Binary Colloidal Crystals Drive Spheroid Formation and Accelerate Maturation of Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Injectable and Conductive Nanomicelle Hydrogel with α-Tocopherol Encapsulation for Enhanced Myocardial Infarction Repair

Substantial advancements have been achieved in the realm of cardiac tissue repair utilizing functional hydrogel materials. Additionally, drug-loaded hydrogels have emerged as a research hotspot for modulating adverse microenvironments and preventing left ventricular remodeling after myocardial infarction (MI), thereby fostering improved reparative outcomes. In this study, diacrylated Pluronic F127 micelles were used as macro-cross-linkers for the hydrogel, and the hydrophobic drug α-tocopherol (α-TOH) was loaded. Through the in situ synthesis of polydopamine (PDA) and the incorporation of conductive components, an injectable and highly compliant antioxidant/conductive composite FPDA hydrogel was constructed. The hydrogel exhibited exceptional stretchability, high toughness, good conductivity, cell affinity, and tissue adhesion. In a rabbit model, the material was surgically implanted onto the myocardial tissue, subsequent to the ligation of the left anterior descending coronary artery. Four weeks postimplantation, there was discernible functional recovery, manifesting as augmented fractional shortening and ejection fraction, alongside reduced infarcted areas. The findings of this investigation underscore the substantial utility of FPDA hydrogels given their proactive capacity to modulate the post-MI infarct microenvironment and thereby enhance the therapeutic outcomes of myocardial infarction.

Artificial tumor matrices and bioengineered tools for tumoroid generation

The tumor microenvironment (TME) is critical for tumor growth and metastasis. The TME contains cancer-associated cells, tumor matrix, and tumor secretory factors. The fabrication of artificial tumors, so-called tumoroids, is of great significance for the understanding of tumorigenesis and clinical cancer therapy. The assembly of multiple tumor cells and matrix components through interdisciplinary techniques is necessary for the preparation of various tumoroids. This article discusses current methods for constructing tumoroids (tumor tissue slices and tumor cell co-culture) for pre-clinical use. This article focuses on the artificial matrix materials (natural and synthetic materials) and biofabrication techniques (cell assembly, bioengineered tools, bioprinting, and microfluidic devices) used in tumoroids. This article also points out the shortcomings of current tumoroids and potential solutions. This article aims to promotes the next-generation tumoroids and the potential of them in basic research and clinical application.

Engineering Cell Microenvironment Using Nanopattern-Derived Multicellular Spheroids and Photo-Crosslinked Gelatin/Hyaluronan Hydrogels

Cell cultures of dispersed cells within hydrogels depict the interaction of the cell-extracellular matrix (ECM) in 3D, while the coculture of different cells within spheroids combines both the effects of cell-cell and cell-ECM interactions. In this study, the cell co-spheroids of human bone mesenchymal stem cells/human umbilical vein endothelial cells (HBMSC/HUVECs) are prepared with the assistance of a nanopattern, named colloidal self-assembled patterns (cSAPs), which is superior to low-adhesion surfaces. A phenol-modified gelatin/hyaluronan (Gel-Ph/HA-Ph) hydrogel is used to encapsulate the multicellular spheroids and the constructs are photo-crosslinked using blue light. The results show that Gel-Ph/HA-Ph hydrogels with a 5%-to-0.3% ratio have the best properties. Cells in HBMSC/HUVEC co-spheroids are more favorable for osteogenic differentiation (Runx2, ALP, Col1a1 and OPN) and vascular network formation (CD31+ cells) compared to HBMSC spheroids. In a subcutaneous nude mouse model, the HBMSC/HUVEC co-spheroids showed better performance than HBMSC spheroids in angiogenesis and the development of blood vessels. Overall, this study paves a new way for using nanopatterns, cell coculturing and hydrogel technology for the generation and application of multicellular spheroids.

