Vol 47, No 7 (2019)

Cardiomyopathy (CMP) is a common group of cardiovascular disorders. Genetic (primary) cardiomyopathies are related to abnormalities in more than 100 genes, including the DES gene encoding desmin protein. Desmin is an essential member of the intermediate filaments, ensuring the structural and functional integrity of myocytes. Mutations in the DES gene result in desmin-related cardiomyopathy with progressive course and poor prognosis. By now, specific therapy for cardiomyopathy has not been developed. Existing conservative and surgical treatment modalities target the rate of heart failure progression and sudden cardiac death prevention but have limited efficacy. The development of gene therapy and genome editing could allow for creating effective and specific methods of gene-based therapy for desminopathies. A  number of studies have been published on the use of gene therapy for various genetic cardiomyopathies including those caused by the DES gene mutations, while genome editing has not been used yet. However, promising results have been obtained with CRISPR/Cas9 and TALEN editing systems to correct for “gain-of-function mutations” in some other genes, such as MYBPC3 and PLN. There is also evidence of the possibility to reduce the symptoms of desmin-related cardiomyopathy up to the normal function by knocking out the mutant DES allele, and preserved protein function provided by expression of the normal allele. We believe that genome editing approaches have an open perspective into the development of specific and effective methods to treat desminopathies.

Epilepsy affects more than 70  million people worldwide. From 30 to 40%  of the patients are resistant to existing medication. This paper describes the current state of the treatment of epilepsy and proposes a  future approach to preventative treatment at earlier stages of epileptogenesis. For preventative treatment biomarkers are needed that predict the development of epilepsy at its earlier stages. Pathological high frequency oscillations are the only acceptable biomarker of epileptogenesis. However, the main limitation of this biomarker is the necessity of implanting of recording electrodes. The search for noninvasive biomarkers of epileptogenesis is one of the hot topics in epilepsy research. There are two potentially interesting directions in this area: search for inflammatory biomarkers in the peripheral blood and analysis of different parameters of imaging methods. In this paper we present approaches for identification of potential epileptogenesis biomarkers by magnetic resonance imaging. Some of magnetic resonance imaging parameters correlate with the existence of pathological high frequency oscillations, may indirectly reflect ongoing inflammation process in the brain and be potential biomarkers of epileptogenesis.

The potential of heart tissues for self-regeneration is not high and supposedly limited to a small number of the niche stem cells. This makes it extremely important to develop regenerative technologies for the myocardium based on modern techniques, for instance, cell re-programming and 3D bioprinting. However, it is often difficult to differentiate the  sensational reports regularly appearing in mass media on “breakthrough” technologies from those that really have practical applications. The article sets out a point of view on the popular technologies for the regeneration of cardiac tissues and myocardium as a whole and reviews their drawbacks. The main problems of the bioprinting approach being actively developed include a low differentiation level with printing by stem cells that does not allow for a full-fledged cardiac tissue without foreign inclusions, as well as technological impossibility, when printing with stem cells, to set up their links with other cells during cell delivery in their corresponding matrix locations. Despite some optimistic reports on the good performance on stem or induced pluripotent cells injections into the myocardial injury zone that were first made public about 20  years ago, nowadays this idea seems rather doubtful, because in the recent years there has been virtually no positive effect of this procedure with a serious risk of complications. As far as growing of heart muscle elements is concerned, the main challenge is the development of the “proper” vascularization of the muscle being grown. At the same time, one has to emphasize practical feasibility of growing relatively small myocardial elements, such as sinus node.

We have analyzed the state-of-the-art methods for sterilization of bone implants. The problem of finding effective bioimplant sterilization methods is still far from its optimal solution and remains as urgent as before. The factors limiting further development of the main biomaterial sterilization methods include limitations related to each existing method and the use of technologies with sterilizing effect. Comparative analysis of the main techniques for bioimplant sterilization that are used in medical and biological areas (treatment with ethylene oxide, radiation, wet warmth, liquid media, and ozone) allows for a conclusion on the advantages of the radiation sterilization. However, the choice is challenged by the dilemma: higher radiation dose would increase the sterilization effect, but at the same time can lead to multiple morphological abnormalities in the tissues, deterioration of their mechanical characteristics, destruction of morphogenetic proteins and consequently to lower efficacy of the reparative bone formation. As a  result, the material can become unsuitable for clinical use. One of the real approaches to solve this problem is to use as low absorbed radiation dose as possible during irradiation of biomaterials, at least to 15 kGy. The developments made by the authors within the last years have shown that such a  result can be achieved by the use of combines sterilization techniques based on combines effects of a  number of physical and chemical factors on the biomaterial being sterilized. Mutual enhancement of the sterilizing effects of these factors creates prerequisites for their synergy, whereby the intensity of each factor can be reduced. This makes it possible to decrease the degree of harmful adverse events associated with each individual factor with higher total effect. The search for innovative solutions for the urgent problems of the bone bioimplant sterilization, for the development of the state-of-the-art health-sparing technologies can be successful only with unification of the efforts by specialists from related sciences. This would allow for creating of breakthrough technologies for sterilization and for optimization of this procedure with achievement of its high efficacy.

