scholarly journals In Vitro Models for the Development of Peripheral Nerve Conduits, Part I: Design of a Fibrin Gel-Based Non-Contact Test

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3573
Author(s):  
Paola De Stefano ◽  
Angelica Silvia Federici ◽  
Lorenza Draghi
Keyword(s):  
Peripheral Nerve ◽  
Clinical Performance ◽  
In Vitro Models ◽  
In Vitro Tests ◽  
Neural Cells ◽  
Animal Testing ◽  
Fibrin Gel ◽  
Specific Implementation

Current clinical strategies to repair peripheral nerve injuries draw on different approaches depending on the extent of lost tissue. Nerve guidance conduits (NGCs) are considered to be a promising, off-the-shelf alternative to autografts when modest gaps need to be repaired. Unfortunately, to date, the implantation of an NGC prevents the sacrifice of a healthy nerve at the price of suboptimal clinical performance. Despite the significant number of materials and fabrication strategies proposed, an ideal combination has not been yet identified. Validation and comparison of NGCs ultimately requires in vivo animal testing due to the lack of alternative models, but in the spirit of the 3R principles, a reliable in vitro model for preliminary screening is highly desirable. Nevertheless, more traditional in vitro tests, and direct cell seeding on the material in particular, are not representative of the actual regeneration scenario. Thus, we have designed a very simple set-up in the attempt to appreciate the relevant features of NGCs through in vitro testing, and we have verified its applicability using electrospun NGCs. To this aim, neural cells were encapsulated in a loose fibrin gel and enclosed within the NGC membrane. Different thicknesses and porosity values of two popular polymers (namely gelatin and polycaprolactone) were compared. Results indicate that, with specific implementation, the system might represent a useful tool to characterize crucial NGC design aspects.

In Vitro Methods as a Tool in Neurotoxicity Studies

1995 ◽  
Vol 23 (4) ◽  
pp. 491-496
Author(s):  
Hanna Tähti ◽  
Leila Vaalavirta ◽  
Tarja Toimela
Keyword(s):  
Risk Evaluation ◽  
Toxicity Testing ◽  
In Vitro Models ◽  
In Vitro Tests ◽  
Industrial Chemicals ◽  
Mercury Compounds ◽  
Toxicological Data ◽  
In Vivo Tests

— There are several hundred industrial chemicals with neurotoxic potential. The neurotoxic risks of most of these chemicals are unknown. Additional methods are needed to assess the risks more effectively and to elucidate the mechanisms of neurotoxicity more accurately than is possible with the conventional methods. This paper deals with general tasks concerning the use of in vitro models in the evaluation of neurotoxic risks. It is based on our previous studies with various in vitro models and on recent literature. The induction of glial fibrillary acidic protein in astrocyte cultures after treatment with known neurotoxicants (mercury compounds and aluminium) is discussed in more detail as an important response which can be detected in vitro. When used appropriately with in vivo tests and with previous toxicological data, in vitro neurotoxicity testing considerably improves risk assessment. The incorporation of in vitro tests into the early stages of risk evaluation can reduce the number of animals used in routine toxicity testing, by identifying chemicals with high neurotoxic potential.

Research On Dental Amalgam: 1982-1986

1988 ◽  
Vol 2 (1) ◽  
pp. 71-82 ◽  
Author(s):  
D.B. Mahler
Keyword(s):  
Clinical Performance ◽  
High Sensitivity ◽  
Dental Amalgam ◽  
Performance Criterion ◽  
Dental Restoration ◽  
In Vitro Tests ◽  
Significant Finding ◽  
Amalgam Restorations

