High rates of cancer incidence and mortality from malignant neoplasms remains an urgent health problem. The development of the most effective therapeutic algorithms is required to improve the survival of cancer patients. An important condition for the discovery of new anticancer drugs and their translation into clinical practice involves the ability to model tumor growth, reproduce the characteristics of human disease, and evaluate measurable effects of pharmacological substances in laboratory facilities. Xenograft models established by direct implantation of fresh tumor tissue samples from individual patients into immunodeficient mice are considered suitable for both preclinical trials and for solving fundamental problems in oncology. The review highlights the significance of patient-derived xenograft models as a platform with high predictive value and the prerequisites that make them the preferred tool for research in cancer biology. The most important methodological aspects in the creation of these models are considered. Methods for obtaining and preparing biological tumor samples for xenotransplantation are discussed. The significance of the immune status, as well as the phenotypic and genetic characteristics of recipient animals, is described. The article presents the limitations of animal models associated with their immunodeficiency status and ways to overcome them. The principles for choosing xenotransplantation sites (heterotopic and orthotopic) and their advantages and disadvantages are discussed. In conclusion, we emphasize the need to continue the work on optimizing PDX (Patient-Derived Xenograft) models to overcome their limitations and to obtain the most reliable and valuable research results in oncology.
Experimental investigations of within-test variability of non-destructive methods to determine concrete strength are reported. Rebound, indentation, ultrasonic (with direct and surface transmissions) and shearing rib methods were among those studied.
Modern tissue engineering approaches are aimed at developing scaffolds that contribute to the development of the whole variety of intercellular interactions that imitate those in a real object.The purpose of the study was to collect and summarize the data on the creation and use of three-dimensional cellular matrices.Material and Methods. A systematic literature search was conducted in the PubMed, Medline, Cyber Leninka and Elibrary databases. Out of the 315 articles searched, 38 were selected for this review.Results. A review of studies devoted to the development of three-dimensional composite structures (scaffolds) and their application in the field of cellular technologies was carried out. Methods for the manufacture of biocompatible structures using both natural biomaterials and synthetic ones, including various hydrogels and titanium alloys, were considered, and some physical and chemical characteristics were also discussed. The review discussed possible applications of 3D composite structures in oncology as one of the possible tools for expanding the fundamental understanding of the patterns of development of the malignant process, but also for use in the development of effective methods of treatment and the search for new drugs. The prospects for the use of scaffolds in the field of experimental oncology, namely in the creation of various types of tumor models, were outlined.Conclusion. Currently, three-dimensional culture systems are replacing two-dimensional models. Advances in this direction are associated with the creation and development of various variants of cell matrices that contribute to the solution of a number of applied problems in the field of creating three-dimensional tumor models in vitro and in vivo, therapy of malignant tumors and restorative medicine.
Purpose of the study. The investigation is aimed to provide a systematic comparison of different contrasting methods for in vivo micro-CT diagnostic of orthotopic colorectal cancer models extracted by ortotopic implantation into the caecum of immunocompromised mice BALB/c Nude lines.Materials and methods. BALB/c Nude (N = 25) female mice were implanted by transplanted human colorectal cancer strain into the cecum. 20 days after the implantation mice were administered with iodine-based contrast agent Optiray by means of different administration method (intravenously, per os, intraperitoneally, per rectum) and micro-CT scans have been registered via Quantum GX2 tomograph. Measurement of tumor nodes was performed both by means of estimation from micro-CT images via RadiAnt DICOM Viewer software and by means of explicit measurements using calipers upon laparotomy and posthumously. At the last stage of the study, the animals were euthanized by cervical dislocation. The tumors were excised, measured with a caliper and placed in 10 % formalin for the standard histological analysis according to the standard methods.Results. The average volumes of tumor xenografts in animals with intravenous, oral, and intraperitoneal contrast administration measured at micro-CT were 53.7 ± 5.2 mm3, 52.7 ± 6.4 mm3 and 63.6 ± 5.6 mm3 respectively; measured at laparotomy – 43.0 ± 5.5 mm3, 44.5 ± 5.4 mm3 and 58.5 ± 5.5 mm3 respectively; measured post-mortem – 55.2 ± 6.6 mm3, 53.2 ± 8.8 mm3 and 65.9 ± 3.8 mm3 respectively. The average volumes of tumor xenografts isolated post-mortem in these groups were comparable with the values shown at micro-CT, but larger than the volumes measured at laparotomy.Conclusion. The results obtained demonstrated that intravenous, peroral and intraperitoneal administration techniques provide the best visualization of laboratory rodents pathological tissue upon in vivo micro-CT diagnostics and thus are preferred.
The aim of the study was to create a patient-derived xenograft (PDX) model of human colorectal cancer and to determine its histologic and molecular characteristics, such as the status of KRAS, NRAS, and BRAF genes and the presence of microsatellite instability.Materials and methods. First generation xenograft models in vivo were created using tumors from patients with colorectal cancer (n = 4) and immunodeficient Balb/c Nude mice (n = 20); second, third, and fourth generation models were created in the same mouse line (n = 3 for each generation). A caliper was used to measure subcutaneous xenografts; their size was calculated by the ellipsoid formula. Cryopreservation involved immersing the samples in a freezing medium (80% RPMI 1640, 10% fetal bovine serum, 10% dimethyl sulfoxide (DMSO)) and storing them at –80 °C. The histologic analysis was performed according to the standard technique (preparation of paraffin blocks and staining of microsections with hematoxylin and eosin). Mutations in the KRAS, NRAS, and BRAF genes were determined by direct Sanger sequencing; microsatellite instability was determined by the fragment analysis at five loci: Bat-25, Bat-26, NR21, NR24, and NR27.Results. Stable, transplantable xenografts of colorectal cancer were obtained from two out of four patients. The average waiting time from the implantation to the growth of the first generation xenograft was 28 days. The latency phase after cryopreservation was comparable to that at the creation of the first generation PDX model. The model reproduced the histotype, grade and mutational status of the KRAS, NRAS, and BRAF genes, as well as microsatellite instability of the donor tumor.Conclusion. The developed model of human colorectal cancer was characterized in terms of growth dynamics, cryopreservation tolerance, and histologic and molecular genetic parameters.
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