Microphysiological stem cell models of the human heart.

Models of heart disease and drug responses are increasingly based on human pluripotent stem cells (hPSCs) since their ability to capture human heart (dys-)function is often better than animal models. Simple monolayer cultures of hPSC-derived cardiomyocytes, however, have shortcomings. Some of these can be overcome using more complex, multi cell-type models in 3D. Here we review modalities that address this, describe efforts to tailor readouts and sensors for monitoring tissue- and cell physiology (exogenously and in situ) and discuss perspectives for implementation in industry and academia.

CDC7-independent G1/S transition revealed by targeted protein degradation.

The entry of mammalian cells into the DNA synthesis phase (S phase) represents a key event in cell division1. According to current models of the cell cycle, the kinase CDC7 constitutes an essential and rate-limiting trigger of DNA replication, acting together with the cyclin-dependent kinase CDK2. Here we show that CDC7 is dispensable for cell division of many different cell types, as determined using chemical genetic systems that enable acute shutdown of CDC7 in cultured cells and in live mice. We demonstrate that another cell cycle kinase, CDK1, is also active during G1/S transition both in cycling cells and in cells exiting quiescence. We show that CDC7 and CDK1 perform functionally redundant roles during G1/S transition, and at least one of these kinases must be present to allow S-phase entry. These observations revise our understanding of cell cycle progression by demonstrating that CDK1 physiologically regulates two distinct transitions during cell division cycle, whereas CDC7 has a redundant function in DNA replication.

PAX7 Balances the Cell Cycle Progression via Regulating Expression of Dnmt3b and Apobec2 in Differentiating PSCs.

PAX7 transcription factor plays a crucial role in embryonic myogenesis and in adult muscles in which it secures proper function of satellite cells, including regulation of their self renewal. PAX7 downregulation is necessary for the myogenic differentiation of satellite cells induced after muscle damage, what is prerequisite step for regeneration. Using differentiating pluripotent stem cells we documented that the absence of functional PAX7 facilitates proliferation. Such action is executed by the modulation of the expression of two proteins involved in the DNA methylation, i.e., Dnmt3b and Apobec2. Increase in Dnmt3b expression led to the downregulation of the CDK inhibitors and facilitated cell cycle progression. Changes in Apobec2 expression, on the other hand, differently impacted proliferation/differentiation balance, depending on the experimental model used.

MEK1 is required for the development of NRAS-driven leukemia.

The dual-specificity kinases MEK1 and MEK2 act downstream of RAS/RAF to induce ERK activation, which is generally considered protumorigenic. Activating MEK mutations have not been discovered in leukemia, in which pathway activation is caused by mutations in upstream components such as RAS or Flt3. The anti-leukemic potential of MEK inhibitors is being tested in clinical trials; however, downregulation of MEK1 promotes Eµ-Myc-driven lymphomagenesis and MEK1 ablation induces myeloproliferative disease in mice, raising the concern that MEK inhibitors may be inefficient or counterproductive in this context. We investigated the role of MEK1 in the proliferation of human leukemic cell lines and in retroviral models of leukemia. Our data show that MEK1 suppression via RNA interference and genomic engineering does not affect the proliferation of human leukemic cell lines in culture; similarly, MEK1 ablation does not impact the development of MYC-driven leukemia in vivo. In contrast, MEK1 ablation significantly reduces tumorigenesis driven by Nras alone or in combination with Myc. Thus, while MEK1 restricts proliferation and tumorigenesis in some cellular and genetic contexts, it cannot be considered a tumor suppressor in the context of leukemogenesis. On the contrary, its role in NRAS-driven leukemogenesis advocates the use of MEK inhibitors, particularly in combination with PI3K/AKT inhibitors, in hematopoietic malignancies involving RAS activation.

Cell cycle regulation of embryonic stem cells and mouse embryonic fibroblasts lacking functional Pax7.

The transcription factor Pax7 plays a key role during embryonic myogenesis and in adult organisms in that it sustains the proper function of satellite cells, which serve as adult skeletal muscle stem cells. Recently we have shown that lack of Pax7 does not prevent the myogenic differentiation of pluripotent stem cells. In the current work we show that the absence of functional Pax7 in differentiating embryonic stem cells modulates cell cycle facilitating their proliferation. Surprisingly, deregulation of Pax7 function also positively impacts at the proliferation of mouse embryonic fibroblasts. Such phenotypes seem to be executed by modulating the expression of positive cell cycle regulators, such as cyclin E.

Epidermal RAF prevents allergic skin disease.

