Enzyme Degradable Polymersomes from Hyaluronic Acid-<i>block</i>-poly(ε-caprolactone) Copolymers for the Detection of Enzymes of Pathogenic Bacteria

We introduce a new hyaluronidase-responsive amphiphilic block copolymer system, based on hyaluronic acid (HYA) and polycaprolactone (PCL), that can be assembled into polymersomes by an inversed solvent shift method. By exploiting the triggered release of encapsulated dye molecules, these HYA-<i>block</i>-PCL polymersomes lend themselves as an autonomous sensing system for the detection of the presence of hyaluronidase, which is produced among others by the pathogenic bacterium Staphylococcus aureus. The synthesis of the enzyme-responsive HYA-<i>block</i>-PCL block copolymers was carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition of ω-azide-terminated PCL and ω-alkyne-functionalized HYA. The structure of the HYA-<i>block</i>-PCL assemblies and their enzyme-triggered degradation and concomitant cargo release were investigated by dynamic light scattering, fluorescence spectroscopy, confocal laser-scanning microscopy, scanning and transmission electron, and atomic force microscopy. As shown, a wide range of reporter dye molecules as well as antimicrobials can be encapsulated into the vesicles during formation and are released upon the addition of hyaluronidase

Identification of DNA methylation changes at <i>cis</i>-regulatory elements during early steps of HSC differentiation using tagmentation-based whole genome bisulfite sequencing

<div><p>Epigenetic alterations during cellular differentiation are a key molecular mechanism which both instructs and reinforces the process of lineage commitment. Within the haematopoietic system, progressive changes in the DNA methylome of haematopoietic stem cells (HSCs) are essential for the effective production of mature blood cells. Inhibition or loss of function of the cellular DNA methylation machinery has been shown to lead to a severe perturbation in blood production and is also an important driver of malignant transformation. HSCs constitute a very rare cell population in the bone marrow, capable of life-long self-renewal and multi-lineage differentiation. The low abundance of HSCs has been a major technological barrier to the global analysis of the CpG methylation status within both HSCs and their immediate progeny, the multipotent progenitors (MPPs). Within this Extra View article, we review the current understanding of how the DNA methylome regulates normal and malignant hematopoiesis. We also discuss the current methodologies that are available for interrogating the DNA methylation status of HSCs and MPPs and describe a new data set that was generated using tagmentation-based whole genome bisulfite sequencing (TWGBS) in order to comprehensively map methylated cytosines using the limited amount of genomic DNA that can be harvested from rare cell populations. Extended analysis of this data set clearly demonstrates the added value of genome-wide sequencing of methylated cytosines and identifies novel important <i>cis</i>-acting regulatory regions that are dynamically remodeled during the first steps of haematopoietic differentiation.</p></div