Brian A. Shapiro, Ph.D.
I have recently joined
ATCC as a Technical Writer, and have 14 years of experience growing a wide
variety of cells. In the coming months, I will
address topics such as how to choose the right cell type for your experiments,
cell line cross-contamination, and microbial contamination in this blog.
Biomedical
scientists often rely on in vitro
cell models for the study of human physiology and the pathogenesis of disease. Human
primary cells (HPCs) are frequently disregarded as a choice for cell cultures,
as they typically require more technical expertise to establish in the
laboratory than other cell types and must be used in early passage. While HPCs
may be challenging to generate, they have much in common with cells in vivo; therefore HPCs may be the
perfect addition to your experiments.
HPCs
can be used to represent normal tissue physiology as they retain many of the
secretory, barrier, contractile, and other physiological functions of their in vivo condition. Further, HPCs usually
have normal expression of tumor suppressor genes and proto-oncogenes; this
allows HPCs to display normal cell cycle controls. The fact that HPCs possess
gene expression patterns similar to cells in
vivo indicates that they would be excellent controls in experiments using tumorigenic
cell lines or cell lines derived from diseased tissue in the study of cancer,
Parkinson’s disease, or microbial infection.
Beyond
their use as controls for pathological studies, HPCs can be applied in a wide
range of experiments that examine normal tissue and organ physiology. For
example, primary human bronchial/tracheal epithelial cells, when cultured in an
air-liquid interface culture system, have been observed to form airway
epithelium, which secretes mucus and exhibit waving cilia1. In
addition, more than one primary cell type may be co-cultured to form complex
tissue systems. For instance, primary human neonatal foreskin keratinocytes
cultured on fibroblasts differentiate into the four functional layers of the
epidermis2. Because organs are
3-D and boast multiple cell types, these co-culture and 3-D culture systems come
close to mimicking physiological organ systems. The similarity to in vivo tissue and organ systems suggest
that these 3-D culture systems have applications in toxicity, tissue
development, carcinogenesis, cosmetic testing, and wound repair studies.
HPC
maintenance is similar to that of any other cell line, thanks to the
availability of optimized media and reagent formulations, affordable cell
matrix solutions, and detailed protocols. An alternative to isolating the cells
yourself is through ordering the cells from a well-known biological resource
center, such as ATCC. ATCC supplies cells from a broad range of tissue
sources and uses cell-specific markers to ensure a high level of purity
post-isolation. In addition, ATCC tests HPCs for viability, as well as
contamination by mycoplasma, bacteria, and yeast. Thus, when the HPCs arrive in
your laboratory, you simply thaw and plate the cells in the appropriate culture
medium. The HPCs can then be treated to stimulate the desired cellular
responses at any time during the maintenance phase.
Considering
the required technical expertise, the expense, and the inaccessibility of source
tissue, the addition of HPCs to a laboratory’s inventory of in vitro models may seem daunting.
However, the rewards to your research are more than worth the trouble. Because HPCs
are untransformed, have similar gene expression as the cells in situ, and exhibit similar physiologic
function as in vivo cells, they are
indispensable for a wide range of experiments that examine normal physiology or
disease pathology.
References
1. Berube K, et
al. Human primary bronchial lung cell constructs: the new respiratory
models. Toxicology 278(3):311-8, 2010.
2. Gangatirkar P, et al. Establishment of 3D organotypic cultures using human
neonatal epidermal cells. Nat Protoc 2(1):178-86, 2007.