Aligned Nanofibrous Net Deposited Perpendicularly on Microridges Supports Endothelium Formation and Promotes the Structural Maturation of hiPSC-Derived Cardiomyocytes

Cell alignment widely exists in various in vivo tissues and also plays an essential role in the construction of in vitro models, such as vascular endothelial and myocardial models. Recently, microscale and nanoscale hierarchical topographical structures have been drawing increasing attention for engineering in vitro cell alignment. In the present study, we fabricated a micro-/nanohierarchical substrate based on soft lithography and electrospinning to assess the synergetic effect of both the aligned nanofibrous topographical guidance and the off-ground culture environment provided by the substrate on the endothelium formation and the maturation of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The morphology, proliferation, and barrier formation of human umbilical vein endothelial cells (HUVECs) as well as the alignment, cardiac-specific proteins, and maturity-related gene expression of hiPSC-CMs on the aligned-nanofiber/microridge (AN-MR) substrate were studied. Compared with the glass slide and the single-aligned nanofiber substrate, the AN-MR substrate enhanced the proliferation, alignment, and cell-cell interaction of HUVECs and improved the length of the sarcomere and maturation-related gene expression of hiPSC-CMs. Finally, the response of hiPSC-CMs on different substrates to two typical cardiac drugs (isoproterenol and E-4031) was tested and analyzed, showing that the hiPSC-CMs on AN-MR substrates were more resistant to drugs than those in other groups, which was related to the higher maturity of the cells. Overall, the proposed micro-/nanohierarchical substrate supports the in vitro endothelium formation and enhances the maturation of hiPSC-CMs, which show great potential to be applied in the construction of in vitro models and tissue engineering.

Binary Colloidal Crystals Promote Cardiac Differentiation of Human Pluripotent Stem Cells via Nuclear Accumulation of SETDB1

Biophysical cues can facilitate the cardiac differentiation of human pluripotent stem cells (hPSCs), yet the mechanism is far from established. One of the binary colloidal crystals, composed of 5 μm Si and 400 nm poly(methyl methacrylate) particles named 5PM, has been applied as a substrate for hPSCs cultivation and cardiac differentiation. In this study, cell nucleus, cytoskeleton, and epigenetic states of human induced pluripotent stem cells on the 5PM were analyzed using atomic force microscopy, molecular biology assays, and the assay for transposase-accessible chromatin sequencing (ATAC-seq). Cells were more spherical with stiffer cell nuclei on the 5PM compared to the flat control. ATAC-seq revealed that chromatin accessibility decreased on the 5PM, caused by the increased entry of histone lysine methyltransferase SETDB1 into the cell nuclei and the amplified level of histone H3K9me3 modification. Reducing cytoskeleton tension using a ROCK inhibitor attenuated the nuclear accumulation of SETDB1 on the 5PM, indicating that the effect is cytoskeleton-dependent. In addition, the knockdown of SETDB1 reversed the promotive effects of the 5PM on cardiac differentiation, demonstrating that biophysical cue-induced cytoskeletal tension, cell nucleus deformation, and then SETDB1 accumulation are critical outside-in signal transformations in cardiac differentiation. Human embryonic stem cells showed similar results, indicating that the biophysical impact of the 5PM surfaces on cardiac differentiation could be universal. These findings contribute to our understanding of material-assistant hPSC differentiation, which benefits materiobiology and stem cell bioengineering.

Maturation of induced pluripotent stem cell-derived cardiomyocytes and its therapeutic effect on myocardial infarction in mouse

Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have an irreplaceable role in the treatment of myocardial infarction (MI), which can be injected into the transplanted area with new cardiomyocytes (Cardiomyocytes, CMs), and improve myocardial function. However, the immaturity of the structure and function of iPSC-CMs is the main bottleneck at present. Since collagen participates in the formation of extracellular matrix (ECM), we synthesized nano colloidal gelatin (Gel) with collagen as the main component, and confirmed that the biomaterial has good biocompatibility and is suitable for cellular in vitro growth. Subsequently, we combined the PI3K/AKT/mTOR pathway inhibitor BEZ-235 with Gel and found that the two combined increased the sarcomere length and action potential amplitude (APA) of iPSC-CMs, and improved the Ca²⁺ processing ability, the maturation of mitochondrial morphological structure and metabolic function. Not only that, Gel can also prolong the retention rate of iPSC-CMs in the myocardium and increase the expression of Cx43 and angiogenesis in the transplanted area of mature iPSC-CMs, which also provides a reliable basis for the subsequent treatment of mature iPSC-CMs.

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BEZ-235 + Gel promotes the maturation of sarcomere structure in iPSC-CMs.

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BEZ-235 + Gel promotes electrophysiological maturation of iPSC-CMs.

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BEZ-235 + Gel increases mitochondrial respiration in iPSC-CMs.

