Spheroid formation and enhanced cardiomyogenic potential of adipose-derived stem cells grown on chitosan

Optimizing Cardiomyocyte Differentiation: Comparative Analysis of Bone Marrow and Adipose-Derived Mesenchymal Stem Cells in Rats Using 5-Azacytidine and Low-Dose FGF and IGF Treatment

Mesenchymal stem cells (MSCs) exhibit multipotency, self-renewal, and immune-modulatory properties, making them promising in regenerative medicine, particularly in cardiovascular treatments. However, optimizing the MSC source and induction method of cardiac differentiation is challenging. This study compares the cardiomyogenic potential of bone marrow (BM)-MSCs and adipose-derived (AD)-MSCs using 5-Azacytidine (5-Aza) alone or combined with low doses of Fibroblast Growth Factor (FGF) and Insulin-like Growth Factor (IGF). BM-MSCs and AD-MSCs were differentiated using two protocols: 10 μmol 5-Aza alone and 10 μmol 5-Aza with 1 ng/mL FGF and 10 ng/mL IGF. Morphological, transcriptional, and translational analyses, along with cell viability assessments, were performed. Both the MSC types exhibited similar morphological changes; however, AD-MSCs achieved 70-80% confluence faster than BM-MSCs. Surface marker profiling confirmed CD29 and CD90 positivity and CD45 negativity. The differentiation protocols led to cell flattening and myotube formation, with earlier differentiation in AD-MSCs. The combined protocol reduced cell mortality in BM-MSCs and enhanced the expression of cardiac markers (MEF2c, Troponin I, GSK-3β), particularly in BM-MSCs. Immunofluorescence confirmed cardiac-specific protein expression in all the treated groups. Both MSC types exhibited the expression of cardiac-specific markers indicative of cardiomyogenic differentiation, with the combined treatment showing superior efficiency for BM-MSCs.

Optimization of transplantation methods using isolated mesenchymal stem/stromal cells: clinical trials of inflammatory bowel diseases as an example

Mesenchymal stem/stromal cells (MSCs) are distributed in various tissues and are used in clinical applications as a source of transplanted cells because of their easy harvestability. Although MSCs express numerous cell-surface antigens, single-cell analyses have revealed a highly heterogeneous cell population depending on the original tissue and donor conditions, including age and interindividual differences. This heterogeneity leads to differences in their functions, such as multipotency and immunomodulatory effects, making it challenging to effectively treat targeted diseases. The therapeutic efficacy of MSCs is controversial and depends on the implantation site. Thus, there is no established recipe for the transplantation of MSCs (including the type of disease, type of origin, method of cell culture, form of transplanted cells, and site of delivery). Our recent preclinical study identified appropriate MSCs and their suitable transplantation routes in a mouse model of inflammatory bowel disease (IBD). Three-dimensional (3D) cultures of MSCs have been demonstrated to enhance their properties and sustain engraftment at the lesion site. In this note, we explore the methods of MSC transplantation for treating IBDs, especially Crohn's disease, from clinical trials published over the past decade. Given the functional changes in MSCs in 3D culture, we also investigate the clinical trials using 3D constructs of MSCs and explore suitable diseases that might benefit from this approach. Furthermore, we discuss the advantages of the prospective isolation of MSCs in terms of interindividual variability. This note highlights the need to define the method of MSC transplantation, including interindividual variability, the culture period, and the transplantation route.

Generation of cardiomyocytes from stem cells cultured on nanofibrous scaffold: Experimental approach for attenuation of myocardial infarction

The current study was constructed to fabricate polyamide based nanofibrous scaffolds (NS) and to define the most promising one for the generation of cardiomyocytes from adipose tissue derived mesenchymal stem cells (ADMSCs). This purpose was extended to assess the potentiality of the generated cardiomyocytes in relieving myocardial infarction (MI) in rats. Production and characterization of NSs were carried out. ADMSCs were cultured on NS and induced to differentiate into cardiomyocytes by specific growth factors. Molecular analysis for myocyte-specific enhancer factor 2 C (MEF2C) and alpha sarcomeric actin (α-SCA) expression was done to confirm the differentiation of ADMSCs into cardiomyocytes for further transplantation into MI induced rats. Implantation of cells in MI afflicted rats boosted heart rate, ST height and PR interval and lessened P duration, RR, QTc and QRS intervals. Also, this type of medication minified serum lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) enzymes activity as well as serum and cardiac troponin T (Tn-T) levels and upraised serum and cardiac α-SCA and cardiac connexin 43 (CX 43) levels. Microscopic feature of cardiac tissue sections of rats in the treated groups revealed great renovation in the cardiac microarchitecture. Conclusively, this attempt gains insight into a realistic strategy for recovery of MI through systemic employment of in vitro generated cardiomyocytes.

Progress in preclinical research on induced pluripotent stem cell therapy for acute myocardial infarction

Induced pluripotent stem cells (iPSCs) are obtained by introducing exogenous genes or adding chemicals to the culture medium to induce somatic cell differentiation. Similarly to embryonic stem cells, iPSCs have the ability to differentiate into all three embryonic cell lines. iPSCs can differentiate into cardiac muscle cells through two-dimensional differentiation methods such as monolayer cell culture and co-culture, or through embryoid body and scaffold-based three-dimensional differentiation methods. In addition, the process of iPSCs differentiation into cardiac muscle cells also requires activation or inhibition of specific signaling pathways,such as Wnt, BMP, Notch signaling pathways to mimic the development of the heart in vivo. In recent years, suspension culturing in bioreactors has been shown to produce large number of iPSCs derived cardiac muscle cells (iPSC-CMs). Before transplantation, it is necessary to purify iPSC-CMs through metabolic regulation or cell sorting to eliminate undifferentiated iPSCs, which may lead to teratoma formation. The transplantation methods for iPSC-CMs are mainly injection of cell suspension and transplantation of cell patches into the infarcted myocardium. Animal studies have shown that transplantation of iPSC-CMs into the infarcted myocardium can improve cardiac function. This article reviews the progress in preclinical studies on iPSC-CMs therapy for acute myocardial infarction and discusses the limitations and challenges of its clinical application to provide references for further clinical research and application.