This paper is a five-year review of selected research papers on dental amalgam which were published during the years 1982 through 1986. Papers presented at scientific dental meetings are also included. During the past five years, clarification of amalgam metallurgy has been made, and a few innovative modifications have been recommended. The addition of palladium, indium, and selenium to dental amalgam has been suggested, but commercial applications have yet to be made. The mechanical property of creep has been studied more extensively, while the applicability of fracture toughness tests has been examined. More work has been done on the microleakage of amalgam restorations, with certain alloy factors showing an influence on this problem. Most in vitro investigations on the use of cavity varnish or resin films beneath amalgam restorations show reduced microleakage. Additionally, many electrochemical investigations were conducted. A most significant finding was that amalgam does not appear to break down in vivo as much as in vitro tests would indicate, the buffering action of saliva being protective in this regard. The marginal fracture evaluation of clinical amalgam restorations is still being used as a major clinical performance criterion, and measuring techniques for this failure mode have been improved. Measurements of metallic ion loss from amalgam were made with instruments of high sensitivity, but no evidence has been found to associate this loss with any disease entity. The rare presence of an allergy to mercury appears to be the only contra-indication for the use of amalgam as a dental restoration. Further research on dental amalgam can lead to improved clinical performance of this most useful restorative material.

Mycotoxin mechanisms of action and health impact: ‘in vitro’ or ‘in vivo’ tests, that is the question

2015 ◽  
Vol 8 (5) ◽  
pp. 573-589 ◽  
Author(s):  
F. Cheli ◽  
C. Giromini ◽  
A. Baldi
Keyword(s):  
Health Effects ◽  
Health Impact ◽  
In Vitro Models ◽  
Mechanisms Of Action ◽  
Animal Testing ◽  
Suitable Alternative ◽  
In Vivo Tests ◽  
Contaminated Food

The aim of this paper is to present examples of in vitro and in vivo tests for mycotoxin mechanisms of action and evaluation of health effects, with a focus on the gut environment and toxicity testing. In vivo investigations may provide information on the net effects of mycotoxins in whole animals, whereas in vitro models represent effective tools to perform simplified experiments under uniform and well-controlled conditions and a suitable alternative to in vivo animal testing providing insights not achievable with animal studies. The main limits of in vitro models are the lack of interactions with other cells and extracellular factors, lack of hormonal or immunological influences, and lack or different levels of in vitro expression of genes involved in the overall response to mycotoxins. The translation of in vitro data into meaningful in vivo effects remains an unsolved problem. The main issues to be considered are the mycotoxin concentration range in accordance with levels encountered in realistic situations, the identification of reliable biomarkers of mycotoxin toxicity, the measurement of the chronic toxicity, the evaluation of single- or multi-toxin challenge. The gastrointestinal wall is the first barrier preventing the entry of undesirable substances. The intestinal epithelium can be exposed to high concentrations of mycotoxins upon ingestion of contaminated food and the amount of mycotoxin consumed via food does not always reflect the amount available to exert toxic actions in a target organ. In vitro digestion models in combination with intestinal epithelial cells are powerful tools to screen and predict the in vivo bioavailability and digestibility of mycotoxins in contaminated food and correctly estimate health effects. In conclusion, in vitro and in vivo tests are complementary approaches for providing a more accurate picture of the health impact of mycotoxins and improved understanding and evaluation of relevant dietary exposure and risk scenarios.

Effect of Arecoline on Regeneration of Injured Peripheral Nerves

2013 ◽  
Vol 41 (04) ◽  
pp. 865-885 ◽  
Author(s):  
Sheng-Chi Lee ◽  
Chin-Chuan Tsai ◽  
Chun-Hsu Yao ◽  
Yuan-Man Hsu ◽  
Yueh-Sheng Chen ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Peripheral Nerve Regeneration ◽  
In Vitro Study ◽  
Control Group ◽  
Neural Cells ◽  
In Vivo Evaluation

