Tissue Eng Part A. 2016 Jul 8. [Epub ahead of print]

Three-dimensional adult cardiac extracellular matrix promotes maturation of human induced pluripotent stem cell-derived cardiomyocytes.

Fong AH¹, Romero-López M², Heylman CM³, Keating M⁴, Tran D⁵, Sobrino A⁶, Tran AQ⁷, Pham HH⁸, Fimbres C⁹, Gershon PD¹⁰, Botvinick EL¹¹, George SC¹², Hughes CC¹³.

Abstract

Pluripotent stem cell-derived cardiomyocytes (CM) have great potential in the development of new therapies for cardiovascular disease. In particular, human induced pluripotent stem cells (iPSC) may prove especially advantageous due to their pluripotency, their self-renewal potential, and their ability to create patient-specific cell lines. Unfortunately, pluripotent stem cell-derived CM are immature, with characteristics more closely resembling fetal CM than adult CM, and this immaturity has limited their use in drug screening and cell-based therapies. Extracellular matrix (ECM) influences cellular behavior and maturation, as does the geometry of the environment - 2D vs. 3D. We therefore tested the hypothesis that native cardiac ECM and 3D cultures might enhance the maturation of iPSC-derived CMs in vitro. We demonstrate that maturation of iPSC-derived CM was enhanced when cells were seeded into a three-dimensional (3D) cardiac ECM scaffold, compared to two-dimensional (2D) culture. 3D cardiac ECM promoted increased expression of calcium handling genes Junctin, CaV1.2, NCX1, HCN4, SERCA2a, Triadin, and CASQ2. Consistent with this, we find that iPSC-derived CM in 3D adult cardiac ECM show increased calcium signaling (amplitude) and kinetics (maximum upstroke and downstroke), compared to cells in 2D. Cells in 3D culture were also more responsive to caffeine, likely reflecting an increased availability of calcium in the sarcoplasmic reticulum. Taken together, these studies provide novel strategies to mature iPSC-derived CMs that may have applications in drug screening and transplantation therapies to treat heart disease.