Abnormal phenotype of cultured fibroblasts in human skin with chronic radiotherapy damage.
OBJECTIVE
The pathophysiological aspects of radiation-induced fibrosis (RIF) have not been well characterized. We therefore cultured human fibroblasts from samples of skin with RIF to investigate the long-term effects of therapeutic irradiation.


METHODS
Biopsies of normal and RIF skin were obtained from patients previously irradiated for cancer, without recurrence. Cells were extracted from dermis samples by the outgrowth technique, seeded as monolayers and cultured at confluence. Enzyme activities and proteins were assayed, RNA was isolated and Northern blot analysis was performed on surviving cells between passages 2 and 5.


RESULTS
RIF cell cultures displayed heterogeneous fibroblasts populations. The initial outgrowth consisted of one-third small cells that floated rapidly, one-third spindle-shaped cells migrating far from the explant to form islets and one-third large pleiomorphic cells. In subsequent subcultures, surviving cells exhibited either myofibroblastic characteristics with a normal proliferative capacity or senescent morphology with a reduced proliferative capacity. These RIF cells had a brief finite lifespan, with dramatically reduced growth rate during their initial outgrowth and the following passages. Study of the antioxidant metabolism showed that Mn superoxide dismutase and catalase activities were significantly weaker in surviving RIF cells than healthy fibroblasts. These exhausted RIF cells exhibited no overexpression of transforming growth factor beta or tissue inhibitor of metalloproteinase.


CONCLUSIONS
Irradiation may lead to apparently contradictory effects such as fibrosis and necrosis in clinical practice. In cell culture, we observed two main cellular phenotypes which may be related to both processes, i.e. myofibroblast-like cells and fibrocyte-like cells. These two phenotypes may represent two steps in the differentiation induced as a long-term effect of therapeutic irradiation of the skin. Cell culture probably accelerates the induction of the terminal differentiation in RIF fibroblasts.
Service d'Oncologie-Radiothérapie, Hôpital Saint-Louis, APHP, Paris, France.
S
S
Delanian
M
M
Martin
A
A
Bravard
C
C
Luccioni
J L
JL
Lefaix
D000328:Adult; D000368:Aged; D001706:Biopsy; D015152:Blotting, Northern; D001943:Breast Neoplasms / Q000532:radiotherapy; D002374:Catalase / Q000096:biosynthesis; D002455:Cell Division / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured / Q000528:radiation effects; D002908:Chronic Disease; D015342:DNA Probes / Q000737:chemistry; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis / Q000528:radiation effects; D011855:Radiodermatitis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D012867:Skin / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D013482:Superoxide Dismutase / Q000096:biosynthesis; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
D015342:DNA Probes; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D016212:Transforming Growth Factor beta; D002374:Catalase; D013482:Superoxide Dismutase