Follicle and melanocyte stem cells, and their application in neuroscience: A Web of Science-based literature analysis.

OBJECTIVE: To identify global research trends of follicle and melanocyte stem cells, and their application in neuroscience. DATA RETRIEVAL: We performed a bibliometric analysis of studies from 2002 to 2011 on follicle and melanocyte stem cells, and their application in neuroscience, which were retrieved from the Web of Science, using the key words follicle stem cell or melanocyte stem cell, and neural, neuro or nerve. INCLUSION CRITERIA: (a) peer-reviewed published articles on follicle and melanocyte stem cells, and their application in neuroscience, which were indexed in the Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items. EXCLUSION CRITERIA: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) a number of corrected papers from the total number of articles. MAIN OUTCOME MEASURES: (1) Distribution of publications on follicle and melanocyte stem cells by years, journals, countries, institutions, institutions in China, and most cited papers. (2) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by years, journals, countries, institutions, and most cited papers.
RESULTS: Of the 348 publications from 2002 to 2011 on follicle and melanocyte stem cells, which were retrieved from the Web of Science, more than half were from American authors and institutes. The most prolific institutions in China for publication of papers on follicle and melanocyte stem cells were the Fourth Military Medical University and Third Military Medical University. The most prolific journals for publication of papers on follicle and melanocyte stem cells were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research. Of the 63 publications from 2002 to 2011 on the application of follicle and melanocyte stem cells in neuroscience, which were retrieved from the Web of Science, more than half were from American authors and institutes, and no papers were from Chinese authors and institutes. The most prolific journals for publication of papers on the application of follicle and melanocyte stem cells in neuroscience were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research.
CONCLUSION: Based on our analysis of the literature and research trends, we found that follicle stem cells might offer further benefits in neural regenerative medicine.

Research Highlights

We performed a bibliometric analysis of studies from 2002 to 2011 on follicle and melanocyte stem cells, and their application in neuroscience, which were retrieved from the Web of Science.

We analyzed the publication year, journals, countries, institutions, and institutions in China. Specifically, we analyzed all the data on follicle and melanocyte stem cells, and their application in neuroscience.

INTRODUCTION

Skin covers the surface of the body, and is the largest of all organs. It is composed of the epidermis, dermis, and subcutaneous tissue and appendages. The antigenicity of skin stem cells is weak, and they not only have the ability to self-renew, they also have multipotency and a strong proliferative ability. Skin stem cells can differentiate into various cells to repair cutaneous deficiencies, such as the cells of the skin, hair follicles, and sweat and sebaceous glands[123].

Follicle stem cells are located in the outer root sheath, i.e. the hair follicle bulge of the lower part of sebaceous glands. Follicle stem cells not only move downward to hair follicle roots to form hair follicles, but can also migrate upward from the hair follicle outer root sheath to generate the epidermis. These cells can even differentiate into neural crest stem cells and subsequently generate neurons and glial cells. Neural crest stem cells can also differentiate into melanocytes and smooth muscle cells, and can promote the repair of injured nerves. When neural crest stem cells in the hair follicle bulge are transplanted into injured peripheral nerves, they can promote axon growth and recovery of nerve functions. Thus, follicle stem cells can be used to repair spinal and auditory nerves to treat spinal cord injury and hearing disorders, respectively, and neurological degeneration[45678]. Follicle stem cells proliferate rapidly in vitro and survive in long-term culture, do not show immunological rejection, and are not hindered by ethical issues. Thus, they can be used in regenerative medicine[9]. Melanocyte stem cells are also widely distributed in the hair follicle bulge. At present, there are relatively few studies of their application in neuroscience.

In this study, we analyzed the research trends of follicle and melanocyte stem cells, and their application in neuroscience, based on a bibliometric analysis of the papers in the Web of Science published from 2002 to 2011.

DATA SOURCES AND METHODOLOGY

Data retrieval

This study used bibliometric analyses to quantitatively and qualitatively investigate research trends of studies on follicle and melanocyte stem cells, and their application in neuroscience. We searched the Web of Science, a research database of publications and citations selected and evaluated by the Institute for Scientific Information in Philadelphia, PA, USA, using the keywords follicle stem cell or melanocyte stem cell, and neural, neuro or nerve. We limited the publication period from 2002 to 2011, and compiled a bibliography of all articles related to follicle melanocyte stem cells, and their application in neuroscience. We downloaded the data on September 4th, 2012.