Advancements in culture technology of adipose-derived stromal/stem cells: implications for diabetes and its complications

Stem cell-based therapies exhibit considerable promise in the treatment of diabetes and its complications. Extensive research has been dedicated to elucidate the characteristics and potential applications of adipose-derived stromal/stem cells (ASCs). Three-dimensional (3D) culture, characterized by rapid advancements, holds promise for efficacious treatment of diabetes and its complications. Notably, 3D cultured ASCs manifest enhanced cellular properties and functions compared to traditional monolayer-culture. In this review, the factors influencing the biological functions of ASCs during culture are summarized. Additionally, the effects of 3D cultured techniques on cellular properties compared to two-dimensional culture is described. Furthermore, the therapeutic potential of 3D cultured ASCs in diabetes and its complications are discussed to provide insights for future research.

Exploring Cutting-Edge Approaches to Potentiate Mesenchymal Stem Cell and Exosome Therapy for Myocardial Infarction

Cardiovascular diseases (CVDs) continue to be a significant global health concern. Many studies have reported promising outcomes from using MSCs and their secreted exosomes in managing various cardiovascular-related diseases like myocardial infarction (MI). MSCs and exosomes have demonstrated considerable potential in promoting regeneration and neovascularization, as well as exerting beneficial effects against apoptosis, remodeling, and inflammation in cases of myocardial infarction. Nonetheless, ensuring the durability and effectiveness of MSCs and exosomes following in vivo transplantation remains a significant concern. Recently, novel methods have emerged to improve their effectiveness and robustness, such as employing preconditioning statuses, modifying MSC and their exosomes, targeted drug delivery with exosomes, biomaterials, and combination therapy. Herein, we summarize the novel approaches that intensify the therapeutic application of MSC and their derived exosomes in treating MI.

Impact of Adipose Tissue Depot Harvesting Site on the Multilineage Induction Capacity of Male Rat Adipose-Derived Mesenchymal Stem Cells: An In Vitro Study

Recently, substantial attention has been paid toward adipose-derived mesenchymal stem cells (AdMSCs) as a potential therapy in tissue engineering and regenerative medicine applications. Rat AdMSCs (r-AdMSCs) are frequently utilized. However, the influence of the adipose depot site on the multilineage differentiation potential of the r-AdMSCs is still ambiguous. Hence, the main objective of this study was to explore the influence of the adipose tissue harvesting location on the ability of r-AdMSCs to express the stem-cell-related markers and pluripotency genes, as well as their differentiation capacity, for the first time. Herein, we have isolated r-AdMSCs from the inguinal, epididymal, peri-renal, and back subcutaneous fats. Cells were compared in terms of their phenotype, immunophenotype, and expression of pluripotency genes using RT-PCR. Additionally, we investigated their potential for multilineage (adipogenic, osteogenic, and chondrogenic) induction using special stains confirmed by the expression of the related genes using RT-qPCR. All cells could positively express stem cell marker CD 90 and CD 105 with no significant in-between differences. However, they did not express the hematopoietic markers as CD 34 and CD 45. All cells could be induced successfully. However, epididymal and inguinal cells presented the highest capacity for adipogenic and osteogenic differentiation (21.36-fold and 11.63-fold for OPN, 29.69-fold and 26.68-fold for BMP2, and 37.67-fold and 22.35-fold for BSP, respectively, in epididymal and inguinal cells (p < 0.0001)). On the contrary, the subcutaneous cells exhibited a superior potential for chondrogenesis over the other sites (8.9-fold for CHM1 and 5.93-fold for ACAN, (p < 0.0001)). In conclusion, the adipose tissue harvesting site could influence the differentiation capacity of the isolated AdMSCs. To enhance the results of their employment in various regenerative cell-based therapies, it is thus vital to take the collection site selection into consideration.

Chitosan and Pectin Hydrogels for Tissue Engineering and In Vitro Modeling

Hydrogels are fascinating biomaterials that can act as a support for cells, i.e., a scaffold, in which they can organize themselves spatially in a similar way to what occurs in vivo. Hydrogel use is therefore essential for the development of 3D systems and allows to recreate the cellular microenvironment in physiological and pathological conditions. This makes them ideal candidates for biological tissue analogues for application in the field of both tissue engineering and 3D in vitro models, as they have the ability to closely mimic the extracellular matrix (ECM) of a specific organ or tissue. Polysaccharide-based hydrogels, because of their remarkable biocompatibility related to their polymeric constituents, have the ability to interact beneficially with the cellular components. Although the growing interest in the use of polysaccharide-based hydrogels in the biomedical field is evidenced by a conspicuous number of reviews on the topic, none of them have focused on the combined use of two important polysaccharides, chitosan and pectin. Therefore, the present review will discuss the biomedical applications of polysaccharide-based hydrogels containing the two aforementioned natural polymers, chitosan and pectin, in the fields of tissue engineering and 3D in vitro modeling.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

Chitosan as Functional Biomaterial for Designing Delivery Systems in Cardiac Therapies

Cardiovascular diseases are a leading cause of mortality across the globe, and transplant surgeries are not always successful since it is not always possible to replace most of the damaged heart tissues, for example in myocardial infarction. Chitosan, a natural polysaccharide, is an important biomaterial for many biomedical and pharmaceutical industries. Based on the origin, degree of deacetylation, structure, and biological functions, chitosan has emerged for vital tissue engineering applications. Recent studies reported that chitosan coupled with innovative technologies helped to load or deliver drugs or stem cells to repair the damaged heart tissue not just in a myocardial infarction but even in other cardiac therapies. Herein, we outlined the latest advances in cardiac tissue engineering mediated by chitosan overcoming the barriers in cardiac diseases. We reviewed in vitro and in vivo data reported dealing with drug delivery systems, scaffolds, or carriers fabricated using chitosan for stem cell therapy essential in cardiac tissue engineering. This comprehensive review also summarizes the properties of chitosan as a biomaterial substrate having sufficient mechanical stability that can stimulate the native collagen fibril structure for differentiating pluripotent stem cells and mesenchymal stem cells into cardiomyocytes for cardiac tissue engineering.

