Remodeling Failing Human Myocardium With Hybrid Cell/Matrix and Transmyocardial Revascularization

Synergistic Effect of Transmyocardial Revascularization and Platelet-Rich Plasma on Improving Cardiac Function After Coronary Artery Bypass Grafting

Background Coronary artery disease (CAD) is a global health burden, contributing to mortality and morbidity. A proportion of patients with CAD suffer from diffuse CAD, where conventional revascularization techniques such as percutaneous coronary intervention and coronary artery bypass grafting (CABG) may be insufficient to adequately restore myocardial perfusion. Transmyocardial revascularization (TMR) uses a laser to create microscopic channels in the myocardium, inducing inflammation, angiogenesis, and neovascularization to improve perfusion to ischemic regions. Platelet-rich plasma (PRP) is an autologous concentrate of platelets that contains a myriad of growth factors and bioactive proteins, which have been shown to promote tissue regeneration and wound healing. The combination of TMR and PRP therapies has been proposed to synergistically enhance myocardial revascularization and functional recovery in patients with advanced CAD undergoing surgical revascularization. Methods This study evaluated the efficacy of combining TMR and PRP with CABG in improving cardiac function in diffuse CAD patients. Fifty-two patients were randomized to CABG alone (n = 16), CABG+TMR (n = 17), CABG+PRP (n = 10), and CABG+TMR+PRP (n = 9). TMR was performed using a holmium:YAG laser to create 10 channels in the inferolateral left ventricular wall. PRP was prepared from autologous whole blood and injected into the myocardium adjacent to the TMR channels. Cardiac function was assessed using speckle-tracking echocardiography preoperatively, postoperatively, and at one-year follow-up. Adverse events, including post-operative atrial fibrillation, acute kidney injury, and readmissions, were also recorded. Statistical analyses were performed to compare outcomes between the treatment groups. Results The CABG+TMR+PRP group showed significantly improved global longitudinal strain (GLS) at one year compared to CABG alone (mean GLS -15.96 vs -12.09, p = 0.02). Post-operative left ventricular ejection fraction trended higher in the TMR+PRP group (57.78%) vs other groups, but not significantly. Post-operative atrial fibrillation was higher in the TMR+PRP group (67% vs 25%, p = 0.04), potentially reflecting increased inflammation. No significant differences were observed in other adverse events. Conclusions The results of this study suggest a synergistic benefit of combining TMR and PRP therapies as an adjunct to CABG in patients with diffuse CAD. The significant improvement in GLS at one year in the TMR+PRP group compared to CABG alone indicates enhanced myocardial remodeling and functional recovery, which may translate to improved long-term outcomes. The higher incidence of postoperative atrial fibrillation in the TMR+PRP group warrants further investigation but may reflect the heightened inflammatory response necessary for angiogenesis and tissue regeneration. Prospective, randomized controlled trials with larger sample sizes and longer follow-up periods are needed to validate these findings and optimize treatment protocols. Nonetheless, concomitant TMR+PRP therapy represents a promising approach to augmenting myocardial revascularization and recovery in patients with advanced CAD undergoing surgical revascularization.

Epicardial placement of human placental membrane protects from heart injury in a swine model of myocardial infarction

