Precision cut tissue slices

Precision cut tissue slices (PCTS), also called simply tissue slices, are specialized samples of biological tissue that are meticulously prepared to have consistent thickness and precise dimensions. These slices are created with a high degree of accuracy, ensuring that researchers can reliably study specific tissue regions or structures for various experimental purposes.

PCTS are generated using several techniques, including automated tissue slicers such as vibratomes from Leica Biosystems and Campden Instruments to overcome the challenges of obtaining uniform tissue sections. These slices serve as valuable tools in biomedical research, allowing scientists to explore tissue behavior, responses to stimuli, and biochemical processes in a controlled and reproducible manner. Their precision and consistency make PCTS an indispensable resource in fields such as toxicology, pharmacology, and organ-specific studies, facilitating a deeper understanding of complex biological systems.

PCTS represent an advancement in the field of experimental biology and medical research. These meticulously crafted tissue sections, typically prepared from vital organs such as the liver, heart, kidney, and lung, have become instrumental in various research applications. PCTS have gained widespread recognition and utilization in research settings, particularly since the development of automated tissue slicers capable of consistently producing relatively thin and precise tissue slices.

Prior to the advent of automated slicers, obtaining uniform and reproducible tissue sections was a formidable challenge. Traditional methods often resulted in inconsistent slice thickness, making it difficult to conduct accurate and reliable experiments. The introduction of automated tissue slicers marked a significant turning point in research methodologies, enabling researchers to overcome these limitations and delve deeper into the intricacies of tissue biology and function.

Types of PCTS

Liver

Main article: Precision cut liver slices

For several decades, organ slices have played a pivotal role in research, offering in vitro systems to explore a wide range of physiological and pathological processes. Among these organs, the liver has been a prominent subject of study due to its significance in toxicology, pharmacology and metabolism research. However, the production of identical slices with consistent thickness was historically a formidable challenge.

Liver slices have been widely employed in the investigation of hepatotoxicity, with a focus on substances like halogenated hydrocarbons. Early research by Tappel and colleagues identified the role of lipid peroxidation, concurrent DNA damage, and decreased protein synthesis during hepatotoxicity. Liver slices also played a crucial role in studying paracetamol-induced liver necrosis and the toxicities of various compounds, including aflatoxin B1, endotoxin, cocaine, and paraquat.

Additionally, liver slices have been valuable in assessing the cytoprotective effects of compounds against xenobiotic-induced toxicity, offering insights into potential antidotes and protective mechanisms. They have also contributed to the understanding of early events in chemically induced hepatocarcinogenesis by detecting DNA adducts and metabolites of carcinogens.

Liver slices have found extensive use in the study of metabolism, both endogenous and exogenous. They have been employed to investigate caffeine metabolism, steroid metabolism, and processes such as gluconeogenesis, lipogenesis, and ureagenesis. Beyond toxicology and pharmacology, liver slices have been used in research related to organ preservation and ischemia.

Kidney

Main article: Precision cut kidney slices

Kidney slices have been integral in diverse areas of research, offering insights into renal responses to toxic substances, as well as the metabolism of both endogenous and exogenous compounds. These slices have been instrumental in studying crucial renal functions, including organic ion transport and renin release.

In toxicology studies, kidney slices have gained extensive use, particularly in recent years. For instance, they have been employed to investigate nephrotoxicity caused by substances like chloroform and cisplatin. Chloroform-induced nephrotoxicity was explored through renal cortical slices, revealing early alterations in transport, gender-specific responses, and insights into its metabolic pathways. The tissue slice model played a key role in identifying phosgene as the toxic metabolite of chloroform in the kidney.

Similarly, cisplatin, an antineoplastic agent linked to acute renal failure, was studied using rat renal cortical slices. These investigations unveiled the drug's uptake, metabolism, secretion mechanisms, and its impact on lipid peroxidation and glutathione levels in renal slices.

