Tissue engineered biomaterial constructs are needed for plastic and reconstructive applications. To successfully form a space-filling tissue, the construct should induce a minimal inflammatory response, create minimal or no fibrotic capsule, and establish a vascular bed within the first few days after implantation to ensure survival of the implanted cells. In addition, the biomaterial should support cellular adhesion and induce tissue ingrowth. A macroporous hydrogel bead using sodium alginate covalently coupled with an arginine, glycine, and aspartic acid-containing peptide was created. A 6-month subcutaneous rat model study was performed to determine if the implanted material induced tissue ingrowth throughout the implantation area and maintained a three-dimensional vascular bed. The implanted materials produced a vascular bed, minimal inflammation and capsule formation, and good tissue ingrowth throughout the experiment. The material retained its bulking capacity by demonstration of no significant change of the cross-sectional area as measured from the center of the implants after the 2-week time point. In addition, the granulation tissue formed around the implant was loosely organized, and the surrounding tissue had integrated well with the implant. These results indicate that this material has the desired properties for the development of soft-tissue-engineering constructs.

ADVERTISEMENT RETURN TO ISSUEPREVNoteControlling Mechanical and Swelling Properties of Alginate Hydrogels Independently by Cross-Linker Type and Cross-Linking DensityKuen Yong Lee, Jon A. Rowley, Petra Eiselt, Erick M. Moy, Kamal H. Bouhadir, and David J. MooneyView Author Information Department of Biomedical Engineering, Chemical Engineering, Biologic & Materials Sciences, and Materials Science & Engineering, University of Michigan, Ann Arbor, Michigan 48109 Cite this: Macromolecules 2000, 33, 11, 4291–4294Publication Date (Web):April 22, 2000Publication History Received21 December 1999Revised23 March 2000Published online22 April 2000Published inissue 1 May 2000https://pubs.acs.org/doi/10.1021/ma9921347https://doi.org/10.1021/ma9921347brief-reportACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views11479Altmetric-Citations404LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Absorption,Biopolymers,Hydrogels,Molecules,Nucleic acid structure Get e-Alerts

Development of tissue-engineered devices may be enhanced by combining cells with porous absorbable polymeric scaffolds before implantation. The cells are seeded throughout the scaffolds and allowed to proliferate in vitro for a predetermined amount of time. The distribution of cells throughout the porous material is one critical component determining success or failure of the tissue-engineered device. This can influence both the successful integration of the device with the host tissue as well as the development of a vascularized network throughout the entire scaffold volume. This research sought to compare different seeding and proliferation methods to select an ideal method for a polyglycolide/aortic endothelial cell system. Two seeding environments, static and dynamic, and three proliferation environments, static, dynamic, and bioreactor, were analyzed, for a total of six possible methods. The six seeding and proliferation combinations were analyzed following a 1-week total culture time. It was determined that for this specific system, dynamic seeding followed by a dynamic proliferation phase is the least promising method and dynamic seeding followed by a bioreactor proliferation phase is the most promising.

Macroporous scaffolds are typically utilized in tissue engineering applications to allow for the migration of cells throughout the scaffold and integration of the engineered tissue with the surrounding host tissue. A method to form macroporous beads with an interconnected pore structure from alginate has been developed by incorporating gas pockets within alginate beads, stabilizing the gas bubbles with surfactants, and subsequently removing the gas. Macroporous scaffolds could be formed from alginate with different average molecular weights (5–200 kDa) and various surfactants. The gross morphology, amount of interconnected pores, and total void volume was investigated both qualitatively and quantitatively. Importantly, macroporous alginate beads supported cell invasion in vitro and in vivo.

There are many clinical situations in which a large tissue mass is required to replace tissue lost to surgical resection (e.g., mastectomy) . It is possible that autologous cell transplantation on biodegradable polymer matrices may provide a new therapy to engineer large tissue which can be used to treat these patients. A number of challenges must be met to engineer a large soft tissue mass. These include the design of (1) a structural framework to maintain a space for tissue development, (2) a space-filling matrix which provides for localization of transplanted cells, and (3) a strategy to enhance vascularization of the forming tissue. In this paper we provide an overview of several technologies which are under development to address these issues. Specifically, support matrices to maintain a space for tissue development have been fabricated from polymers of lactide and glycolide. The ability of these structures to resist compressive forces was regulated by the ratio of lactide to glycolide in the polymer. Smooth muscle cell seeding onto polyglycolide fiber-based matrices has been optimized to allow formation of new tissues in vitro and in vivo. Finally, polymer microsphere drug delivery technology is being developed to release vascular endothelial growth factor (VEGF), a potent angiogenic molecule, at the site of tissue formation. This strategy, which combines several different technologies, may ultimately allow for the engineering of large soft tissues.