Lineage tracing reveals evidence of a popliteal lymphatic muscle progenitor cell that is distinct from skeletal and vascular muscle progenitors

Loss of popliteal lymphatic vessel (PLV) contractions, which is associated with damage to lymphatic muscle cells (LMCs), is a biomarker of disease progression in mice with inflammatory arthritis. Currently, the nature of LMC progenitors has yet to be formally described. Thus, we aimed to characterize the progenitors of PLV-LMCs during murine development, towards rational therapies that target their proliferation, recruitment, and differentiation onto PLVs. Since LMCs have been described as a hybrid phenotype of striated and vascular smooth muscle cells (VSMCs), we performed lineage tracing studies in mice to further clarify this enigma by investigating LMC progenitor contribution to PLVs in neonatal mice. PLVs from Cre-tdTomato reporter mice specific for progenitors of skeletal myocytes (Pax7+ and MyoD+) and VSMCs (Prrx1+ and NG2+) were analyzed via whole mount immunofluorescent microscopy. The results showed that PLV-LMCs do not derive from skeletal muscle progenitors. Rather, PLV-LMCs originate from Pax7−/MyoD−/Prrx1+/NG2+ progenitors similar to VSMCs prior to postnatal day 10 (P10), and from a previously unknown Pax7−/MyoD−/Prrx1+/NG2− muscle progenitor pathway during development after P10. Future studies of these LMC progenitors during maintenance and repair of PLVs, along with their function in other lymphatic beds, are warranted.

Послеродовая инволюция миометрия мышей в условиях острого токсического гепатоза

The goal of the research was to study the structural processes of postpartum myometrial involution of C57Bl/6 mice in conditions of acute CCl4-induced hepatosis. The study was conducted on 60 female C57Bl/6 mice. Animals were divided into 2 groups: 1st – mice of the control group with physiological pregnancy, 2nd – pregnant mice with acute CCl4-induced hepatosis. The main mechanism of the process of postpartum involution of the myometrium of C57Bl/6 mice was clasmacytosis, that was morphologically represented by the presence of cytoplasmic conglomerates in the interstitium, and to a lesser extent myocyte apoptosis. More pronounced manifestations of the processes of involution were observed in the subserous muscle layer, smaller changes were observed in the vascular muscle layer and least of all in the subvascular (submucous) muscle layer. The myometrial involution processes in C57Bl/6 mice under conditions of acute CCl4-induced hepatosis slow down and do not end by the 10th day of the postpartum period, in contrast to mice of the control group.