Inclusion criteria

The inclusion criteria are as follows: (1) published peer-reviewed articles on follicle and melanocyte stem cells, and their application in neuroscience, including original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items, which were indexed in the Web of Science; (2) the years of publication were 2002–2011; and (3) the citation database was Science Citation Index Expanded.

Exclusion criteria

We excluded articles that required manual searching or telephone access, documents that were not published in the public domain, and a number of corrected papers from the total number of articles analyzed.

The outcomes of all articles referring to skin stem cells were assessed using the following criteria. (a) Annual publication output of papers on follicle and melanocyte stem cells. (b) Distribution of publications on follicle and melanocyte stem cells by journals. (c) Distribution of publications on follicle and melanocyte stem cells by countries. (d) Distribution of publications on follicle and melanocyte stem cells by institutions. (e) Distribution of publications on follicle and melanocyte stem cells by institutions in China. (f) Most cited papers on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011. (g) Annual publication output of papers on the application of follicle and melanocyte stem cells in neuroscience. (h) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by journals. (i) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by countries. (j) Distribution of publications on the application of follicle and melanocyte stem cells in neuroscience by institutions. (k) Most cited papers on the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011.

RESULTS

Annual publication output of papers related to follicle and melanocyte stem cells in the Web of Science from 2002 to 2011

A total of 348 publications on follicle and melanocyte stem cells from 2002 to 2011 were retrieved from the Web of Science. The number of relevant publications increased over the 10-year study period, in which five papers were published and included in the Web of Science in 2002, followed by an increase in the number of published papers to 72 in 2011. However, the numbers of papers published slightly decreased in 2007 (Figure 1).

Figure 1

Annual number of publications on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011.

Distribution of output by journal for publications on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011

The Journal of Investigative Dermatology published 52 papers, followed by Pigment Cell & Melanoma Research, and Cell Stem Cell, which published 19 and 15 papers, respectively (Table 1). The next seven top journals were Development, Proceedings of the National Academy of Sciences of the United States of America, Cell, Experimental Dermatology, British Journal of Dermatology, American Journal of Dermatopathology, and Nature.

Table 1

The top 10 journals were selected based on publication output of papers on follicle and melanocyte stem cells between 2002 and 2011

Distribution of output by country for publications on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011

The analysis of the contributions of different countries/states to publications was based on journal articles in which the address and affiliation of at least one author were provided (Figure 2).

Figure 2

The top 10 countries for publications on follicle and melanocyte stem cells from 2002 to 2011.

I: USA; II: Japan; III: UK; IV: Germany; V: Canada; VI: China; VII: Switzerland; VIII: France; IX: Australia; X: Italy.

As shown in Figure 2, it was clear that most papers on follicle and melanocyte stem cells were published in the USA (191 papers), followed by Japan (79 papers). China published 12 papers and ranked 6th. The other prolific countries were the UK, Germany, Canada, Switzerland, France, Australia, and Italy.

Distribution of output by institution for publications on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011

The University of California system and University of Pennsylvania in the USA were the most prolific research institutes (Table 2). Eight of the top 11 research institutes publishing in this field were in the USA, and the other three institutes were in Japan, the UK and Germany, respectively.

Table 2

The top 11 institutes for publications on follicle and melanocyte stem cells from 2002 to 2011.

Distribution of output by institutions in China for publications on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011 (Table 3)

As shown in Table 3, the Fourth Military Medical University and Third Military Medical University were the most prolific research institutes in China for the publication of papers on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011. Each university published three papers. So far at least, the number of papers on follicle and melanocyte stem cells published by Chinese institutions was very few.

Table 3

The top 8 Chinese institutes that published papers on follicle and melanocyte stem cells from 2002 to 2011

Highly cited papers on follicle and melanocyte stem cells in the Web of Science from 2002 to 2011

A total of 348 papers on follicle and melanocyte stem cells were cited in the Web of Science from 2002 to 2011. “Capturing and profiling adult hair follicle stem cells”, published in 2004 by Nature Biotechnology[10], was cited 479 times, which was more citations than any other paper. Of the 10 most cited papers, four were published in Nature, two were published in Proceedings of the National Academy of Sciences of the United States of America, and the remaining four papers were published in four different journals. Of these 10 most cited papers, five were published in 2005, and one each was published in 2002, 2003, 2004, 2007, and 2008 (Table 4).

Table 4

The top 10 cited papers on follicle and melanocyte stem cells from 2002 to 2011

Annual number of publications on the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011.

