Stem cell populations in the heart and the role of Isl1 positive cells

Cardiac progenitor cells are multipotent stem cells isolated from both embryonic and adult hearts in several species and are able to differentiate at least into smooth muscle cells, endothelial cells and cardiomyocytes. The embryonic origin of these cells has not yet been demonstrated, but it has been suggested that these cells may derive from the first and secondary heart fields and from the neural crest. In the last decade, two diffe-rent populations of cardiac progenitor or stem cells have been identified and isolated, i.e., the Islet1 positive (Isl1+) and c-Kit positive (c-Kit+)/Stem Cell Antigen-1 positive (Sca-1+) cells. Until 2012, these two populations have been considered two separate entities with different roles and a different origin, but new evidence now suggests a con-nection between the two populations and that the two populations may represent two subpopulations of a unique pool of cardiac stem cells, derived from a common immature primitive cell. To find a common consensus on this concept is very important in furthe-ring the application of stem cells to cardiac tissue engineering

Structural analysis of rat patellar tendon in response resistance and endurance training.

Little is known about tendon adaptations induced by mechanical loading. Our goal was to evaluate the effects of two different exercise training protocols on adult rat patellar tendon. Ninety-six male Wistar rats were divided into a sedentary group (control), a resistance-trained group and an endurance-trained group. The examinations were performed after 15, 30 and 45 days of training and after 2 weeks of rest since training was stopped. The content of collagen fibers and the cell nuclei number were quantified on tendon cross sections. In order to assess the training effectiveness, we evaluated the heart/body weight ratio, which was higher in 45 day-trained rats than their controls (P<0.01), showing the presence of cardiac hypertrophy. An increase in the content of collagen fibers was observed in the 45 day-trained groups and after 2 weeks of rest in the endurance group. Moreover, both trained groups showed a decrease in cell nuclei number after 30 and 45 days of training and 2 weeks of rest (P<0.05). Endurance and resistance training induces a tendon tissue remodeling that depends on the length and intensity of workload rather than the training type. Further studies are necessary to evaluate whether these structural modifications are associated with an increase in the mechanical strength of tendon

Involvement of caspase-3 and GD3 ganglioside in ceramide-induced apoptosis in Farber disease

Farber's disease (FD) is a rare genetic disorder caused by ceramidase deficiency, which results in ceramide accumulation in lung, liver, colon, skeletal muscle, cartilage, and bone. Although this disease has been symptomatically characterized, little is known about its molecular pathogenetic process. Because recent studies reported that ceramide accumulation induces GD3 ganglioside formation and apoptosis, we investigated, in tissue obtained via colonoscopy from seriously involved patients, the possible involvement of ceramide in FD colonocyte destruction. Histochemical and TUNEL analyses of paraffin-embedded sections revealed that 45 ± 4.3% of FD colonocytes showed morphological signs of apoptosis compared with the 8 ± 2.3% of constitutive epithelial cell death. Importantly, immunohistochemical study for pro-apoptotic factors showed that GD3 accumulation colocalized with active caspase-3 and cleaved K18 in FD colon tissue. These findings provide evidence for a role of the apoptotic ceramide pathway in the pathogenesis of FD

ROLE OF CHAPERONES IN HEALTHY BOWEL AND IBD.

The chaperoning system is the wole complement of chaperones, co-chaperones and chaperone cofactors of the body that preserves cell and tissue homeostasis. Its structural and/or functional defects can cause pathologic conditions, nemed chaperonopathies. Large bowel homeostasis includes a healthy status of the mucosal tissues and the microbiota. An alteration of one of them may determine, in turn, modifications of the other. Molecular chaperones of bacteria and human origin have been implicated in inflammatory bowel disease (IBD). In IBD chaperone levels usually increase and their cellular and subcellular loclization change. This is considered a physiological stress-response of mucosal cells to inflammation. However, chaperones also play active roles in IBD pathogenesis, e.g. perpetuate inflammation. Therefore, IBD can be classified among the chaperonopathies. This classification opens the door to the design and application of new forms of treatment targeting the chaperones, namely chaperonopathy