The RAS pathway is central to epidermal homeostasis, and its activation in tumors or in Rasopathies correlates with hyperproliferation. Downstream of RAS, RAF kinases are actionable targets regulating keratinocyte turnover; however, chemical RAF inhibitors paradoxically activate the pathway, promoting epidermal proliferation. We generated mice with compound epidermis-restricted BRAF/RAF1 ablation. In these animals, transient barrier defects and production of chemokines and Th2-type cytokines by keratinocytes cause a disease akin to human atopic dermatitis, characterized by IgE responses and local and systemic inflammation. Mechanistically, BRAF and RAF1 operate independently to balance MAPK signaling: BRAF promotes ERK activation, while RAF1 dims stress kinase activation. In vivo, JNK inhibition prevents disease onset, while MEK/ERK inhibition in mice lacking epidermal RAF1 phenocopies it. These results support a primary role of keratinocytes in the pathogenesis of atopic dermatitis, and the animals lacking BRAF and RAF1 in the epidermis represent a useful model for this disease.

Clinical and radiological pictures of two newborn babies with manifestations of chondrodysplasia punctata and review of available literature.

BACKGROUND: Chondrodysplasia punctata (CDP) is a rare, heterogeneous congenital skeletal dysplasia, characterized by punctate or dot-like calcium deposits in cartilage observed on neonatal radiograms. A number of inborn metabolic diseases are associated with CDP, including peroxisomal and cholesterol biosynthesis dysfunction and other inborn errors of metabolism such as: mucolipidosis type II, mucopolysacharidosis type III, GM1 gangliosidosis. CDP is also related to disruption of vitamin K-dependent metabolism, causing secondary effects on the embryo, as well as fetal alcohol syndrome (FAS), chromosomal abnormalities that include trisomies 18 and 21, Turner syndrome. CASE REPORT: This article presents clinical data and diagnostic imaging findings of two newborn babies with chondrodysplasia punctata. Children presented with skeletal and cartilage anomalies, dysmorphic facial feature, muscles tone abnormalities, skin changes and breathing difficulties. One of the patients demonstrated critical stenosis of spinal canal with anterior subluxation of C1 vertebra relative to C2. The aim of this article is to present cases and briefly describe current knowledge on etiopathogenesis as well as radiological and clinical symptoms of diseases coexisting with CDP. CONCLUSIONS: Radiological diagnostic imaging allows for visualization of punctate focal mineralization in bone epiphyses during neonatal age and infancy. Determining the etiology of chondrodysplasia punctata requires performing various basic as well as additional examinations, including genetic studies.

Complications of umbilical vein catherisation. Case Report.

BACKGROUND: Umbilical vein catheterization is a relatively easy procedure performed routinely on the neonate intensive care units. It provides a fast central vein access, but some complications have been described in the literature. CASE REPORTS: We presented a case report of a premature infant (34 hbd) with extravasation of the parenteral nutrition and drugs to the liver after umbilical vein catheterization. Fever and increasing biochemical markers of infection were observed. USG revealed a heterogenic, well-limited space of 4 cm in diameter, located in the right lobe of the liver. CT excluded liver abscess. Considering neoplastic process or incorrect location of the catheter of the central vein, we performed liver biopsy. RESULTS: Cytological and biochemical analysis of the aspirated fluid revealed extravasation of parenteral nutrition to the liver. Our case confirms the necessity of controlling a proper location of the central catheter right after its insertion and during hospitalization.

[Results of the treatment of paediatric non-rhabdomyosarcoma. One centre experience]. / Wyniki leczenia miesaków tkanek miekkich nie-rhabdomyosarcoma w jednym osrodku.

UNLABELLED: Non-rhabdomyosarcoma soft tissue sarcomas (NR STS) are a rare group of neoplasms of mesenchymal origin. The incidence of these tumours in children is low and due to it's heterogeneity and different response to chemotherapy and radiotherapy, unified treatment methods have not yet been established. THE AIM of our study was to analyze methods and treatment results of patients with NR STS treated in our centre. MATERIALS AND METHODS: Between 1996 and 2004, 64 patients with NR-STS, aged 2.5-21.5 yrs, were treated in our institution. Treatment protocol included primary tumour resection or biopsy, induction (neoadjuvant) chemotherapy, local treatment: surgery and/or radiotherapy and adjuvant chemotherapy. Results of treatment were analyzed in relation to stage, tumour diameter, extent of surgery and response to chemotherapy. RESULTS: Out of 64 patients, 48 are alive (75%), with a median observation time 4 yrs 3 m. Sixteen patients died: 1 of treatment complications, the rest from basic disease. Four years overall (OS) and event free survival (EFS) are 75% and 64% respectively. Early stage, tumour size less than 5 cm in diameter, radical surgery, complete and very good response to induction chemotherapy had a significant influence on survival. CONCLUSIONS: Our results indicate that besides stage and tumour size, radical surgery played key role in the treatment of NRMSSTS and that radical resections were possible to perform after induction chemotherapy in 33% of patients with primarily unresectable tumours. High number of patients with stage IV disease at diagnosis, occurrence of distant relapses and good response to chemotherapy indicate the necessity for the use of chemotherapy in patients with NR STS.

Adaptation of PCR technique for quantitative estimation of genetic material from different regions of chromosome 21 in cases of trisomy 21.

