Antagonism of stem cell factor/c-kit signaling attenuates neonatal chronic hypoxia-induced pulmonary vascular remodeling.

Background: Accumulating evidence suggests that c-kit-positive cells are present in the remodeled pulmonary vasculature bed of patients with pulmonary hypertension (PH). Whether stem cell factor (SCF)/c-kit-regulated pathways potentiate pulmonary vascular remodeling is unknown. Here, we tested the hypothesis that attenuated c-kit signaling would decrease chronic hypoxia-induced pulmonary vascular remodeling by decreasing pulmonary vascular cell mitogenesis.

Methods: Neonatal FVB/NJ mice treated with nonimmune IgG (placebo), or c-kit neutralizing antibody (ACK2) as well as c-kit mutant mice (WBB6F1-Kit(W-v/+)) and their congenic controls, were exposed to normoxia (FiO2 = 0.21) or hypoxia (FiO2 = 0.12) for 2 wk. Following this exposure, right ventricular systolic pressure (RVSP), right ventricular hypertrophy (RVH), pulmonary vascular cell proliferation, and remodeling were evaluated.

Results: As compared to chronically hypoxic controls, c-kit mutant mice had decreased RVSP, RVH, pulmonary vascular remodeling, and proliferation. Consistent with these findings, administration of ACK2 to neonatal mice with chronic hypoxia-induced PH decreased RVSP, RVH, pulmonary vascular cell proliferation, and remodeling. This attenuation in PH was accompanied by decreased extracellular signal-regulated protein kinase (ERK) 1/2 activation.

Conclusion: SCF/c-kit signaling may potentiate chronic hypoxia-induced vascular remodeling by modulating ERK activation. Inhibition of c-kit activity may be a potential strategy to alleviate PH.