Reduction of Post-Infarct Ventricular Tachycardia by Transplantation of Transgenic Cardiac Fibroblasts

Background: Loss of the gap junction protein connexin43 (Cx43) in the lesion area (IA) after myocardial infarction promotes the occurrence of ventricular tachycardia because (myo)fibroblasts (m)FB hardly express Cx43 and/or spike action potentials. To at least partially compensate this loss, we injected Cx43-(over)expressing cardiac FB into the IA and examined the effects on cardiac function and the incidence of ventricular tachycardia (VTi).

Method: Murine embryonic (E13.5) cardiac fibroblasts (eCFs) were isolated from CD1-WT mice, cultured for 8 days, then transduced overnight with lentiviral constructs (LV, IRES-eGFP or Cx43-IRES-eGFP, MOI = 5) and loaded with magnetic nanoparticles (MNP, Tamra, 25 pg/cell). Subsequently, 200,000 of these cells were injected intramyocardially into cryolesioned hearts of adult female CD1 WT mice with or without application of a magnetic field (±mag, for 10 minutes) to the lesion area. Cardiac function and electrical vulnerability were analyzed 2 weeks (short-term) and 8 weeks (long-term) postoperatively by echocardiography and in vivo electrophysiological studies. The number of engrafted cells and Cx43 content in IA were analyzed by immunohistochemistry and Western blotting. Changes in gene expression of eCFs after lentiviral Cx43 overexpression were analyzed in vitro by RNA-Seq.

Results: The transduction efficiency of both LVs was ~25%, resulting in significantly increased Cx43 expression in Cx43-eCF. Compared with eGFP-eCF, RNA-Seq assay showed increased expression of mFB-specific genes as well as cell–cell junction genes in Cx43-eCF. Use of the MNP-mag system resulted in significantly improved cell engraftment + mag = 60,000 cells versus –mag = 18,000 cells). In vivo electrophysiological assays showed a significant reduction in VTi in Cx43 mice (+mag: VTi 40%, n = 20) compared with controls (MI+eGFP-eCF+mag: VTi 88%, n = 25; MI only: VTi 88.2%, n = 17). This effect was still observed 8 weeks after transplantation (MI+Cx43-eCF+mag: VTi 31.3%, n = 16; MI+eGFP-eCF+mag: VTi 72.2%, n = 18; MI only: VTi 94.1%, n = 17). In addition to VTi, the number of VT events observed during electrophysiological testing was also significantly reduced in Cx43 mice.

Conclusion: Transplantation of Cx43-overexpressing eCF significantly reduced the incidence of VT in the short- and long-term course in a murine infarction model. Use of the MNP-mag system improved cell engraftment within the IA by a factor of >3.

Publikationsverlauf

Artikel online veröffentlicht:
28. Januar 2023