Endovascular laser-tissue interactions and biological responses in relation to endovenous laser therapy

Endovenous laser treatment (ELT) has evolved into a frequently employed modality for the treatment of leg varicose veins. Due to the very high complete response rates, minimal complications and side effects, and the possibility to monitor therapeutic outcome noninvasively by duplex ultrasound, a considerable amount of reports have been published on clinical and translational studies, whereas disproportionally few studies have been performed to elucidate the molecular and cellular basis for post-ELT vessel obliteration. Consequently, this review addresses the putative molecular and cellular mechanisms responsible for varicose vein obliteration following laser irradiation in the context of endovenous laser-tissue interactions. First, the histological profile of laser-treated varicose veins is summarized, and an account is given of the temporal and spatial dynamics of cells involved in inflammation and remodeling in the heat-affected vein segment. Inasmuch as thrombotic occlusion of the venous lumen blocks circulatory access to the affected vessel segment and thermal damage in the vascular wall causes most cells to die, the majority of cells involved in inflammation and remodeling have to be recruited. Second, the (possible) biochemical triggers for the chemotactic attraction of immune cells and fibroblasts are identified, comprising (1) thermal coagula, (2) thrombi, (3) dead and dying cells in the vein wall, and (4) thermally denatured extracellular matrix proteins in the vein wall. The molecular biology underlying the chemotactic signaling and subsequent obliterative remodeling is elucidated. Finally, the relative contribution of every biochemical trigger to obliterative remodeling is addressed

Unaltered liver regeneration in post?cholestatic rats treated with the fxr agonist obeticholic acid

In a previous study, obeticholic acid (OCA) increased liver growth before partial hepatectomy (PHx) in rats through the bile acid receptor farnesoid X‐receptor (FXR). In that model, OCA was administered during obstructive cholestasis. However, patients normally undergo PHx several days after biliary drainage. The effects of OCA on liver regeneration were therefore studied in post‐cholestatic Wistar rats. Rats underwent sham surgery or reversible bile duct ligation (rBDL), which was relieved after 7 days. PHx was performed one day after restoration of bile flow. Rats received 10 mg/kg OCA per day or were fed vehicle from restoration of bile flow until sacrifice 5 days after PHx. Liver regeneration was comparable between cholestatic and non‐cholestatic livers in PHx‐subjected rats, which paralleled liver regeneration a human validation cohort. OCA treatment induced ileal Fgf15 mRNA expression but did not enhance post‐PHx hepatocyte proliferation through FXR/SHP signaling. OCA treatment neither increased mitosis rates nor recovery of liver weight after PHx but accelerated liver regrowth in rats that had not been subjected to rBDL. OCA did not increase biliary injury. Conclusively, OCA does not induce liver regeneration in post‐cholestatic rats and does not exacerbate biliary damage that results from cholestasis. This study challenges the previously reported beneficial effects of OCA in liver regeneration in cholestatic rats