How different are tissue-specific fibroblasts from each other?
I have been told the normal fibroblasts are very similar all over the body. Is this really true?


No.


  Strong evidence indicates that fibroblasts in different parts of the body are intrinsically different, and there may be differences between them even in a single region [3]. 


They have morphological similarities, but they act differently (at least in cultures):


  Examination of skin and lung fibroblasts derived from the same human fetuses revealed significant in vitro differences. Fetal lung cultures had faster cell replication rates, greater [$^3H$]thymidine incorporation into DNA, higher cell numbers at confluency, smaller cell volumes, decreased cellular RNA and protein contents and lengthened in vitro life spans when compared with fetal skin cultures. In addition, these cell cultures had different responses to the addition of hydrocortisone to culture media [1].


They hardly adapt to a different serum (in vitro) [2]. Yet they have a great capacity to differentiate (in vivo):


  [...] fibroblasts also seem to be the most versatile of connective-tissue cells, displaying a remarkable capacity to differentiate into other members of the family. [...] “Mature” fibroblasts with a lesser capacity for transformation may, for example, exist side by side with “immature” fibroblasts (often called mesenchymal cells) that can develop into a variety of mature cell types [3].




References:


E.L. Schneider, Y. Mitsui, K.S. Au, S. Stuart Shorr. Tissue-specific differences in cultured human diploid fibroblasts. Experimental Cell Research. Volume 108, Issue 1, August 1977, Pages 1–6. DOI 10.1016/S0014-4827(77)80002-5
Zamansky, GLEN B., et al. "Adaptation of human diploid fibroblasts in vitro to serum from different sources." Journal of cell science 61.1 (1983): 289-297.
Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. Fibroblasts and Their Transformations: The Connective-Tissue Cell Family. Available from: http://www.ncbi.nlm.nih.gov/books/NBK26889/