Introduction: The human body comprises more than 200 distinct cell types, organized into tissues and organs to fulfill the essential functions required for reproduction and survival. Stem cells are natural cells with the ability to proliferate, self-renew, and differentiate into various somatic cell types in both laboratory and in vivo settings. Two key characteristics define stem cells: their capacity for self-renewal through mitotic division to maintain their population and their ability to differentiate into various specialized cell types. These properties make them ideal candidates for clinical applications. The most potent stem cells, pluripotent cells, include embryonic stem cells and induced pluripotent stem cells, capable of generating both themselves and a wide range of adult somatic cells. However, adult stem cells have more limited differentiation potential.
The heart, the central organ of the circulatory system, is intricately connected to blood vessels to supply blood to other organs. Various methods have been employed to treat myocardial infarction and heart failure, among which cell therapy has emerged as a novel approach, garnering significant attention. In this method, researchers aim to restore lost cells and repair damaged tissue using stem cells, a capability unmatched by other treatment modalities.
History of Stem Cell Research
Methods: This article is a narrative review, with data collected through a systematic evaluation of existing scientific literature on the application of stem cells in treating cardiovascular diseases. The sources include peer-reviewed articles published in Iranian scientific journals and selected international studies up to 2020. Data were gathered by targeted searches in scientific databases such as SID, Magiran, and other relevant platforms. Inclusion criteria for selected articles comprised direct relevance to stem cell applications in myocardial infarction treatment, availability of clinical or preclinical evidence, and publication in reputable journals. The collected data were qualitatively analyzed and categorized based on key themes, including the definition of stem cells, history of research, and clinical applications in cardiac repair. The primary focus was on mesenchymal stem cells derived from bone marrow and their role in cardiac tissue regeneration. Additionally, information on tissue engineering and the use of biomaterials such as scaffolds was extracted from specialized studies.
Results: The review of studies indicates that stem cells, particularly mesenchymal stem cells (MSCs) derived from bone marrow, exhibit significant potential in improving cardiac function following myocardial infarction. Multiple preclinical and clinical studies have reported that MSC transplantation can enhance left ventricular ejection fraction (LVEF), reduce scar tissue, and stimulate angiogenesis in the damaged cardiac region. For instance, a clinical trial utilizing intravenous injection of MSCs in patients with acute myocardial infarction demonstrated significant improvements in ejection fraction, reduced scar volume, and enhanced cardiac contractility over an 18-month period. Similarly, a study by Ozbaran et al. in Turkey showed that combining cell therapy with coronary artery bypass grafting in patients with chronic heart failure improved quality of life and reduced heart failure classification (per the American Heart Association criteria). However, some early studies reported conflicting results, with no significant long-term (beyond 18 months) improvements or enhancements in diastolic function. The primary mechanisms of action for these cells include paracrine signaling and stimulation of cardiac progenitor cells, though complete integration with native cardiac tissue was not observed in the short term. In tissue engineering, the use of bioactive scaffolds such as fibrin combined with myoblasts preserved cardiac wall thickness and promoted angiogenesis. Nevertheless, challenges such as biomechanical mismatch between scaffolds and cardiac tissue persist.
Conclusion: Stem cells, particularly bone marrow-derived mesenchymal stem cells, offer a promising approach for treating myocardial infarction and heart failure due to their unique self-renewal and differentiation capabilities. Studies have demonstrated improvements in cardiac function, reduction in scar tissue, and enhanced patient quality of life. However, challenges such as optimizing cell type, delivery methods, timing, and ensuring long-term safety remain. Recent advances in paracrine signaling and tissue engineering have opened new avenues for developing sustainable and effective therapies in regenerative medicine. Given the limitations of conventional treatments like heart transplantation and pharmacotherapy, cell therapy holds transformative potential for the future of medical treatment, provided ongoing scientific and technical challenges are addressed.