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Gel loaded with mature iPSC-CMs enhanced angiogenesis and gap junction formation at the injection site.

Engineering the maturation of stem cell-derived cardiomyocytes

The maturation of human stem cell-derived cardiomyocytes (hSC-CMs) has been a major challenge to further expand the scope of their application. Over the past years, several strategies have been proven to facilitate the structural and functional maturation of hSC-CMs, which include but are not limited to engineering the geometry or stiffness of substrates, providing favorable extracellular matrices, applying mechanical stretch, fluidic or electrical stimulation, co-culturing with niche cells, regulating biochemical cues such as hormones and transcription factors, engineering and redirecting metabolic patterns, developing 3D cardiac constructs such as cardiac organoid or engineered heart tissue, or culturing under in vivo implantation. In this review, we summarize these maturation strategies, especially the recent advancements, and discussed their advantages as well as the pressing problems that need to be addressed in future studies.

Defined Physicochemical Cues Steering Direct Neuronal Reprogramming on Colloidal Self-Assembled Patterns (cSAPs)

Direct neuronal reprogramming of somatic cells into induced neurons (iNs) has been recently established as a promising approach to generating neuron cells. Previous studies have reported that the biophysical cues of the in vitro microenvironment are potent modulators in the cell fate decision; thus, the present study explores the effects of a customized pattern (named colloidal self-assembled patterns, cSAPs) on iN generation from human fibroblasts using small molecules. The result revealed that the cSAP, composed of binary particles in a hexagonal-close-packed (hcp) geometry, is capable of improving neuronal reprogramming efficiency and steering the ratio of the iN subtypes. Cells exhibited distinct cell morphology, upregulated cell adhesion markers (i.e., SDC1 and ITGAV), enriched signaling pathways (i.e., Hippo and Wnt), and chromatin remodeling on the cSAP compared to those on the control substrates. The result also showed that the iN subtype specification on cSAP was surface-dependent; therefore, the defined physicochemical cue from each cSAP is exclusive. Our findings show that direct cell reprogramming can be manipulated through specific biophysical cues on the artificial matrix, which is significant in cell transdifferentiation and lineage conversion.

Cardiomyocyte Maturation-the Road is not Obstructed

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) represent one of the most promising ways to treat cardiovascular diseases. High-purity cardiomyocytes (CM) from different cell sources could be obtained at present. However, the immature nature of these cardiomyocytes hinders its further clinical application. From immature to mature state, it involves structural, functional, and metabolic changes in cardiomyocytes. Generally, two types of culturing (2D and 3D) systems have been reported to induce cardiomyocyte maturation. 2D culture mainly achieves the maturation of cardiomyocytes through long-term culture, co-culture, supplementation of small molecule compounds, and the application of biophysical cues. The combined use of biomaterial's surface topography and biophysical cues also facilitates the maturation of cardiomyocytes. Cardiomyocyte maturation is a complex process involving many signaling pathways, and current methods fail to fully reproduce this process. Therefore, analyzing the signaling pathway network related to the maturation and producing hPSC-CMs with adult-like phenotype is a challenge. In this review, we summarized the structural and functional differences between hPSC-CMs and mature cardiomyocytes, and introduced various methods to induce cardiomyocyte maturation.

Hybrid Surface Nanostructures Using Chemical Vapor Deposition and Colloidal Self-Assembled Patterns for Human Mesenchymal Stem Cell Culture—A Preliminary Study

