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The Teratoma assay for evaluation of malignancy of stem cells: a systematic review of preclinical and clinical studies.

Projectomschrijving

Door het systematisch onderzoeken van meer dan 400 publicaties over het aantonen van hPSC pluripotentie door middel van teratoma-assays, werd een grote variabiliteit in experimentele opzet opgemerkt. Verrassend genoeg lijken de details van de rapportage niet te zijn verbeterd sinds de eerste hESC-studie in 1998 en in het algemeen werden gegenereerde tumoren oppervlakkig geanalyseerd. Details die bovendien van invloed kunnen zijn op de ontwikkeling van de tumor, zoals de injectievloeistof en de stam en het geslacht van de muizen, worden in de publicaties niet altijd vermeld. Dit soort vooringenomenheid brengt objectieve vergelijkingen tussen verschillende cellijnen in het gedrang, en waardevolle kenmerken kunnen over het hoofd worden gezien. Hoewel er reeds een gevalideerde in vitro test bestaat om de pluripotentie te testen, wordt de in vivo test nog steeds veel gebruikt.

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Samenvatting van de aanvraag

The Teratoma assay is considered the gold standard to test pluripotency and especially malignancy of human embryonic stem cells and induced pluripotent stem cells. The Teratoma assay has two distinct goals: 1) Assessment of pluripotency: to test the developmental potential of a particular cell line, specifically, to determine whether it can differentiate into derivatives of the three germ layers. 2) Assessment of tumorigenicity: to test the potential to give rise to teratoma/teratocarcinoma and other types of malignancy with respect to preclinical safety. This is somewhat simplistic however since a teratoma is actually non-malignant: the risk lies in the presence of residual undifferentiated cells which may transform to malignant teratocarcinomas that resemble germ cell tumors of the testis that occur with high frequency in young men. Teratomas are benign tumours containing complex mixtures of different tissues that look like disorganized embryos. Teratomas develop in immunodeficient mice if human pluripotent stem cells are injected under the kidney capsule, subcutaneously or into the testis . Histological analysis shows derivatives of the three embryonic germ layers (e.g. intestinal structures from endoderm, neural rosettes from ectoderm and muscle from mesoderm). The Teratoma assay was recommended by the leading stem cell organization, the International Society for Stem Cell Research (ISSCR) as part of the basic characterization of human pluripotent stem cells. The Teratoma assay however raises both ethical and animal welfare concerns: (i) the surgery is technically challenging (ii) the animals can develop invasive tumors, and (iii) in vivo tumour growth can be painful. Therefore any such animal experiments require ethical approval but local laws and regulations can be restrictive in some countries. Beside that the assay presents additional serious limitations regarding the experimental procedure as well as the scientific quality of the generated data: It is labor intensive, time consuming and expensive and requires a large number of immunodeficient mice being kept alive in specialized facilities for a minimum period of 2-3 months. Moreover, the assay has never been standardized, either with respect to the site of injection (commonly subcutaneous, kidney capsule and testis capsule are used),the strain of mouse (e.g. NOD-SCID or Beige-SCID mice), the size of the inoculum, or the length of time for tumors to develop. There are anecdotal reports that all of these factors might influence the outcome, but no comprehensive comparison has been made. The goal of this request is to use meta-analysis to study how the teratoma assay have been applied to study malignancy of stem cells in preclinical and clinical studies. In particular we will focus on the various components of the assay and the read-out of the assay.

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Kenmerken

Projectnummer:
114024122
Looptijd: 100%
Looptijd: 100 %
2018
2021
Onderdeel van programma:
Gerelateerde subsidieronde:
Projectleider en penvoerder:
Salvatori
Verantwoordelijke organisatie:
Leids Universitair Medisch Centrum