Annual publication output of papers related to the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011 (Figure 3)

A total of 63 publications on the application of follicle and melanocyte stem cells in neuroscience from 2002 to 2011 were retrieved from the Web of Science. The number of relevant publications increased over the 10-year study period. No papers were published and included in the Web of Science in 2002, but the number of published papers had increased to 12 in 2008. However, the numbers of papers published had slightly decreased in 2004, 2007, 2009, and 2011.

Distribution of output by journal for publications on the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011 (Table 5)

The Journal of Investigative Dermatology published six papers, followed by Pigment Cell & Melanoma Research, which published four papers (Table 5). There were four journals that published three papers each, namely Cell Cycle, Developmental Biology, European Journal of Dermatology, and Seminars in Cell Developmental Biology.

Table 5

The top 14 journals selected based on publication of papers on the application of follicle and melanocyte stem cells in neuroscience between 2002 and 2011

Distribution of output by country for publications on the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011

The analysis of the contributions of different countries/states to publications was based on journal articles in which the address and affiliation of at least one author were provided (Figure 4).

Figure 4

The countries for publications on the application of follicle and melanocyte stem cells in neuroscience from 2002 to 2011.

I: USA; II: Japan; III: Germany; IV: UK; V: Switzerland; VI: Australia; VII: Canada; VIII: Finland; IX: France; X: Iceland; XI: Iran; XII: Poland; XIII: South Korea.

As shown in Figure 4, it was clear that most papers on the application of follicle and melanocyte stem cells in neuroscience were published in the USA (37 papers), followed by Japan (25 papers). The other prolific countries were Germany, the UK, and Switzerland. There is no paper in this area that was published in China.

Distribution of output by institution for publications on the application of follicle and melanocyte stem cells in neuroscience in the Web of Science from 2002 to 2011

Anticancer Inc and the University of California system in the USA were the most prolific research institutes (Table 6).

Table 6

The top 15 institutions for publications on the application of follicle and melanocyte stem cells in neuroscience from 2002 to 2011

Seven of the top 15 research institutes publishing in this field were in the USA, four were in Japan, two were in Germany, and the other two institutes were in Switzerland and the UK, respectively.

Highly cited papers on the application of follicle and melanocyte stem cells in neuroscience in Web of Science from 2002 to 2011

A total of 63 papers on the application of follicle and melanocyte stem cells in neuroscience were cited in the Web of Science from 2002 to 2011. “Nestin expression in hair follicle sheath progenitor cells”, published in 2003 by Proceedings of the National Academy of Sciences of the United States of America[17], was cited 150 times, which was more citations than any other paper. Of the 10 most cited papers, two were published in Proceedings of the National Academy of Sciences of the United States of America, Cancer Research and Cell Cycle respectively, and the remaining four papers were published in four different journals. Of these 10 most cited papers, five were published in 2005, two were published in 2006, and one each was published in 2003, 2007 and 2008 (Table 7).

Table 7

The top 10 cited papers on the application of follicle and melanocyte stem cells in neuroscience from 2002 to 2011

DISCUSSION

Based on Web of Science publications, bibliometric analysis identified several research trends over the past 10 years in studies of follicle and melanocyte stem cells, and their application in neuroscience.

The number of publications on follicle and melanocyte stem cells increased over the 10-year study period. The most prolific journals were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research, and Cell Stem Cell. Of the 348 publications from 2002 to 2011, which were retrieved from the Web of Science, more than half were from American authors and institutes. The most prolific institutions in China were the Fourth Military Medical University and Third Military Medical University.

The number of publications on the application of follicle and melanocyte stem cells in neuroscience increased over the 10-year study period. The most prolific journals were the Journal of Investigative Dermatology, Pigment Cell & Melanoma Research, and Cell Cycle. Of the 63 publications retrieved from the Web of Science, which were published from 2002 to 2011, more than half were from American authors and institutes, and no papers were from Chinese authors and institutes.

At present, scholars have made some achievements in the study of follicle and melanocyte stem cells, and their application in neuroscience[27282930313233], which provides new hope for treatments of nervous system disease by autologous cell transplantation and gene therapy. The technology to induce the differentiation of follicle stem cell is still at an experimental stage, and has not been widely or successfully used in clinical practice. Nevertheless, follicle stem cells have some advantages over other types of stem cells. Follicle stem cells can be obtained easily, proliferate rapidly in vitro, survive in long-term culture, do not undergo immunological rejection, and are not hindered by ethical issues[34353637]. Therefore, these cells are one of the best candidates for cell therapy of nervous system diseases. We have reason to believe that the research prospects in this area are long range. At present, there are relatively few studies on the application of melanocyte stem cells in neuroscience, and their availability has yet to be confirmed.