In vitro models are crucial tools in cancer research because they assist researchers to identify carcinogens, developing cancer therapies, drug discovery, and study about the molecular pathways of tumour growth and spread. Cancer cells are an essential part of any in vitro tumour model. Cancer cell lines are simple to culture, allow for quick comparisons of experiments, and are commonly employed to research tumour cell biology molecular pathways. Tumour cell biology, 3D cell culture, tissue engineering, biomaterials, microfabrication, and microfluidics advancements have facilitated the dynamic development of in vitro tumour models.

1. Cancer Cell Lines
In vitro models are crucial tools in cancer research because they assist researchers to identify
carcinogens, developing cancer therapies, drug discovery, and study about the molecular
pathways of tumour growth and spread. Cancer cells are an essential part of any in vitro
tumour model. Cancer cell lines are simple to culture, allow for quick comparisons of
experiments, and are commonly employed to research tumour cell biology molecular pathways.
Tumour cell biology, 3D cell culture, tissue engineering, biomaterials, microfabrication, and
microfluidics advancements have facilitated the dynamic development of in vitro tumour models.
1. Transwell-Based Models
The migration of cells from one region to another is fundamental to the metastatic process.
Transwell assays are commonly used to evaluate cancer cell migration and invasion.
The three most prevalent transwell-based assays are:
MIGRATION ASSAYS:
The migration assay includes planting cancer cells on
top of a porous membrane and counting how many cells
can migrate throughout the membrane toward a
chemoattractant. This is a simple assay, the rate of
migration via pores towards serum delivers a high
throughput in vitro tumour model.
INVASION ASSAYS:
Invasion assays bring a new layer of complication to this
paradigm by adding an Extracellular Matrix (ECM) layer
on the porous membrane. Despite migration and
invasion assays targeting relatively comparable cell
attributes, it is important to note that some drugs and
gene alterations have a greater effect on invasion
reduction than migration reduction.
TRANSENDOTHELIAL MIGRATION ASSAYS:
Placing a confluent layer of endothelial cells onto a
porous layer is used in transendothelial migration
assays. The cell to cell connections between
endothelial cells and the ECM that they form add
intricacy to this concept. These transendothelial assays
are most typically employed to research brain capillary
endothelium, although other endothelial cell types,
such as HUVECs, can be studied as well.
Applications of Transwell-Based Assays
Studying the influence of chemoattractants on migration and invasion
Studying the influence of other cell types such as fibroblast, macrophages on the invasion of
cancer cells
Isolation of invasive/non-invasive cell types for molecular analysis
Studying relative rates of invasion and migration of various cell types
Testing the influence of antibodies o invasion and migration of the cells
2. Spheroids
Spheroids in Media Spheroids in Matrix Coculture Spheroids
Spheroids are 3D cultured aggregates of cells grown in suspension or embedded in a 3D matrix.
3D spheroids are commonly employed for drug screening, tumour growth and proliferation
research, immunological interactions, and, in the case of spheroids implanted in a matrix,
invasion and matrix remodelling studies. 3D spheroids mimic cell-cell and cell-matrix
interactions as well as transport features between tumour cells and the microenvironment.
Applications of Tumour Spheroids
CELL FUNCTION:
Spheroids are studied for their ability to mimic solid tumours and for their growth
dynamics, structure, and tumour cell biology.
DRUG SCREENING:
Cancer spheroids are commonly used to examine tumour sensitivity and response to
chemotherapeutics, combination treatments, targeted chemotherapy, and drug delivery.
ANGIOGENESIS:
The migration of endothelial cells into tumour spheroids or the development of vascular
networks inside spheroids is frequently used to assess the potential for tumour
vascularization. Tumour-induced angiogenesis has been shown to enhance oxygen
levels and the expression of hypoxia-related and proangiogenic genes.
IMMUNE CELL RESPONSE:
Tumor spheroids are being exploited to explore therapeutic techniques to elicit an
immune response by increasing immune cell infiltration and cytotoxicity.
3. Hybrid Models
There are various forms of in vitro tumour models that are not spheroid or transwell-based.
Embedded ex vivo tumour sections, 3D invasion models, and avascular microfluidic models are
among them. These models combine the complexities of the tumour microenvironment with the
relative ease of an in vitro model.
Model Description Advantages Disadvantages
Embeded ex
vivotumor section
3D invasion
models
Avascular
microfluidic
Primary tumor sections
or biopsies embedded
in gel
Tumor cells or clusters
embedded in a gel
Tumor cells grown in a 2D
microfluidic device,
typically for the study of
migration
Maintains tumor
heterogeneity
Patient-specific assay
Mimics outgrowth into
surrounding tissues
3D microenvironment
Allows real-time tracking
of cells
Balance of complexity and
experimental control
Simple migration assay
Easy to isolate effect of
variables
Allows real time-tracking
of cells
Lacks flow through
vasculature
Lacks vasculature
Lacks tumor complexity
Lacks vasculature
Typically lacks 3D
environment