The study of stem cells in cardiac surgery

Aims: The goal of this project was to evaluate the effectiveness of stem cells in heart failure to optimize them for clinical use. Methods: In the meta-analysis, randomized controlled clinical trials (RCTs) of stem cell treatments for heart failure were retrieved. Primary outcomes were set as all-cause mortality and left ventricular ejection fraction (LVEF) change from baseline. Mean differences and standard deviations between cell therapies and controls were calculated and separated into subgroups based on methodological and clinical differences. In the laboratory, stem cells were expanded with different medium sera and further brought to a severe condition that simulated ischemia-reperfusion injury (AcS). Cell counts and necrotic, apoptotic cells were assessed, and reverse transcription-polymerase chain reaction (RT-PCRs) were performed to measure cell proliferation, cell survival, and gene regulations under normal and stressful conditions. Results: 42 RCTs were retrieved, and 1984 participants were enrolled. Overall, stem cells were proven to reduce mortality and increase ∆LVEF by 2.88% and 2.33% at short- and long-term follow-ups. Results from trial quality assessments and sensitivity analyses indicated existence of bias risks in randomization and performance that significantly affect clinical outcomes lead to false-positive results. Among various cell origins, perinatal stem cells showed 6.48% and 5.22% of LVEF increase. Cord blood-derived mesenchymal stromal cells were chosen for in vitro study. Under human sera, they presented a higher proliferative capacity and shorter expansion time. A higher survival rate was also confirmed against oxidative stress, but apoptosis- and cell cycle-related genes were not regulated in a similar pattern under different medium sera. Conclusions: Overall, stem cell therapy did not show clinical values for improving cardiac contractility in patients with impaired heart functions. The outcomes were significantly influenced by poor blinding methods leading to false-positive results. Optimizing cord blood-derived mesenchymal stem cells (CB-MSCs) through human sera applications seems to be promising due to better performance in proliferation and resistance against acute pro-apoptotic stress.