Ultralow-dose irradiation enables engraftment and intravital tracking of disease initiating niches in clonal hematopoiesis.

Recent advances in imaging suggested that spatial organization of hematopoietic cells in their bone marrow microenvironment (niche) regulates cell expansion, governing progression, and leukemic transformation of hematological clonal disorders. However, our ability to interrogate the niche in pre-malignant conditions has been limited, as standard murine models of these diseases rely largely on transplantation of the mutant clones into conditioned mice where the marrow microenvironment is compromised. Here, we leveraged live-animal microscopy and ultralow dose whole body or focal irradiation to capture single cells and early expansion of benign/pre-malignant clones in the functionally preserved microenvironment. 0.5 Gy whole body irradiation (WBI) allowed steady engraftment of cells beyond 30 weeks compared to non-conditioned controls. In-vivo tracking and functional analyses of the microenvironment showed no change in vessel integrity, cell viability, and HSC-supportive functions of the stromal cells, suggesting minimal inflammation after the radiation insult. The approach enabled in vivo imaging of Tet2+/- and its healthy counterpart, showing preferential localization within a shared microenvironment while forming discrete micro-niches. Notably, stationary association with the niche only occurred in a subset of cells and would not be identified without live imaging. This strategy may be broadly applied to study clonal disorders in a spatial context.

The effect of astaxanthin treatment on the rat model of fetal alcohol spectrum disorders (FASD).

Fetal alcohol spectrum disorder (FASD) caused by mother's exposure to alcohol during pregnancy is a congenital neurological disease of the fetus resulting in fetal developmental and intellectual disabilities, cognitive impairment, and coordination disorder. Excess oxidative stress and neuroinflammatory responses were an important factor in neuropathological changes in FASD. Astaxanthin (AST) was a potent antioxidant and anti-inflammatory carotenoid. Therefore, this study proposed to explore how AST treatment can ameliorate morphological changes in the hippocampus and cognitive impairment in FASD rats by reducing oxidative stress and neuroinflammation in the brain. An alcohol atomizer was used from postnatal day (P) 2 to P10 to induce the FASD rat model. They were treated with AST (10 mg/kg body weight/day, intraperitoneal injection) for 8 consecutive days starting at P53 and sacrificed at P60. FASD rats had growth retardation and facial dysmorphologies, excessive oxidative stress and neuroinflammation in the hippocampus, decreased choline acetyltransferase (ChAT) expression in MS nucleus, spine loss on hippocampal CA1 pyramidal neurons, and poor performance in spatial learning and memory and sensory-motor coordination. After AST treatment, oxidative stress, neuroinflammation, cholinergic system, excitatory synaptic structure and behavior of FASD rats improved. Therefore, our study provided evidence to support the proposal that AST could be considered to treat FASD.