@article {217211,
	title = {Shape retaining injectable hydrogels for minimally invasive bulking},
	journal = {J Urol},
	volume = {172},
	number = {2},
	year = {2004},
	month = {2004 Aug},
	pages = {763-8},
	abstract = {PURPOSE: Particle migration, poor shape definition and/or rapid resorption limit the success of current urethral bulking agents. We propose that shape defining porous scaffolds that allow cell infiltration and anchoring, and may be delivered in a minimally invasive manner may provide many advantageous features.

MATERIALS AND METHODS: Alginate hydrogels were prepared with varying degrees of covalent cross-linking and different pore characteristics. Dehydrated scaffolds were compressed into smaller, temporary forms, introduced into the dorsal subcutaneous space of CD-1 mice by minimally invasive delivery through a 10 gauge angiocatheter and rehydrated in situ with a saline solution delivered through the same catheter. Ionically cross-linked calcium alginate gel served as a control. Specimens were harvested at 2, 6, 12 and 24 weeks to evaluate implant shape retention and volume, cell infiltration and calcification, and the presence of an inflammatory response.

RESULTS: A total of 90 scaffolds were implanted and 95\% were recovered at the site of injection. All of these scaffolds successfully rehydrated and 80\% recovered and maintained their original 3-dimensional shape for 6 months. Scaffold volume and tissue infiltration varied depending on the degree of alginate cross-linking. Highly cross-linked materials (20\% and 35\%) demonstrated the best volume maintenance with the latter facilitating the most tissue infiltration. The inflammatory response was minimal except with the 80\% cross-linked material. Calcification was not observed in covalently cross-linked scaffolds. In contrast, 98\% of calcium alginate implants were calcified.

CONCLUSIONS: Shape retaining porous hydrogels meet many of the requirements necessary for a successful injectable bulking agent and offer advantages over currently used agents.},
	keywords = {Alginates, Animals, Cross-Linking Reagents, Gels, Hydrogels, Implants, Experimental, Male, Mice, Mice, Inbred ICR, Urethra},
	issn = {0022-5347},
	doi = {10.1097/01.ju.0000130466.84214.f7},
	author = {Thornton, Amanda J and Alsberg, Eben and Hill, Elliot E and Mooney, David J}
}