Phenotypic, morphological, and metabolic characterization of vascular-spheres from human vascular mesenchymal stem cells

The ability to form spheroids under non‐adherent conditions is a well‐known property of human mesenchymal stem cells (hMSCs), in addition to stemness and multilineage differentiation features. In the present study, we tested the ability of hMSCs isolated from the vascular wall (hVW‐MSCs) to grow as spheres, and provide a characterization of this 3D model. hVW‐MSCs were isolated from femoral arteries through enzymatic digestion. Spheres were obtained using ultra‐low attachment and hanging drop methods. Immunophenotype and pluripotent genes (SOX‐2, OCT‐4, NANOG) were analyzed by immunocytochemistry and real‐time PCR, respectively. Spheres histological and ultrastructural architecture were examined. Cell viability and proliferative capacity were measured using LIVE/DEATH assay and ki‐67 proliferation marker. Metabolomic profile was obtained with liquid chromatography–mass spectrometry. In 2D, hVW‐MSCs were spindle‐shaped, expressed mesenchymal antigens, and displayed mesengenic potential. 3D cultures of hVW‐MSCs were CD44⁺, CD105^low, CD90^low, exhibited a low propensity to enter the cell cycle as indicated by low percentage of ki‐67 expression and accumulated intermediate metabolites pointing to slowed metabolism. The 3D model of hVW‐MSCs exhibits stemness, dormancy and slow metabolism, typically observed in stem cell niches. This culture strategy can represent an accurate model to investigate hMSCs features for future clinical applications in the vascular field.

Strategies for constructing pluripotent stem cell- and progenitor cell-derived three-dimensional cardiac micro-tissues

Three-dimensional (3D) cardiac micro-tissue is a promising model for simulating the structural and functional features of heart in vitro. This scientific achievement provides a platform for exploration about the mechanisms on the development, damage, and regeneration of tissue, hence, paving a way toward development of novel therapies for heart diseases. However, 3D micro-tissue technology is still in its infant stages faced with many challenges such as incompleteness of the tissue microarchitecture, loss of the resident immune cells, poor reproducibility, and deficiencies in continuously feeding the nutrients and removing wastes during micro-tissue culturing. There is an urgent need to optimize the construction of 3D cardiac micro-tissue and improve functions of the involved cells. Therefore, scaffolds and cell resources for building 3D cardiac micro-tissues, strategies for inducing the maturation and functionalization of pluripotent stem cell- or cardiac progenitor cell-derived cardiomyocytes, and the major challenges were reviewed in this writing to enable future fabrication of 3D cardiac micro-tissues or organoids for drug screening, disease modeling, regeneration treatment, and so on.

Preparation and characterization of 3D human glioblastoma spheroids using an N-octanoyl glycol chitosan hydrogel

The current 2D culture model systems developed for drug screening are not sufficient to reflect the characteristics of in vivo solid tumors. Therefore, more effective in vitro tumor model systems must be developed for translational studies on therapeutic drug screening and testing. Herein, we report a new ultra-low adhesion (ULA) hydrogel for generating 3D cancer cell spheroids as tumor models in vitro. N-octanoyl glycol chitosan (OGC) was synthesized and coated onto the surface of a typical cell culture dish. Cell spheroids were effectively formed on the OGC-coated surface, and phenotypes of the tumor cells were well maintained during culture. More importantly, U373-MG cells cultured on OGC-coated plates were more resistant to doxorubicin than cells cultured on typical plates. Our OGC-based ULA system may offer a convenient method for 3D cell culture to provide enhanced performance in cancer research, drug screening and toxicology.

Specificity of 3D MSC Spheroids Microenvironment: Impact on MSC Behavior and Properties

Mesenchymal stem cells (MSC) have been considered the promising candidates for the regenerative and personalized medicine due to their self-renewal potential, multilineage differentiation and immunomodulatory capacity. Although these properties have encouraged profound MSC studies in recent years, the majority of research has been based on standard 2D culture utilization. The opportunity to resemble in vivo characteristics of cells native niche has been provided by implementation of 3D culturing models such as MSC spheroid formation assesed through cells self-assembling. In this review, we address the current literature on physical and biochemical features of 3D MSC spheroid microenvironment and their impact on MSC properties and behaviors. Starting with the reduction in the cells' dimensions and volume due to the changes in adhesion molecules expression and cytoskeletal proteins rearrangement resembling native conditions, through the microenvironment shifts in oxygen, nutrients and metabolites gradients and demands, we focus on distinctive and beneficial features of MSC in spheroids compared to cells cultured in 2D conditions. By summarizing the data for 3D MSC spheroids regarding cell survival, pluripotency, differentiation, immunomodulatory activities and potential to affect tumor cells growth we highlighted advantages and perspectives of MSC spheroids use in regenerative medicine. Further detailed analyses are needed to deepen our understanding of mechanisms responsible for modified MSC behavior in spheroids and to set future directions for MSC clinical application.

Engineering Human Cardiac Muscle Patch Constructs for Prevention of Post-infarction LV Remodeling

Tissue engineering combines principles of engineering and biology to generate living tissue equivalents for drug testing, disease modeling, and regenerative medicine. As techniques for reprogramming human somatic cells into induced pluripotent stem cells (iPSCs) and subsequently differentiating them into cardiomyocytes and other cardiac cells have become increasingly efficient, progress toward the development of engineered human cardiac muscle patch (hCMP) and heart tissue analogs has accelerated. A few pilot clinical studies in patients with post-infarction LV remodeling have been already approved. Conventional methods for hCMP fabrication include suspending cells within scaffolds, consisting of biocompatible materials, or growing two-dimensional sheets that can be stacked to form multilayered constructs. More recently, advanced technologies, such as micropatterning and three-dimensional bioprinting, have enabled fabrication of hCMP architectures at unprecedented spatiotemporal resolution. However, the studies working on various hCMP-based strategies for in vivo tissue repair face several major obstacles, including the inadequate scalability for clinical applications, poor integration and engraftment rate, and the lack of functional vasculature. Here, we review many of the recent advancements and key concerns in cardiac tissue engineering, focusing primarily on the production of hCMPs at clinical/industrial scales that are suitable for administration to patients with myocardial disease. The wide variety of cardiac cell types and sources that are applicable to hCMP biomanufacturing are elaborated. Finally, some of the key challenges remaining in the field and potential future directions to address these obstacles are discussed.

