title: Synergistic Effect of TGF-β1 And BMP-7 on Chondrogenesis and Extracellular Matrix Synthesis: An In Vitro Study.
abstract: BACKGROUND
  The purpose of the present study seeks to determine the signal timing of BMP-7 and TGF-β1 from a novel chitosan based hydrogel system that may affect chondrocyte proliferation resulting in the presence of a synergism seen conspicuously in consecutive controlled delivery.
  
  
  METHODS
  Four groups of cultured chondrocytes were seeded on a novel designed chitosan based hydrogel. The hydrogel was left empty (control) in one group and loaded with BMP-7, TGF-β1 and their combination in the other groups, respectively. Hydrogel structure was analyzed with scanning electron microscope. The release kinetics of Growth Factors (GFs) was determined with ELISA. Chondrocyte viability and toxicity after being tested with MTS and collagen type II synthesis, were quantified with western blotting. Canonical regression analysis was used for measuring statistical evaluation.
  
  
  RESULTS
  Chitosan based hydrogel allowed controlled release of GFs in different time intervals for BMP-7 and TGF-β1. Double peak concentration gradient was found to be present in the group loaded with both GFs. In this group, substantially higher chondrocyte growth and collagen synthesis were also detected.
  
  
  CONCLUSIONS
  We concluded that, chitosan based hydrogel systems may be adjusted to release GFs consecutively during biodegradation at the layers of surface, which may increase the cell number and enhance collagen type II synthesis.
authors.affiliation: Department of Orthopaedics and Traumatology, Namik Kemal University, School of Medicine, Tekirdag, Turkey.
authors.forename: Alper
authors.initials: A
authors.lastname: Gokce
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Yilmaz
authors.forename: Rifat
authors.initials: R
authors.lastname: Bircan
authors.forename: Murat
authors.initials: M
authors.lastname: Tonbul
authors.forename: Nevzat Selim
authors.initials: NS
authors.lastname: Gokay
authors.forename: Cigdem
authors.initials: C
authors.lastname: Gokce