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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2870_Библиотеки_им_академика_М_И_Перельмана.pdf
190 New Medical Technology in Patient Care: A Physician’s Guide
responses. The lung-on-a-chip can replicate breathing motions and has
been instrumental in studying pulmonary conditions11 and the effects of
environmental toxins. For example, researchers using this device found
that cyclic mechanical strain accentuates the lung’s toxic and inflammatory responses to silica nanoparticles.
Heart-on-a-Chip
This model replicates the cardiac tissue’s structure and function. It is used
for studying heart diseases, drug screening, and understanding the cardiac
tissue’s response to mechanical stress.
12
Liver-on-a-Chip
Liver chips are designed to mimic the liver’s cellular architecture and
function, making them helpful in studying liver diseases, metabolism, and
drug detoxification processes.
13
Brain-on-a-Chip
This chip models the neural networks and can be used to study brain
physiology, neurodegenerative diseases, and the effects of drugs on the
brain.
Gut-on-a-Chip
This model replicates the intestinal microenvironment and is used to study
gut physiology, microbiome interactions, and intestinal diseases.
14
Historical Context and Development
The roots of OOC can be traced back to the early 2000s. Researchers
sought to move beyond the constraints of 2D cell cultures that failed to
accurately represent the cellular microenvironments found in vivo.
The evolution toward 3D systems culminated in the introduction of
“micro-physiological systems” by Lee et al.,15 which aimed to mimic
Organ-on-a-Chip: Revolutionizing Medical Research 191
the complexity and interactions of human tissues more faithfully.
This shift has been pivotal in advancing drug testing and toxicity screening methods.
Advantages of OOC over Traditional Models
Comparison with Animal Models and 2D Cell Cultures
OOC technology offers significant advantages over traditional research
models, particularly when compared to animal models and 2D cell cultures. While providing a whole-organism perspective, animal models
often fail to predict human responses accurately due to interspecies differences. Additionally, ethical concerns and high costs are associated with
animal research. On the other hand, 2D cell cultures, despite being a staple in biological research, lack the complex 3D structure and cell–cell
interactions present in human tissues, limiting their physiological
relevance.
Increased Physiological Relevance
7
OOC systems provide a more physiologically relevant model by replicating the 3D architecture of human organs, including the specific cellular
environments and mechanical forces. OOC systems permit precise control
over the cellular and mechanical environment, enabling the study of drug
effects under various conditions that mimic the dynamic nature of the
human body. This allows for a more accurate simulation of organ functions and interactions. For instance, lung-on-a-chip models can replicate
the mechanical act of breathing, which is crucial for studying respiratory
diseases and treatments.11 Similarly, by adjusting flow rates and mechanical forces in a heart-on-a-chip model, researchers can study the cardiotoxic effects of drugs under different physiological conditions.
16
Improved Toxicity Testing
By recreating specific organs’ physiological conditions and functions,
OOC devices provide a more accurate representation of human biology
than traditional methods such as animal testing or cell cultures. Using OOC
192 New Medical Technology in Patient Care: A Physician’s Guide
devices, researchers can simulate the behavior of organs in a controlled
laboratory setting.17 This allows them to assess the toxicity and potential
side effects of new medications more comprehensively and reliably.
By utilizing OOC technology for toxicity testing, researchers can
observe how a specific organ responds to a medication in real time, mimicking the physiological conditions of the human body. This enables them
to accurately assess the drug’s potential toxicity and its effects on specific
organs or organ systems.
Additionally, OOC devices allow for simultaneous testing of multiple
organs, mimicking the interconnectedness of different organs within the
body. This integrated approach helps researchers understand how different
organs may interact and how potential toxicities may propagate throughout the body.
Potential for Personalized Medicine
OOC technology’s potential in personalized medicine is fascinating and
transformative. OOC technology can create patient-specific models
using cells derived from individual patients. This aspect of OOC technology leverages the ability to use cells derived from individual patients,
often through innovative techniques such as induced pluripotent stem
cell (iPSC) technology. iPSCs have been genetically reprogrammed
to an embryonic stem cell-like state, enabling them to differentiate
into various cell types relevant to different organs. When integrated
into OOC systems, these patient-specific cells can create models that
closely mimic the unique physiological characteristics of an individual’s
organs.
reasons:
18
This personalized modeling is a significant leap forward for several
Enhanced Drug Efficacy and Safety
Traditional drug testing methods rely on average responses from large
populations, which can overlook individual variations in drug metabolism
and efficacy. OOC models using patient-derived cells allow for the assessment of drug responses at a personal level. This can lead to identifying the
most effective drug and dosage for a specific patient, thereby increasing
Organ-on-a-Chip: Revolutionizing Medical Research 193
the likelihood of successful treatment outcomes and reducing the risk of
adverse drug reactions.
Understanding Individual Variability
Different patients can respond differently to the same treatment due to
genetic, environmental, and lifestyle factors. OOC technology can help
understand these individual differences by providing a platform to study
how specific genetic mutations or other factors influence disease progression and treatment response.