Renin secretion, a vital aspect of kidney function, has been extensively studied in kidney slices. Researchers have explored various factors influencing renin release, including toxicants and extracellular sodium levels. Additionally, the role of calcium channels, adrenoceptors, and prostaglandins in modulating renin release has been elucidated using this model.

Moreover, kidney slices have contributed to research on organic ion and cation transport, prostaglandin synthesis, organ preservation techniques, and the metabolism of compounds like diethylstilbestrol. These slices continue to be a valuable resource for a wide range of renal studies, offering a controlled and reproducible platform for scientific investigations.

Lung

Main article: Precision cut lung slices

Lung slices have played a crucial role in advancing our understanding of lung biology and toxicology. Before the introduction of agar-filled precision-cut lung slices in 1992, researchers had already utilized lung slices extensively for various in vitro studies.

Lung slices have been employed to study the toxicities of various compounds, including phosphodiesterases and naphthalene. They have also contributed to research on pulmonary fibrosis by examining the synthesis of extracellular matrix components. These studies have provided insights into the composition of the pulmonary basement membrane and the effects of agents like bleomycin and ozone on collagen synthesis.

Heart

While cultured myocytes have become a standard tool in heart research, heart tissue slices continue to hold appeal for various reasons. Heart slices offer the advantage of maintaining normal cell-cell interactions and not favoring any specific cell population during isolation. Moreover, they can be applied to non-transplantable human tissue, presenting a potential advantage for certain studies.

Heart slices have proven to be valuable for investigating toxicant-induced injury to myocardial tissue. Cardiotoxicity, a severe side effect of some cancer chemotherapy drugs, has been a focal point of research. Studies have examined the impact of compounds like epirubicin, mitoxantrone, and doxorubicin analogs on oxygen uptake and ATP content in rat heart slices. Additionally, heart slices have been used to demonstrate the cytoprotective effects of carnitine derivatives and coenzyme Q against doxorubicin-related cardiotoxicity.

Of particular interest in heart research is the sodium pump, crucial for maintaining ionic gradients essential for the heart's contractile function. Studies using heart slices have explored the stimulation of the sodium pump by digitaloids (ouabain) independently of β-adrenergic stimulation. Furthermore, heart slices have been employed to investigate the effects of diet and age on sodium pump activity and the positive impact of noradrenaline on active ion transport mediated by the pump.

Heart slices have also been used for a wide range of studies involving carnitine transport, β-adrenergic stimulation of cyclic AMP metabolism, and reperfusion injury. These studies highlight the versatility and significance of heart slices as a valuable tool in heart research, providing insights into various aspects of cardiac function and response to toxicants.

Basic preparation

Creating precision cut tissue slices (PCTS) is a meticulous process that involves several essential steps. The use of high quality vibratomes is crucial in ensuring the production of precise and high-quality lung slices for research purposes.

Use of vibratomes

The basic steps involved in preparing PCLS using a vibratome include:

Tissue Selection

Start by carefully selecting lung tissue from the desired species, such as rodents or humans, ensuring the tissue is of high quality and health.

Tissue Embedding

To facilitate slicing and maintain tissue structure, the lung tissue is typically embedded in a suitable medium, such as agarose or gelatin, into the specimen holder or onto the tissue mount of the vibratome.

Slicing Process

The vibratome operates by oscillating a blade vertically or horizontally at high frequencies while the tissue is submerged in a cutting solution. This mechanical oscillation creates thin and precise slices of tissue. Researchers can adjust cutting parameters, such as slice thickness, to meet specific experimental requirements. Typically, PCLS have thicknesses ranging from 200-500µm.

Post-processing

Depending on the research objectives, PCLS may undergo additional steps such as washing, culturing, or treatment with substances of interest, such as drugs or stimuli.

High-throughput PCTS Slices

The vibratome provides high throughput PCTS slices. It allows the rapid and precise preparation of tissue slices, significantly reducing the time and effort required for sectioning large numbers of samples. This capability is particularly beneficial for laboratories and research institutions engaged in drug screening, toxicology studies, and extensive tissue-based experiments. A vibratome is capable of sectioning at least 30 core samples of tissue simultaneously.

