Bacterial genomes accommodate a variety of mobile genetic elements, including bacteriophage-related clusters that encode phage tail-like protein complexes playing a role in interactions with eukaryotic or prokaryotic cells. Such tailocins are unable to replicate inside target cells due to the lack of a phage head with associated DNA. A subset of tailocins mediate antagonistic activities with bacteriocin-like specificity. Functional characterization of bactericidal tailocins of two Pseudomonas putida rhizosphere isolates revealed not only extensive similarity with the tail assembly module of the Pseudomonas aeruginosa R-type pyocins but also differences in genomic integration site, regulatory genes, and lytic release modules. Conversely, these three features are quite similar between strains of the P. putida and Pseudomonas fluorescens clades, although phylogenetic analysis of tail genes suggests them to have evolved separately. Unlike P. aeruginosa R pyocin elements, the tailocin gene clusters of other pseudomonads frequently carry cargo genes, including bacteriocins. Compared with P. aeruginosa, the tailocin tail fiber sequences that act as specificity determinants have diverged much more extensively among the other pseudomonad species, mostly isolates from soil and plant environments. Activity of the P. putida antibacterial particles requires a functional lipopolysaccharide layer on target cells, but contrary to R pyocins from P. aeruginosa, strain susceptibilities surpass species boundaries.

Stroke is the second most common cause of death and is a major cause of permanent disability. Given the current demographic trend of an ageing population and associated increased risk, the prevalence of and socioeconomic burden caused by stroke will continue to rise. Current therapies are unable to sufficiently ameliorate the disease outcome and are not applicable to all patients. Therefore, strategies such as cell-based therapies with mesenchymal stem cell (MSC) or induced pluripotent stem cell (iPSC) pave the way for new treatment options for stroke. These cells showed great preclinical promise despite the fact that the precise mechanism of action and the optimal administration route are unknown. To gain dynamic insights into the underlying repair processes after stem cell engraftment, noninvasive imaging modalities were developed to provide detailed spatial and functional information on the donor cell fate and host microenvironment. This review will focus on MSCs and iPSCs as types of widely used stem cell sources in current (bio)medical research and compare their efficacy and potential to ameliorate the disease outcome in animal stroke models. In addition, novel noninvasive imaging strategies allowing temporospatial in vivo tracking of transplanted cells and coinciding evaluation of neuronal repair following stroke will be discussed.

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Within the field of tissue engineering, natural tissues are reconstructed by combining growth factors, stem cells, and different biomaterials to serve as a scaffold for novel tissue growth. As adequate vascularization and innervation are essential components for the viability of regenerated tissues, there is a high need for easily accessible stem cells that are capable of supporting these functions. Within the human tooth and its surrounding tissues, different stem cell populations can be distinguished, such as dental pulp stem cells, stem cells from human deciduous teeth, stem cells from the apical papilla, dental follicle stem cells, and periodontal ligament stem cells. Given their straightforward and relatively easy isolation from extracted third molars, dental stem cells (DSCs) have become an attractive source of mesenchymal-like stem cells. Over the past decade, there have been numerous studies supporting the angiogenic, neuroprotective, and neurotrophic effects of the DSC secretome. Together with their ability to differentiate into endothelial cells and neural cell types, this makes DSCs suitable candidates for dental tissue engineering and nerve injury repair.