Accelerating Personalized Therapy Development
In the context of diseases with high variability among individuals, such as
many cancers and genetic disorders, OOC technology can accelerate the
development of personalized therapies. By testing therapeutic agents on
cells that carry the patient’s specific disease traits, researchers can more
rapidly identify potential treatments tailored to individual needs.
Reducing Reliance on Animal Testing
Personalized OOC models can reduce the need for animal testing, which,
aside from ethical considerations, often fails to accurately predict human
responses due to interspecies differences. This shift aligns with ethical
research practices, improves the relevance and accuracy of preclinical
studies, and potentially reduces the time and costs associated with animal
testing. An example is the development of lung-on-a-chip models for toxicity testing of inhaled substances that reduce the reliance on animal inhalation studies, which are often complex and expensive.
19
Current Advances in OOC Technology
Multiorgan Integration
Recent developments in OOC technology have led to the creation of
sophisticated “body-on-a-chip” or “human-on-a-chip” systems. These
advanced models can simulate interactions between multiple organs,
194 New Medical Technology in Patient Care: A Physician’s Guide
offering a comprehensive view of systemic responses to medications and
diseases. This holistic approach is crucial for understanding complex
human physiology.
20
Use of Human iPSCs
There is a growing trend in employing human induced pluripotent stem
cells (iPSCs) in OOC models. iPSCs are versatile and capable of differentiating into various cell types. This adaptability enables the development
of patient-specific models, significantly enhancing the potential of OOCs
in personalized medicine.
18
High-Throughput Drug Screening
OOCs are increasingly designed for high-throughput screening, allowing
rapid evaluation of multiple drug candidates or toxicological analyses.
This capability is vital for expediting drug development and reducing
associated costs.
9
Sensor Integration and Automation
State-of-the-art OOCs now feature integrated sensors for real-time tracking of biological changes, including pH and oxygen levels. Combined
with automated systems, these enhancements facilitate continuous, precise data collection and analysis, improving research efficiency and
accuracy.
21,22
Disease Modeling
The application of OOC technology in modeling complex diseases represents a significant advancement in biomedical research. This technology
offers profound insights into disease mechanisms and facilitates the development of novel therapeutics.23 Its versatility allows it to model a wide
range of diseases, from cancers and neurodegenerative disorders to infectious diseases, each with unique challenges and requirements.
Organ-on-a-Chip: Revolutionizing Medical Research 195
Cancer Research
In cancer research, OOC technology provides a dynamic platform for
studying tumor growth, metastasis, and microenvironment.24 Traditional
cancer models often fail to replicate tumors’ complex 3D structures and
cell–cell interactions. OOC models can overcome these limitations by
replicating the 3D architecture of cancer tissues, allowing for studying
tumor cell behavior in a more physiologically relevant context. This
includes understanding how cancer cells interact with surrounding tissues,
how they respond to various anticancer drugs, and how they might develop
resistance to treatments.
Neurodegenerative Disorders
Neurological disorders account for an estimated 6.3% of the global disease burden.25 However, developing drugs for central nervous system
(CNS) disorders is particularly challenging and prone to failure. The
approval process for CNS drugs typically takes 38% longer compared to
drugs for non-CNS conditions.26 OOC techniques may provide a quicker,
cheaper path to drug development. For neurodegenerative diseases such as
Alzheimer’s and Parkinson’s, OOC technology offers a platform to study
the intricate workings of the brain’s cellular and molecular environment.27
Brain-on-a-chip models can mimic the neural tissue’s complexity, enabling researchers to study the pathophysiology of these disorders in real
time. This includes analyzing the role of amyloid plaques, tau protein
tangles, and other factors in neurodegeneration. Such models are invaluable for screening potential neuroprotective drugs and understanding the
disease’s progression at a cellular level.
28
Infectious Diseases
Animal experiments, commonly used in developing treatments for infectious
diseases, face several challenges. They often require extensive optimization
over a long period, are expensive, and raise ethical issues.
many pathogens are specific to certain species, making it hard to replicate
the disease accurately in animal models. This species dependence
29,30
Additionally,
196 New Medical Technology in Patient Care: A Physician’s Guide
complicates applying findings from animal studies to human cases.31 OOC
technology, which uses human cells, obviates many of these challenges.
OOC technology is also pivotal in studying infectious diseases, especially in the context of emerging pathogens and antibiotic resistance.32
Lung-on-a-chip models, for instance, have been used to study respiratory
infections, including COVID-19. These models can replicate the lung’s
response to pathogens, providing insights into disease progression and the
efficacy of antiviral drugs. Additionally, gut-on-a-chip models study gastrointestinal infections, inflammatory bowel disease, and the microbiome’s role in health and disease.
33,34
Vascularization and Fluid Dynamics
Advanced OOCs now include features that mimic vascular structures and
dynamic fluid flow, mirroring the in vivo environment more closely.35
These features are essential for studying processes such as cancer metastasis and enhancing drug delivery research.
36
Biomaterial Developments
Ongoing research is focused on creating new biomaterials for OOC construction. These materials aim to replicate the natural extracellular matrix
more accurately, improving cell functionality and longevity within the
37
chips.
