Neuroblastoma cells injected into experimental mature teratoma reveal a tropism for embryonic loose mesenchyme

Abstract

Abstract. Embryonic neural tumors are responsible for a disproportionate number of cancer deaths in children. Although dramatic improvements in survival for pediatric malignancy has been achieved in previous years advancements seem to be slowing down. For the development of new enhanced therapy and an increased understanding of the disease, pre-clinical models better capturing the neoplastic niche are essential. Tumors of early childhood present in this respect a particular challenge. Here, we explore how components of the embryonic process in stem-cell induced mature teratoma can function as an experimental in vivo microenvironment instigating the growth of injected childhood neuroblastoma (NB) cell lines. Three human NB cell lines, IMR-32, Kelly and SK-N-BE(2), were injected into mature pluripotent stem cell-induced teratoma (PSCT) and compared to xenografts of the same cell lines. Proliferative NB cells from all lines were readily detected in both models with a typical histology of a poorly differentiated NB tumor with a variable amount of fibrovascular stroma. Uniquely in the PSCT microenvironment, NB cells were found integrated in a non-random fashion. Neuroblastoma cells were never observed in areas with well-differentiated somatic tissue i.e. bone, muscle, gut or areas of other easily identifiable tissue types. Instead, the three cell lines all showed initial growth exclusively occurring in the embryonic loose mesenchymal stroma, resulting in a histology recapitulating NB native presentation in vivo. Whether this reflects the 'open' nature of loose mesenchyme more easily giving space to new cells compared to other more dense tissues, the rigidity of matrix providing physical cues modulating NB characteristics, or if embryonic loose mesenchyme may supply developmental cues that attracted or promoted the integration of NB, remains to be tested. We tentatively hypothesize that mature PSCT provide an embryonic niche well suited for in vivo studies on NB. IntroductionKey knowledge is still missing for the successful cure of aggressive neuroblastoma (NB), representing one of the most deadly pediatric malignancies (1-4). Neuroblastoma is a small round cell tumor of childhood and is considered to arise from dedifferentiation of primordial neural crest cells that populate the sympathetic trunks and the adrenal medulla (reviewed in ref. 5). During this process, an aberrant response to microenvironment cues may play an important role in modulating the tumor phenotype, and hence also lead to the variable clinical presentations of NB in patients. The clinical presentation spans from a benign type with the ability to spontaneously regress to a variant with a high rate of recurrence, metastatic spread and a high frequency of therapy-resistance. Current consensus supports the importance of a strong interplay with the surrounding tissue promoting tumor growth and spread (6). Thus, pre-clinical studies of childhood NB would for increased relevance benefit from in vivo models better matching the embryonic neoplastic niche i...

Niche-Dependent Gene Expression Profile of Intratumoral Heterogeneous Ovarian Cancer Stem Cell Populations

“…Extension of the findings using the hESC-derived microenvironment to other tumors will be needed to demonstrate broad relevance. To date, reproducibility of our previously published results has been demonstrated in two independent publications indicating that the hESC-based model express bona fide human tumor blood vessels and enhance tumor engraftment rate by primary human ovarian CSC-like [37], and that the hESC-based model enable the implantation and growth of childhood neuroectodermal tumors biopsies as it provides an embryonic niche well suited for in vivo studies of neuroblastoma [64]. In addition, mechanistic studies will be required to assess the functional role of the genes exposed in this study.…”

Tropism of the in situ growth from biopsies of childhood neuroectodermal tumors following transplantation into experimental teratoma

“…The mechanism for such tropism now remains to be tested and we see primarily three main possibilities; (i) the "open" nature of loose mesenchyme may more easily give space to new cells compared to other more dense tissues, (ii) the biophysical properties of the extracellular matrix such as rigidity may provide physical cues, "mechanotransductive signalling," as suggested by Lam et al 21 Alternatively (iii) components of the loose myxoid ground or factors derived from the various cell types present in embryonic loose mesenchyme may supply developmental cues that attract or promote integration. 12 To what extent tropism may be dependent on heterologous versus autologous microenvironments could possibly also be addressed further by using teratomas from induced pluripotent stem cells derived from patients with various tumor types.…”

“…This raised to us an intriguing prospect that the embryonic human microenvironment in experimental teratoma could be well matched for studies of childhood tumors of early neuroectodermal origin. In a recent study, we tested this notion by injecting three childhood neuroblastoma (NB) tumor cell lines into mature teratoma, and in parallel as xenografts . Here, we expand the studies on cell lines to using fresh biopsy materials from children with different types of neuroectodermal tumors.…”

“…In a recent study, we tested this notion by injecting three childhood neuroblastoma (NB) tumor cell lines into mature teratoma, and in parallel as xenografts. 12 Here, we expand the studies on cell lines to using fresh biopsy materials from children with different types of neuroectodermal tumors.…”

Teratoma: from spontaneous tumors to the pluripotency/malignancy assay

“…Recently, a mature pluripotent stem cell‐induced teratoma (PSCT) has been used as an experimental in vivo microenvironment suitable for in vivo culture of injected cancer cell lines. Neuroblastoma cells revealed a tropism for embryonic loose mesenchyme of teratomas, which resulted in a histology recapitulating NB native presentation in vivo . However, it was shown that rats carrying experimental teratomas were partially or totally protected against the induction (by a single injection of a potent carcinogen) or transplantation of malignant tumors (adenocarcinoma and lymphoma) that killed 100% of the controls, a result which suggested that embryonal tissues are the source of tumor inhibitory factors .…”