Pre- and postnatal diagnosis of chromosomal aberrations is generally based on conventional cytogenetic analysis. In this paper, we have devised a quantitative polymerase chain reaction (Q-PCR) method to determine gene dose effects and applied it in cases of regular trisomy 21 as a model. The method is based on quantitative assessment of PCR products after using primers amplifying DNA fragments located in the pericentromeric, heterochromatic, euchromatic and telomeric regions of chromosome 21. A gene dose effect on the amount of PCR product in cases of trisomy 21 was confirmed. Moreover, a correlation between the amount of the PCR product of the examined sequences and their location in the chromosome was observed. The obtained results suggest that the Q-PCR technique can be applied in the diagnosis of aneuploidies.

The dog genome map and its use in mammalian comparative genomics.

The dog genome organization was extensively studied in the last ten years. The most important achievements are the well-developed marker genome maps, including over 3200 marker loci, and a survey of the DNA genome sequence. This knowledge, along with the most advanced map of the human genome, turned out to be very useful in comparative genomic studies. On the one hand, it has promoted the development of marker genome maps of other species of the family Canidae (red fox, arctic fox, Chinese raccoon dog) as well as studies on the evolution of their karyotype. But the most important approach is the comparative analysis of human and canine hereditary diseases. At present, causative gene mutations are known for 30 canine hereditary diseases. A majority of them have human counterparts with similar clinical and molecular features. Studies on identification of genes having a major impact on some multifactorial diseases (hip dysplasia, epilepsy) and cancers (multifocal renal cystadenocarcinoma and nodular dermatofibrosis) are advanced. Very promising are the results of gene therapy for certain canine monogenic diseases (haemophilia, hereditary retinal dystrophy, mucopolysaccharidosis), which have human equivalents. The above-mentioned examples prove a very important model role of the dog in studies of human genetic diseases. On the other hand, the identification of gene mutations responsible for hereditary diseases has a substantial impact on breeding strategy in the dog.

Prenatal detection of maternal UPD15 in a new case with i(15p) by Timing Replication Test (TRT) and methylation analysis.

DNA replication kinetics of the Prader-Willi/Angelman Critical Region (PWACR) was studied with and without synchronisation in human amniotic cell cultures obtained from 20 cases with normal karyotype and 4 cases with a marker of chromosome 15, respectively. A Timing Replication Test (TRT) was performed by synchronisation of amniotic cell cultures and followed by interphase FISH to analyse and compare the early/late replication patterns in SNRPN and UBE3A genes between the homologues of chromosome 15. Asynchronous replication patterns of the analysed genes were observed in both amniotic cell cultures but the percentage of interphase nuclei presenting with asynchronous replication was significantly increased in the cultures with synchronisation (40-51%), as compared to those without synchronisation (20-23%). The evaluations, performed by means of TRT, showed asynchronous replication patterns on control values: between 39% and 46% of cells in all the cases with inv dup(15). In contrast, the percentage of cells with asynchronous replication in the case with i(15p) was significantly decreased (3-6%), as compared to the control value, and it may be indicated by uniparental disomy of chromosome 15 (UPD15). In addition, those results have been confirmed by molecular evaluation, using the methylation diagnostic test for diagnosis of the Prader-Willi Syndrome.

Inv(10) in a patient with hypogonadotropic hypogonadism.

Hypogonadotropic hypogonadism (HH) was diagnosed in a 22-year-old patient with 46,XY,inv(10) karyotype. It may be associated with some gene mutations of chromosome X, (KAL-1: Kallman syndrome; and DAX-1: congenital adrenal hypoplasia), as well as of certain autosomes, including chromosome 10. This study aimed to: (1) elucidate the aetiopathogenesis of the disease in the studied case: (2) diagnose chromosome aberrations as accurately as possible: and (3) determine if the observed clinical picture can be referred to the diagnosed chromosomal aberration or it is a mere coincidence. The FISH technique, with the use of non-commercial DNA probes, was applied for a precise description of chromosome breaking points. The application of FISH enabled karyotype description: 46,XY, inv(10)(p15.2q11.22).ish inv(10)(p15.2q21.3)(p15x3)(q21x3)(p15conq21x2). The SSCP method revealed no mutation within the DAX-1 gene and no deletion in the KAL-1 gene.

[Detection of chromosomal aneuploidies in fetus by multiplex Q-PCR method]. / Szybka diagnostyka aneuploidii chromosomowych u plodu za pomoca metody multiplex Q-PCR.

With application of the quantitative PCR, Q-PCR, two cases of aneuploidy: trisomy 18 and trisomy 21 were detected in the course of routine prenatal diagnosis in amniotic cells DNA obtained from 1.5 ml of the amniotic fluid. The conventional cytogenetic methods confirmed the diagnosis and the following karyotypes were established: 47,XY,+21 and 47,XX,+13. The presented results show that by means of the Q-PCR the aneuploidy diagnosis can be obtained within 48 hours.