Human umbilical cord mesenchymal stem cells combined with pirfenidone upregulates the expression of RGS2 in the pulmonary fibrosis in mice

OBJECTIVE: The therapeutic effect of umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in combination with pirfenidone (PFD) on pulmonary fibrosis in mice and its possible mechanism were investigated. METHODS: C57BL/6 mice were randomly divided into six groups: control group, model group, P(10) group, P(30) group, P(100) group, and P(300) group. Modeled by tracheal intubation with 3 mg/kg bleomycin drip, each dose of PFD was administered daily by gavage from day 7 onwards. The mice were observed continuously for 21 days and survival was recorded. Lung tissues were collected on day 21, and hematoxylin–eosin (HE) and Masson staining were performed to assess morphological changes and collagen deposition in the lungs. Collagen content was measured by the Sircol method, and fibrosis marker levels were detected by PCR and Western blot. Another batch of C57BL/6 mice was then randomly divided into five groups: hUC-MSC control group, model group, P(100) group, hUC-MSC treatment group, and hUC-MSCs + P(30) group. On day 7, 5 × 10(5) hUC-MSCs were injected into the tail vein, the mice were administered PFD gavage daily from day 7 onwards, and their survival was recorded. Lung tissues were collected on day 21 to detect pathological changes, the collagen content, and the expression of regulator of G protein signaling 2 (RGS2). Pulmonary myofibroblasts (MFBs) were divided into an MFB group and an MFB + hUC-MSCs group; different doses of PFD were administered to each group, and the levels of RGS2, intracellular Ca(2+), and fibrosis markers were recorded for each group. RESULTS: Compared with other PFD group doses, the P(100) group had significantly improved mouse survival and lung pathology and significantly reduced collagen and fibrosis marker levels (p < 0.05). The hUC-MSCs + P(30) group had significantly improved mouse survival and lung pathology, significantly reduced collagen content and fibrosis marker levels (p < 0.05), and the efficacy was better than that of the P(100) and hUC-MSCs groups (p < 0.05). RGS2 expression was significantly higher in the MSCs + P(30) group compared with the P(100) and hUC-MSCs groups (p < 0.05). PFD increased RGS2 expression in MFBs (p < 0.05) in a dose-dependent manner. Compared with PFD and hUC-MSCs treatment alone, combination of hUC-MSCs and PFD increased RGS2 protein levels, significantly decreased intracellular Ca(2+) concentration, and significantly reduced fibrosis markers. CONCLUSION: The findings suggest that hUC-MSCs combined with low-dose PFD have a therapeutic effect better than that of the two treatments used separately. Its effect on attenuating bleomycin-induced pulmonary fibrosis in mice is related to the increase of RGS2. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12931-022-02192-6.