Microvascular diseases: is a new era coming?

The microvascular bed is an anatomical entity which comprises myriads of small arterioles, capillaries and venules. Microvessels and surrounding tissue metabolism are tightly coupled; consequently they are equipped with many, very specific and fine-tuned mechanisms allowing permanent, precise regulation of nutrient delivery. The review thoroughly describes the structure and physiology of arterioles and capillaries as well as the specialized means to investigate them. Microcirculation has been largely neglected for decades, mainly because of lack of technical possibilities for visualization and quantitation. However the past years have completely renewed the scientific interest, due to the combination of the availability of new techniques in human research and the recognition that the microcirculation is autonomically and causally involved in diseases previously thought to be essentially a question of macrocirculation. Today we start to see that microangiopathy is not only a consequence of large vessel diseases but can be the source of many pathologies in both cardiovascular and metabolic disorders, the best example -developed here- being the cardiometabolic syndrome or prediabetes. With very few exceptions, pentoxifylline and the antidiabetic metformin, no specific treatments have been developed for treating disorders at the microcirculatory level. Metformin has unique, intrinsic actions specifically at the level of terminal arterioles, which are completely independent of its antidiabetic effect. Other drugs are shortly described which have revealed a potential interest in this field. Our review aims at showing that microcirculation is entering a new era, starting with rapidly increasing knowledge of its intimate functioning and worth specific pharmacological developments.