Structure and Biological Properties of Catheter Injectable Hydrogels

Background: Injectable scaffolds, a unique therapeutic method used for tissues that are difficult to reach, are needed in many tissue-engineering applications. Catheter delivery of hydrogel based scaffolds is novel and provides unique challenges and design parameters for the biomaterial. The main goal of this research is to develop and study new hydrogel formulations based on gelatin and alginate, crosslinked by carbodiimide, which can be mixed with air and injected through delicate long catheters, and used as porous scaffolds for treating a variety of internal ailments.

Methods: The effects of the formulation parameters on the structural characteristics and on the biological properties (cytotoxicity and cell adhesion) were studied, as well as the effects of foaming the polymer with various polymer-to-air ratios. The influence of hydrogel injection rate (with and without cells) via catheters of 40 cm and 100 cm was also studied. The microstructure was characterized using a confocal microscope and the porosity and pore size were determined.

Results: Cell adhesion results indicated that both fibroblast and mesenchymal cells strongly adhere to the hydrogel scaffolds. The cytotoxicity results indicated excellent viability for both mesenchymal and fibroblast cells when exposed to the polymer.

Conclusion: Our technology, which combines tissue engineering with minimally-invasive administration, is novel and is expected to provide new solutions to old, unmet needs.