Highlights d Single-cell RNA sequencing of human lymph nodes unveils six types of LECs d LECs lining the floor and ceiling of the SCS, MS, and valve are the main types d LECs of the SCS floor and MS highly express neutrophil chemoattractants d Human MS LECs support neutrophil adhesion in the LN medulla via CD209

Xiang et al. scRNA-seq of Lymph Node Lymphatic Vasculature HIGHLIGHTS Computational alignments ("trajectories") predict LN LEC organization in situ, revealing a continuum of phenotypes punctuated by specialized clusters. Multiple intermediate phenotypes suggest LEC malleability. Gene profiles define niche-specific functional specialization. Medullary sinus LECs are comprised of Ptx3-LECs and Marco-LECs.-Distinct mechanisms for pathogen interactions and matrix modeling.-Ptx3-LECs: paracortical and central medullary sinuses near hilus; enriched for genes driving lymphangiogenic responses and lymphocyte egress.-Marco-LECs: peri-follicular medullary sinuses; macrophageassociated genes, complement and coagulation cascade. Niche-specific responses to inflammation.-IFN gene responses in SCS floor and medullary sinus LECs.-Suppression of LEC identity genes in responding subsets. Conserved and unique LEC subsets and gene programs across species.-Core subsets common to mouse and human.-Greater diversity of subsets and intermediates in human LN LECs.

Organ replacement regenerative therapy is purported to enable the replacement of organs damaged by disease, injury or aging in the foreseeable future. Here we demonstrate fully functional hair organ regeneration via the intracutaneous transplantation of a bioengineered pelage and vibrissa follicle germ. The pelage and vibrissae are reconstituted with embryonic skin-derived cells and adult vibrissa stem cell region-derived cells, respectively. The bioengineered hair follicle develops the correct structures and forms proper connections with surrounding host tissues such as the epidermis, arrector pili muscle and nerve fibres. The bioengineered follicles also show restored hair cycles and piloerection through the rearrangement of follicular stem cells and their niches. This study thus reveals the potential applications of adult tissue-derived follicular stem cells as a bioengineered organ replacement therapy.

IR spectra of phenol-Arn (PhOH-Arn) clusters with n=1 and 2 were measured in the neutral and cationic electronic ground states in order to determine the preferential intermolecular ligand binding motifs, hydrogen bonding (hydrophilic interaction) versus pi bonding (hydrophobic interaction). Analysis of the vibrational frequencies of the OH stretching motion, nuOH, observed in nanosecond IR spectra demonstrates that neutral PhOH-Ar and PhOH-Ar2 as well as cationic PhOH+-Ar have a pi-bound structure, in which the Ar atoms bind to the aromatic ring. In contrast, the PhOH+-Ar2 cluster cation is concluded to have a H-bound structure, in which one Ar atom is hydrogen-bonded to the OH group. This pi-->H binding site switching induced by ionization was directly monitored in real time by picosecond time-resolved IR spectroscopy. The pi-bound nuOH band is observed just after the ionization and disappears simultaneously with the appearance of the H-bound nuOH band. The analysis of the picosecond IR spectra demonstrates that (i) the pi-->H site switching is an elementary reaction with a time constant of approximately 7 ps, which is roughly independent of the available internal vibrational energy, (ii) the barrier for the isomerization reaction is rather low(<100 cm(-1)), (iii) both the position and the width of the H-bound nuOH band change with the delay time, and the time evolution of these spectral changes can be rationalized by intracluster vibrational energy redistribution occurring after the site switching. The observation of the ionization-induced switch from pi bonding to H bonding in the PhOH+-Ar2 cation corresponds to the first manifestation of an intermolecular isomerization reaction in a charged aggregate.