Abstract
Fire-related smoke inhalation-induced acute lung injury (SI-ALI) is a
prevalent condition in modern fires, characterized by high mortality and
a lack of targeted therapeutic options. Previous research has been
hindered by instability in smoke generation and modeling methods,
limiting the investigation of SI-ALI mechanisms. This study, for the
first time, utilized organ-on-a-chip and organoid technologies,
optimizing chip design and precisely controlling smoke generation from
non-metallic materials to establish a human-relevant, physiologically
accurate model of fire-related SI-ALI. The results demonstrate that this
model effectively simulates the alveolar-capillary barrier and
replicates key pathological features of lung injury, including oxidative
stress, apoptosis, immune cell adhesion, inflammatory responses,
capillary leakage, and mitochondrial damage. Injury responses of
endothelial and epithelial cells to smoke exposure were thoroughly
assessed at the organ level. Integrating proteomics and molecular
biology techniques, along with comparisons to animal models, identified
disease-specific pathways related to the spliceosome and carbon
metabolism, as well as pathogenic molecules such as
catechol-O-methyltransferase (COMT) and nitrilase 1 (NIT1). Furthermore,
molecular docking of COMT revealed potential therapeutic candidates from
the FDA-approved drug library, including Ractopamine HCl and
Bimatoprost. The efficacy of intravenous vitamin C combined with
nebulized budesonide was validated on the chip model, establishing a
foundation for clinical applications. This study provides a robust model
for investigating fire-related SI-ALI and offers novel insights into
underlying mechanisms and therapeutic development.
Keywords : Organ-on-a-Chip; Organoids; Acute Lung Injury; Fire
Incidents; Molecular Docking; Drug Screening
Introduction
Fire-related smoke inhalation-induced acute lung injury (SI-ALI) is
among the most prevalent clinical injuries. The combustion of
non-metallic materials indoors during a fire releases significant
amounts of toxic substances, which can cause severe damage to the
respiratory tract. In extreme cases, this can progress to acute
respiratory distress syndrome (ARDS) or even multiple organ dysfunction
syndrome (MODS)[1]. Studies have shown that burn
patients with concurrent inhalation lung injury have a 40% higher
mortality rate[2].
Unlike other forms of SI-ALI, such as those induced by cigarette smoke,
wood burning, or exposure to single toxic gases[3,
4], fire-related SI-ALI is considerably more complex, especially in
the modern era, due to the new composite materials used in modern wood
manufacturing. Traditional wood, once the primary material for indoor
furnishings, has largely been replaced by synthetic rubbers, resins, and
other high-molecular-weight non-metallic materials. The combustion of
these mixed materials during a fire releases large quantities of toxic
gases, including hydrogen cyanide (HCN), carbon monoxide (CO), and
benzene[5]. These toxic gases, along with
hazardous particulates, enter the respiratory system, triggering a
cascade of pathological events such as oxidative stress, immune cell
infiltration, inflammatory responses, and disruption of the
alveolar-vascular barrier[6]. Unfortunately, no
targeted therapies are currently available for fire-related SI-ALI, with
treatment primarily relying on mechanical ventilation and supportive
care. An appropriate model is essential for investigating the mechanisms
of fire-related SI-ALI and developing effective therapeutics.
However, current models of fire-related SI-ALI face two significant
challenges: the inhomogeneity of smoke generation and the inherent
limitations of traditional animal and cell models. First, the
composition and concentration of smoke can vary greatly depending on
fire conditions, such as temperature and material
composition[7], leading to the lack of
reproducibility in these models. Moreover, traditional animal models,
although commonly employed to investigate the mechanisms and replicate
the pathological processes of SI-ALI[8, 9], are
inherently limited due to physiological and genetic differences between
animals and humans. These models are further constrained by ethical
considerations, adherence to the 3R principles (Reduction, Replacement,
Refinement), and the high costs and time demands associated with their
use. Additionally, understanding the complex interactions between
different cell types and elucidating their specific roles in SI-ALI is
challenging in these models.
On the other hand, single-cell line models, frequently used in toxicity
screening and mechanistic studies, also fail to accurately represent the
complexity of SI-ALI[10, 11]. The lung comprises a
diverse array of cell types—including epithelial, vascular, stromal
and immune cells—that interact in complex pathophysiological
processes. Furthermore, exposing lung epithelial cells to smoke extract
in liquid form does not adequately simulate actual smoke exposure, as
certain hydrophobic components of smoke are insoluble. Therefore, there
is an urgent need to develop a stable, reproducible, human-derived model
that is versatile and physiologically relevant, capable of faithfully
replicating the pathological processes of fire-related SI-ALI.
Organ-on-a-chip technology offers a promising solution to the
limitations inherent in traditional models[12].
Microengineered breathing lung chips have been developed to simulate
human airway responses to cigarette smoke, particularly within the
context of chronic obstructive pulmonary disease
(COPD)[13]. These lung-on-chips (LOCs) have also
been employed to study the nanotoxicity of TiO₂ and ZnO nanoparticles on
lung epithelial and endothelial cells, demonstrating the cytotoxicity,
reactive oxygen species (ROS) production, and apoptosis induced by these
nanoparticles[14]. Advanced LOCs serve as highly
efficient platforms for drug screening, enabling the use of techniques
such as transcriptomics, proteomics, and computational molecular biology
to investigate disease pathology and facilitate drug
development[15]. Additionally, lung organoids,
which retain the unique cellular components and genetic characteristics
of lung tissue, allow for the creation of more physiologically relevant
disease models, thereby improving the accuracy of drug
screening[16]. The integration of lung-on-a-chip
and organoid technologies holds significant potential for simulating the
pathological processes of fire-related SI-ALI, elucidating underlying
mechanisms, and identifying effective treatments.
This study pioneers the integration of organ-on-a-chip and organoid
technologies, enhancing the organ-on-a-chip system based on previous
research. Materials were carefully blended to reflect the proportions of
non-metallic components typically found in modern yachts, with precise
control over the combustion process. The composition and concentration
of smoke were monitored in real-time using Fourier-transform infrared
spectroscopy (FTIR), effectively simulating the smoke production process
during actual fires. Building on this foundation, a lung-on-a-chip model
for fire-related SI-ALI was developed, successfully replicating key
pathological processes in vitro and examining the responses of various
cell types to smoke-induced damage. The study, combined with animal
models, molecular biology techniques, proteomics, and molecular docking,
explored the unique pathogenic mechanisms of fire-related SI-ALI and
identified potential therapeutic drugs. Furthermore, the chip platform
was utilized to evaluate the therapeutic potential of nebulized
budesonide combined with intravenous vitamin C, with these findings
validated in the organoid chip model. This research establishes a new
paradigm for studying fire-related SI-ALI, providing valuable insights
into its pathology and potential treatments.
Materials and methods