RIPK3 Expression in Fibroblasts in an in vivo and in vitro Skin Wound Model: A Controversial Result

One of the major problems of regenerative medicine is the development of hypertrophic scars and keloids. The protein kinase RIPK3 is involved in necroptosis; however, recent evidence indicates that it also has non-canonical functions, including its involvement in the development of renal fibrosis. The aim of our work was to study the expression of RIPK3 in mouse and human skin models of fibrotic processes. A subpopulation of RIPK3+Vim+ cells was found in both human keloid and a mouse wound, with the cell number being significantly greater in the mouse wound bed compared to healthy skin. Real-time polymerase chain reaction (RT-PCR) detected expression of the Ripk3 and fibroblast biomarkers Acta2, Fap, Col1a1, and Fn1 in the cells isolated from the wound bed, indicating that RIPK3 can be expressed by wound bed fibroblasts. An analysis of the human fibroblasts stained with anti-RIPK3 antibodies demonstrated an increase in the fluorescence intensity in the presence of lipopolysaccharide (LPS) at concentrations of 5, 10, 25, 50, and 100 ng/ml and TGF-β at concentrations of 0.1, 1, 2, and 5 ng/ml compared to the control. At the same time, the expression levels of RIPK3 and fibroblast activation markers in the presence of TGF-β and LPS did not differ significantly from the control. It is possible that RIPK3 expression in wound fibroblasts is not directly associated with fibrotic processes, and that kinase plays a different, yet unknown role in wound healing. KEYWORDS scarring, keloid, skin, fibroblasts, cell culture, RIPK3.

Survival of human cells in tissue-engineered constructs stored at room temperature

Tissue-engineered constructs (TECs), the dermal equivalent (DE) and the skin equivalent (SE), are allogenic equivalents of the skin and derm used to treat critical skin loss. Selection of storage conditions that contribute to longer shelf life, thereby expanding the possibilities of logistics and use, is one of the major issues related to the TECs development. The study was aimed to determine the shelf life of the DE and SE TECs stored in normal saline at room temperature by assessing morphology and viability of the cells on their surface, along with the levels of endothelial growth factor (VEGF) secreted by these cells. Using the MTT assay and staining with vital dye, we discovered the following: when TECs of both types were stored in normal saline, the cells viability and metabolic activity decreased by more than 50% by days 3–4 of storage. Furthermore, these decreased faster in DEs than in SEs. Morphology of the cells isolated from DEs and SEs after the 3-day storage remained unchanged. Mesenchymal stem cells on the surface of TECs kept producing VEGF after TECs culture medium was changed for saline solution (confirmed by immunofluorescence assay), which could indicate that the cells retained essential secretory activity.

Hypopharyngeal reconstruction using prelaminated autologous bio-engineered pectoralis major flaps

After removal of metastatic malignant tumors of the hypopharynx and larynx, hypopharyngeal defects are formed. To restore the hypopharynx, a mucosa and a muscular component are needed.

The objective of this study is to develop a hypopharyngeal reconstruction technique using prelaminated pectoralis major flap with mucosal epithelium analogue from autologous epithelial layers.

Materials and methods. Nine patients underwent reconstruction of the hypopharynx using bioengineered prelaminated pectoralis major flaps. The mucosa was restored by tissue-engineered autologous epithelial cell layers that were obtained by culturing in vitro cells isolated from skin biopsies that were previously obtained from patients.

Results. Oral nutrition was restored in all cases. Pharyngeal stenosis was detected in one (11%) patient. A stratified squamous epithelium on the pectoral fascia was revealed in 67% of cases at week 2 after prelamination, in 89% of cases at week 4 after reconstruction and in 100% of cases at month 3, 6, 12 and 24 after reconstruction.

Conclusion. Reconstruction using prelaminated bioengineered flaps allows recreating the anatomical integrity and function of the hypopharynx.

Type 2 Diabetes Mellitus: Pathogenic Features and Experimental Models in Rodents

Type 2 diabetes mellitus (T2DM) is the most common endocrine disorder (90%) in the world; it has numerous clinical, immunological, and genetic differences from type 1 diabetes mellitus. The pathogenesis of T2DM is complex and not fully clear. To date, animal models remain the main tool by which to study the pathophysiology and therapy of T2DM. Rodents are considered the best choice among animal models, because they are characterized by a small size, short induction period, easy diabetes induction, and economic efficiency. This review summarizes data on experimental models of T2DM that are currently used, evaluates their advantages and disadvantages vis-a-vis research, and describes in detail the factors that should be taken into account when using these models. Selection of a suitable model for tackling a particular issue is not always trivial; it affects study results and their interpretation.