Experimental applications

Precision Cut Tissue Slices (PCTS) have emerged as invaluable tools across a spectrum of experimental applications, encompassing pharmacology, toxicology, and physiology. These meticulously crafted tissue samples have enhanced the understanding of various organ systems, each finding unique utility in specific research areas.

Pharmacology

Liver slices serve as essential tools in pharmacological investigations, shedding light on drug metabolism and biotransformation. They offer insights into drug interactions, enzymatic activity, and the effects of various compounds on hepatic tissue. Researchers turn to lung slices to delve into the impact of pharmaceutical agents on pulmonary function. These slices facilitate the examination of drug-induced changes in vital parameters such as oxygen uptake, ATP content, and surfactant production, providing critical insights into respiratory pharmacology. Heart tissue slices prove invaluable in the study of cardiotoxicity induced by a range of pharmaceuticals, particularly antineoplastic agents. They enable the evaluation of drug effects on cardiac oxygen consumption, ATP levels, and sodium pump activity.

Toxicology

Kidney slices stand as versatile models for nephrotoxicity studies, enabling researchers to elucidate the impact of toxicants on renal function, metabolism, and transport systems. These slices facilitate the exploration of mechanisms underlying drug-induced kidney damage. Liver slices play a pivotal role in toxicological research, unveiling the hepatotoxic effects of a wide range of substances. They assist in identifying toxic metabolites, understanding oxidative stress, and evaluating the protective effects of compounds against liver injury. Lung slices serve as instrumental tools in investigating toxicant-induced lung injury, encompassing fibrosis and alterations in metabolic parameters. They offer critical insights into the consequences of chemical exposure on lung tissue and its physiological functions.

Physiology

Heart tissue slices authentically represent cardiac physiology, making them ideal for studies on ion transport, contractility, and the impact of various compounds on sodium pump activity. They contribute significantly to our comprehension of cardiac function across different conditions. Kidney slices provide researchers with a platform to investigate renal physiology, encompassing ion transport, hormone secretion, and metabolic processes. These slices serve as a valuable resource for studying the intricate regulatory mechanisms governing renal function. Precision-cut brain slices play a pivotal role in neuroscience research, enabling the exploration of synaptic transmission, neural circuits, and the effects of pharmacological agents on brain tissue. They bridge the gap between cellular and whole-brain studies, offering insights into complex neurological processes.

Advantages of PCTS

Precision Cut Tissue Slices (PCTS) have become indispensable tools in biomedical research due to their numerous advantages. These advantages include precise and consistent preparation, preservation of tissue architecture, reproducibility, controlled experimental conditions, reduced ethical concerns, flexibility for various research questions, human relevance, time efficiency, smaller sample size requirements, and interdisciplinary applications. In summary, PCTS offer precision, reproducibility, and versatility, advancing our understanding of organ function, drug responses, and toxicological mechanisms while reducing ethical concerns and the need for in vivo experiments.

Limitations of PCTS

Precision Cut Tissue Slices (PCTS) offer significant advantages but also present certain limitations. PCTS have a limited viable lifespan, which can be challenging for long-term experiments. While they preserve tissue architecture, they may lose specific cellular context. These slices represent thin cross-sections, limiting the study of deeper tissue layers. Additionally, PCTS lack some in vivo physiological features, such as blood flow and neural regulation. Variability between human tissue donors can influence experimental outcomes. Prolonged culturing of PCTS can be difficult due to viability and structural changes over time. Expertise in tissue sectioning is essential for high-quality PCTS preparation. This process can be resource-intensive, requiring specialized equipment and personnel. Ethical considerations arise when using human tissue samples. Availability of specific tissues for PCTS preparation may be limited, and compatibility with experimental assays should be assessed. Finally, findings from animal-derived PCTS may not always directly translate to human physiology due to species-specific differences.