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Although iron oxide nanoparticles (IRONs) were applied in clinical magnetic resonance imaging in vivo and magnetic tissue engineering in vitro widely, the underlying effects of IRONs on the development of cardiomyocytes especially the intercellular junctions, intercalated discs (IDs), remain an unknown issue. Given the critical role of three-dimensional (3D) engineered cardiac tissues (ECTs) in evaluation of nanoparticles toxicology, it remained necessary to understand the effects of IRONs on IDs assembly of cardiomyocytes in 3D environment. In this study, we first reconstituted collagen/Matrigel based ECTs in vitro and prepared IRONs with 2,3-dimercaptosuccinic acid (DMSA-IRONs). We found that the internalization of DMSA-IRONs by cardiac cells in dose-dependent manner was not associated with the cell distribution in 3D environment by determination of Prussian blue staining and transmission electronic microscopy. Significantly, through determination of western blotting and immunofluorescence of connexin 43, N-cadherin, desmoplakin, and plakoglobin, DMSA-IRONs enhanced the assembly of gap junctions, decreased mechanical junctions (adherens junctions and desmosomes) of cardiac cells but not in dose-dependent manner in ECTs at seventh day. In addition, DMSA-IRONs increased the vesicles secretion of cardiac cells in ECTs apparently compared to control groups. Overall, we conclude that the internalization of DMSA-IRONs by cardiac cells in dose-dependent manner enhanced the assembly of electrochemical junctions and decreased the mechanical related microstructures. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 121-130, 2018. [ABSTRACT FROM AUTHOR]

Axonal degeneration underlies many debilitating diseases including hereditary spastic paraplegias (HSPs). HSPs are a large heterogeneous group of neurodegenerative diseases characterized by axonopathy involving the long corticospinal tract. How axons of these cortical projection neurons specifically degenerate in HSPs remains largely unclear partially due to the lack of human models to monitor the dynamic process of axonal degeneration. With the development of induced pluripotent stem cell (iPSC) technology, patient-specific iPSCs are successfully generated from HSP patients, providing a unique paradigm to study the axonal degeneration in patient-derived neurons in live cultures. In this chapter, we will summarize the procedures to examine axonal defects in iPSC models of HSPs and discuss the challenges and future applications in order to rescue axonal degeneration in HSPs., (© 2021. Springer Science+Business Media, LLC.)

Impaired axonal development and degeneration underlie debilitating neurodegenerative diseases including hereditary spastic paraplegia, a large group of inherited diseases. Hereditary spastic paraplegia is caused by retrograde degeneration of the long corticospinal tract axons, leading to progressive spasticity and weakness of leg and hip muscles. There are over 70 subtypes with various underlying pathophysiological processes, such as defective vesicular trafficking, lipid metabolism, organelle shaping, axonal transport, and mitochondrial dysfunction. Although hereditary spastic paraplegia consists of various subtypes with different pathological characteristics, defects in mitochondrial morphology and function emerge as one of the common cellular themes in hereditary spastic paraplegia. Mitochondrial morphology and function are remodeled by mitochondrial dynamics regulated by several key fission and fusion mediators. However, the role of mitochondrial dynamics in axonal defects of hereditary spastic paraplegia remains largely unknown. Recently, studies reported perturbed mitochondrial morphology in hereditary spastic paraplegia neurons. Moreover, downregulation of mitochondrial fission regulator dynamin-related protein 1, both pharmacologically and genetically, could rescue axonal outgrowth defects in hereditary spastic paraplegia neurons, providing a potential therapeutic target for treating these hereditary spastic paraplegia. This mini-review will describe the regulation of mitochondrial fission/fusion, the link between mitochondrial dynamics and axonal defects, and the recent progress on the role of mitochondrial dynamics in axonal defects of hereditary spastic paraplegia., Competing Interests: None