NANOS3 downregulation in Down syndrome hiPSCs during primordial germ cell-like cell differentiation

Human infertility is a complex disorder at the genetic, molecular, cellular, organ, and hormonal levels. New developing technology based on the generation of human primordial germ cell-like cells (hPGCLCs) from induced pluripotent stem cells (hiPSCs) might improve understanding of early germ cell development (specification, migration, gametogenesis, and epigenetic reconstitutions), as well as offering a solution for infertility and hereditary disorders. In this study, we differentiated hiPSCs with trisomy 21 into hPGCLCs. In vitro-derived germ cells from hiPSCs with Down syndrome (DS) express hPGCLC core circuitry, EOMES, SOX17, and PRDM14 at relatively low levels. TFAP2C and PRDM1 were expressed and remained elevated, whereas NANOS3 and NANOG were downregulated in BMP4-induced hiPSCs with DS. The low level of NANOG and NANOS3 expression might negatively influence hPGCLC generation in DS hiPSCs. We suggest that DS hPGCLCs could be a suitable model for studying human early germ cell development, the epigenetic and molecular mechanisms of PGC specification and formation, as well as related infertility disorders, such as azoospermia and teratozoospermia.

Immortalization of Human Keratinocytes Using the Catalytic Subunit of Telomerase

A new stable line of human keratinocytes was obtained. The cells have altered morphology, both abnormal chromosomal composition and expression of keratinocyte markers, do not show contact inhibition, could be cultured in various media and have limited stratification ability in vitro. Upon transplantation into nude mice the cells have tumorigenic properties.

Wal Mutant Mice Have a Mutation Associated with Autism Spectrum Disorders

The waved alopecia (wal) mutation arose spontaneously in mice. Phenotypically, the wal mutation in a homozygous recessive state is manifested by a wavy coat. Over time, partial baldness develops, which leads to a thinning of the coat in mice. The molecular nature of the genetic defect in wal is still unknown; however, the coordinates of the chromosome locus in which the wal gene is located, a section of about 10⁷ bp in length, has been determined in mouse chromosome 14. We examined the wal locus by sequencing the exons of candidate genes in which the mutation was expected, and performed genome-wide sequencing to identify the cause of the wal mutation. The sequences of exons of candidate genes located in this region did not carry changes that could lead to a change in the structure of the protein. However, outside the wal zone, a mutation in the Slc9a9 gene was found that is probably not associated with the wal phenotype. According to the literature, a mutation in the Slc9a9 gene leads to autism spectrum disorders. This is the first discovered spontaneous mutation in the Slc9a9 gene in mice.

Expression of Protein Kinases RIPK-1 and RIPK-3 in Mouse and Human Hair Follicle

Expression of cell death regulators RIPK-1 and RIPK-3 in mouse and human hair follicle structures was studied by immunohistochemistry. At anagen and catagen stages of mouse hair follicle, RIPK-1+ cells were located in the inner root sheath, whereas RIPK-3+ cells were found in the inner and outer root sheath, dermal papilla, and interfollicular epidermis. RIPK-1 expression intensity was low in the early anagen and increased as mature anagen and catagen approached. RIPK-1+ and RIPK-3+ cells were also found in human hair follicle. It is assumed that the role of necroptosis markers in hair follicle life activity is independent of programmed cell death and that they may have yet unknown functions and take part in noncanonical signal cascades.

A Simplified Streptozotocin-Induced Diabetes Model in Nude Mice

Preclinical studies of human cellular and tissue-based products (HCT/Ps) for transplantation therapy of type 1 diabetes mellitus (T1DM) necessarily involve animal models, particularly mouse models of diabetes induced by streptozotocin (STZ). These models should mimic the clinical and metabolic manifestations of T1DM in humans (face validity) and be similar to T1DM in terms of the pathogenetic mechanism (construct validity). Furthermore, since HCT/Ps contain human cells, modeling of diabetes in immune-deficient animals is obligatory. Here we describe the most simplified diabetes model in Nude mice. Diabetes was induced in 31 males by a single intraperitoneal injection of STZ in normal saline at a medium-to-high dose of 150 mg/kg body weight. Fourteen control animals received only saline. Non-fasting plasma glucose (PG) levels were measured periodically for 50 days. All STZ-treated mice survived beyond 50 days. By day 15 after STZ administration, 22 of 31 (71%) mice developed stable diabetes based on the following criteria: (1) non-fasting PG ≥ 15 mmol/L on consecutive measurements up until day 50; (2) no diabetes remission. The mean non-fasting PG in mice with stable diabetes over the period of 35 days was equal to 25.7 mmol/L. On day 50, mean plasma insulin concentration, mean pancreatic insulin content, and the average number of β-cells in pancreatic islets were 2.6, 8.4, and 50 times lower, respectively, than in the control animals. We consider that our Nude mouse model of diabetes meets face validity and construct validity criteria and can be used in preclinical studies of HCT/Ps.