Surface coatings are critical in biomaterials and biomedical devices. Chemical vapor deposition (CVD) is a well-known technology for the generation of thin films on a surface. However, the granular structures produced using CVD are rare. Recently, we used PPX-C, an excellent insulating material, for granular structure coating using CVD. Colloidal self-assembly is also a well-established method to generate granular structures named colloidal self-assembled patterns (cSAPs). In this study, we combined these two technologies to generate hierarchical granular structures and tested the biophysical effect of these hybrid surfaces on human bone marrow mesenchymal stem cells (hBMSCs). Two CVD-derived granular structures were made using water or glycerin droplets (i.e., CVD or GlyCVD surfaces). Water drops generate porous particles, while glycerin drops generate core–shell particles on the surface. These particles were dispersed randomly on the surface with sizes ranging from 1 to 20 μm. These CVD surfaces were hydrophobic (WCA ~ 80–110 degrees). On the other hand, a binary colloidal crystal (BCC), one type of cSAPs, composed of 5 μm Si and 400 nm carboxylated polystyrene (PSC) particles, had a close-packed structure and a hydrophilic surface (WCA ~ 45 degrees). The hybrid surfaces (i.e., CVD-BCC and GlyCVD-BCC) were smooth (Ra ~ 1.1–1.5 μm) and hydrophilic (WCA ~ 50 degrees), indicating a large surface coverage of BCC dominating the surface property. The hybrid surfaces were expected to be slightly negatively charged due to naturally charged CVD particles and negatively charged BCC particles. Cell adhesion was reduced on the hybrid surfaces, leading to an aggregated cell morphology, without reducing cell activity, compared to the flat control after 5 days. qPCR analysis showed that gene expression of type II collagen (COL2) was highly expressed on the GlyCVD-BCC without chemical induction after 3 and 14 days compared to the flat control. This proof-of-concept study demonstrates the potential of combining two technologies to make hybrid structures that can modulate stem cell attachment and differentiation.

Combinatorial Approach of Binary Colloidal Crystals and CRISPR Activation to Improve Induced Pluripotent Stem Cell Differentiation into Neurons

Conventional methods of neuronal differentiation in human induced pluripotent stem cells (iPSCs) are tedious and complicated, involving multistage protocols with complex cocktails of growth factors and small molecules. Artificial extracellular matrices with a defined surface topography and chemistry represent a promising venue to improve neuronal differentiation in vitro. In the present study, we test the impact of a type of colloidal self-assembled patterns (cSAPs) called binary colloidal crystals (BCCs) on neuronal differentiation. We developed a CRISPR activation (CRISPRa) iPSC platform that constitutively expresses the dCas9-VPR system, which allows robust activation of the proneural transcription factor NEUROD1 to rapidly induce neuronal differentiation within 7 days. We show that the combinatorial use of BCCs can further improve this neuronal differentiation system. In particular, our results indicate that fine tuning of silica (Si) and polystyrene (PS) particle size is critical to generate specific topographies to improve neuronal differentiation and branching. BCCs with 5 μm silica and 100 nm carboxylated PS (PSC) have the most prominent effect on increasing neurite outgrowth and more complex ramification, while BCCs with 2 μm Si and 65 nm PSC particles are better at promoting neuronal enrichment. These results indicate that biophysical cues can support rapid differentiation and improve neuronal maturation. In summary, our combinatorial approach of CRISPRa and BCCs provides a robust and rapid pipeline for the in vitro production of human neurons. Specific BCCs can be adapted to the late stages of neuronal differentiation protocols to improve neuronal maturation, which has important implications in tissue engineering, in vitro biological studies, and disease modeling.

Harnessing Focal Adhesions to Accelerate p53 Accumulation and Anoikis of A549 Cells Using Colloidal Self-Assembled Patterns (cSAPs)

Extracellular matrix (ECM) of the tumor microenvironment (TME), including topography and biological molecules, is crucial in cancer cell attachment, growth, and even the sensitivity to the chemo and cell drugs treatment. This study hypothesizes that mimic ECM structures can alter the attachment and drug sensitivity of cancer cells. A family of artificial ECM called colloidal self-assembled patterns (cSAPs) was fabricated to mimic tumor ECM structures. Cell adhesion, proliferation, and drug sensitivity of the A549 non-small cell lung cancer (NSCLC) cells were studied on 24 cSAPs, named cSAP#1-cSAP#24, where surface topography and wettability were distinct. The results showed that cell adhesion and cell spreading were generally reduced on cSAPs compared to the flat controls. In addition, the synergistic effect of cSAPs and several chemo drugs on cell survival was investigated. Interestingly, A549 cells were more sensitive to the combination of doxorubicin and cSAP#4. Under this condition, the focal adhesion kinase (FAK) signaling was downregulated while p53 signaling was upregulated, confirmed by real-time PCR and western blot analysis. It indicates that the specific surface structure could induce higher drug sensitivity and in vitro anoikis of A549 cells. A serum alternative, human platelet lysate (hPL), and different cSAPs were examined to verify our hypothesis. The result further confirmed that cell adhesion strongly affected the drug sensitivity of A549 cells. This study demonstrates that the tumor ECM is vital in cancer cell activity and drug sensitivity; therefore, it should be considered in drug discovery and therapeutic regimens.

