Establishment of a new retinoblastoma mouse model by intravitreal injection of human retinoblastoma Y79 cells into nude mice eyes - Comparison of SLO/OCT vs. histological follow up

Abstract

 

Purpose

 

Retinoblastoma is the most frequent ocular tumor in children and if let untreated, can cause death. The aim of this study was to create a novel xenograft-nude mouse-model, which closely resembles the situation in the patients and to investigate the development and spread of the tumor by using SLO/OCT as well as histology methods.

 

Methods

 

Human retinoblastoma Y79 cells were intravitreally injected in both eyes of immune-deficient nude mice. The mice were closely monitored for any phenotype changes during the whole experiment. The frequency of retinoblastoma incidence and growth velocity were analysed 3, 6, 9 and 12 weeks after cell injection. The tumor was characterized in vivo by SLO/OCT as well as ex vivo by electron microscopy and hematoxylin eosin (HE) staining. Moreover, potentially occurring metastases were investigated via histological screening of internal organs.

 

Results

 

Already three weeks post-injection, animals developed a retinoblastoma. After five weeks, the eyes began to swell in individual animals and they showed a similar phenotype to that of untreated retinoblastoma patients. After 12 weeks, 67.5% of all analyzed eyes (29 of 42) presented a retinoblastoma. The SLO/OCT analysis could only be performed in eyes with a tumor at an early stage (till week three). In all cases in which SLO/OCT- analysis was possible, the results were in accordance with the histological analysis (Fig 1a-c). The tumors were found in the vitreous body and in some cases also within the retina and the subretinal space. In only one mouse, brain metastases were observed.

 

Conclusions

 

Our retinoblastoma mouse model mimics the situation observed in patients. At early stages, the SLO/OCT analysis correlated with the histology findings. Therefore SLO/OCT can be used for the detection of tumors and might be used for monitoring the success of potential therapy approaches. When the tumors were too large, only histological investigations were possible.

 

 

Figure 1: Three weeks after intravitreal injection of Y79 cells in nude mice eyes the cells formed a tumor (red arrow), which broke through the retina (red circle). a) SLO image, b) OCT image and c) the corresponding HE-stained slide (X100).

 

Keywords: 703 retinoblastoma • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 599 microscopy: light/fluorescence/immunohistochemistry