Sustained endothelial progenitor cell dysfunction after chronic hypoxia-induced pulmonary hypertension

Area of Science:

• Cardiovascular Biology
• Regenerative Medicine
• Pulmonary Hypertension Research

Background:

• Endothelial progenitor cells (EPCs) are crucial for repairing damaged blood vessels and forming new ones.
• The impact of chronic hypoxia on bone marrow-derived EPCs and their role in pulmonary hypertension (PH) is not well understood.
• Tissue engineering with EPCs holds potential for treating PH, but their function under hypoxic conditions needs investigation.

Purpose of the Study:

• To investigate the endogenous mobilization and homing of EPCs in mice exposed to chronic hypoxia, a condition mimicking PH.
• To assess the therapeutic potential of transferred EPCs in a PH model and evaluate their functional status after hypoxic exposure.
• To elucidate the mechanisms underlying hypoxia-induced dysfunction in EPCs.

Main Methods:

• Utilized green fluorescent protein bone marrow chimeric mice subjected to chronic hypoxia.
• Employed flow cytometry and EPC culture to analyze cell mobilization and function.
• Evaluated EPC migration, adhesion, vascular network incorporation, nitric oxide production, and neovascularization capacity in vitro and in vivo (hind limb ischemia model).

Main Results:

• Chronic hypoxia led to increased peripheral EPC mobilization but limited their recruitment into remodeling lung vessels.
• Transferred EPCs, even when cultured under specific conditions, failed to reverse pulmonary hypertension, indicating functional impairment.
• Hypoxic EPCs exhibited significantly reduced migration, adhesion, vascular network incorporation, and nitric oxide production compared to normoxic EPCs.

Conclusions:

• Chronic hypoxia induces significant functional impairment in EPCs, compromising their regenerative capabilities.
• The dysfunctional phenotype of hypoxic EPCs, characterized by reduced integrin expression, mitochondrial dysfunction, and increased senescence, limits their therapeutic efficacy.
• Understanding hypoxia-induced EPC dysfunction provides critical insights for developing improved cell-based therapies for vascular diseases like pulmonary hypertension.