Regulatory and Ethical Focus
With the increasing prevalence of OOC technology, there is a heightened
focus on regulatory and ethical considerations, especially in its application to drug testing and personalized medicine. Issues surrounding the use
of human cells are being addressed with greater scrutiny.
38
Challenges and Limitations of OOC Technology
While OOC technology offers transformative potential in biomedical
research and drug development, several challenges and limitations must
Organ-on-a-Chip: Revolutionizing Medical Research 197
be addressed. This section delves into the technical and fabrication challenges and biological challenges such as cell sourcing, longevity, complexity, and regulatory and adoption hurdles.
Technical and Fabrication Challenges
Microfabrication Complexity
The intricate design of OOC systems requires advanced microscale engineering and microfabrication techniques, which can be complex and
costly. Ensuring reproducibility and scalability for widespread use
remains a significant challenge.
Material Biocompatibility
Selecting materials that are biocompatible and can mimic the mechanical
properties of the native extracellular matrix is challenging.39 The materials
must also be compatible with imaging and analytical techniques. Recent
developments in biomedical engineering have led to the creation of microscale heart tissue models using microfluidic OOC systems.40 These systems are commonly made from poly(dimethyl siloxane) (PDMS), a
material chosen for its biocompatibility, nontoxic nature, and affordability.41
Additionally, PDMS is flexible, transparent, and easily shaped into microfluidic designs through soft lithography and photolithography techniques.42 This makes it an ideal material for rapidly producing customized
OOC models.
11
Biological Challenges
Cell Sourcing
The emergence of iPSC technology has made obtaining patient-specific
stem cells with minimal invasiveness easier.43 iPSCs are versatile and can
be transformed into different types of cells. This feature is especially beneficial for creating tissues that match a patient’s human leukocyte antigen
(HLA) profile in multi-organ-on-a-chip (multi-OOC) systems.44 However,
obtaining human cells that accurately represent the diversity of patient
198 New Medical Technology in Patient Care: A Physician’s Guide
populations is a significant challenge. The use of primary cells, stem cells,
or differentiated cells each comes with limited availability, variability, and
ethical concerns.
45
Longevity and Complexity
Maintaining the viability and functionality of cells in OOC systems over
extended periods is challenging. Furthermore, replicating the complex
interactions of human organs, including immune responses and hormonal
signaling, is still a significant hurdle.9 Maintaining cell viability and functionality over extended periods in OOC systems presents significant challenges. This difficulty is compounded when attempting to replicate the
intricate interactions of human organs, such as immune responses and
hormonal signaling.
Long-Term Viability and Functionality
In OOC systems, cells must survive and function effectively for extended
periods to yield meaningful data. This requires a carefully controlled
microenvironment, including nutrient supply, waste removal, and appropriate physical stimuli. However, over time, cells in OOC systems can
experience stress or exhaustion, leading to altered functionality or cell
death.
The study by Sung et al.46 using a liver-on-a-chip model highlighted
the challenges of maintaining liver cell functions over extended periods,
which is crucial for long-term toxicity studies.
Complex Organ Interactions
Human organs do not function in isolation; they interact in complex ways,
influenced by the immune system and hormonal signals. Replicating these
interactions in OOC systems is challenging. For instance, the immune
system involves dynamic interactions between various cell types and signaling molecules, which are difficult to mimic in vitro. For example, in a
study by Maschmeyer et al.,46 researchers developed a multiorgan chip
integrating human skin, liver, and immune system models. Despite its
Organ-on-a-Chip: Revolutionizing Medical Research 199
success, the study highlighted the complexity of accurately replicating
immune responses and organ crosstalk.
47
Hormonal Signaling
Hormones play a critical role in regulating organ functions. In OOC systems, replicating the endocrine system’s complex hormonal signaling
pathways is formidable. This includes the production and secretion of
hormones and their dynamic interactions with multiple organs. A study by
Wagner et al. on a body-on-a-chip system attempted to incorporate hormonal signaling pathways. The research underscored the complexity of
integrating endocrine functions with other organ models to achieve a
holistic representation of body physiology.
48
Regulatory and Adoption Hurdles
Standardization and Validation
For OOC technology to be widely adopted, especially in drug testing and
regulatory processes, standardization of protocols and validation of models are essential. This includes demonstrating reproducibility and relevance to human physiology. Several consortia have published position
papers outlining a shared vision among numerous stakeholders about the
need for standardization to progress the OOC field. For instance, the
ORCHID project has pinpointed standardization as a critical factor for
advancing European OOC technologies.49 Similarly, the 2019 workshop
report by the Transatlantic Think Tank for Toxicology (t4) compiled
insights from 46 international stakeholders,50 and the Standards Coordinating Body in the United States is pushing for international standards for
OOC platforms.
Regulatory Acceptance
Gaining acceptance from regulatory bodies such as the FDA for using
OOC systems in drug approval processes is a significant challenge.
Approval involves demonstrating that OOC models are as predictive,