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One of the most important medical interventions for individuals with heart valvular disease is heart valve replacement, which is not without substantial challenges, particularly for pediatric patients. Due to their biological properties and biocompatibility, natural tissue-originated scaffolds derived from human or animal sources are one type of scaffold that is widely used in tissue engineering. However, they are known for their high potential for immunogenicity. Being free of cells and genetic material, decellularized xenografts, consequently, have low immunogenicity and, thus, are expected to be tolerated by the recipient's immune system. The scaffold ultrastructure and ECM composition can be affected by cell removal agents. Therefore, applying an appropriate method that preserves intact the structure of the ECM plays a critical role in the final result. So far, there has not been an effective decellularization technique that preserves the integrity of the heart valve's ultrastructure while securing the least amount of genetic material left. This study demonstrates a new protocol with untraceable cells and residual DNA, thereby maximally reducing any chance of immunogenicity. The mechanical and biochemical properties of the ECM resemble those of native heart valves. Results from this study strongly indicate that different critical factors, such as ionic detergent omission, the substitution of Triton X-100 with Tergitol, and using a lower concentration of trypsin and a higher concentration of DNase and RNase, play a significant role in maintaining intact the ultrastructure and function of the ECM. [ABSTRACT FROM AUTHOR]

The single‐stranded DNA/RNA binding protein WHIRLY1 is a major chloroplast nucleoid‐associated protein required for the compactness of nucleoids. Most nucleoids in chloroplasts of WHIRLY1‐knockdown barley plants are less compact compared to nucleoids in wild‐type plants. The reduced compaction leads to an enhanced optical cross‐section, which may cause the plastid DNA to be a better target for damaging UV‐B radiation. To investigate this hypothesis, primary foliage leaves, chloroplasts, and nuclei from wild‐type and WHIRLY1‐knockdown plants were exposed to experimental UV‐B radiation. Thereafter, total, genomic and plastid DNA were isolated, respectively, and analyzed for the occurrence of cyclobutane pyrimidine dimers (CPDs), which is a parameter for genome stability. The results of this study revealed that WHIRLY1‐deficient chloroplasts had strongly enhanced DNA damages, whereas isolated nuclei from the same plant line were not more sensitive than nuclei from the wild‐type, indicating that WHIRLY1 has different functions in chloroplasts and nucleus. This supports the hypothesis that the compaction of nucleoids may provide protection against UV‐B radiation. [ABSTRACT FROM AUTHOR]