Increased Mesenchymal Stem Cell Functionalization in Three-Dimensional Manufacturing Settings for Enhanced Therapeutic Applications

Mesenchymal stem/stromal cell (MSC) exist within their in vivo niches as part of heterogeneous cell populations, exhibiting variable stemness potential and supportive functionalities. Conventional extensive 2D in vitro MSC expansion, aimed at obtaining clinically relevant therapeutic cell numbers, results in detrimental effects on both cellular characteristics (e.g., phenotypic changes and senescence) and functions (e.g., differentiation capacity and immunomodulatory effects). These deleterious effects, added to the inherent inter-donor variability, negatively affect the standardization and reproducibility of MSC therapeutic potential. The resulting manufacturing challenges that drive the qualitative variability of MSC-based products is evident in various clinical trials where MSC therapeutic efficacy is moderate or, in some cases, totally insufficient. To circumvent these limitations, various in vitro/ex vivo techniques have been applied to manufacturing protocols to induce specific features, attributes, and functions in expanding cells. Exposure to inflammatory cues (cell priming) is one of them, however, with untoward effects such as transient expression of HLA-DR preventing allogeneic therapeutic schemes. MSC functionalization can be also achieved by in vitro 3D culturing techniques, in an effort to more closely recapitulate the in vivo MSC niche. The resulting spheroid structures provide spatial cell organization with increased cell–cell interactions, stable, or even enhanced phenotypic profiles, and increased trophic and immunomodulatory functionalities. In that context, MSC 3D spheroids have shown enhanced “medicinal signaling” activities and increased homing and survival capacities upon transplantation in vivo. Importantly, MSC spheroids have been applied in various preclinical animal models including wound healing, bone and osteochondral defects, and cardiovascular diseases showing safety and efficacy in vivo. Therefore, the incorporation of 3D MSC culturing approach into cell-based therapy would significantly impact the field, as more reproducible clinical outcomes may be achieved without requiring ex vivo stimulatory regimes. In the present review, we discuss the MSC functionalization in 3D settings and how this strategy can contribute to an improved MSC-based product for safer and more effective therapeutic applications.

Hypoxia Onset in Mesenchymal Stem Cell Spheroids: Monitoring With Hypoxia Reporter Cells

The therapeutic and differentiation potential of human mesenchymal stems cells (hMSCs) makes these cells a promising candidate for cellular therapies and tissue engineering. On the path of a successful medical application of hMSC, the cultivation of cells in a three-dimensional (3D) environment was a landmark for the transition from simple two-dimensional (2D) testing platforms to complex systems that mimic physiological in vivo conditions and can improve hMSC curative potential as well as survival after implantation. A 3D arrangement of cells can be mediated by scaffold materials where cells get entrapped in pores, or by the fabrication of spheroids, scaffold-free self-organized cell aggregates that express their own extracellular matrix. Independently from the cultivation method, cells expanded in 3D experience an inhomogeneous microenvironment. Many gradients in nutrient supply, oxygen supply, and waste disposal from one hand mimic in vivo microenvironment, but also put every cell in the 3D construct in a different context. Since oxygen concentration in spheroids is compromised in a size-dependent manner, it is crucial to have a closer insight on the thresholds of hypoxic response in such systems. In this work, we want to improve our understanding of oxygen availability and consequensing hypoxia onset in hMSC spheroids. Therefore, we utilized human adipose tissue-derived MSCs (hAD-MSCs) modified with a genetical sensor construct to reveal (I) the influence of spheroid production methods and (II) hMSCs cell number per spheroid to detect the onset of hypoxia in aggregates. We could demonstrate that not only higher cell numbers of MSCs, but also spheroid formation method plays a critical role in onset of hypoxia.

Adipose-derived mesenchymal stem cell seeded Atelocollagen scaffolds for cardiac tissue engineering

ADMSCs were isolated from subcutaneous adipose tissue, characterized and cultured in vitro. GFP-labeled ADMSCs can grow and proliferate well on the Atelocollagen scaffolds, and induced by 5-aza the cells can differentiate into cardio-like cells. 3D cultured ADMSCs on Atelocollagen scaffolds were transplanted into mice ischemia myocardium, and have good biocompatibility with host cardio tissue.

Modeling Cardiovascular Diseases with hiPSC-Derived Cardiomyocytes in 2D and 3D Cultures

In the last decade, the generation of cardiac disease models based on human-induced pluripotent stem cells (hiPSCs) has become of common use, providing new opportunities to overcome the lack of appropriate cardiac models. Although much progress has been made toward the generation of hiPSC-derived cardiomyocytes (hiPS-CMs), several lines of evidence indicate that two-dimensional (2D) cell culturing presents significant limitations, including hiPS-CMs immaturity and the absence of interaction between different cell types and the extracellular matrix. More recently, new advances in bioengineering and co-culture systems have allowed the generation of three-dimensional (3D) constructs based on hiPSC-derived cells. Within these systems, biochemical and physical stimuli influence the maturation of hiPS-CMs, which can show structural and functional properties more similar to those present in adult cardiomyocytes. In this review, we describe the latest advances in 2D- and 3D-hiPSC technology for cardiac disease mechanisms investigation, drug development, and therapeutic studies.

Current research trends and challenges in tissue engineering for mending broken hearts

Cardiovascular disease (CVD) is among the leading causes of mortality worldwide. The shortage of donor hearts to treat end-stage heart failure patients is a critical problem. An average of 3500 heart transplant surgeries are performed globally, half of these transplants are performed in the US alone. Stem cell therapy is growing rapidly as an alternative strategy to repair or replace the damaged heart tissue after a myocardial infarction (MI). Nevertheless, the relatively poor survival of the stem cells in the ischemic heart is a major challenge to the therapeutic efficacy of stem-cell transplantation. Recent advancements in tissue engineering offer novel biomaterials and innovative technologies to improve upon the survival of stem cells as well as to repair the damaged heart tissue following a myocardial infarction (MI). However, there are several limitations in tissue engineering technologies to develop a fully functional, beating cardiac tissue. Therefore, the main goal of this review article is to address the current advancements and barriers in cardiac tissue engineering to augment the survival and retention of stem cells in the ischemic heart.

