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Bibliometric Analysis of Core Papers Fundamental to Tissue Engineering


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V. Use of the term "tissue engineering"

CHI has conducted an analysis of the use of the term: "tissue engineering" in the research literature. This work was undertaken using a set of papers downloaded from PubMed . The papers were found by searching for the term "tissue eng*" in titles or abstracts.5 Table 2 reports the results of this work. The table reports the number of papers by year overall, for research and review papers, and by subject matter. The subject matter section is ordered by year of first appearance, which is reported in the "1st year" column.

At the time the search was conducted, in mid-2001, 685 papers were identified that used the term tissue engineering, or a variant, in their titles or abstracts. 68% of the papers were research papers and 29% were review papers.6 The abstracts and titles were read, and the papers were classified by contents. Thus we can see that bone & cartilage and more basic research, not associated with any particular body part, are the two dominant categories, each accounting for about 20% of the papers. Only 6% of the papers concerned skin, which might seem low since skin is a rather well developed application. The skin papers also begin rather late, in 1995. We hypothesize that work on skin was an independent stream, going much farther back in time, and only in 1995 did someone draw the connection to work on other tissues by using the term "tissue engineering." 7% of the papers were found to be outside the field. This frequently occurred in review articles which described the available, not very satisfactory, options for treating a medical condition and then held out the hope that tissue engineering would provide better solutions in future.

There seem to be three phases to the use of the term "tissue engineering." In 1984/85 JR Wolter and RF Meyer imagined the possibility of tissue engineering after removing from an eye a prosthesis that had been in place 20 years. Their abstract reads as follows:

Clinical observation and cytological study of a reasonably successful keratoprosthesis removed along with a corneal button about 20 years after its implantation in an aphakic eye revealed an acellular epithelium-like film on its outer surface, firm anchoring of its supporting skirt by stable fibrous connections to the corneal stroma, and a continuous separating membrane composed of a homogeneous proteinaceous film and fibroblast-like cells of macrophage origin on its inner surface. The significance of the successful adaptation of the plastic materials of the prosthesis to the tissues of the cornea and the fluids of the inner eye for the future of tissue engineering in the region of the eye is discussed.

After a gap of a few years, a second phase began in 1989 and lasted through 1997, during which time the term "tissue engineering" began to be used regularly in abstracts and titles. During this period, the term was applied to work concerning all the main organs closely connected to tissue engineering: bone, cartilage, blood vessels, liver, skin, neurons and also to biomedical materials.

The third phase began in 1998 and continues. Recent years have seen dramatic growth in the use of the term "tissue engineering". 1998 saw more than a doubling of papers using the term as compared to 1997, and the number almost doubled again in 1999. In this phase we also see a few papers concerning other organs, and in fact the return of papers concerning eyes.

Overall, the growth in the use of the term "tissue engineering" in titles and abstracts seems not unlike the growth in number of core papers fundamental to tissue engineering that is reported in Figure 1.

Table 2 - Papers using the term "tissue engineering" in their titles or abstracts

Category 1st year Papers % Share 1984 1985 ... 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
All papers 1984 685 100% 1 1   1 1 8 9 7 11 14 30 30 79 153 214 126
                                       
Research 1984 466 68% 1 1   1 1 3 3 4 2 8 18 18 55 103 137 111
Review 1991 199 29%           4 5 3 8 6 11 11 23 46 71 11
Other 1991 20 3%         1 1   1   1 1 1 4 6 4
                                       
Ophthalmology 1984 6 1% 1 1                       3 1  
Cardiovascular 1989 77 11%       1   1 2 2 2 1 1 2 11 15 28 11
General 1990 83 12%         1 2 4 2 3 2 3 6 9 13 27 11
Bone & Cartilage 1991 149 22%           2     4 3 5 5 18 38 49 25
Basic 1991 147 21%           1 2 3 1 3 11 7 19 24 42 34
Outside field 1991 48 7%           1     1 1 2 1 5 10 13 14
Liver 1991 15 2%           1 1     1 1 1   2 5 3
Skin 1995 38 6%                   2 2 3 8 8 10 5
Pancreas 1995 4 1%                   1     1 1   1
Neural 1996 16 2%                     1   2 2 7 4
Dentistry 1996 14 2%                     1 1 1 3 6 2
Tendon & Ligament 1996 10 1%                     1     7 2  
Kidney 1996 7 1%                     2 2 2 1    
Muscle 1997 9 1%                       2 1 4 2  
Genitourinary 1998 27 4%                         2 5 13 7
Gene Therapy 1999 9 1%                           7 2  
Other tissue 1999 9 1%                           3 4 2
Meniscus 1999 6 1%                           4   2
Stem Cells 1999 4 1%                           1 3  
Digestive 1999 4 1%                           2   2
Lung 2001 3 0%                               3



5 This paper set was one input to the filtering process described above, but is really a different set of papers. Some of these papers are in the final analysis set and some are not. [Back to text]
 
6 The other 3% were classified as "other." Examples include: a discussion of recent patents in tissue engineering, or a discussion of recent regulatory changes relevant to tissue engineering. [Back to text]
 

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