Brain Tumors Incited by Blood Stem Cells June 28, 2021 A positive link has been found between tumor-associated blood stem cells and glioblastoma progression. This link is supported by evidence from experiments in which blood stem cells were co-cultured with tumor organoids. (The fluorescently labeled tumor organoids in this image were grown from patient cells.) In these experiments, the blood stem cells were shown to promote glioblastoma cell proliferation and PD-L1 expression. [K. Stratmann and C. Dobersalske, German Cancer Research Center] Glioblastomas are more inclined to dig in and spread out if they are egged on by hematopoietic stem cells. To “dig in,” the glioblastomas become more immunosuppressive. To “spread out,” they support the proliferation of cancer cells, promoting malignancy. The connection between immunosuppressive/malignant glioblastomas and blood stem cells was discovered by scientists affiliated with the German Cancer Consortium (DKTK). These scientists suggest that their work could open up new possibilities for developing more effective immunotherapies against glioblastomas, the most aggressive brain malignancies in adults.