Colloidal Self-Assembled Patterns Maintain the Pluripotency and Promote the Hemopoietic Potential of Human Embryonic Stem Cells

The generation of blood cells in a significant amount for clinical uses is still challenging. Human pluripotent stem cells-derived hemopoietic cells (hPSC-HCs) are a promising cell source to generate blood cells. Previously, it has been shown that the attached substrates are crucial in the maintenance or differentiation of hPSCs. In this study, a new family of artificial extracellular matrix (ECM) called colloidal self-assembled patterns (cSAPs: #1-#5) was used for the expansion of mouse and human PSCs. The optimized cSAP (i.e., #4 and #5) was selected for subsequent hemopoietic differentiation of human embryonic stem cells (hESCs). Results showed that the hematopoietic potential of hESCs was enhanced approx 3-4 folds on cSAP #5 compared to the flat control. The cell population of hematopoietic progenitors (i.e., CD34+CD43+ cells) and erythroid progenitors (i.e., CD71+GPA+ cells) were enhanced 4 folds at day 8 and 3 folds at day 14. RNA sequencing analysis of cSAP-derived hESCs showed that there were 300 genes up-regulated and 627 genes down-regulated compared to the flat control. The enriched signaling pathways, including up-regulation (i.e., Toll-like receptor, HIF-1a, and Notch) or down-regulation (i.e., FAs, MAPK, JAK/STAT, and TGF-β) were classic in the maintenance of hESC phenotype Real time PCR confirmed that the expression of focal adhesion (PTK2, VCL, and CXCL14) and MAPK signaling (CAV1) related genes was down-regulated 2-3 folds compared to the flat control. Altogether, cSAP enhances the pluripotency and the hematopoietic potential of hESCs that subsequently generates more blood-like cells. This study reveals the potential of cSAPs on the expansion and early-stage blood cell lineage differentiation of hPSCs.

Maturation strategies and limitations of induced pluripotent stem cell-derived cardiomyocytes

Induced pluripotent stem cells (iPSCs) have the ability to differentiate into cardiomyocytes (CMs). They are not only widely used in cardiac pharmacology screening, human heart disease modeling, and cell transplantation-based treatments, but also the most promising source of CMs for experimental and clinical applications. However, their use is largely restricted by the immature phenotype of structure and function, which is similar to embryonic or fetal CMs and has certain differences from adult CMs. In order to overcome this critical issue, many studies have explored and revealed new strategies to induce the maturity of iPSC-CMs. Therefore, this article aims to review recent induction methods of mature iPSC-CMs, related mechanisms, and limitations.

Harnessing Colloidal Self-Assembled Patterns (cSAPs) to Regulate Bacterial and Human Stem Cell Response at Biointerfaces In Vitro and In Vivo

The generation of complex physicochemical signals on the surface of biomedical materials is still challenging despite the fact that a broad range of surface modification methods have been developed over the last few decades. Colloidal self-assembled patterns (cSAPs) are combinations of unique colloids differing in size and surface chemistry acting as building blocks that can be programmed to generate surface patterns with exquisite control of complexity. This study reports on producing a variety of pre-modified colloids for the fabrication of cSAPs as well as post-assembly modifications to yield complex surfaces. The surface of cSAPs presents hierarchical micro- and nanostructures, localized hydrophilic/hydrophobic characteristics, and tunable surface functionality imparted by the individual colloids. The selected cSAPs can control bacterial adhesion (S. aureus, P. aeruginosa, and E. coli) and affect the cell cycle of human bone marrow stem cells (hBMSCs). Moreover, in a mouse subcutaneous model, cSAPs with selective [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium (SBMA) modification can reduce the inflammatory response after being challenged with bacteria. This study reveals that functionalized cSAPs are versatile tools for controlling cellular responses at biointerfaces, which is instructive for biomaterials or biodevices.