Mesenchymal Stem Cell Therapy-Is the Vessel Half Full or Half Empty?

The urgency of the search and introduction into medical practice of the method for the therapy of severe forms of pneumonia COVID-19 is due to the lack of effective treatment methods that can destroy the pathogen. Expectations of a good clinical effect from the application of mesenchymal stem cells (MSCs) are not groundless: there is a scientific justification in using MSCs for the treatment of inflammatory diseases and of the proven mechanisms of their action. Along with this, there are very little reliable data about the mechanism of MSCs' action when they are systemically administrated to a human or on the distribution of cells in the body and the long-term consequences of such administration. Data from model experiments are contradictory both concerning the specific action of MSCs and their safety. If clinical studies show an acceptable risk/benefit ratio for the application of MSCs, countries in which such studies have been conducted can expect their introduction into medical practice. In Russia, it is necessary to initiate experimental verification of the specific action of MSCs and the risks of their use in COVID-19 conditions in a sufficient quantity, and, in parallel, to create a mechanism for accelerated but justified admission of biomedical cell products into practice.

Melatonin Stimulates Epithelium Migration in Wound Models In Vitro and In Vivo

We studied the effect of bovine brain gangliosides, individual ganglioside GM1, and melatonin on the rate of wound closure under in vitro conditions and the effect of melatonin on the rate of wound healing under in vivo conditions. It was shown that bovine brain gangliosides and melatonin reliably increased cell migration in the experimental wound model. This effect was detected when the cell cultures were treated with the test preparations after wound infliction and when the cultures of human keratinocytes were pretreated before wounding. Analysis of the effect of melatonin on the rate of wound healing in vivo showed that melatonin accelerated this process, especially at the middle stages corresponding to the proliferation phase (days 3-6 after surgery). Histological analysis revealed intensification of epidermal cell proliferation at the edges of the wound starting from day 4 after surgery.

Detection of small numbers of iPSCs in different heterogeneous cell mixtures with highly sensitive droplet digital PCR

Induced pluripotent stem cells (iPS cells) are a prospective resource for regenerative biomedicine. iPS cells can differentiate into any type of stem, progenitor and somatic cells to help replace structures within damaged organs or tissues. However, iPS cells themselves, can produce malignant tumors if they are injected into the body of an immunocompatible or immunodeficient recipient. Thus, it is necessary to detect any residual iPS cells content in biomedical cell products obtained from iPS cells and destined for transplantation. In this article we describe searches for iPS cells in heterogeneous cell mixtures, using two different methods-quantitative RT-PCR and droplet digital PCR (ddPCR). In experiments with various heterogeneous mixtures, including mixtures with neural stem cells, we found that the OCT4, TDGF1 and LIN28 genes are the best markers for such a search, and droplet digital PCR provides the greatest measurement accuracy, which is 0.002%. Thus, we have confirmed the advantage of using droplet digital PCR in the search for pluripotent stem cells in heterogeneous cell mixtures. We hope that this data can be useful for biosafety control in regenerative biomedicine.

Modern Technologies Deriving Human Primordial Germ Cells in vitro

Primordial germ cells (PGCs) are a unique type of stem cells capable of giving rise to totipotent stem cells and ensuring the fertility of an organism and the transfer of its genome to the next generation. PGC research is an important perspective research field of developmental biology that handles many questions of embryogenesis and holds promise for treatments of infertility in the future. Considering ethical concerns related to human embryos, the main research approach in understanding the biology of human PGCs is in vitro studies. In this review, we consider the historical perspective of human PGC studies in vitro, the main existing models, and further outlooks and applications in medicine and science.

Pathogenesis of Type 1 Diabetes Mellitus and Rodent Experimental Models

The global prevalence of diabetes mellitus and its severe complications is on the rise. The study of the pathogenesis of the onset and the progression of complications related to the disease, as well as the search for new therapeutic agents and methods of treatment, remains relevant. Experimental models are extremely important in the study of diabetes. This survey contains a synthesis of the most commonly used experimental animal models described in scientific literature. The mechanisms of the streptozotocin model are also analyzed and discussed, as it is considered as the most adequate and easily reproducible diabetes model. A review of the significant advantages and disadvantages of the described models has also been conducted.

