Panhematopoietic RNA barcoding enables kinetic measurements of nucleate and anucleate lineages and the activation of myeloid clones following acute platelet depletion

BACKGROUND

Platelets and erythrocytes constitute over 95% of all hematopoietic stem cell output. However, the clonal dynamics of HSC contribution to these lineages remains largely unexplored.

RESULTS

We use lentiviral genetic labeling of mouse hematopoietic stem cells to quantify output from all lineages, nucleate, and anucleate, simultaneously linking these with stem and progenitor cell transcriptomic phenotypes using single-cell RNA-sequencing. We observe dynamic shifts of clonal behaviors through time in same-animal peripheral blood and demonstrate that acute platelet depletion shifts the output of multipotent hematopoietic stem cells to the exclusive production of platelets. Additionally, we observe the emergence of new myeloid-biased clones, which support short- and long-term production of blood cells.

CONCLUSIONS

Our approach enables kinetic studies of multi-lineage output in the peripheral blood and transcriptional heterogeneity of individual hematopoietic stem cells. Our results give a unique insight into hematopoietic stem cell reactivation upon platelet depletion and of clonal dynamics in both steady state and under stress.

Platelet Depletion/Transfusion as a Lethal Factor in a Colitis-associated Cancer Mouse Model

BACKGROUND/AIM

TLR-4 Knock-out (KO) mice are protected from colitis-associated cancer in the established AOM/DSS mouse model. The aim of this study was to assess whether the TLR4 KO mice would still be protected from carcinogenesis after platelet depletion and transfusion with TLR4 wild-type platelets.

MATERIALS AND METHODS

Thirty-two female C57BL6 mice were divided into 6 groups. Among the three groups that received Azoxymethane/Dextran Sulfate Sodium (AOM/DSS), one group included TLR4KO mice, which were depleted of their platelets and were then transfused with platelets from TLR4 wild-type mice. The other two groups included wild-type and TLR-4KO mice that only received AOM/DSS.

RESULTS

All 6 animals in the KO group that underwent platelet depletion/transfusion succumbed. Three of them died before the administration of DSS and three in the week following DSS administration. In contrast, mice in the other two groups experienced less weight loss and only 1 mouse died in each of them.

CONCLUSION

Platelet depletion/transfusion was detrimental in TLR-4 transgenic mice that received AOM/DSS.