Scaffold-free cell sheet/cell patch engineering is a yet another attractive approach
for producing multi-layered cardiac patch. This technique was first developed in
Japan by Kushida and co-workers. In this technology, a temperature-responsive
culture surface is first fabricated by layering a temperature-responsive polymer (e.g.
poly (N-isopropylacrylamide)) onto polystyrene petri plates. Monolayers of CMs
are then grown on such cell culture plates and, upon confluency, are recovered as an
intact cell sheet by lowering the temperature to 20 °C. Scaffold-free multi-layered
cell sheets are then generated as 3D tissue by stacking of these monolayer sheets
using a silicon mould (Haraguchi et al. 2014). Scaffold-free vascularized CMs
patches have also been developed by Stevens et al. (2009) by utilizing a rotating
orbital shaker. The 3D myocardial tissue, developed from these stacked CMs
sheets, resembled native heart tissue and showed synchronous beats (Haraguchi
et al. 2011). In a clinical trial conducted in Japan, transplantation of autologous
myoblast cell sheets was shown to improve the cardiac dysfunction in heart failure
cases (Matsuura et al. 2014). However, the stacked cell sheets are generally limited
in thickness up to 3 layers (*80 µm) due to the lack of vascularization and oxygen
transport to the centre of the tissue. Furthermore, cell sheet tissue lack native
orientation and spatial placement of cardiac cells. The later can however, be
overcome by photolithography-based microtexturing of culture dishes before
growing the monolayers (Isenberg et al. 2008).
Decellularized whole heart tissue has also been used as scaffold for CTE.
Cadaveric hearts can be decellularized by using detergents to obtain whole heart
ECM scaffolds with well preserved natural 3D structure of ECM, vascular architecture, mechanical anisotropy, competent acellular valves and intact chamber
geometry. The decellularized whole heart can then be re-seeded with CMs and
endothelial cells (ECs) and, cultured in a perfusion bioreactor to generate a spontaneously beating ‘whole heart’, which can be used as allograft or xenograft (Ozlu
et al. 2019). Such strategy has been successful in both human and animal. It is also
possible to develop personalized bioartificial hear by seeding of patient’s own cells
(Kang et al. 2020). Unfortunately, re-seeding of cells into the decelluralized heart in
a uniform manner is quite difficult and requires specialized multi-stimulation
bioreactor to provide coordinated mechanical and electrical stimulation and nutrient
supply (Wang et al. 2013a). To circumvent non-uniform re-seeding some studies
have suggested the sectioning of myocardium into 2 mm thick portions before
decellularization and using them as cardiac patches (Wang et al. 2010). In other
studies, decellularized matrix of heart or other organ has been incorporated into
scaffolds for CTE.
18.3 Natural Biomaterials Used in ‘Classical’ CTE
Cells within a tissue are surrounded by ECMs that are composed of biomolecules
and fibers, synthesized by cells themselves, blood vessels and innervating neurons.
The ECMs provide micro-niche whose physico-chemical microenvironment allows
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P. Pushp and M. K. Gupta
for producing multi-layered cardiac patch. This technique was first developed in
Japan by Kushida and co-workers. In this technology, a temperature-responsive
culture surface is first fabricated by layering a temperature-responsive polymer (e.g.
poly (N-isopropylacrylamide)) onto polystyrene petri plates. Monolayers of CMs
are then grown on such cell culture plates and, upon confluency, are recovered as an
intact cell sheet by lowering the temperature to 20 °C. Scaffold-free multi-layered
cell sheets are then generated as 3D tissue by stacking of these monolayer sheets
using a silicon mould (Haraguchi et al. 2014). Scaffold-free vascularized CMs
patches have also been developed by Stevens et al. (2009) by utilizing a rotating
orbital shaker. The 3D myocardial tissue, developed from these stacked CMs
sheets, resembled native heart tissue and showed synchronous beats (Haraguchi
et al. 2011). In a clinical trial conducted in Japan, transplantation of autologous
myoblast cell sheets was shown to improve the cardiac dysfunction in heart failure
cases (Matsuura et al. 2014). However, the stacked cell sheets are generally limited
in thickness up to 3 layers (*80 µm) due to the lack of vascularization and oxygen
transport to the centre of the tissue. Furthermore, cell sheet tissue lack native
orientation and spatial placement of cardiac cells. The later can however, be
overcome by photolithography-based microtexturing of culture dishes before
growing the monolayers (Isenberg et al. 2008).
Decellularized whole heart tissue has also been used as scaffold for CTE.
Cadaveric hearts can be decellularized by using detergents to obtain whole heart
ECM scaffolds with well preserved natural 3D structure of ECM, vascular architecture, mechanical anisotropy, competent acellular valves and intact chamber
geometry. The decellularized whole heart can then be re-seeded with CMs and
endothelial cells (ECs) and, cultured in a perfusion bioreactor to generate a spontaneously beating ‘whole heart’, which can be used as allograft or xenograft (Ozlu
et al. 2019). Such strategy has been successful in both human and animal. It is also
possible to develop personalized bioartificial hear by seeding of patient’s own cells
(Kang et al. 2020). Unfortunately, re-seeding of cells into the decelluralized heart in
a uniform manner is quite difficult and requires specialized multi-stimulation
bioreactor to provide coordinated mechanical and electrical stimulation and nutrient
supply (Wang et al. 2013a). To circumvent non-uniform re-seeding some studies
have suggested the sectioning of myocardium into 2 mm thick portions before
decellularization and using them as cardiac patches (Wang et al. 2010). In other
studies, decellularized matrix of heart or other organ has been incorporated into
scaffolds for CTE.
18.3 Natural Biomaterials Used in ‘Classical’ CTE
Cells within a tissue are surrounded by ECMs that are composed of biomolecules
and fibers, synthesized by cells themselves, blood vessels and innervating neurons.
The ECMs provide micro-niche whose physico-chemical microenvironment allows
620
P. Pushp and M. K. Gupta