This study utilized visualization analysis software CiteSpace6.4.2R, VOSviewer1.6.19, and Microsoft Excel 2019 for visualization processing. VOSviewer is a commonly used bibliometric tool developed and released by Nees Jan van Eck and Ludo Waltman in 2015. This software specializes in the visual analysis of bibliometric networks, where a group of related nodes can be allocated into distinct groups and differentiated by different colors, with nodes that have similar or close colors indicating higher relevance. CiteSpace is a software developed by Dr. Chaomei Chen and his team in 2004, which can used for visualizing and analyzing scientific literature. The software can help researchers analyze citation networks, keyword networks, and author collaboration networks, among other types of information, making it more convenient for researchers to understand the forefront of research fields, hotspots, and development trends. This study employed both software packages to generate graphical representations from different aspects, including annual publication distribution, country and region distribution, institutional distribution, popular authors, journals, citation and reference frequencies, and more, to comprehensively analyze and study the knowledge map. Keyword cluster maps and burst word maps were also generated for a more in-depth analysis.

The volume of published articles can demonstrate the current global trends and cutting-edge hotspots in a particular field (19). Figure 2 shows the global publication volume of articles related to the therapeutic effects of microRNA in axonal regeneration after PNI, collected from the Web of Science database over the past decade. It is not difficult to see that there were two peaks in the publication of articles in this field in 2019 and 2022. From 2015 to 2022, the number of articles published per year remained above 10, especially in 2022, when a total of 31 articles were published, the highest in the history of article publications so far. Although the annual distribution of article publications fluctuated slightly, the overall trend was that an increasing number of articles were published each year. Since the collection of research data ended on June 1, 2023, there are currently only 4 articles published in 2023. However, based on the average number of published articles in these years, there is still a good chance of exceeding 10 publications by the end of this year.

In terms of the number of articles published, China ranks first with 108 articles, while the United States ranks second with 34 articles (Figures 3, 4), and these two countries’ articles account for 81.6% of the total, indicating that China and the United States are in a dominant position in this field. In particular, China almost occupies half of the global article output, which highlights its leading role in the treatment of axonal regeneration after PNI using miRNA in the world. From the analysis of the number of citations, China and the United States still occupy the top two positions, with 2,352 and 1,673 citations, respectively, (Figure 4). However, the average number of citations per article is 49.2 and 46.4 for the United States and Germany, respectively, ranking first and second, while China ranks fifth with 21.5 citations, tied with Austria. This also reflects that although China ranks high in the total number of articles published, there is still a certain gap in the quality of the articles compared to developed countries in Europe and America.

A total of 199 institutions globally have contributed to the research field of the therapeutic effects of microRNA on axon regeneration after peripheral nerve injury. Among the top 10 institutions in terms of publication volume, 7 of them are from China, with Nantong University ranking first in publication volume with 31 articles and 734 citations. Although the University of Würzburg has only published 4 articles, its citation frequency of 81.2 times is significantly higher than that of other institutions, indicating the high academic recognition of the quality of its publications worldwide. Among Chinese institutions, Jilin University has the highest citation frequency of 54.5 times, ranking top among domestic universities in terms of article level and quality. Using Citespace software for cluster analysis of these institutions (Figure 5), the size of the nodes reflects the number of articles published, with larger nodes indicating a greater number of publications. The thicker the lines between each node, the more frequent the collaboration between the two institutions represented by the nodes. Analysis shows that domestic institutions tend to collaborate more frequently with other domestic institutions, with thinner lines and fewer publications in collaboration with foreign institutions” (Table 1).

From 2003 to 2023, 846 authors worldwide have published relevant articles. Among the top five authors in terms of publication volume, four are from the Key Laboratory of Neuroregeneration at Nantong University. Professor Yi Sheng ranks first with 14 articles. In contrast, Academician Xiao Song Gu, the director of the Key Laboratory of Neuroregeneration at Nantong University, ranks first in terms of average citations per article with 49.5 (Table 2).

Table 3 and Figure 6 illustrate the distribution of related academic journals publishing articles on the therapeutic effects of microRNAs in axon regeneration after PNI. The journal “Frontiers in Molecular Neuroscience” published the highest number of articles at a total of 12. Although both the “International Journal of Molecular Sciences” and the “Neurochemical Research” published the same number of articles, at 7, the latter received the most citations and had the highest average citations per article, with 230 and 32.8, respectively. The top five journals in terms of impact factor all exceeded 4.0, with an average of 5.19. “Neural Regeneration Research” had the highest impact factor, at 6.05.

The number of citations can reflect the influence of an article in the target field (20). Table 4 lists the top 5 most cited articles worldwide, with Professor Shi Ying Li’s article “Let-7 microRNAs Regenerate Peripheral Nerve Regeneration by Targeting Nerve Growth Factor” published in the journal Molecular Therapy accumulating 34 citations. Meanwhile, Professor Bin Yu from the Key Laboratory of Neural Regeneration at Nantong University has 3 articles with citation counts of 27, 24, and 24 respectively, entering the top five rankings. This also demonstrates that Professor Yu has a wealth of knowledge and experience in the field. The five papers were published in five different journals, including Molecular Therapy, Journal of Cell Science, PLOS ONE, the Journal of Neuroscience, and Nucleic Acids Research, all of which are influential journals in the field of biomedical research. All of the papers focus on the role of microRNAs in neural injury and regeneration, indicating that microRNAs are a hot research topic in this field.

