ИСТИНА

Heart failure (HF) is among the socially significant diseases, involving over 2% of the adult population in the developed countries. According to the data of the European Society of Cardiology, patients with moderate or even minor manifestations of HF may have an increased risk of hospitalization and mortality. However, diagnostics of the early stages of HF remains complicated due to the absence of specific symptoms and objective criteria. We have suggested an indicator of the HF severity based on the perivascular tissue parameters(the perivascular zone (PZ) size) obtained by common digital capillaroscopy, which allows for fast non-invasive measurements. Light area around nail fold capillaries, which is referred to as PZ, is a standard feature of nail fold video capillaroscopy images. Though it is observed in the majority of capillaroscopic studies, it has been rarely used as a clinically significant parameter: the origin of PZ and the reasons underlying its sensitivity to pathological processes accompanying cardiovascular disease has not been discussed up to date and are unknown. In this work, we present a detailed investigation of the nail fold tissues using two-photon tomography. This method is based on the possibility of tissue imaging using short pulse excitation of nonlinear optical signals such as second optical harmonics (SHG, second harmonic generation) and two-photon excited autofluorescence (TPAEF). Also, fluorescence lifetime imaging (FLIM) can be applied to investigate molecular species in tissue when performing two-photon tomography. Recently, we have demonstrated the possibilities of this approach in studying the papillary dermis blood vessels and localization of structural proteins [1]. Here, we demonstrate a detailed 3D structure of the nail fold tissues on the molecular and cellular levels aimed at the explanation of capillaroscopy-derived parameters to impairments in blood microcirculation. [1] E. Shirshin, Y. Gurfinkel and B. Author, Two-photon autofluorescence lifetime imaging of human skin papillary dermis in vivo: assessment of blood capillaries and structural proteins localization, Scientific Reports, 7:1171, (2017).