RNA, a crucial molecule in protein synthesis and gene expression regulation, plays an essential role in organisms. RNA modifications, acting as epigenetic marks, subtly adjust the structure, stability, and function of RNA, thereby regulating gene expression and exerting profound effects on cellular functions and organismal health. These natural modifications, together with RNA editing that alters nucleotide sequence of mRNA, constitute the epitranscriptome, which is vital for cellular metabolism. With the rapid advancement of biotechnology, RNA-based therapies and technologies have emerged as a frontier in biotech research. Various RNA drugs, including small interfering RNA (siRNA), antisense oligonucleotides (ASO), mRNA vaccines, and the small guide RNA (sgRNA) required for CRISPR gene editing, have been continuously developed. It has been widely demonstrated that RNA modifications can alter the physicochemical properties of RNA, enhance resistance to nucleases, reduce immunogenicity, and optimize in vivo functionality, leading to their extensive application in RNA-related biotechnologies. Furthermore, the variety of RNA modifications has expanded beyond natural modifications with the invention of an increasing number of artificial modifications. This review delves into the common types of RNA modifications, including base, ribose, and phosphate modifications, discussing their impact on RNA structure and how these modifications influence the biological characteristics of RNA. The current applications of these modifications in the biotechnology field are summarized, highlighting their significance in RNA-based therapies.

Numerous preanalytical variables (sample collection, pretreatment and storage conditions, miRNA extraction, etc.) can influence miRNA detection. Understanding the various properties of miRNA, especially its stability in biofluids, is important in various types of miRNA studies, both fundamental and applied. This study aimed to evaluate the influence of plasma storage conditions and certain RNA extraction parameters on stability of endogenous miRNAs in human blood plasma. We report stability kinetics of four endogenous miRNAs (-16, -19b, -23a, -451a) and cel-miR-39 as exogenous miRNA under short and long-term incubation at different temperatures as well as the effect of long-term storage on extracellular vesicles miRNAs stability. The most stable of the endogenous ones was miRNA-23a. When studying archival samples (1–2 and 9–10 years of storage) of blood plasma from healthy donors, it was shown, that the concentrations of all endogenous miRNAs are steadily decreasing. These findings further show that endogenous miRNA levels do not remain stable during prolonged storage at −20°C. Although packaging of miRNA in extracellular vesicles stabilizes miRNA to some extent, it nevertheless the level decreases over a period of time from 6 months to 6 years. We have also evaluated the effect of the reagents used in the extraction process on miRNA recovery. The addition of guanidine isothiocyanate containing denaturation buffer alone prevented degradation of the synthetic cel-miR-39 miRNA spiked-in to blood plasma. In the presence of denaturation buffer with or without 2-mercaptoethanol the yields were higher than with just 2-mercaptoethanol or in the absence of any agents. Addition of the commercial RNA-stabilizing agent RNAlater did not result in significant retention of miRNA in plasma, but significantly worsened the efficiency of miRNA isolation. Thus, the degradation rate of miRNAs can be affected by their structure and packaging. Addition of various stabilization solutions to biofluids can affect the efficiency of miRNA extraction.

The polarization of macrophages towards an anti-inflammatory and/or pro-tissue repairing phenotype has shown promising potential in the treatment of ischemic diseases. Macrophages play a crucial role in promoting the growth of new blood vessels in ischemic tissue by clearing apoptotic debris caused by hypoxia, recruiting immune cells that support tissue repair, and releasing a variety of cytokines and growth factors. However, there is still a significant knowledge gap regarding the effective induction of this specific macrophage polarization. Non-coding RNAs have demonstrated promise in regulating macrophage activity, although there is a need for more efficient delivery system. Exosomes, which are cell-derived extracellular vesicles ranging from 30 nm to 200 nm in size, have emerged as promising carriers of non-coding RNAs for regulating macrophage activity. This review will discuss the important role of macrophage polarization in ischemic diseases and explore the potential of non-coding RNAs delivered by exosomes in modulating macrophage polarization.