Abstract
Purpose: :
The brain-derived neurotrophic factor (BDNF), among other neurotrophic factors, is known for its preventive effect against retinal degeneration. We have previously reported that the immortalized rat Müller cell line, TR-MUL, act protectively on rat retinal ganglion cells through the secretion of humoral factors (ARVO 2009). In this study, we modified the TR-MUL for stable expression of BDNF and attempted to encapsulate the modified cells with future in-vivo manipulation in view.
Methods: :
To obtain a cell line that stably expresses BDNF (the BD-TM4 cell line), TR-MUL cells were transfected with a plasmid that contains the BDNF gene. The BD-TM4 cells were encapsulated in 0.5% alginate at a density of 50,000 cells/capsule. Dehydrogenase activity in encapsulated cells and BDNF levels released from the capsules were quantified at days 3, 7, 14, and 21 after encapsulation by WST-8 assay and ELISA respectively. Immunostaining for glutamine synthetase (GS), a marker for the Müller cell, was performed to evaluate cell functionality.
Results: :
The encapsulated Müller cells, which initially appeared as round-shaped and isolated, gradually started to aggregate to form inhomogeneous regions. Dehydrogenase activity in encapsulated cells was significantly higher at day 21 than at day 3. The capsules continuously secreted BDNF throughout 21 days at the range of 3.8-2.5 pg/day/capsule. The cells had remained immunoreactive for GS at day 21.
Conclusions: :
These results demonstrate that alginate-encapsulated BDNF-secreting Müller cells maintain its viability and functionality at least for 21days.
Keywords: Muller cells • growth factors/growth factor receptors • retinal culture