The present study provides in vitro and in vivo evaluation of arecoline on peripheral nerve regeneration. In the in vitro study, we found that arecoline at 50 μg/ml could significantly promote the survival and outgrowth of cultured Schwann cells as compared to the controls treated with culture medium only. In the in vivo study, we evaluated peripheral nerve regeneration across a 10-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve chamber filled with the arecoline solution. In the control group, the chambers were filled with normal saline only. At the end of the fourth week, morphometric data revealed that the arecoline-treated group at 5 μg/ml significantly increased the number and the density of myelinated axons as compared to the controls. Immunohistochemical staining in the arecoline-treated animals at 5 μg/ml also showed their neural cells in the L4 and L5 dorsal root ganglia ipsilateral to the injury were strongly retrograde-labeled with fluorogold and lamina I–II regions in the dorsal horn ipsilateral to the injury were significantly calcitonin gene-related peptide-immunolabeled compared with the controls. In addition, we found that the number of macrophages recruited in the distal sciatic nerve was increased as the concentration of arecoline was increased. Electrophysiological measurements showed the arecoline-treated groups at 5 and 50 μg/ml had a relatively larger nerve conductive velocity of the evoked muscle action potentials compared to the controls. These results indicate that arecoline could stimulate local inflammatory conditions, improving the recovery of a severe peripheral nerve injury.

scholarly journals Cuprizone-Induced Neurotoxicity in Human Neural Cell Lines Is Mediated by a Reversible Mitochondrial Dysfunction: Relevance for Demyelination Models

2021 ◽  
Vol 11 (2) ◽  
pp. 272
Author(s):  
Eva Martínez-Pinilla ◽  
Núria Rubio-Sardón ◽  
Sandra Villar-Conde ◽  
Gemma Navarro ◽  
Eva del Valle ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cell Metabolism ◽  
In Vitro Models ◽  
Demyelinating Diseases ◽  
New Drugs ◽  
Neural Cells ◽  
Dependent Manner ◽  
Human Neuroblastoma

Suitable in vivo and in vitro models are instrumental for the development of new drugs aimed at improving symptoms or progression of multiple sclerosis (MS). The cuprizone (CPZ)-induced murine model has gained momentum in recent decades, aiming to address the demyelination component of the disease. This work aims at assessing the differential cytotoxicity of CPZ in cells of different types and from different species: human oligodendroglial (HOG), human neuroblastoma (SH-SY5Y), human glioblastoma (T-98), and mouse microglial (N-9) cell lines. Moreover, the effect of CPZ was investigated in primary rat brain cells. Cell viability was assayed by oxygen rate consumption and by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-based (MTT) method. Our results demonstrated that CPZ did not cause death in any of the assayed cell models but affected mitochondrial function and aerobic cell respiration, thus compromising cell metabolism in neural cells and neuron-glia co-cultures. In this sense, we found differential vulnerability between glial cells and neurons as is the case of the CPZ-induced mouse model of MS. In addition, our findings demonstrated that reduced viability was spontaneous reverted in a time-dependent manner by treatment discontinuation. This reversible cell-based model may help to further investigate the role of mitochondria in the disease, and study the molecular intricacies underlying the pathophysiology of the MS and other demyelinating diseases.

The Application of in Vitro Models to Research on Demineralization and Remineralization of the Teeth

1995 ◽  
Vol 9 (3) ◽  
pp. 175-193 ◽  
Author(s):  
D.J. White
Keyword(s):  
Analytical Techniques ◽  
Test Methods ◽  
In Vitro Models ◽  
In Vitro Tests ◽  
In Vitro Testing ◽  
In Vitro Test ◽  
Dental Tissues ◽  
Testing Protocols