Pathogenesis of Type 1 Diabetes Mellitus and Rodent Experimental Models

The global prevalence of diabetes mellitus and its severe complications is on the rise. The study of the pathogenesis of the onset and the progression of complications related to the disease, as well as the search for new therapeutic agents and methods of treatment, remains relevant. Experimental models are extremely important in the study of diabetes. This survey contains a synthesis of the most commonly used experimental animal models described in scientific literature. The mechanisms of the streptozotocin model are also analyzed and discussed, as it is considered as the most adequate and easily reproducible diabetes model. A review of the significant advantages and disadvantages of the described models has also been conducted.

[The significance of fibroblasts in experimental modeling of proliferative vitreoretinopathy]

AIM

to investigate the role of heterogeneous fibroblasts in the development of epiretinal membrane in eyes with modeled proliferative vitreoretinopathy.

MATERIAL AND METHODS

The material for investigation were 6 eyes of 3 Chinchilla rabbits. Suspended fibroblasts (fibroblasts of the human skin - 200000 cells in 0.1 ml) were injected into the vitreous cavity via the pars plana. The animals were followed up for 1 month and then made out of the experiment. The eyes were enucleated and fixed in 10% neutral buffered formalin for routine histological examination. Microscopy was performed on the Leica system.

RESULTS

The main clinical and morphological criteria for a rabbit model of PVR induced by intravitreal injection of heterogenic fibroblasts have been established: epiretinal membrane formation, changes in intraocular structures (the retinal pigment epithelium and retina), and inflammation (due to transplantation immunity). Particularities of the epiretinal membrane development and the role of different intraocular structures have been described.

CONCLUSION

The experimental fibroblastic model of PVR reproduces the final, fibrous, stage of PVR, which is significant for efficacy evaluation of antiproliferative drugs.

New genes for accurate normalization of qRT-PCR results in study of iPS and iPS-derived cells

iPSC-derived cells (from induced pluripotent stem cells) are a useful source that provide a powerful and widely accepted tool for the study of various types of human cells in vitro. Indeed, iPSC-derived cells from patients with hereditary diseases have been shown to reproduce the hallmarks of these diseases in vitro, phenotypes that can then also be manipulated in vitro. Quantitative reverse transcription PCR (qRT-PCR) is often used to characterize the progress of iPSC differentiation, validate mature cell types and to determine levels of pathological markers. Quantitative reverse transcription PCR (qRT-PCR) is used to quantify mRNA levels. This method requires some way of normalizing the data, typically by relating the obtained levels of gene expression to the levels of expression of a "house keeping gene", a gene whose expression is presumed not to change during manipulation of the cells. In the literature, typically only one such reference gene is used and its stability of expression during cell manipulation is not demonstrated. We are not aware of any study systematically looking at the expression of such genes in human iPSC or during their differentiation into neurons. Here we compare the expression of 16 reference genes in iPSC, neural stem cells (NSC) and neurons derived from iPSC. The applications GeNorm and NormFinder were used to identify the most suitable reference genes. We showed that ACTb, C1orf43, PSMB4, GAPDH and HMBS have the most stable expression. The use of these reference genes allows an accurate normalization of qRT-PCR results in all the cell types discussed above. We hope that this report will help to enable the performance of proper qRT-PCR results normalization in studies with iPSC-derived cells and in disease-modeling reports.

[STEM CELL NICHES AND REGENERATIVE MEDICINE]

The review is devoted to modern state of science in the area of stem cell niches. Fundamental characteristics of niche including extracellular matrix are considered. Key principles of niche functioning are demonstrated by the example of hematopoietic and epithelial cells. Special section discusses the use of stem cells and their microenvironment in regenerative medicine.