The role of keywords in an article is significant, as they can more or less extract and reflect the core of an article. Among the 1,047 collected keywords, the top 10 are microRNAs, expression, neuropathic pain, miRNA, peripheral nerve injury, regeneration, sciatic-nerve, Schwann cell, migration, and proliferation (Table 5). MicroRNAs have appeared a total of 79 times and are the most frequently used keyword. Through VosViewer analysis (Figure 7), the 37 keywords that appeared more than 10 times were categorized into three clusters, and the size of each node reflects its frequency. MicroRNAs have become the most representative term in this field. Figure 8 reflects the relationship between keyword nodes and time. The closer the node color to yellow, the more recent the appearance of the keyword. It is not difficult to find that the majority of the keyword frequency distribution concentrates between 2016 and 2023. By analyzing the frequency of keywords, with CiteSpace visualization software, it is equally found that microRNAs are the most popular keyword (Figure 9). This also shows that this field is closely related to microRNAs in terms of development trends.

The outbreak keywords phenomenon refers to the increase in the frequency of a certain keyword during a specific period. Figure 10 displays the top 10 burst word diagrams, where the keyword with the highest burst intensity is ‘Schwann cell’, which first appeared in 2018 and experienced a four-year burst. Schwann cells, as glial cells unique to the peripheral nervous system, possess remarkable plasticity and play a crucial role in axonal regeneration after PNI, as evidenced by a great deal of research (7, 20, 21). The most recent burst keyword is ‘mesenchymal stem cells’, which started to become the hotspot in 2021 and continued until 2023. Mesenchymal stem cells are a type of cell with self-replication ability and differentiation potential. Andrea Lavorato et al.’s study (22) elucidated the application prospects of this cell in peripheral nerve regeneration. Chen et al.’s 2019 research (23) confirmed that Schwann cell-like cells differentiated from mesenchymal stem cells could promote myelin sheath formation, and miRNA-24 overexpressed in SCLC contributed to the therapeutic effect of sciatic nerve injury in SCLC. A recent study has shown that miRNAs can regulate the proliferation, differentiation, and immunoregulatory functions of MSCs (24). By regulating the expression levels of miRNAs, the biological characteristics of MSCs can be affected, further influencing their potential for tissue repair and regeneration (25). Additionally, MSCs themselves can release extracellular vesicles rich in miRNAs, and miRNAs delivered by these vesicles can affect the gene expression and function of surrounding cells (26).

Bibliometrics, as a branch of information science, plays an increasingly important role in the field of medicine. It not only provides researchers with visual and simplified knowledge structures, but also reflects the overall trends, hotspots, and directions of the research content (27, 28). The collected literature data, after being visualized and mapped using CiteSpace 6.4.2R and VOSviewer 1.6.19, can greatly assist authors in analysis and research. Web of Science is a data services platform provided by Clarivate Analytics, as the largest and most comprehensive academic resource library in the world, covering biomedical, engineering, natural science, social science, humanities, and arts, with more than 8,700 core journals, regarded as the data source platform by this study (25). It also includes information on cited references, authors, sources, and publication years. Furthermore, it offers powerful functions such as quick search, advanced search, and citation search. It not only provides information on the latest articles but also on high-quality journals from the past. Therefore, using the Web of Science Core Collection as the data source is most appropriate for this study (29, 30).

MicroRNAs are undoubtedly a popular research direction in contemporary medical fields, and the co-occurrence of popular keywords further verifies this fact. Through analysis of the knowledge graph, we can see that all the keywords included in the research are divided into three different clusters, and microRNAs have a high frequency in all three clusters. The red cluster mainly covers the expression pathway and neuropathic pain, the green cluster mainly includes peripheral nerves, Schwann cells, and the sciatic nerve, and the yellow and purple cluster involves axon regeneration, repair, and functional recovery. These clusters reflect the current hotspots and future development trends in this field. The red cluster represents the expression pathway-related field, the green cluster represents the neurological field, and the yellow cluster represents the neural repair and regeneration field. In addition, we can also observe that before 2016, early research was mainly focused on gene expression and neuropathic pain-related directions, while after 2016, the focus of research began to shift toward neural and injury repair directions. This further infers that future development trends will mainly focus on research in neural regeneration and functional recovery. Studying the role of different microRNAs in neural regeneration and gene expression regulation to reveal specific mechanisms and find effective diagnosis and treatment methods for PNIs has become a frontier hotspot and future research direction in this field.

The limitations of this study can be summarized as follows: firstly, the collected and screened article data are all collected from the Web of Science Core Database. Although this database is considered the most complete and authoritative database, data omissions are inevitable. Secondly, this study only included English-language articles, and high-quality articles from non-English classes were not included in the analysis, which may lead to selection bias. Last but not least, the Web of Science Core Database is updated in real-time, so the analysis results we obtained in this study have temporal limitations. However, existing research still provides useful insights and guidance for our research direction and design.