Although iron oxide nanoparticles (IRONs) were applied in clinical magnetic resonance imaging in vivo and magnetic tissue engineering in vitro widely, the underlying effects of IRONs on the development of cardiomyocytes especially the intercellular junctions, intercalated discs (IDs), remain an unknown issue. Given the critical role of three-dimensional (3D) engineered cardiac tissues (ECTs) in evaluation of nanoparticles toxicology, it remained necessary to understand the effects of IRONs on IDs assembly of cardiomyocytes in 3D environment. In this study, we first reconstituted collagen/Matrigel based ECTs in vitro and prepared IRONs with 2,3-dimercaptosuccinic acid (DMSA-IRONs). We found that the internalization of DMSA-IRONs by cardiac cells in dose-dependent manner was not associated with the cell distribution in 3D environment by determination of Prussian blue staining and transmission electronic microscopy. Significantly, through determination of western blotting and immunofluorescence of connexin 43, N-cadherin, desmoplakin, and plakoglobin, DMSA-IRONs enhanced the assembly of gap junctions, decreased mechanical junctions (adherens junctions and desmosomes) of cardiac cells but not in dose-dependent manner in ECTs at seventh day. In addition, DMSA-IRONs increased the vesicles secretion of cardiac cells in ECTs apparently compared to control groups. Overall, we conclude that the internalization of DMSA-IRONs by cardiac cells in dose-dependent manner enhanced the assembly of electrochemical junctions and decreased the mechanical related microstructures. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 121-130, 2018., (© 2016 Wiley Periodicals, Inc.)

Stem cell-based therapy remains one of the promising approaches for cardiac repair and regeneration. However, its applications are restricted by the limited efficacy of cardiac differentiation. To address this issue, we examined whether carbon nanotubes (CNTs) would provide an instructive extracellular microenvironment to facilitate cardiogenesis in brown adipose-derived stem cells (BASCs) and to elucidate the underlying signaling pathways. In this study, we systematically investigated a series of cellular responses of BASCs due to the incorporation of CNTs into collagen (CNT-Col) substrates that promoted cell adhesion, spreading, and growth. Moreover, we found that CNT-Col substrates remarkably improved the efficiency of BASCs cardiogenesis by using fluorescence staining and quantitative real-time reverse transcription-polymerase chain reaction. Critically, CNTs in the substrates accelerated the maturation of BASCs-derived cardiomyocytes. Furthermore, the underlying mechanism for promotion of BASCs cardiac differentiation by CNTs was determined by immunostaining, quantitative real-time reverse transcription-polymerase chain reaction, and Western blotting assay. It is notable that β1-integrin-dependent TGF-β1 signaling pathway modulates the facilitative effect of CNTs in cardiac differentiation of BASCs. Therefore, it is an efficient approach to regulate cardiac differentiation of BASCs by the incorporation of CNTs into the native matrix. Importantly, our findings can not only facilitate the mechanistic understanding of molecular events initiating cardiac differentiation in stem cells, but also offer a potentially safer source for cardiac regenerative medicine.

Objective: To investigate a method for preparing decellularized rat heart scaffold, and to detect and evaluate the decellularized scaffold., Methods: The decellularized rat heart scaffold was prepared by retrograde perfusion with a combination of enzymatic and Triton X-100 detergent methods to remove the populations of resident cells, and then the decellularized scaffold was observed by gross, toluidine blue staining, HE staining, scanning electron microcope (SEM), Alcian blue staining, and immunohistochemisty staining to evaluate the structure and essential component of extracellular maxtix (ECM) in the scaffold., Results: Tissue engineered scaffold based on decellularized whole heart ECM was successfully prepared, which maintained not only the gross morphology of the heart, but also the intact vascular structure and ultrastructural conformation that certified by toluidine blue staining, HE staining, and SEM analyses. Alcian blue staining and immunohistochemisty staining showed that the essential components of ECM, such as collagen type I, glycosaminoglycan, fibronectin, and Laminin were remained in decellularized whole heart matrix., Conclusion: The decellularized whole heart ECM prepared by method mentioned can maintain the intact structure of rat heart and basic compositions of extracellular matrices, so it could be suitable for further studies of tissue engineered scaffolds for whole heart reconstruction.