Programming Colloidal Self-Assembled Patterns (cSAPs) into Thermo-Responsible Hybrid Surfaces for Controlling Human Stem Cells and Macrophages

Hybrid surfaces with tunable topography, chemistry, and stiffness have potential to rebuild native extracellular matrix (ECM) and manipulate cell behavior in vitro. However, the fabrication of controllable hybrid surfaces is still challenging. In this study, colloidal self-assembly technology was used to program particles into highly ordered structures with hybrid chemistry and stiffness at biointerfaces. These colloidal self-assembled patterns (cSAPs), including unary, binary, and ternary cSAPs, composed of silicon (Si), polystyrene (PS), and/or poly(N-isopropylacrylamide) (pNIPAM) nanogels (PNGs), were fabricated using either coassembly or layer-by-layer (LBL) methods. The selected binary cSAPs (i.e., PS/PNG and PNG/PS) have a tunable surface topography and wettability between 25 and 37 °C; thus, they can be used as dynamic cell culture substrates. Human adipose-derived mesenchymal stem cells (hASCs), bone marrow-derived mesenchymal stem cells (hBMSCs), and macrophages (THP-1) were investigated on these hybrid cSAPs under a static or dynamic system. The results showed that hybrid cSAPs significantly influenced the focal adhesions, cell morphology, cell migration, and gene expressions of stem cells. In general, stem cells had more vinculin puncta, smaller spreading size, and faster migration speed than the TCPS control. Hybrid cSAPs up-regulated gene expressions of focal adhesion kinase (FAK) and chondrocytes (AGG and SOX9) under static culture, while they also up-regulated osteocytes (COL1 and RUNX2) under dynamic culture. THP-1 macrophages were at M0 state on all cSAPs under static culture. However, cells became sensitive under dynamic culture. For example, some M1 genes (i.e., IL6, CD68, and TNFα) and M2 genes (i.e., IL10 and CD206) were down-regulated, while other M1 genes (i.e., IL1β) and M2 genes (i.e., TGF-β and IL1ra) were up-regulated, depending on the particle combinations. In conclusion, new hybrid cSAPs with thermoresponsive surface properties are versatile materials for stem cells and macrophages manipulation.

Transplantation of human induced pluripotent stem cell-derived cardiomyocytes improves myocardial function and reverses ventricular remodeling in infarcted rat hearts

Background

Human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have shed great light on cardiac regenerative medicine and specifically myocardial repair in heart failure patients. However, the treatment efficacy and the survival of iPSC-CMs in vivo after transplantation have yielded inconsistent results.

Objectives

The objective of this study was to evaluate the ability of human iPSC-CMs to improve myocardial function in a rat postinfarction heart failure model.

Methods

Eight-week-old male Sprague-Dawley rats were randomly selected to receive an intramyocardial injection of 5% albumin solution with or without 1 × 10⁷ human iPSC-CMs 10 days after undergoing left anterior descending (LAD) coronary artery ligation. Cyclosporine A and methylprednisolone were administered before iPSC-CM injection and until the rats were killed to prevent graft rejection. Cardiac function was evaluated by echocardiography. The survival of grafted cardiomyocytes was confirmed by observing the fluorescent cell tracer Vybrant™ CM-DiI or expression of the enhanced green fluorescent protein (eGFP) in transplanted cells, or survival was demonstrated by polymerase chain reaction (PCR)-based detection of human mitochondrial DNA. Sirius red stain was used to evaluate the fibrosis ratio. Hematoxylin-eosin staining was used to observe the formation of teratomas.

Results

Four weeks after intramyocardial injection of iPSC-CMs, animals undergoing iPSC-CM transplantation had lower mortality than the control group. Animals injected with cell-free solution (control group) demonstrated significant left ventricular (LV) functional deterioration, whereas grafting of iPSC-CMs attenuated this remodeling process. In the control group, the ejection fraction deteriorated by 10.11% (from 46.36 to 41.67%), and fractional shortening deteriorated by 9.23% (from 24.37 to 22.12%) by 4 weeks. In the iPSC-CM injection group, the ejection fraction improved by 18.86% (from 44.09 to 52.41%), and fractional shortening improved by 23.69% (from 23.08 to 28.54%). Cell labeling, tracking, and molecular biology techniques indicated that the grafted cardiomyocytes survived in the rat heart 1 month after iPSC-CM transplantation. Myocardial fibrosis was also attenuated in the iPSC-CM treatment group.

Conclusions

Human iPSC-CM grafts survived in infarcted rat hearts and restored myocardial function 4 weeks after transplantation. Cell replacement therapy also reversed ventricular remodeling, indicating the potential of iPSC-CMs for cardiac repair strategies.

Electronic supplementary material

The online version of this article (10.1186/s13287-020-01602-0) contains supplementary material, which is available to authorized users.