ABSTRACT
The use of engineered cardiac tissue for high-throughput drug screening/toxicology assessment remains largely unexplored. Here we propose a scaffold that mimics aspects of cardiac extracellular matrix while preserving the contractility of cardiomyocytes. The scaffold is based on a poly(caprolactone) (PCL) nanofilm with magnetic properties (MNF, standing for magnetic nanofilm) coated with a layer of piezoelectric (PIEZO) microfibers of poly(vinylidene fluoride-trifluoroethylene) (MNF+PIEZO). The nanofilm creates a flexible support for cell contraction and the aligned PIEZO microfibers deposited on top of the nanofilm creates conditions for cell alignment and electrical stimulation of the seeded cells. Our results indicate that MNF+PIEZO scaffold promotes rat and human cardiac cell attachment and alignment, maintains the ratio of cell populations overtime, promotes cell-cell communication and metabolic maturation, and preserves cardiomyocyte (CM) contractility for at least 12 days. The engineered cardiac construct showed high toxicity against doxorubicin, a cardiotoxic molecule, and responded to compounds that modulate CM contraction such as epinephrine, propranolol and heptanol.
Subject(s)
Myocardial Contraction/physiology , Myocytes, Cardiac/metabolism , Nanostructures/chemistry , Tissue Scaffolds/chemistry , Animals , Anti-Arrhythmia Agents/pharmacology , Cell Communication , Cells, Cultured , Coculture Techniques , Doxorubicin/pharmacology , Drug Evaluation, Preclinical , Electric Stimulation , Extracellular Matrix/drug effects , Extracellular Matrix/metabolism , Humans , Hydrocarbons, Fluorinated/chemistry , Magnetic Phenomena , Myocytes, Cardiac/drug effects , Polyesters/chemistry , Rats , Rats, Wistar , Time Factors , Tissue Engineering , Vasoconstrictor Agents/pharmacology , Vinyl Compounds/chemistryABSTRACT
Chromium toxicity is strongly dependent on its oxidation state. Cr(VI) is carcinogenic and mutagenic, although its in vivo and in vitro toxic effects are related to its intracellular fate. Inside the cells, Cr(VI) is rapidly reduced to stable Cr(III). As Cr(V) and Cr(IV) species have been reported to be formed in the Cr(VI) reduction pathways, Cr(VI)-induced damage is thought, at least in part, to arise from these hypervalent species. The study of Cr(VI) reduction mechanisms and the characterization of the effects of each reactive intermediate constitute important steps towards a better understanding of chromium toxicity. The purpose of this work is to enlarge the scope of Cr(VI)-induced alterations in mouse to other chromium species. Our studies have led to the in situ preparation of a new Cr(V) complex, 1Cr(V)-BT](2-), a stable compound at neutral pH, which mimics Cr(VI) reduction intermediates. The effect of Cr(V) on the histology of mice liver is assessed and compared with similar Cr(VI) assays. Liver toxicity was examined after single administrations of Cr(VI) or [Cr(V)-BT](2-) to mice. Both compounds produced reversible hepatic damage in a time-dependent manner. However, Cr(V) toxic effects have proved to be more rapid than with Cr(VI), permitting the role of Cr(VI) intermediates formed during intracellular chromium reduction to be highlighted.
Subject(s)
Chemical and Drug Induced Liver Injury/pathology , Chromium/toxicity , Animals , Chromium/chemistry , Male , Mice , Structure-Activity RelationshipABSTRACT
AIM: The functional integrity of the blood-testis barrier (BTB) in male mice exposed to Cr(V) was studied in order to clarify the mechanism underlying testicular injury. METHODS: Adult male mice were subcutaneously injected repeated doses of 8.02 micromol (0.5 ml) of Cr/mouse.day for 5 days. Animals receiving a similar volume of bis(hydroxyethyl)-aminotris(hydroxymethyl)methane buffer (BT) were used as controls. The animals were sacrificed on day 6 and small fragments of seminiferous tubules, approximately 8-10 mm length, were incised and sutured at both ends. They were exposed in vitro to horseradish peroxidase-containing culture medium for 10 minutes. Tissues were then fixed and processed for ultrastructural studies. RESULTS: Controls and Cr(V)-treated group resulted in the uptake of the tracer by Sertoli cells. However, the major finding consisted in the permeability of the BTB only in the Cr(V)-group, as evidenced by the presence of the tracer within the junctions between the neighbouring Sertoli cells. CONCLUSION: The BTB is disrupted in mice submitted to Cr(V). The permeability of the BTB is a crucial feature to be investigated for the understanding of lesions within the seminiferous tubule.