Valproic Acid Increases the Hepatic Differentiation Potential of Salivary Gland Cells

The studies of cell plasticity and differentiation abilities are important problems in modern cellular biology. The use of histone deacetylase inhibitor - valproic acid is a promising approach to increasing the differentiation efficiency of various cell types. In this paper we investigate the ability of mouse submandibular salivary gland cells to differentiate into the hepatic direction and the effect of valproic acid on the efficiency of this differentiation. It was shown that the gene expression levels of hepatocyte markers (Aat, Afp, G6p, Pepck, Tat, Cyp3a13) and liver-enriched transcription factors (Hnf-3, Hnf-3, Hnf-4, Hnf-6) were increased after differentiation in salivary gland cells. Valproic acid increases the specificity of hepatic differentiation, reducing the expression levels of the ductal (Krt19, Hhex1, Cyp7a1) and acinar (Ptf1a) markers. After valproic acid exposure, the efficiency of hepatic differentiation also increases, as evidenced by the increase in the gene expression level of Alb and Tdo, and increase in urea production by differentiated cells. No change was found in DNA methylation of the promoter regions of the genes; however, valproic acid treatment and subsequent hepatic differentiation largely affected the histone H3 methylation of liver-enriched genes. Thus, mouse submandibular salivary gland cells are capable of effective differentiation in the hepatic direction. Valproic acid increases the specificity and efficiency of the hepatic differentiation of these cells.

Valproic Acid Increases the Hepatic Differentiation Potential of Salivary Gland Cells

The studies of cell plasticity and differentiation abilities are important problems in modern cellular biology. The use of histone deacetylase inhibitor - valproic acid is a promising approach to increasing the differentiation efficiency of various cell types. In this paper we investigate the ability of mouse submandibular salivary gland cells to differentiate into the hepatic direction and the effect of valproic acid on the efficiency of this differentiation. It was shown that the gene expression levels of hepatocyte markers (Aat, Afp, G6p, Pepck, Tat, Cyp3a13) and liver-enriched transcription factors (Hnf-3α, Hnf-3β, Hnf-4α, Hnf-6) were increased after differentiation in salivary gland cells. Valproic acid increases the specificity of hepatic differentiation, reducing the expression levels of the ductal (Krt19, Hhex1, Cyp7a1) and acinar (Ptf1a) markers. After valproic acid exposure, the efficiency of hepatic differentiation also increases, as evidenced by the increase in the gene expression level of Alb and Tdo, and increase in urea production by differentiated cells. No change was found in DNA methylation of the promoter regions of the genes; however, valproic acid treatment and subsequent hepatic differentiation largely affected the histone H3 methylation of liver-enriched genes. Thus, mouse submandibular salivary gland cells are capable of effective differentiation in the hepatic direction. Valproic acid increases the specificity and efficiency of the hepatic differentiation of these cells.

Generation of iPS Cells from Human Hair Follice Dermal Papilla Cells

Dermal papilla (DP) cells are unique regional stem cells of the skin that induce formation of a hair follicle and its regeneration cycle. DP are multipotent stem cells; therefore we supposed that the efficiency of DPC reprogramming could exceed that of dermal fibroblasts reprogramming. We generated induced pluripotent stem cells from human DP cells using lentiviral transfection with Oct4, Sox2, Klf4, and c-Myc, and cultivation of cells both in a medium supplemented with valproic acid and at a physiological level of oxygen (5%). The efficiency of DP cells reprogramming was ~0.03%, while the efficiency of dermal fibroblast reprogramming under the same conditions was ~0.01%. Therefore, we demonstrated the suitability of DP cells as an alternative source of iPS cells.

Generation of iPS Cells from Human Hair Follice Dermal Papilla Cells

Dermal papilla (DP) cells are unique regional stem cells of the skin that induce formation of a hair follicle and its regeneration cycle. DP are multipotent stem cells; therefore we supposed that the efficiency of DPC reprogramming could exceed that of dermal fibroblasts reprogramming. We generated induced pluripotent stem cells from human DP cells using lentiviral transfection with Oct4, Sox2, Klf4, and c-Myc, and cultivation of cells both in a medium supplemented with valproic acid and at a physiological level of oxygen (5%). The efficiency of DP cells reprogramming was ~0.03%, while the efficiency of dermal fibroblast reprogramming under the same conditions was ~0.01%. Therefore, we demonstrated the suitability of DP cells as an alternative source of iPS cells.

The Role of Integrins in the Development and Homeostasis of the Epidermis and Skin Appendages

Integrins play a critical role in the regulation of adhesion, migration, proliferation, and differentiation of cells. Because of the variety of the functions they play in the cell, they are necessary for the formation and maintenance of tissue structure integrity. The trove of data accumulated by researchers suggests that integrins participate in the morphogenesis of the epidermis and its appendages. The development of mice with tissue-specific integrin genes knockout and determination of the genetic basis for a number of skin diseases in humans showed the significance of integrins in the biology, physiology, and morphogenesis of the epidermis and hair follicles. This review discusses the data on the role of different classes of integrin receptors in the biology of epidermal cells, as well as the development of the epidermis and hair follicles.