CD90 + cardiac fibroblasts reduce fibrosis of acute myocardial injury in rats.

OBJECTIVE: To explore the differentiation tendency of CD90+ cardiac fibroblast (CFs) into cardiomyogenic cells in vitro and repair functions in acute myocardial infarction rats.

METHODS: CD90+ subpopulation was sorted from rat CFs by flow cytometry. 10 μmoL/L of 5-Azacytosine (5-aza) was used to induce differentiation of CFs into cardiomyogenic cells. An acute myocardial infarction model was prepared by ligation of the rat left anterior descending coronary artery. After nuclei were labeled by DAPI, induced CD90+ CFs were injected into the infarction marginal zone. Before coronary ligation, 40 min after ligation, and at 7 and 14 days after cell transplantation, cardiac function changes were detected by ultrasound imaging system respectively. cTnT and endothelial cell marker VIII factor were detected by immunofluorescence staining. Infarct size was examined by TTC staining. Fibrosis was evaluated with masson's trichrome staining, vimentin, type I and type III collagen staining.

RESULTS: CD90+ CFs sorted by flow cytometry was 34.9%. On day 28 after induction, the cTnT positive rate was 61.17 ± 9.75%. Left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) at days 7 and 14 after transplantation were significantly increased compared with those before transplantation (P < 0.05). LVEF and LVFS at the 14th day after transplantation were also significantly increased compared with those at the 7th day (LVEF: 61.40 ± 2.45% vs. 56.25 ± 2.9%, LVFS: 33.21 ± 0.68% vs. 30.26 ± 2.06%, P < 0.01). Additionally, small numbers of CD90+ CFs differentiated into cardiomyocytes and became involved in neovascularization. CD90+ CFs and CFs reduced myocardial infarct size at days 14. It was significantly smaller in rats with CFs transplantation group than those in MI group(24.78 ± 2.28% vs. 31.28 ± 2.83%, P < 0.05), and it was also significantly smaller in rats with CD90+ CFs transplantation group than those in CFs transplantation group (17.47 ± 4.15% vs. 24.78 ± 2.28%, P < 0.05). Meanwhile, The percentage of fibrotic area and vimentin, type I and type III collagen in the infarct border zone and infarct area were both significantly reduced in CD90 + CFs.

CONCLUSION: CD90+ CFs is the preponderant subpopulation of cardiomyogenic differentiation, with potential use as seed cells in basic and clinical research of heart regeneration and repair.