Liver
The comparative histopathological characteristics of age-related changes in the liver in the studied groups of rats are presented in Table 3. In liver sections of the control group of young male rats, all animals had liver architecture corresponding to the histological norm. With hematoxylin and eosin staining, the liver consisted of numerous hepatic lobules formed by cords of hepatocytes radiating outward from the central vein to the lobule periphery, separated by sinusoids (Table 3). Hepatocytes had a polygonal shape with eosinophilic granular cytoplasm and vesicular-basophilic nuclei. Masson’s trichrome staining showed collagen fibers in the walls of the portal tract vessels but absent in the extracellular matrix (Table 3). Histochemical staining (PAS) revealed glycogen in the form of violet-purple fragments in the cytoplasm of most hepatocytes in all animals (Figure 9).
Animals in the old untreated group, showed evidence of age-related changes with hematoxylin and eosin staining including; hepatocyte vacuolization, inflammatory/immune changes with lymphocyte and plasma cell infiltration (Figure 9 or Table 3). Hepatic sections of all animals in the group were characterized by microvesicular vacuolization of hepatocyte cytoplasm (Table 3). Two out of three animals in the group, displayed some hepatocytes contained nuclei of various shapes and sizes, and binucleated hepatocytes in some fields (Figure 9). No signs of central venous congestion were observed in any animal in the group. Portal tracts in all three animals of the group were characterized by dilated and congested portal veins and hyperplasia (cysts) of bile ducts, and an increase in the number of lymphocytes and plasmacytic cells infiltrating between hepatocytes in the portal areas was observed (Table 3). Masson’s trichrome staining showed proliferation of collagen fibers in the portal tracts with individual thick and long collagen fibers in the extracellular matrix of all animals (Table 3). Histochemical staining (PAS) showed that most hepatocytes were PAS-negative or contained a few scattered glycogen granules of violet-purple color in less than 10% of hepatocytes in all rats (Figure 9).
However, focal microvesicular vacuolization of hepatocytes and focal lymphocytic infiltration were observed in all animals in the exosome only group. Cellular pleomorphism, part of hepatocytes contained nuclei of variable size and shape, as well as binucleated hepatocytes and hyperplasia (cysts) of bile ducts observed in two of the animals in the group (Table 3). Masson’s trichrome staining in all animals showed perioportal proliferation of collagen fibers (Table 3). Histochemical staining (PAS) showed that most hepatocytes were PAS-negative or contained a small amount of glycogen of violet-purple color, and in one animal glycogen was present in less than 61% of hepatocytes (Table 3) and (Figure 9).
Interestingly, all animals in the group that was treated with quercetin loaded exosomes exhibited focal microvesicular vacuolization of hepatocytes, focal lymphocytic infiltration, and hyperplasia or cysts of bile ducts (Table 3). Two of the animals showed abnormalities in nuclear size and chromatin distribution, and binucleated hepatocytes. Masson’s trichrome staining in all animals showed perioportal proliferation of collagen fibers (Table 3). Histochemical staining (PAS) in histological liver sections of two animals revealed glycogen in less than 10% of hepatocytes, and in one case – in 11-30% of hepatocytes (Table 3). While two of the animals that received free quercetin, exhibited focal microvesicular vacuolization of hepatocytes, binucleated hepatocytes, lymphoplasmacytic infiltration, and hyperplasia (cysts) of bile ducts, all of animals exhibited perioportal fibrosis (Table 3). Glycogen in all animals was detected in less than 10% of hepatocytes (Table 3).