Engineering a robust and anisotropic cardiac-specific extracellular matrix scaffold for cardiac patch tissue engineering.

Extracellular matrix (ECM) fabricated using human induced pluripotent stem cells (hiPSCs)-derived cardiac fibroblasts (hiPSC-CFs) could serve as a completely biological scaffold for an engineered cardiac patch, leveraging the unlimited source and outstanding reproducibility of hiPSC-CFs. Additionally, hiPSC-CF-derived ECM (hiPSC-CF-ECM) holds the potential to enhance maturation of exogenous cardiomyocytes, such as hiPSC-derived cardiomyocytes (hiPSC-CMs), by providing a microenvironment rich in cardiac-specific biochemical and signaling cues. However, achieving sufficient robustness of hiPSC-CF-ECM is challenging. This study aims to achieve appropriate ECM deposition, scaffold thickness, and mechanical strength of an aligned hiPSC-CF-ECM by optimizing the culture period, ranging from 2 to 10 weeks, of hiPSC-CFs grown on micro-grated substrates, which can direct the alignment of both hiPSC-CFs and their secreted ECM. The hiPSC-CFs demonstrated a production rate of 13.5 µg ECM per day per 20,000 cells seeded. An anisotropic nanofibrous hiPSC-CF-ECM scaffold with a thickness of 20.0 ± 2.1 µm was achieved after 6 weeks of culture, followed by decellularization. Compositional analysis through liquid chromatography-mass spectrometry (LC-MS) revealed the presence of cardiac-specific fibrillar collagens, non-fibrillar collagens, and matricellular proteins. Uniaxial tensile stretching of the hiPSC-CF-ECM scaffold indicated robust tensile resilience. Finally, hiPSCs-CMs cultured on the hiPSC-CF-ECM exhibited alignment following the guidance of ECM nanofibers and demonstrated mature organization of key structural proteins. The culture duration of the anisotropic hiPSC-CF-ECM was successfully refined to achieve a robust scaffold containing structural proteins that resembles cardiac microenvironment. This completely biological, anisotropic, and cardiac-specific ECM holds great potential for cardiac patch engineering.

Detergent-Based Decellularization for Anisotropic Cardiac-Specific Extracellular Matrix Scaffold Generation.

Cell-derived extracellular matrix (ECM) has become increasingly popular in tissue engineering applications due to its ability to provide tailored signals for desirable cellular responses. Anisotropic cardiac-specific ECM scaffold decellularized from human induced pluripotent stem cell (hiPSC)-derived cardiac fibroblasts (hiPSC-CFs) mimics the native cardiac microenvironment and provides essential biochemical and signaling cues to hiPSC-derived cardiomyocytes (hiPSC-CMs). The objective of this study was to assess the efficacy of two detergent-based decellularization methods: (1) a combination of ethylenediaminetetraacetic acid and sodium dodecyl sulfate (EDTA + SDS) and (2) a combination of sodium deoxycholate and deoxyribonuclease (SD + DNase), in preserving the composition and bioactive substances within the aligned ECM scaffold while maximumly removing cellular components. The decellularization effects were evaluated by characterizing the ECM morphology, quantifying key structural biomacromolecules, and measuring preserved growth factors. Results showed that both treatments met the standard of cell removal (less than 50 ng/mg ECM dry weight) and substantially preserved major ECM biomacromolecules and growth factors. The EDTA + SDS treatment was more time-efficient and has been determined to be a more efficient method for generating an anisotropic ECM scaffold from aligned hiPSC-CFs. Moreover, this cardiac-specific ECM has demonstrated effectiveness in supporting the alignment of hiPSC-CMs and their expression of mature structural and functional proteins in in vitro cultures, which is crucial for cardiac tissue engineering.

Spark Plasma Sintered B4C-Structural, Thermal, Electrical and Mechanical Properties.

The structural, thermal, electrical and mechanical properties of fully dense B4C ceramics, sintered using Spark Plasma Sintering (SPS), were studied and compared to the properties of B4C ceramics previously published in the literature. New results on B4C's mechanical responses were obtained by nanoindentation and ring-on-ring biaxial strength testing. The findings contribute to a more complete knowledge of the properties of B4C ceramics, an important material in many industrial applications.