b2815 Tissue Engineering and Nanotheranostics “9.61x6.69”
90 Tissue Engineering and Nanotheranostics
clinical applications due to their inability to appreciably replicate and
replace lost tissue. Stem cell derived cardiomyocytes could provide a
cellular base for cardiovascular disease therapies, in particular for myo-
cardial infarction or heart failure.
In 1985, Doetschman et al. described the spontaneous differen-
tiation of mouse embryoid bodies into cardiomyocytes, albeit with
very low efficiency, demonstrating the potential to derive cardiomyo-
cytes by in vitro culture techniques.^52 In 2002, Xu et al. published a
feeder cell free method to differentiate cardiomyocytes characterized
by spontaneous contraction as well as cellular markers including
α-myosin heavy chain, cardiac troponin I and T, and cardiac transcrip-
tion factor Nkx2.5.^53 This protocol requires the formation of embry-
oid bodies and used Percoll density centrifugation to isolate a
population with 70% purity, but very low (~1%) efficiency.^53 They
further reported supplemental factors tested to try to improve differ-
entiation efficiency and showed that DMSO and retinoic acid did not
increase cardiomyocyte differentiation while decitabine, a hypometh-
ylating agent, provided efficiency enhancements when added in later
stages of differentiation.^53
Laflamme et al. used a similar differentiation strategy in 2005 to
derive cardiomyocytes to graft into rat hearts.^54 They showed that
human myocardial tissue developed in healthy rat hearts from the
hESC derived cardiomyocytes.^54 In 2007, Laflamme et al. attempted
to graft these cardiomyocytes into infarcted rat hearts with minimal
success.^55 As a result they tried using a novel monolayer culture tech-
nique with sequential additions of Activin A and BMP4 resulting in a
30% efficient differentiation to cardiomyocytes.^55 In 2008, Yang et al.
used a similar differentiation technique to derive cardiomyocytes and
identify an early cardiac progenitor cell type.^56 By selecting for KDR
positive and C-KIT negative cells, they achieved 50% efficiency for
cardiomyocyte differentiation.^56 While these strategies are more effi-
cient and use monolayer culture techniques, they rely on centrifuga-
tion or gene expression based purification methods to isolate pure
populations of cardiomyocytes, which is not ideal for clinical use.
In 2010, Paige et al. described the role of Wnt/β-catenin signaling
in cardiac differentiation.^57 They showed inhibition of Wnt/β-catenin
