Protein Marker Determines Fibroblast Destiny

Researchers studying the cells that make up the immune defense system have found that fibroblasts expressing Thy-1, a protein involved in growth function, can become myofibroblasts while those with no Thy-1 have the potential to become lipofibroblasts.

Myofibroblasts contain substantial arrays of actin microfilaments, myosin, and other muscle proteins arranged in such a way as to suggest that they produce contractile forces. They are commonly described as occurring in granulation tissue (formed during wound healing) and in certain forms of arterial thickening where they are found in the intima. Myofibroblasts behave in much the same way as smooth muscle cells and have markers characteristic of these cells. Myofibroblasts are normally inconspicuous in healthy tissue but become active after injury or trauma. When uncontrolled, myofibroblasts lead to fibrosis of the liver, kidneys, lungs, and heart.
Lipofibroblasts are cells that capture lipids from the serum and pass these lipids on to type two epithelial cells, where they are incorporated into surfactant phospholipids. Lipofibroblasts have no role in scarring, but develop into fat cells and lead to thyroid eye disease and the harmful buildup of fatty tissue in the liver, spleen, and bone marrow.
Investigators from the University of Rochester (NY, USA; www.rochester.edu) used fibroblasts from human uterine and eye tissue to show that fibroblasts expressing Thy-1, a protein involved in growth function, could become myofibroblasts while those with no Thy-1 had the potential to become lipofibroblasts. These findings were published in the October 2003 issue of the American Journal of Pathology.

"This is the first clear demonstration that certain kinds of human fibroblasts can develop into scar-type or fat-type cells,” explained senior author Dr. Richard P. Phipps, professor of environmental medicine, microbiology, and immunology at the University of Rochester. "In fact, our results show that some fibroblasts may prove to be a useful diagnostic tool by providing clues to the severity of a disease or who might be prone to abnormal wound healing.”




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