Left ventricular ultrastructure in pulmonary stenosis and in tetralogy of Fallot

Nanotechnology as a tool to advance research and treatment of non-oncologic urogenital diseases

Nanotechnology represents an expanding area of research and innovation in almost every field of science, including Medicine, where nanomaterial-based products have been developed for diagnostic and therapeutic applications. Because of their small, nanoscale size, these materials exhibit unique physical and chemical properties that differ from those of each component when considered in bulk. In Nanomedicine, there is an increasing interest in harnessing these unique properties to engineer nanocarriers for the delivery of therapeutic agents. Nano-based drug delivery platforms have many advantages over conventional drug administration routes as this technology allows for local and transdermal applications of therapeutics that can bypass the first-pass metabolism, improves drug efficacy through encapsulation of hydrophobic drugs, and allows for a sustained and controlled release of encapsulated agents. In Urology, nano-based drug delivery platforms have been extensively investigated and implemented for cancer treatment. However, there is also great potential for use of nanotechnology to treat non-oncologic urogenital diseases. We provide an update on research that is paving the way for clinical translation of nanotechnology in the areas of erectile dysfunction (ED), overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and catheter-associated urinary tract infections (CAUTIs). Overall, preclinical and clinical studies have proven the utility of nanomaterials both as vehicles for transdermal and intravesical delivery of therapeutic agents and for urinary catheter formulation with antimicrobial agents to treat non-oncologic urogenital diseases. Although clinical translation will be dependent on overcoming regulatory challenges, it is inevitable before there is universal adoption of this technology to treat non-oncologic urogenital diseases.

[Ultrastructural features of cardiomyocytes in infants with tetralogy of Fallot in the first year of life]

OBJECTIVE

To analyze cardiomyocyte (CMC) ultrastructural changes in the right ventricle outflow tract (RVOT) of infants with tetralogy of Fallot (TF) in the first years of life and to compare the findings with clinical parameters in these patients.

MATERIAL AND METHODS

Intraoperative RVOT myocardial biopsy specimens obtained from 51 patients aged 3-33 months with TF during radical correction of defect were investigated. CMC diameter and length were measured using the semithin myocardial sections stained with periodic acid-Schiff. The ultrathin sections were examined in the electron microscope.

RESULTS

The diameter of CMCs in the RVOT of infants with TF varied significantly (7.3-17.0 µm) and averaged 10.8±2.2 µm; a large number of multinucleated CMCs were observed. There were ultrastructural signs of incomplete differentiation of CMCs: active myofibril assembly in the free sarcoplasmic region; gap junctions on the lateral surfaces of CMCs; and centrioli in their sarcoplasm. Myofibrillogenesis in babies under 6 months increased in response to hemodynamic overload and hypoxemia. In addition, organelles suggestive of the synthetic activity of CMCs, such as cisterns and vesicles of the Golgi complex and granular endoplasmic reticulum, were detected in the sarcoplasm of a number of CMCs. TF infants' myocardium also displayed focal disorders of CMC interposition; the change in the shape of myocytes was accompanied by the appearance of additional lateral insert discs. Some CMCs showed the abnormal localization of the nucleus beneath the sarcolemma, sarcoplasmic bulging areas, and dystrophic changes.

CONCLUSION

There were ultrastructural features characteristic for the myocardium that was at the state of active growth and differentiation (increases in the diameter and length of CMCs and in the number of nuclei; myofibrillogenesis; signs of synthetic and proliferative activity along with insignificant dystrophic changes) in the CMCs of myocardial RVOT in infants with TF in the first years of life.

Hypoxia induces PGC-1α expression and mitochondrial biogenesis in the myocardium of TOF patients

PGC-1alpha, a potent transcriptional coactivator, is the major regulator of mitochondrial biogenesis and activity in the cardiac muscle. The dysregulation of PGC-1alpha and its target genes has been reported to be associated with congenital and acquired heart diseases. By examining myocardium samples from patients with Tetralogy of Fallot, we show here that PGC-1alpha expression levels are markedly increased in patients compared with healthy controls and positively correlated with the severity of cyanosis. Furthermore, hypoxia significantly induced the expression of PGC-1alpha and mitochondrial biogenesis in cultured cardiac myocytes. Mechanistic studies suggest that hypoxia-induced PGC-1alpha expression is regulated through the AMPK signaling pathway. Together, our data indicate that hypoxia can stimulate the expression of PGC-1alpha and mitochondrial biogenesis in the cardiac myocytes, and this process might provide a potential adaptive mechanism for cardiac myocytes to increase ATP output and minimize hypoxic damage to the heart.

Mouse model carrying H222P-Lmna mutation develops muscular dystrophy and dilated cardiomyopathy similar to human striated muscle laminopathies

Laminopathies are a group of disorders caused by mutations in the LMNA gene encoding A-type lamins, components of the nuclear lamina. Three of these disorders affect specifically the skeletal and/or cardiac muscles, and their pathogenic mechanisms are still unknown. We chose the LMNA H222P missense mutation identified in a family with autosomal dominant Emery-Dreifuss muscular dystrophy, one of the striated muscle-specific laminopathies, to create a faithful mouse model of this type of laminopathy. The mutant mice exhibit overtly normal embryonic development and sexual maturity. At adulthood, male homozygous mice display reduced locomotion activity with abnormal stiff walking posture and all of them die by 9 months of age. As for cardiac phenotype, they develop chamber dilation and hypokinesia with conduction defects. These abnormal skeletal and cardiac features were also observed in the female homozygous mice but with a later-onset than in males. Histopathological analysis of the mice revealed muscle degeneration with fibrosis associated with dislocation of heterochromatin and activation of Smad signalling in heart and skeletal muscles. These results demonstrate that LmnaH222P/H222P mice represent a good model for studying laminopathies affecting striated muscles as they develop a dystrophic condition of both skeletal and cardiac muscles similar to the human diseases.

Ventricular myoarchitecture in tetralogy of Fallot

BACKGROUND

Little attention has been paid to the architecture of the muscle fibres of the ventricular walls in congenitally malformed hearts. In this study the gross pattern of myocardial fibres in normal hearts was compared with that in cases of tetralogy of Fallot.

METHODS AND RESULTS

After morphological examination nine specimens with tetralogy were dissected to study the ventricular myoarchitecture. Changes were found in the shape of the malformed ventricles. The ventricular walls were arranged in layers in all hearts. Superficial and deep layers were present in both ventricles, with the superficial layer showing a more oblique orientation in the specimens with tetralogy than in normal hearts. Modifications of muscle fibre that were related to the type of malformation were seen in the deep layer. A middle layer was present in the left ventricles of normal hearts and specimens with tetralogy: this showed a horizontal orientation in both groups. In contrast, a middle layer was found in the right ventricle only in specimens showing tetralogy.

CONCLUSIONS

The malformed hearts showed modifications in ventricular shape, in the arrangement of muscle in the right ventricle, and in the overall myoarchitecture. These changes could well be the consequence of the same agent (or agents) that caused the structural defect.