title: Maturation of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) in 3D collagen matrix: Effects of niche cell supplementation and mechanical stimulation.
abstract: Cardiomyocytes derived from human embryonic stem cells (hESC-CMs) are regarded as a promising source for regenerative medicine, drug testing and disease modeling. Nevertheless, cardiomyocytes are immature in terms of their contractile structure, metabolism and electrophysiological properties. Here, we fabricate cardiac muscle strips by encapsulating hESC-CMs in collagen-based biomaterials. Supplementation of niche cells at 3% to the number of hESC-CMs enhance the maturation of the hESC-CMs in 3D tissue matrix. The benefits of adding mesenchymal stem cells (MSCs) are comparable to that of adding fibroblasts. These two cell types demonstrate similar effects in promoting the compaction and cell spreading, as well as expression of maturation markers at both gene and protein levels. Mechanical loading, particularly cyclic stretch, produces engineered cardiac tissues with higher maturity in terms of twitch force, elastic modulus, sarcomere length and molecular signature, when comparing to static stretch or non-stretched controls. The current study demonstrates that the application of niche cells and mechanical stretch both stimulate the maturation of hESC-CMs in 3D architecture. Our results therefore suggest that this 3D model can be used for in vitro cardiac maturation study.
  
  
  
  Cardiomyocytes derived from human embryonic stem cells (hESC-CMs) are regarded as being a promising source of cells for regenerative medicine, drug testing and disease modeling. Nevertheless, cardiomyocytes are immature in terms of their contractile structure, metabolism and electrophysiological properties. In the current study, we have fabricated cardiac muscle strips by encapsulating hESC-CMs in collagen-based biomaterials and demonstrated that supplementation of mesenchymal niche cells as well as provision of mechanical loading particularly stretching have significantly promoted the maturation of the cardiomyocytes and hence improved the mechanical functional characteristics of the tissue strips. Specifically, with 3% niche cells including both fibroblasts and mesenchymal stem cells, a more mature hESC-CMs derived cardiac strip was resulted, in terms of compaction and spreading of cells, and upregulation of molecular signature in both gene and protein expression of maturation. Mechanical loading, particularly cyclic stretch, produces engineered cardiac tissues with higher maturity in terms of molecular signature markers and functional parameters including twitch force, elastic modulus and sarcomere length, when comparing with static stretch or non-stretched controls. The current study demonstrates that the application of niche cells and mechanical stretch both stimulate the maturation of hESC-CMs in 3D architecture, resulting in more mature cardiac strips. Our results contribute to bioengineering of functional heart tissue strips for drug screening and disease modeling.
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Stem Cell and Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: C W
authors.initials: CW
authors.lastname: Kong
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: M H
authors.initials: MH
authors.lastname: Tong
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: W H
authors.initials: WH
authors.lastname: Chooi
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: N
authors.initials: N
authors.lastname: Huang
authors.affiliation: Stem Cell and Regenerative Medicine Consortium, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
authors.forename: R A
authors.initials: RA
authors.lastname: Li
authors.affiliation: Tissue Engineering Laboratory, Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region. Electronic address: bpchan@hku.hk.
authors.forename: B P
authors.initials: BP
authors.lastname: Chan
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D018920:Coculture Techniques; D003094:Collagen / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D000066449:Human Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D055153:Stem Cell Niche / Q000187:drug effects*; D013314:Stress, Mechanical; D023822:Tissue Engineering
chemical_list: D003094:Collagen
keywords: Heart tissue engineering; Human embryonic stem cell; Maturation; Mechanical loading; Mesenchymal cell