The Effect of Ambient Storage Conditions on the Recombinant Protein Secretion Rates and Cell Viability of Polymer Encapsulated Human Retinal Pigmented Epithelial Cells Genetically Engineered to Secrete Ciliary Neurotrophic Factor

Abstract

Abstract: : Purpose: The Neurotech NT-501 cell-encapsulated device for intraocular delivery of CNTF to the posterior cavity of the eye has been evaluated in vitro under a variety of temperature and holding conditions. This study examines devices containing either NTC-201-6A cells (high producer) or NTC-201-10 cells (low producer) over a wide range of ambient temperature conditions and holding periods for the purpose of evaluating transportation feasibility to the clinical site. Methods: NT-501 devices were manufactured with an average length of 1.1 cm, sterilized, and loaded with either of the two cell lines. Following a two-week hold period at 37°C in a closed container with 40 mL endothelial serum-free media (ENDO-SFM), devices were incubated in environmental chambers at temperature conditions ranging from 3°C to 48.4°C including variable temperature cycles. Several groups were cycled between the temperature extremes and then allowed to remain at room temperature for 1 week. At the end of the incubation period, CNTF production was analyzed by incubating the device in fresh ENDO-SFM for 24 hours followed by detection with an ELISA. Cell density was assessed using image analysis on plastic sections generated after the 24-hour pulse. Results: CNTF levels for both groups were generally unaffected by temperature variations, although the 6A group showed declining CNTF secretion and cell density above 44°C. Cell density in both groups was consistent with CNTF output and devices showed favorable morphology throughout all conditions, excluding temperatures above 44°C. Device output and histology remained optimal even following the 1-week room temperature hold after the most extreme simulated shipping cycle. Conclusions: The NT-501 device is extremely robust and able to withstand extremely variable ambient conditions, including cycles between temperature extremes. A shipping package has been designed in parallel with these studies to ensure the delivery of active devices to the clinic.

Keywords: clinical (human) or epidemiologic studies: sys • vitreous