Immunohistochemical and Ultrastructural Study of Fibroblast Differentiation

ABSTRACT

The histogenesis of the myofibroblast continues to be a controversial issue. The most popular view is that the myofibroblast is derived directly from the fibroblast. The important role of myofibroblasts in the synthesis of collagen and in wound contraction was demonstrated initially in granulation tissue in experimental animals. Four settings are recognized in which myofibroblasts are the principal proliferative cells reparative responses, pseudoneoplastic disorders, stromal response to neoplasia, and true neoplasms, both benign and malignant. To identify of fibroblastic cells with smooth muscle differentiation features in the nonneoplastic and neoplastic lesions, we examined a variety of histological, immunohistochemical and ultrastructural features of 7 cases of granulation tissue, 7 of hypertrophic scar, 10 of chronic persistent hepatitis, 10 of chronic active hepatitis, 7 of liver cirrhosis, 7 of fibromatosis, 42 of cervical intraepithelial neoplasia, 14 of microinvasive carcinoma, 14 of invasive carcinoma, 7 of fibroma, 20 of fibrosarcoma and 72 of malignant fibrous histiocytoma. Antibodies against alpha-smooth muscle actin and desmin were used in a biotin-streptavidin procedures. The results of immunohistochemical and electron microscopical examinations yielded virtually identical findings. The identification of fibroblastic cells with smooth muscle cell differentiation features in the desmoplastic reactions of carcinomas, fibroma, fibrosarcoma and malignant fibrous histiocytoma offers also novel diagnostic and prognostic perspectives, that might help in evaluating preneoplastic lesions and malignant lesions. So degree of proliferative myofibroblasts was helpful diagnostic aid in differentiation of chronic persistent hepatitis, chronic active hepatitis and liver cirrhosis.