Cardiac ischemic reperfusion injury (IRI) is paradoxically instigated by reestablishing blood-flow to ischemic myocardium typically from a myocardial infarction (MI). Although revascularization following MI remains the standard of care, effective strategies remain limited to prevent or attenuate IRI. We hypothesized that epicardial placement of human placental amnion/chorion (HPAC) grafts will protect against IRI. Using a clinically relevant model of IRI, swine were subjected to 45 min percutaneous ischemia followed with (MI + HPAC, n = 3) or without (MI only, n = 3) HPAC. Cardiac function was assessed by echocardiography, and regional punch biopsies were collected 14 days post-operatively. A deep phenotyping approach was implemented by using histological interrogation and incorporating global proteomics and transcriptomics in nonischemic, ischemic, and border zone biopsies. Our results established HPAC limited the extent of cardiac injury by 50% (11.0 ± 2.0% vs. 22.0 ± 3.0%, p = 0.039) and preserved ejection fraction in HPAC-treated swine (46.8 ± 2.7% vs. 35.8 ± 4.5%, p = 0.014). We present comprehensive transcriptome and proteome profiles of infarct (IZ), border (BZ), and remote (RZ) zone punch biopsies from swine myocardium during the proliferative cardiac repair phase 14 days post-MI. Both HPAC-treated and untreated tissues showed regional dynamic responses, whereas only HPAC-treated IZ revealed active immune and extracellular matrix remodeling. Decreased endoplasmic reticulum (ER)-dependent protein secretion and increased antiapoptotic and anti-inflammatory responses were measured in HPAC-treated biopsies. We provide quantitative evidence HPAC reduced cardiac injury from MI in a preclinical swine model, establishing a potential new therapeutic strategy for IRI. Minimizing the impact of MI remains a central clinical challenge. We present a new strategy to attenuate post-MI cardiac injury using HPAC in a swine model of IRI. Placement of HPAC membrane on the heart following MI minimizes ischemic damage, preserves cardiac function, and promotes anti-inflammatory signaling pathways.

Inflammation-mediated matrix remodeling of extracellular matrix-mimicking biomaterials in tissue engineering and regenerative medicine

Extracellular matrix (ECM)-mimicking biomaterials are considered effective tissue-engineered scaffolds for regenerative medicine because of their biocompatibility, biodegradability, and bioactivity. ECM-mimicking biomaterials preserve natural microstructures and matrix-related bioactive components and undergo continuous matrix remodeling upon transplantation. The interaction between host immune cells and transplanted ECM-mimicking biomaterials has attracted considerable attention in recent years. Transplantation of biomaterials may initiate injuries and early pro-inflammation reactions characterized by infiltration of neutrophils and M1 macrophages. Pro-inflammation reactions may lead to degradation of the transplanted biomaterial and drive the matrix into a fetal-like state. ECM degradation leads to the release of matrix-related bioactive components that act as signals for cell migration, proliferation, and differentiation. In late stages, pro-inflammatory cells fade away, and anti-inflammatory cells emerge, which involves macrophage polarization to the M2 phenotype and leukocyte activation to T helper 2 (Th2) cells. These anti-inflammatory cells interact with each other to facilitate matrix deposition and tissue reconstruction. Deposited ECM molecules serve as vital components of the mature tissue and influence tissue homeostasis. However, dysregulation of matrix remodeling results in several pathological conditions, such as aggressive inflammation, difficult healing, and non-functional fibrosis. In this review, we summarize the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. STATEMENT OF SIGNIFICANCE: Extracellular matrix (ECM)-mimicking biomaterials are effectively used as scaffolds in tissue engineering and regenerative medicine. However, dysregulation of matrix remodeling can cause various pathological conditions. Here, the review describes the characteristics of inflammatory responses in matrix remodeling after transplantation of ECM-mimicking biomaterials. Additionally, we discuss the intrinsic linkages between matrix remodeling and tissue regeneration. We believe that understanding host immune responses to matrix remodeling of transplanted biomaterials is important for directing effective tissue regeneration of ECM-mimicking biomaterials. Considering the close relationship between immune response and matrix remodeling results, we highlight the need for studies of the effects of clinical characteristics on matrix remodeling of transplanted biomaterials.

Decellularized Extracellular Matrix Materials for Cardiac Repair and Regeneration

Decellularized extracellular matrix (dECM) is a promising biomaterial for repairing cardiovascular tissue, as dECM most effectively captures the complex array of proteins, glycosaminoglycans, proteoglycans, and many other matrix components that are found in native tissue, providing ideal cues for regeneration and repair of damaged myocardium. dECM can be used in a variety of forms, such as solid scaffolds that maintain native matrix structure, or as soluble materials that can form injectable hydrogels for tissue repair. dECM has found recent success in many regeneration and repair therapies, such as for musculoskeletal, neural, and liver tissues. This review focuses on dECM in the context of cardiovascular applications, with variations in tissue and species sourcing, and specifically discusses advances in solid and soluble dECM development, in vitro studies, in vivo implementation, and clinical translation.