To evaluate the regenerative capacity of non-supplemented and bioactive patches made of decellularized porcine cardiac extracellular matrix (pcECM) and characterize the biological key factors involved in possible cardiac function (CF) restoration following acute and 8weeks chronic MI. pcECM is a key natural biomaterial that can affect cardiac regeneration following myocardial infarction (MI), through mechanisms, which are still not clearly understood. Wistar rats underwent MI and received pcECM patch (pcECM-P) treatment in either acute or chronic inflammatory phases. Treated, sham operated (no MI), and control (MI without treatment) animals, were compared through echocardiography, hemodynamics, pathological evaluation and analyses of various mRNA and protein level markers. Our results show that in both acute and long-term chronic MI models, pcECM promotes significant cardiac function improvement, which is correlated to progenitor (GATA4(+), c-kit(+)) and myocyte (MYLC(+), TRPI(+)) recruitment. Interestingly, recruited progenitors, isolated using laser capture microdissection (LCM), expressed both early and late cardiomyocyte (CM) differentiation markers, suggesting differentiation towards the CM lineage. Recruited CM-like cells organized in a partially striated and immature muscle fiber arrangement that presented connexin43 -a crucial mediator of cardiac electrical conductivity. Concomitantly, pcECM was rapidly vascularized, and induced a constructive remodeling process as indicated by increased M2/M1 macrophage phenotypic ratio and pathological evaluation. Acellular pcECM patch implants alone, i.e., without added biologics, are bioactive, and exert potent efficacy, stimulating biological regenerative processes that cooperatively lead to a cardiac progenitor-based restoration of function, even after scar tissue had already formed. MI ('heart attack') remains the leading cause of heart failure and death in developed-countries. Restoration of cardiac function requires active turnover of damaged heart contracting cells (CM), however, CM endogenous regeneration is not efficient and is a matter of controversy. We show that a bioactive biomaterial alone-decellularized heart tissue (pcECM)-without added cells or growth factors, can elicit a complex regenerative response even after irreversible scarring. The pcECM patch induces macrophage polarization towards constructive remodeling and cardiomyocyte progenitor cell (GATA4(+), c-kit(+)) recruitment (evidenced at both mRNA and protein levels) resulting in de novo immature striated-like muscle patterns (MLC(+), TrpI(+), connexin43(+)). We, therefore, suggest this bioactive pcECM can model cardiac regeneration, and serve as a candidate for fast-track clinical application.

In this paper, we present a novel flexible endoscope (FE) which is well suited to minimally invasive cardiac surgery (MICS). It is named the cardioscope. The cardioscope is composed of a handle, a rigid shaft, a steerable flexible section, and the imaging system. The flexible section is composed of an elastic tube, a number of spacing disks, a constraint tube, and four wires. It employs the constrained wire-driven flexible mechanism (CWFM) with a continuum backbone, which enables the control of both the angulation and the length of the flexible section. Compared to other endoscopes, e.g., rigid endoscope (RE) and fixed-length FE, the cardioscope is much more dexterous. The cardioscope can bend over 180 deg in all directions, and the bending is decoupled from the distal tip position. Ex vivo tests show that the cardioscope is well suited to MICS. It provides much wider scope of vision than REs and provides good manipulation inside confined environments. In tests, the cardioscope successfully explored the full heart through a single hole, which shows that the design is promising. Despite being designed for MICS, the cardioscope can also be applied to other minimally invasive surgeries (MISs), such as laparoscopy, neurosurgery, transnasal surgery, and transoral surgery.

A crucial question in post-ischemic cell therapy refers to the ideal method of cell delivery to the heart. We hypothesized that epicardial implantation of subamnion-cord-lining mesenchymal stem cells (CL-MSC) angiogenic spheroids embedded within fibrin grafts (SASG) facilitates donor cell survival and enhances cardiac function in failing rat hearts. Furthermore, we compared the efficacy of this approach applied through two delivery methods. Spheroids made of 1.5×10(4) human CL-MSC coated with 2×10(3) human umbilical vein endothelial cells were self-assembled in hanging drops. SASG were constructed by embedding 150 spheroids in fibrin matrix. Except for untreated rats (MI, n=8), grafts were implanted 2 weeks after myocardial infarction upon confirmation of ensued heart failure through thoracotomy: SASG (n=8) and fibrin graft (FG, n=8); or video-assisted thoracoscopic surgery (VATS): SASG-VATS (n=8) and FG-VATS (n=7). In vivo CL-MSC survival was comparable between both SASG-treated groups throughout the study. SASG and SASG-VATS animals had decreased left ventricular end-diastolic pressure relative to untreated animals, and increased fractional shortening compared to MI and FG controls, 4 weeks after treatment. A 14.1% and 6.2% enhancement in ejection fraction from week 2 to 6 after injury was observed in SASG/SASG-VATS, paralleled by improvement in cardiac output. Treated hearts had smaller scar size, and more blood vessels than MI, while donor CL-MSC contributed to arteriogenesis within the graft and infarct areas. Taken together, our data suggest that SASG treatment has the potential to restore failing hearts by preserving cardiac function and inducing myocardial revascularization, while attenuating cardiac fibrosis. Furthermore, we introduce a method for minimally invasive in situ graft assembly.

Myocardial restoration using tissue-engineered grafts to regenerate the ischemic myocardium offers improved donor cell retention, yet a limited cell survival resulting from poor vascularization needs to be addressed. A cell type derived from the subamnion, namely, cord-lining mesenchymal stem cells (CL-MSC), has recently been identified. Here we present a restorative strategy that combines a fibrin graft containing human CL-MSC and omental flap providing, thereby, cell-, structural-, and angiogenic support to the injured myocardium. The graft consisted of a mixture of 2×10⁶ CL-MSC-GFP-Fluc and fibrin. Myocardial infarction (MI) was induced in nude rats and following confirmation of ensued heart failure with echocardiography 2 weeks after injury, therapeutic intervention was performed as follows: untreated (MI, n=7), CL-MSC graft (CL-MSCG, n=8), CL-MSCG and omental flap (CL-MSCG+OM, n=11), and omental flap (OM, n=8). In vivo bioluminescence imaging at 1, 3, 7, and 14 days post-treatment indicated comparable early donor cell viability between the CL-MSCG and CL-MSCG+OM. Treatment with CL-MSCG+OM improved the myocardial function as assessed by the measurement of end-diastolic left ventricular (LV) pressure (3.53±0.34 vs. 5.21±0.54 mmHg, p<0.05), contractility (+dP/dt, 3383.8±250.78 mmHg vs. 2464.9±191.8 mmHg, p<0.05), and the relaxation rate (−dP/dt, −2707.2±250.7 mmHg vs. 1948.7±207.8 mmHg, p<0.05), compared to MI control 6 weeks after ischemic injury. Furthermore, evidence of a 20.32% increase in the ejection fraction was observed in CL-MSCG+OM rats from week 2 to 6 after injury. Both CL-MSCG and CL-MSCG+OM led to an enhanced cardiac output (p<0.05), and attenuated the infarct size (35.7%±4.2% and 34.7%±4.8%), as compared to MI (60.7%±3.1%; p<0.01 and p<0.001, respectively). All treated groups had a higher arteriole density than controls. Yet, a higher amount of functional blood vessels, and a 20-fold increase in arteriole numbers were found in CL-MSCG+OM. Altogether, CL-MSCGs supplemented with vascular supply have the potential to repair the failing, chronically ischemic heart by improving myocardial revascularization, attenuating remodeling, and ameliorating cardiac dysfunction.