cell biology and tissue engineering. Improvements have been made in the basic
requirements of cell culture in terms of required sample volume, the supply of
nutrients, control of physicalfactors, and continuous monitoring and manipulation of
cellular processes. The realization of techniques utilized for maintenance and growth
of cellsin vitrois an important milestone in the field of biological sciences [ 6 ]. Apart
from the often-cited advantages of MF like faster response times, lower reagent
volumes, and the potential for integration; the most important benefit of using the
technology for biology is the ability to tailor the cellular microenvironment. Latest
organ-on-a-chip applications of MF allow thefabrication of smallest functional units of
a single organ or multiple organs [ 7 ]. These kinds of devices present a more physio-
logically relevantin vitromodel compared to cells cultured in dishes. The unprece-
dented control over spatial and temporal gradients and patterns can be attained while
moving from macro- to microscale, which is otherwise not possible with traditional
Petri dishes. So far, MF applications have been used in many experimental parts of cell
manipulation and analysis, such as cell trapping/sorting, cell culture, cytotoxicity,
PCR, DNA sequencing, and gene analysis.In the next section, we will discuss on
the advancement made by LoC technologiesin stem cell research, neurology, drug
discovery, latest fabricated organs on a chip and single cell analysis.
2.1 Stem Cell Research
Stem cells are the cells that are capable of continued self-renewal through replica-
tion and becoming precursor cells of a specific tissue types. It offers a steady supply
of physiologically relevant cells from pathogen-free sources that bothin vivoand
in vitrocan differentiate into mature somatic cells [ 8 ]. These cells are being success-
fully used in replacement of cells lost due to degenerative disease and repair of
damaged tissue [ 9 ]. Other examples of stem cell application are in bone healing, repair
of the suspensory ligament, and injury to the nervous system, as well as inflammatory,
relieve in arthritis and immune suppression [ 10 ]. Regenerative medicine through stem
cell therapy is becoming popular and is considered to be the future milestone in the
therapeutics. The conventional techniques involved in stem cell experiments are not
appropriate as they poorly mimic the physiological cellular environment, and suffer
from inaccurate spatial and temporal control. They also give reduced throughput, lack
of scalability and reproducibility. On the other hand novel LoC platforms can much
better mimic the complexity ofin vivotissue and provide a more precise control of
different parameters. This capability can be very helpful for understanding the biology
and improving the clinical potential of stem cell-based therapies [ 8 , 10 ].
A lot of research has been conducted, where stem cells have been used to study
various life processes. Klein et al. developed a high-throughput droplet-MF
approach for barcoding the RNA from thousands of individual cells for subsequent
analysis by next-generation sequencing and analyzed mouse embryonic stem cells
[ 11 ]. They used the analysis to infer gene expression relationships which can be
useful for various biological studies. The MF device fabricated was 80 mm deep
8 Biological Applications of Microfluidics System 193