Progress in in vivo and in situ experimentation has led many researchers to speculate as to the relevance and importance of in vitro testing protocols in caries research. A Medline/Biosis search for the present review revealed well over 300 citations (since 1989) documenting in vitro tests associated with caries research on mineralization and fluoride reactivity. The present survey documents these recent applications of in vitro test methods in both mechanistic and 'profile'* caries research. In mechanistic studies, in vitro protocols over the past five years have made possible detailed studies of dynamics occurring in mineral loss and gain from dental tissues and the reaction dynamics associated with fluoride anticaries activity. Similarly, in profile applications, in vitro protocols make possible the inexpensive and rapid-yet sensitive-assessment of F anticaries efficacy within fluoride-active systems, and these tests represent a key component of product activity confirmation. The ability to carry out single variable experiments under highly controlled conditions remains a key advantage in in vitro experimentation, and will likely drive even further utilization, as advances continue in physical-chemical and analytical techniques for substrate analysis in these protocols. Despite their advantages, in vitro testing protocols have significant limitations, most particularly related to their inability to simulate the complex biological processes involved in caries.

Recent Progress in the Eye Irritation Test

1993 ◽  
Vol 9 (6) ◽  
pp. 1017-1025 ◽  
Author(s):  
Ih Chu ◽  
Peter Toft
Keyword(s):  
Animal Studies ◽  
In Vitro Tests ◽  
Animal Testing ◽  
Regulatory Requirements ◽  
Eye Irritation ◽  
Significant Development ◽  
In Vivo Test ◽  
Irritation Test

The rabbit eye irritation test based on the Draize method is required for the hazard assessment of chemicals and products that may come into contact with the eye. Due to the potential for the suffering of animals and subjectivity of the test, many modifications of the method have been made that involved a reduction in the number of animals and a refinement of techniques. Additionally, there has been significant development of in vitro alternatives. This paper reviews recent advances in the in vivo test and in vitro alternatives, as well as regulatory requirements. While the refinement of in vivo protocols has resulted in a reduction in the number and discomfort on animals, the development of in vitro alternatives could lead to an eventual replacement of animal studies. In view of the inherent simplicity of many in vitro methods, some of which comprise cell cultures, further research into the relevance/mechanism of effects is required. Batteries of in vitro tests, when properly validated, may be considered as replacements for animal testing.

Limitations on the Reliability of In Vitro Predictive Toxicity Models to Predict Pulmonary Toxicity in Rodents

2016 ◽  
Author(s):  
Jeremy M. Gernand
Keyword(s):  
Meta Analysis ◽  
Information Value ◽  
Screening Tests ◽  
In Vitro Tests ◽  
Screening Methods ◽  
Toxicity Screening ◽  
Animal Testing ◽  
Risk Models

Given the rapidly proliferating varieties of nanomaterials and ongoing concerns that these novel materials may pose emerging occupational and environmental risks, combined with the possibility that each variety might pose a different unique risk due to the unique combination of material properties, researchers and regulators have been searching for methods to identify hazards and prioritize materials for further testing. While several screening tests and toxic risk models have been proposed, most have relied on cellular-level in vitro data. This foundation enables answers to be developed quickly for any material, but it is yet unclear how this information may translate to more realistic exposure scenarios in people or other more complex animals. A quantitative evaluation of these models or at least the inputs variables to these models in the context of rodent or human health outcomes is necessary before their classifications may be believed for the purposes of risk prioritization. This paper presents the results of a machine learning enabled meta-analysis of animal studies attempting to use significant descriptors from in vitro nanomaterial risk models to predict the relative toxicity of nanomaterials following pulmonary exposures in rodents. A series of highly non-linear random forest models (each made up of an ensemble of 1,000 regression tree models) were created to assess the maximum possible information value of the in vitro risk models and related methods of describing nanomaterial variants and their toxicity in rat and mouse experiments. The variety of chemical descriptors or quantitative chemical property measurements such as bond strength, surface charge, and dissolution potential, while important in describing observed differences with in vitro experiments, proved to provide little indication of the relative magnitude of inflammation in rodents (explained variance amounted to less than 32%). Important factors in predicting rodent pulmonary inflammation such as primary particle size and chemical type demonstrate that there are critical differences between these two toxicity assays that cannot be captured by a series of in vitro tests alone. Predictive models relying primarily on these descriptors alone explained more than 62% of the variance of the short term in vivo toxicity results. This means that existing proposed nanomaterial toxicity screening methods are inadequate as they currently stand, and either the community must be content with the slower and more expensive animal testing to evaluate nanomaterial risks, or further conceptual development of improved alternative in vitro screening methodologies is necessary before manufacturers and regulators can rely on them to promote safer use of nanotechnology.

