Progress made in the use of animal models for the study of high-risk, nonmuscle invasive bladder cancer

Mice engrafted with human hematopoietic stem cells support a human myeloid cell inflammatory response in vivo

Mice engrafted with human CD34⁺ hematopoietic stem and progenitor cells (CD34⁺ -HSPCs) have been used to study human infection, diabetes, sepsis, and burn, suggesting that they could be highly amenable to characterizing the human inflammatory response to injury. To this end, human leukocytes infiltrating subcutaneous implants of polyvinyl alcohol (PVA) sponges were analyzed in immunodeficient NSG mice reconstituted with CD34⁺ -HSPCs. It was reported that human CD45⁺ (hCD45⁺ ) leukocytes were present in PVA sponges 3 and 7 days postimplantation and could be localized within the sponges by immunohistochemistry. The different CD45⁺ subtypes were characterized by flow cytometry and the profile of human cytokines they secreted into PVA wound fluid was assessed using a human-specific multiplex bead analyses of human IL-12p70, TNFα, IL-10, IL-6, IL1β, and IL-8. This enabled tracking the functional contributions of HLA-DR⁺ , CD33⁺ , CD19⁺ , CD62L⁺ , CD11b⁺ , or CX3CR1⁺ hCD45⁺ infiltrating inflammatory leukocytes. PCR of cDNA prepared from these cells enabled the assessment and differentiation of human, mouse, and uniquely human genes. These findings support the hypothesis that mice engrafted with CD34⁺ -HSPCs can be deployed as precision avatars to study the human inflammatory response to injury.

FGFR3b Extracellular Loop Mutation Lacks Tumorigenicity In Vivo but Collaborates with p53/pRB Deficiency to Induce High-grade Papillary Urothelial Carcinoma

Missense mutations of fibroblast growth factor receptor 3 (FGFR3) occur in up to 80% of low-grade papillary urothelial carcinoma of the bladder (LGP-UCB) suggesting that these mutations are tumor drivers, although direct experimental evidence is lacking. Here we show that forced expression of FGFR3b-S249C, the most prevalent FGFR3 mutation in human LGP-UCB, in cultured urothelial cells resulted in slightly reduced surface translocation than wild-type FGFR3b, but nearly twice as much proliferation. When we expressed a mouse equivalent of this mutant (FGFR3b-S243C) in urothelia of adult transgenic mice in a tissue-specific and inducible manner, we observed significant activation of AKT and MAPK pathways. This was, however, not accompanied by urothelial proliferation or tumorigenesis over 12 months, due to compensatory tumor barriers in p16-pRB and p19-p53-p21 axes. Indeed, expressing FGFR3b-S249C in cultured human urothelial cells expressing SV40T, which functionally inactivates pRB/p53, markedly accelerated proliferation and cell-cycle progression. Furthermore, expressing FGFR3b-S243C in transgenic mouse urothelium expressing SV40T converted carcinoma-in-situ to high-grade papillary urothelial carcinoma. Together, our study provides new experimental evidence indicating that the FGFR3 mutations have very limited urothelial tumorigenicity and that these mutations must collaborate with other genetic events to drive urothelial tumorigenesis.