Prolonged cell persistence with enhanced multipotency and rapid angiogenesis of hypoxia pre-conditioned stem cells encapsulated in marine-inspired adhesive and immiscible liquid micro-droplets

Stem cell therapies are emerging regenerative treatments for ischemic and chronic diseases. Although high cell retention and prompt angiogenesis are prerequisites to improving efficacy, advancements have not yet been developed. Here, we proposed long-term surviving and angiogenesis-inducing stem cell with high cell retention thanks to fluid immiscible liquid micro-droplets bio-inspired by a glue modality 'complex coacervate' found in the sandcastle worm. Formed by the Coulombic force between polycationic MAP and polyanionic hyaluronic acid, the exploited coacervate micro-droplets enabled the encapsulation of stem cells. The underwater adhesiveness facilitated integrating the encapsulated stem cells onto various surfaces with impressive cell retention after facile injection. Stem cells encapsulated in the coacervate platform formed cell clusters capable of pre-adjusting to hypoxia by expressing hypoxia-inducible factor 1α (HIF-1α), increasing viability and reducing apoptosis under hypoxia and ischemia as well as normoxia. Interestingly, multipotent and angiogenic factors were significantly enhanced by HIF-1α expression. In the in vivo evaluation, the coacervate platform showed impressive angiogenesis with biocompatibility and long-term cell retention capacity with sustainable release as protein factories. Therefore, the proposed MAP-based water-immiscible, injectable, sticky, and bioactive 3D coacervate micro-droplets offers a promising tool for chronic diseases in body fluid-rich environments. STATEMENT OF SIGNIFICANCE: High cell retention, long-term survival, and rapid angiogenesis are prerequisites of successful stem cell therapy. However, no previous advancements have simultaneously satisfied all of these requirements. In this work, we clearly developed a novel, revolutionary stem cell carrier platform with underwater adhesiveness from a mussel-derived glue protein and water immiscibility from a sandcastle-worm-inspired glue modality via 'complex coacervation'. To the best of our knowledge, no report has emerged employing coacervate as a stem cell therapeutic platform. This fluid-immiscible, injectable, sticky, and bioactive 3-dimensional stem cell micro-droplets demonstrated the excellent stem cell retention and viability under hypoxia environments and enhanced multipotent and angiogenic effects with minimal immune response.

3D printing approaches for cardiac tissue engineering and role of immune modulation in tissue regeneration

Conventional tissue engineering, cell therapy, and current medical approaches were shown to be successful in reducing mortality rate and complications caused by cardiovascular diseases (CVDs). But still they have many limitations to fully manage CVDs due to complex composition of native myocardium and microvascularization. Fabrication of fully functional construct to replace infarcted area or regeneration of progenitor cells is important to address CVDs burden. Three-dimensional (3D) printed scaffolds and 3D bioprinting technique have potential to develop fully functional heart construct that can integrate with native tissues rapidly. In this review, we presented an overview of 3D printed approaches for cardiac tissue engineering, and advances in 3D bioprinting of cardiac construct and models. We also discussed role of immune modulation to promote tissue regeneration.

Cellular Spheroids of Mesenchymal Stem Cells and Their Perspectives in Future Healthcare

Intrinsic cellular properties of several types of cells are dramatically altered as the culture condition shifts from two-dimensional (2D) to three-dimensional (3D) environment. Currently, several lines of evidence have demonstrated the therapeutic potential of mesenchymal stem cells (MSCs) in regenerative medicine. MSCs not only replenish the lost cells, they also promote the regeneration of impaired tissues by modulating the immune responses. Following the development of 3D cell culture, the enhanced therapeutic efficacy of spheroid-forming MSCs have been identified in several animal disease models by promoting differentiation or trophic factor secretion, as compared to planar-cultured MSCs. Due to the complicated and multifunctional applications in the medical field, MSCs are recently named as medicinal signaling cells. In this review, we summarize the predominant differences of cell–environment interactions for the MSC spheroids formed by chitosan-based substrates and other scaffold-free approaches. Furthermore, several important physical and chemical factors affecting cell behaviors in the cell spheroids are discussed. Currently, the understanding of MSCs spheroid interactions is continuously expanding. Overall, this article aims to review the broad advantages and perspectives of MSC spheroids in regenerative medicine and in future healthcare.

The micromass formation potential of human adipose-derived stromal cells isolated from different various origins

BACKGROUND

Adult stem cells appear to be a promising subject for tissue engineering, representing an individual material for regeneration of aged and damaged cells. Especially adipose derived stromal cells (ADSC), which are easily to achieve, allow an encouraging perspective due to their capability of differentiating into miscellaneous cell types. Here we describe the in vitro formation of human subcutaneous, visceral and omental ADSC micromasses and compare their histological attributes while being cultivated on collagen membranes.

METHODS

Subcutaneous, visceral and omental fat tissue derived cells were isolated and processed according to standard protocols. Positively stained cells for CD13, CD44 and CD90 were cultivated on agarose in order to study micromass formation using a special method of cell tracking. Stained paraffin-embedded micromasses were analysed morphologically before and after being plated on collagen membranes.

RESULTS

The micromass formation process was similar in all three tissue types. Subcutaneous fat tissue derived micromasses turned out to develop a more homogeneous and compact shape than visceral and omental tissue. Nevertheless all micromasses adhered to collagen membranes with visible spreading of cells. The immune histochemical (IHC) staining of subcutaneous, visceral and omental ADSC micromasses shows a constant expression of CD13 and a decrease of CD44 and CD 90 expression within 28 days. After that period, omental fat cells don't show any expression of CD44.

CONCLUSION

In conclusion micromass formation and cultivation of all analysed fat tissues can be achieved, subcutaneous cells appearing to be the best material for regenerative concepts.

Current Trends in Biomaterial Utilization for Cardiopulmonary System Regeneration

The cardiopulmonary system is made up of the heart and the lungs, with the core function of one complementing the other. The unimpeded and optimal cycling of blood between these two systems is pivotal to the overall function of the entire human body. Although the function of the cardiopulmonary system appears uncomplicated, the tissues that make up this system are undoubtedly complex. Hence, damage to this system is undesirable as its capacity to self-regenerate is quite limited. The surge in the incidence and prevalence of cardiopulmonary diseases has reached a critical state for a top-notch response as it currently tops the mortality table. Several therapies currently being utilized can only sustain chronically ailing patients for a short period while they are awaiting a possible transplant, which is also not devoid of complications. Regenerative therapeutic techniques now appear to be a potential approach to solve this conundrum posed by these poorly self-regenerating tissues. Stem cell therapy alone appears not to be sufficient to provide the desired tissue regeneration and hence the drive for biomaterials that can support its transplantation and translation, providing not only physical support to seeded cells but also chemical and physiological cues to the cells to facilitate tissue regeneration. The cardiac and pulmonary systems, although literarily seen as just being functionally and spatially cooperative, as shown by their diverse and dissimilar adult cellular and tissue composition has been proven to share some common embryological codevelopment. However, necessitating their consideration for separate review is the immense adult architectural difference in these systems. This review also looks at details on new biological and synthetic biomaterials, tissue engineering, nanotechnology, and organ decellularization for cardiopulmonary regenerative therapies.

