Pluripotency describes the ability of stem cells to differentiate into derivatives of the three germ layers. In reporting new human pluripotent stem cell lines, their clonal derivatives or the... Show morePluripotency describes the ability of stem cells to differentiate into derivatives of the three germ layers. In reporting new human pluripotent stem cell lines, their clonal derivatives or the safety of differentiated derivatives for transplantation, assessment of pluripotency is essential. Historically, the ability to form teratomas in vivo containing different somatic cell types following injection into immunodeficient mice has been regarded as functional evidence of pluripotency. In addition, the teratomas formed can be analyzed for the presence of malignant cells. However, use of this assay has been subject to scrutiny for ethical reasons on animal use and due to the lack of standardization in how it is used, therefore questioning its accuracy. In vitro alternatives for assessing pluripotency have been developed such as ScoreCard and PluriTest. However, it is unknown whether this has resulted in reduced use of the teratoma assay. Here, we systematically reviewed how the teratoma assay was reported in publications between 1998 (when the first human embryonic stem cell line was described) and 2021. Our analysis of >400 publications showed that in contrast to expectations, reporting of the teratoma assay has not improved: methods are not yet standardized, and malignancy was examined in only a relatively small percentage of assays. In addition, its use has not decreased since the implementation of the ARRIVE guidelines on reduction of animal use (2010) or the introduction of ScoreCard (2015) and PluriTest (2011). The teratoma assay is still the preferred method to assess the presence of undifferentiated cells in a differentiated cell product for transplantation since the in vitro assays alone are not generally accepted by the regulatory authorities for safety assessment. This highlights the remaining need for an in vitro assay to test malignancy of stem cells. Show less
Hulsker, C.C.C.; Mansori, I. el; Fiocco, M.; Zsiros, J.; Wijnen, M.H.W.; Looijenga, L.H.J.; ... ; Steeg, A.F.W. van der 2021
Simple Summary Germ cell tumours are a heterogeneous group of neoplasms and are predominantly midline tumours occurring from birth to late adulthood. Suboptimal outcomes remain for several groups... Show moreSimple Summary Germ cell tumours are a heterogeneous group of neoplasms and are predominantly midline tumours occurring from birth to late adulthood. Suboptimal outcomes remain for several groups of patients, including adolescents, and patients with extragonadal tumours, high tumour markers at diagnosis or platinum-resistant disease. The aim of our systematic review was to explore survival rates internationally over the past two decades in order to better define future practice and treatment strategies and also to define specific subgroups with inferior outcomes. The results of our systematic review describe the heterogeneous nature of germ cell tumours in different anatomical locations, impacting on stage at presentation, treatment modalities used and survival data. Despite this heterogeneity, subpopulations can be defined which have an inferior survival and where future research and more individualised treatment would help to improve survival. Objective: This systematic review and meta-analysis was performed to explore overall survival (OS) and event free survival (EFS) rates internationally over the past two decades and to define specific subgroups with inferior outcomes which may demand different treatment strategies. Methods: The search focused on malignant extracranial germ cell tumours (GCTs) in the paediatric population. The initial database search identified 12,556 articles; 32 articles were finally included in this review, comprising a total of 5095 patients. Results: The studies were heterogeneous, varying from single institution reports to large prospective trials. Older studies, describing eras where non-platinum-based chemotherapy regimens were used, showed clearly worse outcomes. Survival for stage I-II gonadal disease is excellent. On the other hand, patients with an initial alpha-fetoprotein (AFP) > 10,000 ng/mL or kU/L, age > 11 years and stage IV disease confer a survival disadvantage. For testicular disease in particular, lymphovascular invasion and certain histopathological subtypes, such as embryonal carcinoma (EC) and mixed malignant GCTs, survival is poorer. Survival data for sacrococcygeal and mediastinal GCTs show a heterogeneous distribution across studies in this review, independent of year of publication. Patients > 12 years presenting with a mediastinal GCT pose a subpopulation which fares worse than GCTs in other locations or age groups. This is independent of AFP levels, stage of disease or treatment protocol, and these patients may demand a different treatment strategy. Conclusions: This review describes the heterogeneous nature of GCTs in different anatomical locations, impacting on stage at presentation, treatment modalities used and survival data. Despite this heterogeneity, in line with the current developmental biology-based classification system, subpopulations can be defined which have an inferior EFS and OS and where future research and more individualised treatment would help to improve survival. Show less
