Hematopoietic stem cell transplantation is one of the options for a medical procedure, mainly used in the treatment of oncology and hematology, as well as some malignant tumors. Since gaining additional knowledge about these cells’ functioning increases the chance of a successful transplant, there is a need for special research. This article is precisely such a study that focuses on CD166 – activated leukocyte cell adhesion molecules (Zhang et al., 2019). These molecules mediate homophilic and heterophilic interactions and are also a critical component in the repopulation of the hematopoietic stem. However, it has so far been unclear whether there is a link between the homophilic interaction of CD166 and the increased hematopoietic potential of stem cells. The paper aimed to investigate this molecule’s interaction with stem cells to confirm that the homophilic interaction of CD166 can lead to more robust endpoints. This theory was successfully demonstrated by single-cell RNA analysis of stem cells of wild-type mice.
Materials and Methods
Wild-type mice raised at Indiana University were used as a source of stem cells, on which further studies were carried out. The mice were 8 to 12 weeks old, and mice were of both sexes (Zhang et al., 2019). The cells were removed from the tibia and femur bones, after which they were washed with specialized solvents. Besides, mononuclear cells from normal human umbilical cord blood were also obtained for further research. For assays and phenotyping, culture plates were coated with a recombinant mouse or human protein. In the first case, the colonies were counted on the 7th day, and in the second – on the 14th. ScRNA-Seq was used as the primary method, after which the obtained data were processed and analyzed concerning the Gaussian distribution using the Mann-Whitney test and the Fisher exact test. Finally, Ingenuity Pathway Analysis was applied to modify essential genes and create biological networks.
To assess the effect of CD166 on hematopoietic function, CFU production was analyzed using the example of various cultures, including those with separation by the presence of LSK cells. This division was necessary to obtain more precise results using clonogenic assays. Studies have shown that the increase in CD166 + LSK cells’ culture is almost eight times higher than the analogous process with the culture of CD166-LSK cells (Zhang et al., 2019). A follow-up study focused on a recombinant mouse protein, and its effects on other cells found the activation of signaling pathways from homophilic CD166 interactions. Further analysis methods look at the interaction of CD166 with different types of cells under various conditions to reveal as much of the interplay as possible. For example, it was found that the absence of homophilic interactions of the designated molecules leads to negative consequences. Finally, a chimerism analysis was performed to reveal post-transplant effects and the relationship between different cell types, which showed a short-term impact on stem cells’ repopulation potential.
CD166 is an essential group of molecules present in various tissues but has the greatest effect in groups of cells associated with dynamic growth. Current and ongoing studies have not found any association between the heterophilic interaction between CD166 and CD6. Consequently, the study focused on homophilic effects, as these molecules have the potential to become prognosis markers and therapeutic targets (Zhang et al., 2019). The tests carried out gave an interesting result in the form of a completely different gene expression of freshly isolated cells. The loss of CD166 involvement led to the suppression of genes associated with stem cells’ normal functioning. Finally, after analyzing all possible interactions and signals that appear in this case, the authors of the article concluded the importance of homophilic interactions of CD166. As practice shows, these synergies with stem cells are necessary to maintain the normal functioning and production of cells. Therefore, these molecules’ homophilic response can be successfully used as an aid in hematopoietic stem cell transplantation.
Zhang, J., Ghosh, J., Mohamad, S.F., Zhang, C., Huang, X., Capitano, M.L., Gunawan, A.M., Cooper, S., Guo, B., Cai, Q., Broxmeyer, H.E., & Srour, E.F. (2019). CD166 engagement augments mouse and human hematopoietic progenitor function via activation of stemness and cell cycle pathways. Stem Cells, 37(10), 1319-1330. Web.