Figure 1

PubMed entries for tissue engineering in the rheumatic diseases. (a) The first entry for the key word 'tissue engineering', also called 'regenerative medicine', in the National Center for Biotechnology database PubMed was in 1984. In 1994, 23 manuscripts were added, and 10 years later, 1,605 were added. In 2008, 2,706 entries for 'tissue engineering' and 688 for 'regenerative medicine' were introduced into PubMed. (b) The first two entries for both 'cartilage' and 'tissue engineering' or 'bone' and 'tissue engineering' were in 1991, accounting for 22% of all 'tissue engineering' and 'regenerative medicine' entries. Since that year, both values varied between approximately 15% and 30%. Surprisingly, the number of PubMed entries for 'tissue engineering' or 'regenerative medicine' and 'arthritis' (36 entries in 2007, which accounted for 1% of all 'tissue engineering' and 'regenerative medicine' entries) or 'osteoarthritis' (30 entries in 2007 or 0.9%) is very low and in recent years has not increased to a degree worth mentioning. (c) The number of entries for the key word 'mesenchymal stem cells' has also increased dramatically from 1 in 1991 to 1,140 in the first 7 months of 2008. From these 1,140 entries, only 25 were for 'arthritis' and 'mesenchymal stem cells' and 18 were for 'osteoarthritis' and 'mesenchymal stem cells'.