Abstract
Abstract: :
Purpose: Tissue transplantation to rescue degenerating retina is one of the strategies being utilized for treatment of Retinitis Pigmentosa (RP). However, lack of availability of reliable donor tissue/ cells has been a continuing problem. Retinal progenitors offer attractive alternatives. We have previously reported generation of 3D structures from human progenitors in the NASA bioreactor. The purpose of this study was to investigate whether neurotrophin upregulation in the bioreactor contributes to generation of the 3D structures. Methods: Non-transformed human retinal progenitors were grown in the NASA bioreactor on cytodex3 beads, alone or as a co-culture with RPE. 3D structures generated were evaluated by scanning and transmmission electron microscopy, immunocytochemistry and Western blot analysis. RT-PCR was performed using appropriate primers; amplified products generated for different cycles were evaluated. Results: Retinal-RPE co-cultures showed a higher degree of differentiation and layering. Several retinal cell types could be identified, by immunophenotyping, in the multi-layered structures generated in the bioreactor of which photoreceptors were most well defined and differentiated. RT-PCR data revealed that neurotrophins bFGF, TGFα , CNTF and BDNF were all upregulated in cells co-cultured in the bioreactor as compared to monolayer cultures, whereas the house keeping gene GADPH remained unchanged. There was a significant correlation between higher level of BDNF and CNTF and the complexity of tissue-like structures generated in the bioreactor. Conclusion: NASA's bioreactor possibly promotes tissue formation by upregulation of neurotrophins. Our results appear significant not only for tissue generation, but also in light of findings by others that the same neurotrophins can rescue degenerating photoreceptors in animal models of RP.
Keywords: 423 growth factors/growth factor receptors • 472 microscopy: electron microscopy • 476 molecular biology