title: The effect of scaffold pore size in cartilage tissue engineering.
abstract: BACKGROUND
  The effect of scaffold pore size and interconnectivity is undoubtedly a crucial factor for most tissue engineering applications. The aim of this study was to examine the effect of pore size and porosity on cartilage construct development in different scaffolds seeded with articular chondrocytes.
  
  
  METHODS
  We fabricated poly-L-lactide-co-trimethylene carbonate scaffolds with different pore sizes, using a solvent-casting/particulate-leaching technique. We seeded primary bovine articular chondrocytes on these scaffolds, cultured the constructs for 2 weeks and examined cell proliferation, viability and cell-specific production of cartilaginous extracellular matrix proteins, including GAG and collagen.
  
  
  RESULTS
  Cell density significantly increased up to 50% with scaffold pore size and porosity, likely facilitated by cell spreading on the internal surface of bigger pores, and by increased mass transport of gases and nutrients to cells, and catabolite removal from cells, allowed by lower diffusion barriers in scaffolds with a higher porosity. However, both the cell metabolic activity and the synthesis of cartilaginous matrix proteins significantly decreased by up to 40% with pore size. We propose that the association of smaller pore diameters, causing 3-dimensional cell aggregation, to a lower oxygenation caused by a lower porosity, could have been the condition that increased the cell-specific synthesis of cartilaginous matrix proteins in the scaffold with the smallest pores and the lowest porosity among those tested.
  
  
  CONCLUSIONS
  In the initial steps of in vitro cartilage engineering, the combination of small scaffold pores and low porosity is an effective strategy with regard to the promotion of chondrogenesis.
authors.affiliation: Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan - Italy.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Nava
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan - Italy.
authors.forename: Lorenza
authors.initials: L
authors.lastname: Draghi
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering ''Giulio Natta'' and Unità di Ricerca Consorzio INSTM, Politecnico di Milano, Milan - Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Giordano
authors.affiliation: Laboratory of Biological Structure Mechanics (LaBS), Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan - Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Pietrabissa
mesh_terms: D000818:Animals; D002356:Cartilage / Q000737:chemistry / Q000166:cytology; D002417:Cattle; D002470:Cell Survival; D048271:Chitosan / Q000737:chemistry*; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism; D008422:Materials Testing; D011091:Polyesters / Q000737:chemistry*; D016062:Porosity; D023822:Tissue Engineering; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D011091:Polyesters; C016240:polycaprolactone; D048271:Chitosan