In vitro culture of isolated primary hepatocytes and stem cell-derived hepatocyte-like cells for liver regeneration
© The Author(s) 2015. This article is published with open access at Springerlink.com and journal.hep.com.cn
In vitro culture of isolated primary hepatocytes and stem cell-derived hepatocyte-like cells for liver regeneration
Chenxia Hu 0
Lanjuan Li 0
0 Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, School of Medicine, First Affiliated Hospital, Zhejiang University , Hangzhou 310006 , China
liver regeneration; primary hepatocyte; stem cell; hepatocyte-like cell; in vitro culture
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Various liver diseases result in terminal hepatic failure, and
liver transplantation, cell transplantation and artificial liver
support systems are emerging as effective therapies for
severe hepatic disease. However, all of these treatments are
limited by organ or cell resources, so developing a sufficient
number of functional hepatocytes for liver regeneration is a
priority. Liver regeneration is a complex process regulated
by growth factors (GFs), cytokines, transcription factors
(TFs), hormones, oxidative stress products, metabolic
networks, and microRNA. It is well-known that the function of
isolated primary hepatocytes is hard to maintain; when
cultured in vitro, these cells readily undergo
dedifferentiation, causing them to lose hepatocyte function. For this
reason, most studies focus on inducing stem cells, such as
embryonic stem cells (ESCs), induced pluripotent stem cells
(iPSCs), hepatic progenitor cells (HPCs), and mesenchymal
stem cells (MSCs), to differentiate into hepatocyte-like cells
(HLCs) in vitro. In this review, we mainly focus on the nature
of the liver regeneration process and discuss how to
maintain and enhance in vitro hepatic function of isolated primary
hepatocytes or stem cell-derived HLCs for liver
regeneration. In this way, hepatocytes or HLCs may be applied for
clinical use for the treatment of terminal liver diseases and
may prolong the survival time of patients in the near future.
Viral hepatitis, fatty liver disease, drug-induced liver injury,
liver cirrhosis, hepatic carcinoma, and other liver diseases
can cause acute or chronic liver failure. Approximately 10%
of patients with liver disease succumb to their condition while
waiting for liver sources each year (Kim et al., 2006).
Liver transplantation was once the only therapeutic option
for patients with end stage liver diseases, and its clinical use
was limited due to limited donor availability, surgical injuries,
a high incidence of surgical complications and the high cost
of the treatment (Duan et al., 2013). Later, cell
transplantation and artificial liver support emerged as effective methods
for compensation of lost liver function and increased the
survival rate of patients; however, these two methods are
also limited by the availability of effective cell sources and
equipment. The inability of hepatocytes to proliferate in vitro
and the severely inadequate supply of hepatocytes due to
donor shortage are still the main problems for primary human
hepatocyte-based treatments. Stem cells have been
proposed as an ideal cell source because they have potent
selfrenewal, low immunogenicity, and the capacity to
differentiate into various cell types. Furthermore, they can generate
unlimited hepatocytes with incomplete function (Sancho-Bru
et al., 2009) that are generally defined as hepatocyte-like
cells (HLCs). HLCs can be derived from multiple stem cell
types, such as embryonic stem cells (ESCs), induced
pluripotent stem cells (iPSCs), hepatic progenitor cells
(HPCs), and mesenchymal stem cells (MSCs). Therefore, it
is crucial to develop robust methods for differentiating stem
cells into mature hepatocytes in vitro for clinical use.
Here, we present an overview of isolated primary
hepatocytes and stem cell-derived HLCs used for liver
regeneration and describe how the in vitro environment in which they
are cultured is continuously being optimized to mimic in vivo
conditions and maintain hepatic function. The main
disadvantages, histologic origin, 3D, and co-culture environment
for in vitro culture of isolated hepatocytes or stem
cellderived hepatocytes were demonstrated in Table 1.
Optimization of in vitro culturing of functional hepatocytes will
solve the issues of limited cell numbers and limited function,
and sufficient numbers of functional hepatocytes will be used
to promote liver regeneration directly or indirectly.
NATURE OF LIVER REGENERATION
The liver serves as a major storage site of glycogen and
vitamin A and is one of only a few organs in adults that are
capable of regeneration. Normal mature hepatocytes and
cholangiocytes stay in the G0 phase of the cell cycle, exhibit
a quiescent phenotype and show minimal turnover, but in
response to partial hepatectomy (PH), they can undergo cell
proliferation to compensate for the lost cells, a process
called liver regeneration. However, severe damage caused
by liver diseases can signif (...truncated)