Objective: Accumulation of intimal smooth muscle cells (SMC) is an important event in vein graft-stenosis. Different SMC sources have been reported, but their interrelations have been poorly studied. In a mouse vein graft model we investigated whether recipient-derived intimal SMCs are recruited from the surrounding tissue and whether blockage of SMC recruitment from the surrounding tissue and/or the donor vein will reduce neointimal formation.
Methods: To detect recipient-derived cells, wild-type veins were implanted into ROSA26 transgenic mice. To block cell recruitment from the surrounding tissue, implanted veins were isolated with a tube-shaped plastic film. To exclude vein-derived cells in the neointimal formation, acellular veins were implanted.
Results: In vein grafts isolated from the surrounding tissue the recipient contribution became minimal, but the total number of SMCs was not decreased. Acellular grafts contained an equal number of intimal SMCs as cellular controls after 4 weeks. Isolation of acellular grafts from the surrounding tissue decreased the number of intimal SMCs by 90%.
Conclusions: Recipient-derived SMCs are mainly recruited from the surrounding tissue. Cell recruitment from either the vein or the surrounding tissue is enough to form a neointima. Therefore, a simultaneous inhibition of both these sources is needed to reduce accumulation of intimal SMCs.