Injectable Scaffolds for Tissue Engineering Applications

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. The effects of the formulation parameters on the mechanical properties in tension and on the physical properties (gelation time, viscosity, porosity, and weight loss rate) was studied. The effects of polymer-to-air ratio on these properties was studied as well. Finally, the influence of injection via catheters of 40 cm and 100 cm was studied. Our best studied formulations exhibited gelation times in the range of 22-42 sec, viscosities in the range of 0.08- 0.28 Pa-sec, tensile strength of 4-18 KPa and tensile modulus of 5-17 KPa. The properties were not affected by injection via long catheters. This study presents proof of the concept of using Gelatin-Alginate hydrogels as injectable scaffolds through long catheters.