“9.61x6.69” b2815 Tissue Engineering and Nanotheranostics
Directed Differentiation of Human Pluripotent Stem Cells 87
oncostatin M, and Dex, the resulting cells expressed adult liver cell
markers and displayed functional hepatocyte characteristics such as
albumin secretion, LDL uptake, glycogen storage, and inducible
cytochrome P450 activity.^42 In 2009, Cai et al. demonstrated that
another similar protocol was effective in directing differentiation from
iPSCs to hepatocyte-like cells.^43 While these cells exhibited many
hepatocyte characteristics, the hESC and iPSC derived hepatocyte-
like cells failed to produce the same functionality as adult hepatocytes.
Albumin secretion, urea synthesis, and cytochrome P450 activities
tested substantially lower than adult hepatocytes.^43 Similar results
were obtained by Duan et al. using a similar differentiation strategy
with the addition of BMP4 and DMSO to the culture.^44
Basma et al. devised a three-stage differentiation using Activin A
to induce the definitive endoderm, HGF and DMSO for hepatic
specification, and Dex during the maturation stage.^45 To further
enrich their hepatic-like cell population, they selected ASGPR positive
cells by fluorescence activated cell sorting. The ASGPR positive cells
displayed higher secretion of albumin, urea, and AAT, but the func-
tionality still fell short of primary hepatocytes.^45 In 2013, Hannan
et al. described a protocol that they used to generate hepatocyte-like
cells from hESCs and iPSCs with 80% efficiency.^46 This strategy has
five different stages and requires 25 days to generate the hepatocyte
like cells.^46 These cells were observed to express rapidly decreasing
levels of fetal hepatocyte markers as they matured; however about
10 days after the differentiation, the cells died off as functionality
decreased.^46 As a result, hepatic differentiation methods need further
refinement to improve the maturation stages in order to achieve
improved mature hepatocyte functionality.
3.2.3. Lung progenitors
Lung epithelial cells line the respiratory tract. They participate in gas
exchange, prevent infection, and remove foreign pathogens. These
cells offer potential uses for disease modeling, drug testing, and clini-
cal transplantation for conditions like cystic fibrosis (CF) where the
lung endothelial cells lack normal function, producing a thicker
