Yamasaki Yu, Matsuura Katsuhisa, Sasaki Daisuke, Shimizu Tatsuya
Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan.
Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
Regen Ther. 2021 Apr 10;18:66-75. doi: 10.1016/j.reth.2021.03.007. eCollection 2021 Dec.
Myocardial recovery is one of the targets for heart failure treatment. A non-negligible number of heart failure with reduced ejection fraction (EF) patients experience myocardial recovery through treatment. Although myocardial hypoxia has been reported to contribute to the progression of heart failure even in non-ischemic cardiomyopathy, the relationship between contractile recovery and re-oxygenation and its underlying mechanisms remain unclear. The present study investigated the effects of hypoxia/re-oxygenation on bioengineered cardiac cell sheets-tissue function and the underlying mechanisms.
Bioengineered cardiac cell sheets-tissue was fabricated with human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) using temperature-responsive culture dishes. Cardiac tissue functions in the following conditions were evaluated with a contractile force measurement system: continuous normoxia (20% O) for 12 days; hypoxia (1% O) for 4 days followed by normoxia (20% O) for 8 days; or continuous hypoxia (1% O) for 8 days. Cell number, sarcomere structure, ATP levels, mRNA expressions and Ca transients of hiPSC-CM in those conditions were also assessed.
Hypoxia (4 days) elicited progressive decreases in contractile force, maximum contraction velocity, maximum relaxation velocity, Ca transient amplitude and ATP level, but sarcomere structure and cell number were not affected. Re-oxygenation (8 days) after hypoxia (4 days) was associated with progressive increases in contractile force, maximum contraction velocity and relaxation time to the similar extent levels of continuous normoxia group, while maximum relaxation velocity was still significantly low even after re-oxygenation. Ca transient magnitude, cell number, sarcomere structure and ATP level after re-oxygenation were similar to those in the continuous normoxia group. Hypoxia/re-oxygenation up-regulated mRNA expression of PLN.
Hypoxia and re-oxygenation condition directly affected human bioengineered cardiac tissue function. Further understanding the molecular mechanisms of functional recovery of cardiac tissue after re-oxygenation might provide us the new insight on heart failure with recovered ejection fraction and preserved ejection fraction.
心肌恢复是心力衰竭治疗的目标之一。相当数量的射血分数降低（EF）的心力衰竭患者通过治疗实现了心肌恢复。尽管有报道称，即使在非缺血性心肌病中，心肌缺氧也会促进心力衰竭的进展，但收缩恢复与复氧之间的关系及其潜在机制仍不清楚。本研究调查了缺氧/复氧对生物工程心脏细胞片组织功能的影响及其潜在机制。
使用温度响应培养皿，用人诱导多能干细胞衍生的心肌细胞（hiPSC-CM）制备生物工程心脏细胞片组织。用收缩力测量系统评估以下条件下的心脏组织功能：持续常氧（20% O₂）12天；缺氧（1% O₂）4天，然后常氧（20% O₂）8天；或持续缺氧（1% O₂）8天。还评估了这些条件下hiPSC-CM的细胞数量、肌节结构、ATP水平、mRNA表达和Ca²⁺瞬变。
缺氧（4天）导致收缩力、最大收缩速度、最大舒张速度、Ca²⁺瞬变幅度和ATP水平逐渐降低，但肌节结构和细胞数量未受影响。缺氧（4天）后的复氧（8天）与收缩力、最大收缩速度和舒张时间逐渐增加相关，达到与持续常氧组相似的水平，而复氧后最大舒张速度仍显著较低。复氧后的Ca²⁺瞬变幅度、细胞数量、肌节结构和ATP水平与持续常氧组相似。缺氧/复氧上调了PLN的mRNA表达。
缺氧和复氧条件直接影响人类生物工程心脏组织功能。进一步了解复氧后心脏组织功能恢复的分子机制可能为我们提供关于射血分数恢复和射血分数保留的心力衰竭的新见解。
