Differentiation and growth of vascular smooth muscle cells in experimental hypertension

In this review we have analyzed the present knowledge about the differentiation and growth processes in vascular smooth muscle cells (SMC) in hypertension. The study of smooth muscle (SM) and nonmuscle (NM) myosin isoform expression has permitted us to identify a three-stage specific maturational pathway, namely, fetal, postnatal, and adult. In the renovascular (rabbit) and genetic (rat) models of hypertension, adaptive changes occurring in hypertensive vessels make SMC resemble those found in the early stages of development (smooth muscle plasticity). In fact, based on SM- and NM-myosin isoform distribution, postnatal-type SMC predominate in the arterial media during the early remodeling of the arterial wall that occurs in hypertension, whereas postnatal- and fetal-type SMC predominate in the intimal thickening. Locally produced or activated autocrine/paracrine factors, such as growth factors or cytokines, along with circulating hormones, seem to be involved in the growth response or changes in the differentiation pattern of SMC. Thus, these factors not only play a specific role in the regulation of blood pressure, but also are likely to be responsible for the remodeling of the arterial wall in hypertension.