Engineering principles for guiding spheroid function in the regeneration of bone, cartilage, and skin

There is a critical need for strategies that effectively enhance cell viability and post-implantation performance in order to advance cell-based therapies. Spheroids, which are dense cellular aggregates, overcome many current limitations with transplanting individual cells. Compared to individual cells, the aggregation of cells into spheroids results in increased cell viability, together with enhanced proangiogenic, anti-inflammatory, and tissue-forming potential. Furthermore, the transplantation of cells using engineered materials enables localized delivery to the target site while providing an opportunity to guide cell fate in situ, resulting in improved therapeutic outcomes compared to systemic or localized injection. Despite promising early results achieved by freely injecting spheroids into damaged tissues, growing evidence demonstrates the advantages of entrapping spheroids within a biomaterial prior to implantation. This review will highlight the basic characteristics and qualities of spheroids, describe the underlying principles for how biomaterials influence spheroid behavior, with an emphasis on hydrogels, and provide examples of synergistic approaches using spheroids and biomaterials for tissue engineering applications.

Osteochondral Regeneration with a Scaffold-Free Three-Dimensional Construct of Adipose Tissue-Derived Mesenchymal Stromal Cells in Pigs

Osteochondral lesion is a major joint disease in humans. Therefore, this study was designed to investigate the regeneration of articular cartilage and subchondral bone, using three-dimensional constructs of autologous adipose tissue-derived mesenchymal stromal cells without any biocompatible scaffolds. Mesenchymal stromal cells were harvested by liposuction from seven pigs, isolated enzymatically, and expanded until construct creation. The pig models had two osteochondral defects (cylindrical defects with a diameter of 5.2 mm and a depth of 5 mm) in one of their patello-femoral grooves. A columnar structure consisting of approximately 770 spheroids of 5 × 10⁴ autologous mesenchymal stromal cells were implanted into one of the defects (implanted defect), while the other defect was not implanted (control). The defects were evaluated pathologically at 6 months (in three pigs) and 12 months (in five pigs) after implantation. At 6 months after surgery, histopathology revealed active endochondral ossification underneath the plump fibrocartilage in the implanted defects, but a deficiency of fibrocartilaginous coverage in the controls. At 12 months after surgery, the fibrocartilage was transforming into hyaline cartilage as thick as the surrounding normal cartilage and the subchondral bone was thickening in the implanted defects. The histological averages of the implanted sites were significantly higher than those in the control sites at both 6 and 12 months after surgery. The implantation of a scaffold-free three-dimensional construct of autologous mesenchymal stromal cells into an osteochondral defect can induce regeneration of hyaline cartilage and subchondral bone structures over a period of 12 months.

An injectable non-cross-linked hyaluronic-acid gel containing therapeutic spheroids of human adipose-derived stem cells

For chronic wounds, the delivery of stem cells in spheroidal structures can enhance graft survival and stem cell potency. We describe an easy method for the 3D culture of adipose-derived stem/stromal cells (ASCs) to prepare a ready-to-use injectable. We transferred suspensions of monolayer-cultured ASCs to a syringe containing hyaluronic acid (HA) gel, and then incubated the syringe as a 3D culture vessel. Spheroids of cells formed after 12 h. We found that 6 × 10⁶ ASCs/ml in 3% HA gel achieved the highest spheroid density with appropriate spheroid sizes (20-100 µm). Immunocytology revealed that the stem cell markers, NANOG, OCT3/4, SOX-2, and SSEA-3 were up-regulated in the ASC spheroids compared with those in nonadherent-dish spheroids or in monolayer cultured ASCs. In delayed wound healing mice models, diabetic ulcers treated with ASC spheroids demonstrated faster wound epithelialization with thicker dermis than those treated with vehicle alone or monolayer cultured ASCs. In irradiated skin ulcers in immunodeficient mice, ASC spheroids exhibited faster healing and outstanding angiogenic potential partly by direct differentiation into α-SMA+ pericytes. Our method of 3D in-syringe HA gel culture produced clinically relevant amounts of ready-to-inject human ASC microspheroids that exhibited superior stemness in vitro and therapeutic efficacy in pathological wound repair in vivo.

The therapeutic potential of three-dimensional multipotent mesenchymal stromal cell spheroids

The efficiency of clinical trials involving transplantation of multipotent mesenchymal stromal cells (MSCs) is often insufficient due to harsh conditions present within the target tissue including hypoxia, low nutrient supply as well as inflammatory reactions. This indicates the necessity for optimization of cell-based therapy approaches which might include either modification of the cell manufacturing process or specific cell pretreatment procedures prior to transplantation. Recent reports confirm evidence that the aggregation of MSCs into three-dimensional (3D) multicellular spheroids results in enhancement of the overall therapeutic potential of cells, by improving the anti-inflammatory and angiogenic properties, stemness and survival of MSCs after transplantation. Such an MSCs spheroid generation approach may open new opportunities for the enlargement of MSCs applications in clinical research and therapy. However, the unification and optimization of 3D spheroid generation techniques, including the selection of appropriate clinical-grade culture conditions and methods for their large-scale production, are still of great importance. The current review addresses questions regarding therapeutic-associated properties of 3D multicellular MSCs spheroids in vitro and during preclinical animal studies, with special attention to the possibilities of translating these research achievements toward further clinical manufacturing and applications.

