Hypoxic-conditioned cardiosphere-derived cell sheet transplantation for chronic myocardial infarction

Advanced Cardiac Patches for the Treatment of Myocardial Infarction

Myocardial infarction is a cardiovascular disease characterized by a high incidence rate and mortality. It leads to various cardiac pathophysiological changes, including ischemia/reperfusion injury, inflammation, fibrosis, and ventricular remodeling, which ultimately result in heart failure and pose a significant threat to global health. Although clinical reperfusion therapies and conventional pharmacological interventions improve emergency survival rates and short-term prognoses, they are still limited in providing long-lasting improvements in cardiac function or reversing pathological progression. Recently, cardiac patches have gained considerable attention as a promising therapy for myocardial infarction. These patches consist of scaffolds or loaded therapeutic agents that provide mechanical reinforcement, synchronous electrical conduction, and localized delivery within the infarct zone to promote cardiac restoration. This review elucidates the pathophysiological progression from myocardial infarction to heart failure, highlighting therapeutic targets and various cardiac patches. The review considers the primary scaffold materials, including synthetic, natural, and conductive materials, and the prevalent fabrication techniques and optimal properties of the patch, as well as advanced delivery strategies. Last, the current limitations and prospects of cardiac patch research are considered, with the goal of shedding light on innovative products poised for clinical application.

The preclinical and clinical progress of cell sheet engineering in regenerative medicine

Cell therapy is an accessible method for curing damaged organs or tissues. Yet, this approach is limited by the delivery efficiency of cell suspension injection. Over recent years, biological scaffolds have emerged as carriers of delivering therapeutic cells to the target sites. Although they can be regarded as revolutionary research output and promote the development of tissue engineering, the defect of biological scaffolds in repairing cell-dense tissues is apparent. Cell sheet engineering (CSE) is a novel technique that supports enzyme-free cell detachment in the shape of a sheet-like structure. Compared with the traditional method of enzymatic digestion, products harvested by this technique retain extracellular matrix (ECM) secreted by cells as well as cell-matrix and intercellular junctions established during in vitro culture. Herein, we discussed the current status and recent progress of CSE in basic research and clinical application by reviewing relevant articles that have been published, hoping to provide a reference for the development of CSE in the field of stem cells and regenerative medicine.

Cardiac regeneration following myocardial infarction: the need for regeneration and a review of cardiac stromal cell populations used for transplantation

Myocardial infarction is a leading cause of death globally due to the inability of the adult human heart to regenerate after injury. Cell therapy using cardiac-derived progenitor populations emerged about two decades ago with the aim of replacing cells lost after ischaemic injury. Despite early promise from rodent studies, administration of these populations has not translated to the clinic. We will discuss the need for cardiac regeneration and review the debate surrounding how cardiac progenitor populations exert a therapeutic effect following transplantation into the heart, including their ability to form de novo cardiomyocytes and the release of paracrine factors. We will also discuss limitations hindering the cell therapy field, which include the challenges of performing cell-based clinical trials and the low retention of administered cells, and how future research may overcome them.

Freezing of cell sheets using a 3D freezer produces high cell viability after thawing

In cell therapy, transplanting an appropriate number of cells to the target site is crucial. One way to achieve this is to transplant cell sheets. Transplantation of cell sheets has already been utilized for various diseases in clinical practice. However, reducing the cost of cell sheet utilization is essential so as to facilitate the spread of regenerative medicine. Several ways to reduce costs are available, one of which is the use of allogenic cells. Another alternative is the use of cell sheets, which necessitates the development of methods for freezing cell sheets. This is the first study to report the use of a 3D Freezer for freezing cells. 3D Freezers have been used in the field of food processing and technology for a long time. The 3D Freezer freezes objects using cold air at a uniform temperature from all directions. In this study, we analyzed the cooling speed of human fibroblast sheets in 11 cell preservation solutions using a 3D Freezer and a Program Freezer. The cooling speed was −2 °C per min in the 3D Freezer. Supercooling in 10 cell preservation solutions was lower in the 3D Freezer than in the Program Freezer. Cell viability after freeze–thaw of the cell sheets using 3D Freezer was more than 70% in five cell preservation solutions. The levels of hepatocyte growth factor and transforming growth factor-β1 were the same not only in the fibroblast sheets frozen using the five cell preservation solutions but also in the non-frozen fibroblast sheets. These results suggest that the 3D Freezer can freeze implantable cell sheets immediately after thawing.

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3D Freezer operates using cold air with uniform temperature directed at an object from all directions.

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3D Freezer was trialed for freezing 3D cell sheets for the first time.

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3D Freezer can generate high cell viability after freezing and thawing for cell therapy.

Mechanical properties of cell sheets and spheroids: the link between single cells and complex tissues

Cell aggregates, including sheets and spheroids, represent a simple yet powerful model system to study both biochemical and biophysical intercellular interactions. However, it is becoming evident that, although the mechanical properties and behavior of multicellular structures share some similarities with individual cells, yet distinct differences are observed in some principal aspects. The description of mechanical phenomena at the level of multicellular model systems is a necessary step for understanding tissue mechanics and its fundamental principles in health and disease. Both cell sheets and spheroids are used in tissue engineering, and the modulation of mechanical properties of cell constructs is a promising tool for regenerative medicine. Here, we review the data on mechanical characterization of cell sheets and spheroids, focusing both on advances in the measurement techniques and current understanding of the subject. The reviewed material suggest that interplay between the ECM, intercellular junctions, and cellular contractility determines the behavior and mechanical properties of the cell aggregates.