3D Bioprinting of Model Tissues That Mimic the Tumor Microenvironment.

The tumor microenvironment (TME) influences cancer progression. Therefore, engineered TME models are being developed for fundamental research and anti-cancer drug screening. This paper reports the biofabrication of 3D-printed avascular structures that recapitulate several features of the TME. The tumor is represented by a hydrogel droplet uniformly loaded with breast cancer cells (106 cells/mL); it is embedded in the same type of hydrogel containing primary cells-tumor-associated fibroblasts isolated from the peritumoral environment and peripheral blood mononuclear cells. Hoechst staining of cryosectioned tissue constructs demonstrated that cells remodeled the hydrogel and remained viable for weeks. Histological sections revealed heterotypic aggregates of malignant and peritumoral cells; moreover, the constituent cells proliferated in vitro. To investigate the interactions responsible for the experimentally observed cellular rearrangements, we built lattice models of the bioprinted constructs and simulated their evolution using Metropolis Monte Carlo methods. Although unable to replicate the complexity of the TME, the approach presented here enables the self-assembly and co-culture of several cell types of the TME. Further studies will evaluate whether the bioprinted constructs can evolve in vivo in animal models. If they become connected to the host vasculature, they may turn into a fully organized TME.

Balkan endemic nephropathy and aristolochic acid I: an investigation into the role of soil and soil organic matter contamination, as a potential natural exposure pathway.

Aristolochic acids (AAs) are carcinogenic and nephrotoxic plant alkaloids present in Aristolochia species, used in traditional medicine. Recent biomolecular and environmental studies have incriminated these toxins as an etiological agent in Balkan endemic nephropathy (BEN), a severe kidney disease occurring in the Balkan Peninsula. The questions on how the susceptible populations are exposed to these toxins have not yet been clearly answered. Exposure to AAs through the food chain, and environmental pollution (soil/dust), could provide an explanation for the presence of BEN in the countries where no folkloric use of the plant has been documented (Bulgaria, Croatia). Additional exposure pathways are likely to occur, and we have shown previously that AAs can contaminate crop plants through absorption from soil, under controlled laboratory environment. Here, we attempt to provide additional support to this potential exposure pathway, by revealing the presence of AAI in soil and soil organic matter samples collected from BEN and non-BEN areas. The samples were processed in order to be analyzed by high-pressure liquid chromatography, and ion trap mass spectrometry. Our results showed the presence of AAI in small concentrations, both in BEN and non-BEN soils, especially where Aristolochia plants and seeds were present.

Explants-isolated human placenta and umbilical cord cells share characteristics of both epithelial and mesenchymal stem cells.

In recent years, identification of new sources of adult stem cells developed rapidly, pursuing to find easily available tissues, which will give rise to homogenous stem cells populations. Up to present, bone marrow-derived mesenchymal stem cells (BM-MSCs) are unanimously considered to fulfill the criteria for being used in clinical settings, but adipose stem cells, placental and umbilical cord stem cells, and other tissue-derived stem cells are making their way to being used at least in autologous transplantation. We isolated cellular populations from placental tissue and umbilical cord using the explants method. The placental (PL) and umbilical cord (UC)-derived cells were cultured and expanded in appropriate conditions for generation of stem cells. We assessed the stemness characteristics of the tissue-isolated cells and compared them to an established MSCs line. For this purpose, we determined the immunophenotype, morphological and ultrastructural characteristics, as well as functional abilities of PL- and UC-derived cells. Flow cytometric evaluation of cells revealed presence of CD90, CD73, and CD105 stem cells markers, while the cells were negative for CD34, CD45 and HLA-DR. Immunocytochemical staining showed that 100% of PL- and UC-derived cells are positive for vimentin and CD105 expression, while cytokeratin was revealed in less than 10% in both tissue-isolated cells. Morphological and ultrastructural characteristics of cells exposed analogous cellular size and intracellular organization, similar to MSCs, but detailed view of UC-derived cells by transmission electron microscopy (TEM) demonstrated presence of intercellular junctions-desmosomes, similar to epithelial cells. Both PL- and UC-derived cells confirmed their trilineage potential, being able to differentiate into adipocytes, osteoblasts, and chondrocytes in different proportions. Flow chamber in vitro assay was used to determine to what extent PL- and UC-derived cells are able to adhere to substrates (VCAM and ICAM) and we showed progressively decreased adhesion of both cellular types, inversely proportional to the generated shear stress. We may conclude that explants-isolated placental and umbilical cord cells are endowed with characteristics of both epithelial and mesenchymal stem cells, and purification procedures are additionally required for safe use of these cells in diverse clinical applications.