Chitosan-assisted differentiation of porcine adipose tissue-derived stem cells into glucose-responsive insulin-secreting clusters

The unique advantage of easy access and abundance make the adipose-derived stem cells (ADSCs) a promising system of multipotent cells for transplantation and regenerative medicine. Among the available sources, porcine ADSCs (pADSCs) deserve especial attention due to the close resemblance of human and porcine physiology, as well as for the upcoming availability of humanized porcine models. Here, we report on the isolation and conversion of pADSCs into glucose-responsive insulin-secreting cells. We used the stromal-vascular fraction of the dorsal subcutaneous adipose from 9-day-old male piglets to isolate pADSCs, and subjected the cells to an induction scheme for differentiation on chitosan-coated plates. This one-step procedure promoted differentiation of pADSCs into pancreatic islet-like clusters (PILC) that are characterized by the expression of a repertoire of pancreatic proteins, including pancreatic and duodenal homeobox (Pdx-1), insulin gene enhancer protein (ISL-1) and insulin. Upon glucose challenge, these PILC secreted high amounts of insulin in a dose-dependent manner. Our data also suggest that chitosan plays roles not only to enhance the differentiation potential of pADSCs, but also to increase the glucose responsiveness of PILCs. Our novel approach is, therefore, of great potential for transplantation-based amelioration of type 1 diabetes.

Can the outcomes of mesenchymal stem cell-based therapy for myocardial infarction be improved? Providing weapons and armour to cells

Use of mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been found to have infarct-limiting effects in numerous experimental and clinical studies. However, recent meta-analyses of randomized clinical trials on MSC-based MI therapy have highlighted the need for improving its efficacy. There are two principal approaches for increasing therapeutic effect of MSCs: (i) preventing massive MSC death in ischaemic tissue and (ii) increasing production of cardioreparative growth factors and cytokines with transplanted MSCs. In this review, we aim to integrate our current understanding of genetic approaches that are used for modification of MSCs to enable their improved survival, engraftment, integration, proliferation and differentiation in the ischaemic heart. Genetic modification of MSCs resulting in increased secretion of paracrine factors has also been discussed. In addition, data on MSC preconditioning with physical, chemical and pharmacological factors prior to transplantation are summarized. MSC seeding on three-dimensional polymeric scaffolds facilitates formation of both intercellular connections and contacts between cells and the extracellular matrix, thereby enhancing cell viability and function. Use of genetic and non-genetic approaches to modify MSC function holds great promise for regenerative therapy of myocardial ischaemic injury.

Assembling Composite Dermal Papilla Spheres with Adipose-derived Stem Cells to Enhance Hair Follicle Induction

Intradermal adipose tissue plays an essential role for hair follicles (HFs) regeneration by regulating hair cycles. However, the effect of reconstruction of HFs and the involvement of adipose-related cells are poorly understood. We investigated assembly strategies for the interactions of dermal papilla (DP) cells with adipose-derived stem cells (ASCs) in promoting hair formation. DP cells lose DP traits during adherent culture, but preserved DP markers with a unified sphere diameter by seeding on chitosan-coated microenvironments. Next, ASCs isolated from rats were co-cultured with DP spheres by different assembling approaches to determine their interactions; a mixed sphere of ASCs with DP cells (MA-DPS), or a core-shell structure, outer ASCs shell and an inner DP core (CSA-DPS). CSA-DPS exhibited superior DP characteristics compared to MA-DPS. Conditional medium from ASCs, but not differentiated adipocytes, promoted DP markers and functional alkaline phosphatase activity from the DP cells. In vivo patch assay showed the core-shell assembling of CSA-DPS can reconstruct cellular arrangements and microenvironmental niches as dominated by PPARα signal in ASCs to induce the greater hair induction than MA-DPS or DP spheres alone. Therefore, the assembling of a core-shell sphere for DP with ASCs could reconstruct the HF cellular arrangement for hair formation. This paper set the groundwork for further evaluation of the input of other cell types.

Inhibition of Rho-Associated Protein Kinase Increases the Angiogenic Potential of Mesenchymal Stem Cell Aggregates via Paracrine Effects

The aggregation of multiple cells, such as mesenchymal condensation, is an important biological process in skeletal muscle development, osteogenesis, and adipogenesis. Due to limited in vivo study model systems, a simple and effective in vitro three-dimensional (3D) aggregation system is required to study the mechanisms of multicellular aggregation and its applications. We first generated controlled mesenchymal stem cell (MSC) aggregates using a bioprinting technique to monitor their aggregation and sprouting. We induced the angiogenic potential of the MSCs through chemical inhibition of the Rho/Rho-associated protein kinase (ROCK) pathway, which led to hairy sprouting in the aggregates. The angiogenic potential of this 3D construct was then tested by subcutaneously implanting the Matrigel with 3D MSC aggregates in a rat. Treatment of 3D MSCs with the ROCK inhibitor, Y27632, increased their angiogenic activity in vivo. The gene expressions and histological staining indicated that angiogenesis and neovascularization were mainly regulated by the paracrine factors secreted from human 3D MSC constructs. Our results demonstrate the enhancement of the angiogenic potential of the MSC constructs through the secretion of vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) by the inhibition of the Rho/ROCK pathway.

Therapeutic Potential of Human Adipose-Derived Stem/Stromal Cell Microspheroids Prepared by Three-Dimensional Culture in Non-Cross-Linked Hyaluronic Acid Gel

Three-dimensional culture of mesenchymal stem/stromal cells for spheroid formation is known to enhance their therapeutic potential for regenerative medicine. Spheroids were prepared by culturing human adipose-derived stem/stromal cells (hASCs) in a non-cross-linked hyaluronic acid (HA) gel and compared with dissociated hASCs and hASC spheroids prepared using a nonadherent dish. Preliminary experiments indicated that a 4% HA gel was the most appropriate for forming hASC spheroids with a relatively consistent size (20-50 µm) within 48 hours. Prepared spheroids were positive for pluripotency markers (NANOG, OCT3/4, and SOX-2), and 40% of the cells were SSEA-3-positive, a marker of the multilineage differentiating stress enduring or Muse cell. In contrast with dissociated ASCs, increased secretion of cytokines such as hepatocyte growth factor was detected in ASC spheroids cultured under hypoxia. On microarray ASC spheroids showed upregulation of some pluripotency markers and downregulation of genes related to the mitotic cell cycle. After ischemia-reperfusion injury to the fat pad in SCID mice, local injection of hASC spheroids promoted tissue repair and reduced the final atrophy (1.6%) compared with that of dissociated hASCs (14.3%) or phosphate-buffered saline (20.3%). Part of the administered hASCs differentiated into vascular endothelial cells. ASC spheroids prepared in a HA gel contain undifferentiated cells with therapeutic potential to promote angiogenesis and tissue regeneration after damage.

