IGF-1 Delivery via Osmotic Minipumps

Osmotic minipumps (ALZET^® 2006, DURECT Corporation, Cupertino, CA, USA; pumping rate 0.15 µL/h) were filled and connected to a hook-delivery device (HDD) consisting of a commercially available silicone catheter (ALZET^® rat jugular catheter, DURECT Corporation, USA; 0.94 mm OD; 0.51 mm ID) and a small hook-shaped stainless-steel tip (Nordson Optimum^® #7018433, Nordson Deutschland GmbH, Erkrath, Germany) with an outer diameter of 0.31 mm [43 (link)]. Pumps for control animals were filled with artificial perilymph (AP; 145 mM NaCl, 2.7 mM KCl, 2.0 mM MgSO₄, 1.2 mM CaCl₂, 5.0 mM HEPES, pH = 7.4 with 0.1% guinea pig serum albumin) [96 (link)]. The pumps of the treatment group were filled with IGF-1 (Recombinant Human IGF-1, #100-11, PeproTech^® Germany, Hamburg, Germany) in a concentration of 2 μg/mL diluted in AP. The pumping rate of the osmotic pump results in a release of 0.3 ng IGF-1 per hour. During the priming time of 60 h each pumps’ function was macroscopic controlled by fluid drain out of the catheters’ tip [43 (link)]. After the in vivo experiment, the pumping of the explanted pumps was re-checked the same way.