Rationale: Riboflavin (vitamin B₂) is one of the most promising agents for photodynamic therapy (PDT). However, its use is limited by the excitation in the ultraviolet (UV) and visible spectral ranges and, as a result, by a small penetration into biological tissue not exceeding a few millimeters. This problem could be solved by approaches ensuring excitation of riboflavin molecules within tumor tissues by infrared (IR) light. Upconversion nanoparticles (UCNPs) can be potentially considered as mediators able to effectively convert the exciting radiation of the near IR range, penetrating into biological tissue to a 3 cm depth, into the photoluminescence in the UV and visible spectral ranges.

Aim: To evaluate the efficacy of UCNPs for IR-mediated riboflavin activation in the depth of tumor tissue during PDT.
Materials and methods: The water-soluble riboflavin flavin mononucleotide (FMN, Pharmstandard-UfaVITA, Russia) was used as a photosensitizer in in vitro and in vivo experiments. The in vitro experiments were performed on human breast adenocarcinoma SK-BR-3, human glioblastoma U-87 MG, and rat glioma C6 cell lines. Lewis lung carcinoma (LLC) inoculated to hybrid BDF1 mice was used as a model to demonstrate the delivery of FMN to the tumor. UCNPs with a core/shell structure [NaYF4:Yb³⁺, Tm³⁺/NaYF4] were used for photoactivation of FMN in vivo. PDT based on FMN, UCNPs and laser radiation 975 nm (IR) was performed on mouse xenografts of human breast adenocarcinoma SKBR-3.

Results: We were able to show that FMN could act as an effective in vitro photosensitizer for SK-BR-3, U-87 MG, and C6 cell lines. FMN IC50 values for glioma cells were ~30 μM, and for SK-BR-3 cell line ~50 μM (24 h incubation, irradiation 4.2 J/cm²). In the LLC model, the appropriate concentration of FMN (30 μM and above) can be achieved in the tumor as a result of systemic administration of FMN (at 2 and 24 hours after injection). The effect of PDT using near IR light for UCNP-mediated excitation of FMN was demonstrated in mouse xenografts SKBR-3, with the tumor growth inhibition of 90±5%.

Conclusion: The study has demonstrated the possibility to use riboflavin (vitamin B₂) as a photosensitizer for PDT. The photoexcitation of FMN via the anti-Stokes photoluminescence of UCNPs allows for implementation of the PDT technique with the near IR spectral range.

Rationale: An increase in vascular tone is believed to be a major factor leading to arterial hypertension (AH). There are no means for a direct measurement of the vascular tone in clinical practice. Perfusion assessment by laser Doppler flowmetry (LDF) allows for an indirect evaluation of the vascular tone of the microcirculation system. Perfusion is assessed by the change in blood flow per unit of time in the given area. Therefore, this parameter should be inversely correlated with vascular tone. Aim: To compare the forearm skin perfusion measured by LDF in patients with AH and healthy volunteers with normal blood pressure, and to review the feasibility of this parameter for the assessment of the microvasculature tone.

Materials and methods: The study was carried out in two groups: group one, patients with AH (n = 43; age 62 [57; 71] years), and group 2, healthy volunteers without AH (n = 62; age 28 [24; 37] years). The perfusion in the forearm skin was measured by LDF for 2 minutes without any functional tests. "Baseline perfusion” for each subject was calculated as the average perfusion rate in a representative portion of the microcirculatory curve.

Results: Median of basic perfusion in the forearm skin in the patients with AH is significantly higher than that in the normotensive individuals: 4.88 [2.87; 8.98] PU and 3.41 [2.47; 4.99] PU, respectively (p = 0.013). The interquartile range of the baseline perfusion in the control group was chosen as provisional threshold values for the "normal” perfusion level. In 39.5% of patients with AH, their basic perfusion was within the "normal level”; 46.5% of the patients had the baseline perfusion above the "normal level”, which might be due to reduced tone of the peripheral vessels. Only 14.0% of the patients had a decreased level of the basic perfusion.

Conclusion: An increase in the skin perfusion in some patients with AH may indicate a decrease in their peripheral vascular tone, which could be a potential compensatory reaction in response to the rise in blood pressure. The results obtained could have been influenced by the age-related changes in the cardiovascular system, drug therapy, etc. Further studies into the specifics of peripheral vasculature seem reasonable. They can contribute to the understanding of the pathophysiology of AH in a given patient and, in future, could be used to guide a personalized choice of therapy.