Cardiomyocyte maturation: advances in knowledge and implications for regenerative medicine

Abstract

Our knowledge of pluripotent stem cell (PSC) biology has advanced to the point where we now can generate most cells of the human body in the laboratory. PSC-derived cardiomyocytes can be generated routinely with high yield and purity for disease research and drug development, and these cells are now gradually entering the clinical research phase for the testing of heart regeneration therapies. However, a major hurdle for their applications is the immature state of these cardiomyocytes. In this Review, we describe the structural and functional properties of cardiomyocytes and present the current approaches to mature PSC-derived cardiomyocytes. To date, the greatest success in maturation of PSC-derived cardiomyocytes has been with transplantation into the heart in animal models and the engineering of 3D heart tissues with electromechanical conditioning. In conventional 2D cell culture, biophysical stimuli such as mechanical loading, electrical stimulation and nanotopology cues all induce substantial maturation, particularly of the contractile cytoskeleton. Metabolism has emerged as a potent means to control maturation with unexpected effects on electrical and mechanical function. Different interventions induce distinct facets of maturation, suggesting that activating multiple signalling networks might lead to increased maturation. Despite considerable progress, we are still far from being able to generate PSC-derived cardiomyocytes with adult-like phenotypes in vitro. Future progress will come from identifying the developmental drivers of maturation and leveraging them to create more mature cardiomyocytes for research and regenerative medicine.

Quantitative Evaluation of the Sarcomere Network of Human hiPSC-Derived Cardiomyocytes Using Single-Molecule Localization Microscopy

“…The acquired PALM data indicate that the organization of the sarcomere network in iPSC-derived CM is comparable to neonatal CM as no significant differences have been found for sarcomere length and z-Disc thickness. This is in agreement with numerous studies showing that the differentiation status of CMs generated from stem cells resemble an embryonic or neonatal state [4,21,22]. The average sarcomere length in iPSC-derived CM is about 1.84 µm, which corresponds to former reports showing that the distance between two adjacent sarcomeres is~1.7-2.0 µm (Figure 2) [14,16,23].…”

“…The immature phenotype of iPSC derived CMs limits their potential for cell-based therapies, drug development and cardiovascular research. Although many strategies have been applied to improve the cardiac differentiation and maturation of stem cells, researchers failed to generate iPSCs CMs with properties matching their adult counterparts [4]. In this regard, it is of uttermost importance to provide techniques that help to evaluate the maturation level of iPSC-derived CMs.…”

“…CM derived from iPSCs have been shown to be suitable for regenerative therapies and drug development [1][2][3]. However, the proper maturation is a common problem as iPSC-CM do not display the same morphological and functional features as their adult counterparts, rather resembling fetal CM [4,5]. In this regard, it has been found that the low level of maturation can be critical in drug development since immature CM seem to be more susceptible to HERG blockers than mature CM [6].…”

“…Following image acquisition and data reconstruction, sarcomere length and z-disc thickness were determined. Sarcomere length was evaluated by measuring the distance between intensity peaks, corresponding to adjacent α-actinin labelled filaments(1)(2)(3)(4)(5). z-disc thickness was automatically analyzed, and the mean width of each filament was calculated.…”

Microfluidics-enabled 96-well perfusion system for high-throughput tissue engineering and long-term all-optical electrophysiology

“…We found improved viability and higher-amplitude intracellular calcium transients in cells under continuous perfusion compared to static cultures. Future experiments with HT-µUPS will help improve iPSC-CM metabolic maturity 8,24,25 by continuous non-contact (optical) stimulation while perfusion insures oxygenation and metabolic balance.…”