Acta Biomaterialia 2 (2006) 313–320 www.actamat-journals.com 1742-7061/$ - see front matter  2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.actbio.2005.12.007 Chitosan scaVolds: Interconnective pore size and cartilage engineering Dominique J. GriVon a,¤ , M. Reza Sedighi a , David V. SchaeVer a,b , Jo Ann Eurell a,b , Ann L. Johnson a a Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, 1008 W Hazelwood Drive, Urbana, IL 61802, United States b Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, United States Received 29 June 2005; received in revised form 7 December 2005; accepted 29 December 2005 Abstract This study was designed to determine the eVect of interconnective pore size on chondrocyte proliferation and function within chitosan sponges, and compare the potential of chitosan and polyglycolic acid (PGA) matrices for chondrogenesis. Six million porcine chondro- cytes were seeded on each of 52 prewetted scaVolds consisting of chitosan sponges with (1) pores 610 m in diameter (n D 10, where n is the number of samples); (2) pores measuring 10–50 m in diameter (n D 10); and (3) pores measuring 70–120 m in diameter (n D 10), ver- sus (4) polyglycolic acid mesh (n D 22), as a positive control. Constructs were cultured for 28 days in a rotating bioreactor prior to scan- ning electron microscopy (SEM), histology, and determination of their water, DNA, glycosaminoglycan (GAG) and collagen II contents. Parametric data was compared (p D 0.05) with an ANOVA and Tukey’s Studentized range test. PGA constructs consisted essentially of a matrix containing more cells than normal cartilage. Whereas very few remnants of PGA remained, chitosan scaVolds appeared intact. DNA and GAG concentrations were greater in PGA scaVolds than in any of the chitosan groups. However, chitosan sponges with the largest pores contained more chondrocytes, collagen II and GAG than the matrix with the smallest pores. Constructs produced with PGA contained less water and more GAG than all chitosan groups. Chondrocyte proliferation and metabolic activity improved with increasing interconnective pore size of chitosan matrices. In vitro chondrogenesis is possible with chitosan but the composition of constructs pro- duced on PGA more closely approaches that of natural cartilage.  2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Chitosan; Cartilage; Engineering; Interconnectivity; Chondrocytes 1. Introduction Tissue engineering is a rapidly developing Weld, whereby cells are allowed to proliferate and organize their extracellu- lar matrix in a three-dimensional (3-D) lattice to form ex vivo a clinically functional tissue, exhibiting histochemi- cal, biochemical and biomechanical properties identical to native, healthy tissue. The ideal matrix for in vitro chondro- genesis has yet to be determined and the list of biomaterials tested for cartilage repair is extensive [1,2]. Among these, a polyglycolic acid (PGA) mesh has been used extensively as a resorbable substrate onto which chondrocytes produce implant-free cartilage after 4 weeks of dynamic culture [3,4]. Although this matrix sustains chondrogenesis, its applica- tion has been limited by the mechanical properties of engineered constructs and their lack of integration with adja- cent tissues [5,6]. Whereas byproducts of polymers used for biomedical applications, such as polylactic and polyglycolic acids may induce a foreign-body reaction, chitosan, a natu- ral aminopolysaccharide, is degraded into neutral or weak- base sugars that are physiologic precursors of natural GAG [7–9]. Chitosan is formed by alkaline deacetylation of chitin, the second most abundant natural polysaccharide, primarily obtained as a subproduct of shell Wsh, such as crabs and shrimps [10,11]. Its superior biocompatibility has been attrib- uted to its structural similarity with glycosaminoglycans * Corresponding author. Tel.: +1 217 244 1208; fax: +1 217 244 1475. E-mail address: dgriVon@uiuc.edu (D.J. GriVon).