function in posttranscriptional regulation of gene expression. They are powerful regulators of various cellular activities including cell growth, differentiation, development, and apoptosis. They have been linked to many diseases, and currently miRNA-mediated clinical trial has shown promising results for treatment of cancer and viral infection. This review provides an overview and update on miRNAs biogenesis, regulation of miRNAs expression, their biological functions, and role of miRNAs in epigenetics and cell-cell communication. In addition, alteration of miRNAs following exercise, their associationwith diseases, and therapeutic potential will be explained. Finally, miRNA bioinformatics tools and conventional methods for miRNA detection and quantification will be discussed.

Background: A hot new topic in medical treatment is the use of mesenchymal stem cells (MSC) in therapy. The low frequency of this subpopulation of stem cells in bone marrow (BM) necessitates their in vitro expansion prior to clinical use. We evaluated the effect of long term culture on the senescence of these cells.

Purpose The long-term follow-up results of patients with acute promyelocytic leukemia (APL) treated with all-trans retinoic acid and chemotherapy show high cure rates. Several studies have shown high efficacy of single-agent arsenic trioxide in newly diagnosed APL. However, long-term follow-up results are needed. Patients and Methods One hundred ninety-seven patients with newly diagnosed APL were treated with arsenic trioxide 0.15 mg/kg daily intravenous infusion until complete remission (CR). After achieving CR, the patients received one to four more courses of therapy with arsenic trioxide as consolidation and were observed with reverse-transcriptase polymerase chain reaction studies from peripheral blood (to detect of minimal residual disease) every 3 months or until relapse or death. Results The morphologic CR rate was 85.8%. The most common cause of remission failure was early death owing to APL differentiation syndrome (13.2%). The most important prognostic factor for early mortality was a high WBC count at presentation. The 5-year disease-free survival (DFS) rate was 66.7% ± 4% (SE). Relapse after 5 years in CR was rare. The 5-year overall survival (OS) rate by intention-to-treat analysis was 64.4% ± 4%. In patients who achieved CR, OS and DFS were identical. Conclusion The long-term follow-up of newly diagnosed patients with APL treated with single-agent arsenic trioxide shows high rates of DFS and OS.