SIGNIFICANCE

This study shows the therapeutic value of human adipose-derived stem cell spheroids prepared in hyarulonic acid gel. The spheroids have various benefits as an injectable cellular product and show therapeutic potential to the stem cell-depleted conditions such as diabetic chronic skin ulcer.

Biomaterial Approaches for Stem Cell-Based Myocardial Tissue Engineering

Adult and pluripotent stem cells represent a ready supply of cellular raw materials that can be used to generate the functionally mature cells needed to replace damaged or diseased heart tissue. However, the use of stem cells for cardiac regenerative therapies is limited by the low efficiency by which stem cells are differentiated in vitro to cardiac lineages as well as the inability to effectively deliver stem cells and their derivatives to regions of damaged myocardium. In this review, we discuss the various biomaterial-based approaches that are being implemented to direct stem cell fate both in vitro and in vivo. First, we discuss the stem cell types available for cardiac repair and the engineering of naturally and synthetically derived biomaterials to direct their in vitro differentiation to the cell types that comprise heart tissue. Next, we describe biomaterial-based approaches that are being implemented to enhance the in vivo integration and differentiation of stem cells delivered to areas of cardiac damage. Finally, we present emerging trends of using stem cell-based biomaterial approaches to deliver pro-survival factors and fully vascularized tissue to the damaged and diseased cardiac tissue.

Enhanced Autophagy of Adipose-Derived Stem Cells Grown on Chitosan Substrates

Autophagy is an important protein quality control mechanism for cells under stress conditions to promote cell survival. Modulation of autophagy on biomaterial substrates is rarely reported. In this study, the autophagy of adipose-derived stem cells (ADSCs) cultured on chitosan (CS) substrates was examined. Compared to the traditional monolayer culture, ADSCs cultured on CS substrates showed spheroid formation as well as a prolonged upregulation of autophagosomal marker-microtubule-associated protein 1 light chain 3 (LC3) II protein expression. In addition, the green fluorescent protein tagged-LC3 (GFP-LC3) expressing ADSCs also revealed more GFP-LC3 puncta on CS substrates. The enhanced autophagy on CS substrates was associated with Ca(2+), while ethylene glycol tetraacetic acid (EGTA), a Ca(2+) chelator, repressed the autophagy in a dose-dependent manner. Moreover, ADSC spheroids on CS substrates demonstrated a higher survival rate and autophagy response upon H2O2 treatment. The upstream components of autophagy signal pathway-UNC51-like kinase 1 (Ulk1), autophagy-related protein 13 (Atg13), and autophagy/beclin-1 regulator 1 (Ambra1) genes were more highly expressed in ADSC spheroids before and after adding H2O2 than those in the conventional culture. EGTA also decreased the cell viability and autophagy-associated gene expression for ADSC spheroids on CS substrates after H2O2 treatment. Therefore, we suggest that three-dimensional (3D) cell culture on CS may confer ADSCs the ability to increase the autophagic flux in response to stimulations in a Ca(2+)-dependent manner.

The effect of elastic biodegradable polyurethane electrospun nanofibers on the differentiation of mesenchymal stem cells

Biodegradable polyurethane (PU) was synthesized based on using poly(ɛ-caprolactone) (PCL) as the soft segment. Fibers in different diameters (200-400nm, 600-800nm, and 1.4-1.6μm) were then made by electrospinning PU solution in N,N-dimethylacetamide and 2,2,2-trifluoroethanol. Human bone marrow derived mesenchymal stem cells (hMSCs) in the form of single dispersed cells or aggregates were seeded on the electrospun meshes for evaluation of cell behavior. Differentiation experiments showed that hMSC aggregates on electrospun fibers had greater differentiation capacities than single cells. Besides, nanofibers of 200-400nm diameters significantly promoted the osteogenic and chondrogenic differentiation of hMSCs than fibers of the other diameters. The effect of substrate elasticity was further elucidated by comparing cell behaviors on the nanofibers of PCL-based PU and those of pure PCL. The more elastic PU nanofibers demonstrated more osteogenic and chondrogenic induction potential than PCL electrospun fibers. We suggested that the elastic nanofibers seeded with hMSC aggregates may be advantageous for cartilage and bone tissue engineering.

Promotion of cardiac differentiation of brown adipose derived stem cells by chitosan hydrogel for repair after myocardial infarction

The ability to restore heart function by replacement of diseased myocardium is one of the great challenges in biomaterials and regenerative medicine. Brown adipose derived stem cells (BADSCs) present a new source of cardiomyocytes to regenerate the myocardium after infarction. In this study, we explored an injectable tissue engineering strategy to repair damaged myocardium, in which chitosan hydrogels were investigated as a carrier for BADSCs. In vitro, the effect and mechanism of chitosan components on the cardiac differentiation of BADSCs were investigated. In vivo, BADSCs carrying double-fusion reporter gene (firefly luciferase and monomeric red fluorescent protein (fluc-mRFP)) were transplanted into infarcted rat hearts with or without chitosan hydrogel. Multi-techniques were used to assess the effects of treatments. We observed that chitosan components significantly enhanced cardiac differentiation of BADSCs, which was assessed by percentages of cTnT(+) cells and expression of cardiac-specific markers, including GATA-4, Nkx2.5, Myl7, Myh6, cTnI, and Cacna1a. Treatment with collagen synthesis inhibitors, cis-4-hydroxy-D-proline (CIS), significantly inhibited the chitosan-enhanced cardiac differentiation, indicating that the enhanced collagen synthesis by chitosan accounts for its promotive role in cardiac differentiation of BADSCs. Longitudinal in vivo bioluminescence imaging and histological staining revealed that chitosan enhanced the survival of engrafted BADSCs and significantly increased the differentiation rate of BADSCs into cardiomyocytes in vivo. Furthermore, BADSCs delivered by chitosan hydrogel prevented adverse matrix remodeling, increased angiogenesis, and preserved heart function. These results suggested that the injectable cardiac tissue engineering based on chitosan hydrogel and BADSCs is a useful strategy for myocardium regeneration.