Histological and immunohistochemical study on the effect of stem cell therapy on bleomycin induced pulmonary fibrosis in albino rat

Aim of work: To demonstrate the bleomycin induced histological changes in the lung and the possible protective and/or therapeutic effect of stem cell therapy.

Materials and methods: Study was carried out on 36 adult male albino rats, classified into 4 groups: group I (control), group II (bleomycin treated group), group III (early stem cell treated group: immediately after bleomycin), group IV (late stem cell treated group: 7 days after bleomycin). Sections were taken at the 14(th) day of experiment. stained with Hematoxylin and Eosin, Masson's trichrome, immunohistochemichal stains for α-SMA & PCNA. Sections were examined by light & immunofluroscent microscopy. Area percent of collagen fibers, area percent & optical density of α-SMA immunopositive cells were measured as well as the number of H&E and PCNA stained pneumocytes type II was counted.

Results: Group II showed, thickening of septa, extravasation of blood, dividing pneumocytes type II cells with acinar formation, cellular infiltration, fibroblast cells, almost complete loss of normal lung architecture in certain fields, consolidation and replacement of the lung tissue with fibrous tissue in other fields. Restoring of lung tissue with significant decrease in mean area % of collagen fibers, α-SMA immunopositive cells were detected in group III.

Conclusions: Early treatment with bone marrow derived mesenchymal stem cells (BMSCs) immediately after bleomycin administration showed a significant reduction in fibrotic changes, however the late treatment with BMSCs (7 days) after bleomycin administration showed non significant results.