Primary tissue or hiPSC derived VSMCs have been previously u

Primary tissue- or hiPSC-derived VSMCs have been previously used to establish vascular tissue constructs with different scaffold materials, such as polyglycolic acid, fibrin, and poly-L-lactic further information (Bajpai et al., 2012; Niklason et al., 1999; Sundaram et al., 2014; Wang et al., 2010). However, these artificial materials are significantly different from the natural extracellular matrix produced by VSMCs. In contrast, our unique scaffold-free technique has enabled fabrication of patient-specific tissue constructs engineered entirely from human VSMCs and the extracellular matrix they produce. The facile, one-step cell-seeding process results in robust, scaffold-free tissue constructs within a short duration of culture time (less than 2 weeks) without specialized equipment. Finally, these tissue rings may be useful as modular building blocks to generate tubular tissue constructs to be used for vascular grafts (Gwyther et al., 2011a, 2011b), or as model in vitro vascular tissues for drug discovery and to study human disease mechanisms. In the future, we will fabricate tissue rings from various lineage-specific hiPSC-VSMCs and disease-specific VSMCs for disease modeling and drug screening. Further optimization of the culture conditions such as use of Ficoll, a macromolecular crowder, in the culture medium will be tested in order to enhance the strength of the tissue rings (Zeiger et al., 2012). Finally, our methodology can potentially be extended to fabricate tissue rings from other types of cells derived from patient-specific hiPSCs for the construction of mechanically robust engineered tissues for disease research and treatment.
Experimental Procedures
Author Contributions
Acknowledgments We would like to thank Drs Laura Niklason and Liqiong Gui for their timely scientific suggestions and Dr Daniel Greif for his suggestions on the manuscript. This work is supported by NSF DGE-1144804 (K.L. and M.R.), NIH1K02HL101990-01, 1R01HL116705-01, Connecticut\'s Regenerative Medicine Research Fund (R.M.R.F.) and 12-SCB-YALE-06 (Y.Q.). Control 2 human iPSC line is a generous gift of Dr I-Ping Chen from the University of Connecticut Health Science Center.
Introduction The advent of human induced pluripotent stem cell (hiPSC) technology and protocols to efficiently differentiate cardiomyocytes (CM) (Burridge et al., 2012) have opened the perspective to use hiPSC-CM for cardiac research or drug development. This biotechnology advancement also boosted the development of test systems to evaluate hiPSC-CM electrophysiology (reviewed in Hoekstra et al., 2012), impedance (Guo et al., 2013; Scott et al., 2014), field potentials (Caspi et al., 2009; Harris et al., 2013; Navarrete et al., 2013; Clements and Thomas, 2014; Riedel et al., 2014; Qu and Vargas, 2015), action potentials and calcium transients with fluorescent dyes, and cellular shortening video-optically (Lee et al., 2012; Lopez-Izquierdo et al., 2014; Feaster et al., 2015; Pointon et al., 2015). These assays may improve preclinical drug development and safety toxicology, because current systems are based either on recombinant cell lines or animal cells, both susceptible to typical shortcomings. HiPSC-CM promise an intact, human cardiomyocyte context in which a drug and/or principle is tested. Moreover, patient-specific cell lines offer (1) the perspective of testing drugs in a wide spectrum of genetic backgrounds and (2) individualized risk prediction and testing of adverse drug effects. Different technologies have been employed for predictive toxicology application (Braam et al., 2010; Pointon et al., 2015), and many studies have successfully demonstrated disease-specific phenotypes in hiPSC-CM from patients with inherited cardiac diseases (reviewed in Moretti et al., 2013; Karakikes et al., 2015). Most test systems use hiPSC-CM as 2D layers on rigid plastic cell-culture dishes that do not allow the cells to perform physiological auxotonic contractions (Nishimura et al., 2004). Contractile function, the main feature of the heart, can only be analyzed in a very restricted manner.