Cardiomiócitos humanos derivados de células tronco pluripotentes induzidas: aspectos morfológicos e funcionais

Abstract

The advent of induced pluripotent human stem cells (hiPSC or iPSCs) has caused great expectations in the scientific and clinical field. Since they are derived from somatic cells, they can grow indefinitely in vitro without losing their pluripotency and have enormous potential of differentiation, being able to differentiate in many cell types such as cardiac myocytes. Despite the vast efforts to develop therapies based in stem cells, iPSC-derived cardiomyocytes (iPSCs-CMs) have impaired basal function compared with the adult cells in cardiac tissue. In this work, we propose a maturation protocol consisting of the simple supplementation of the culture medium with triiodothyronine (T3) hormone, insulin-like growth factor type 1 (IGF-1) and dexamethasone, here called TDI, is sufficient for cell maturation. Treatment with TDI induced an increase in cell area, cell elongation and better sarcomere organization. In addition, was observed an increase in mRNA expression for some maturation markers such as MYH7, FKBP5 and PPARα. When compared to non-treated cells, the cells exposed to TDI had a calcium transient larger in amplitude and with faster decay kinetics, with prolonged action potential as well. Also, these cells had larger calcium content on the sarcoplasmic reticulum. This may be associated with the increase in mRNA levels for SERCA2A that was observed in iPSC's-CM's treated with TDI. Furthermore, TDI-treated cells were used to mount cardiac microtissues (CMT), along with endothelial cells and fibroblasts. These tissues had enhanced static force and increase in dynamic force during the contraction of this tissue, corroborating with the data obtained from their cellular morphology and calcium handling. In conclusion, use of TDI has proved a simple and robust method of maturation of iPSC's-CM's and may be an alternative to obtaining cardiac tissues in vitro with better chance to successful engraftment in patients' hearts.