scholarly journals Peripheral Nerve Injury Treatments and Advances: One Health Perspective

2021 ◽  
Author(s):  
Bruna Lopes ◽  
Patrícia Sousa ◽  
Rui Alvites ◽  
Mariana Branquinho ◽  
Ana Sousa ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
One Health ◽  
In Vitro Models ◽  
Health Concern ◽  
In Vivo Models ◽  
Surgical Methods ◽  
Function Impairment

Peripheral nerve injuries (PNI) can have several etiologies, such as trauma and iatrogenic interventions that can lead to the loss of structure and/or function impairment. These changes can cause a partial or complete loss of motor and sensory functions, physical disability, and neuropathic pain, what in turn can affect the quality of life. For those reasons, PNI is a major public health concern. This review aims to revisit the concepts associated with the PNI. First, the anatomy of the peripheral nerve is detailed to explain the different types of injury. Then, some of the available therapeutic strategies are explained, including surgical methods, pharmacological therapies, and the use of cell-based therapies alone or in combination with biomaterials in the form of tube guides. Nevertheless, even with the various available treatments, it is difficult to achieve a perfect outcome with complete functional recovery. This review aims to explain the urge for new approaches and to understand the methods to evaluate nerve regeneration in a One Health perspective. In vitro models followed by in vivo models are very important to be able to translate the achievements to human medicine.

scholarly journals Nanotherapeutic Modulation of Human Neural Cells and Glioblastoma in Organoids and Monocultures

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2434
Author(s):  
Issan Zhang ◽  
Paula Lépine ◽  
Chanshuai Han ◽  
María Lacalle-Aurioles ◽  
Carol X.-Q. Chen ◽  
...  
Keyword(s):  
In Vitro Models ◽  
Neural Cells ◽  
Dependent Manner ◽  
Lipocalin 2 ◽  
Human Microglia ◽  
Anti Inflammatory ◽  
Molecular Patterns ◽  
The Brain

Inflammatory processes in the brain are orchestrated by microglia and astrocytes in response to activators such as pathogen-associated molecular patterns, danger-associated molecular patterns and some nanostructures. Microglia are the primary immune responders in the brain and initiate responses amplified by astrocytes through intercellular signaling. Intercellular communication between neural cells can be studied in cerebral organoids, co-cultures or in vivo. We used human cerebral organoids and glioblastoma co-cultures to study glia modulation by dendritic polyglycerol sulfate (dPGS). dPGS is an extensively studied nanostructure with inherent anti-inflammatory properties. Under inflammatory conditions, lipocalin-2 levels in astrocytes are markedly increased and indirectly enhanced by soluble factors released from hyperactive microglia. dPGS is an effective anti-inflammatory modulator of these markers. Our results show that dPGS can enter neural cells in cerebral organoids and glial cells in monocultures in a time-dependent manner. dPGS markedly reduces lipocalin-2 abundance in the neural cells. Glioblastoma tumoroids of astrocytic origin respond to activated microglia with enhanced invasiveness, whereas conditioned media from dPGS-treated microglia reduce tumoroid invasiveness. Considering that many nanostructures have only been tested in cancer cells and rodent models, experiments in human 3D cerebral organoids and co-cultures are complementary in vitro models to evaluate nanotherapeutics in the pre-clinical setting. Thoroughly characterized organoids and standardized procedures for their preparation are prerequisites to gain information of translational value in nanomedicine. This study provides data for a well-characterized dendrimer (dPGS) that modulates the activation state of human microglia implicated in brain tumor invasiveness.

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