Chitosan supports the expression of extracellular matrix proteins in humanosteoblasts and chondrocytes

The search for biocompatible materials that can support the growth and phen otypic expression of osteoblasts and chondrocytes is a major challenge in t he application of tissue engineering techniques for the repair of bone and cartilage defects. Chitosan, a copolymer of glucosamine and N-acetylglucosa mine, may provide an answer to this search. Chitosan is the deacetylated pr oduct of chitin, a ubiquitous biopolymer found in the exoskeleton of insect s and marine invertebrates. Little is known about the utility of chitosan i n propagating human osteoblasts and chondrocytes. In this study, we test th e hypothesis that chitosan promotes the survival and function of osteoblast s and chondrocytes. Chitosan (4%, w/v in 2% HAc) was coated onto plastic co verslips that had been fitted into 24-well plates. Human osteoblasts and ar ticular chondrocytes were seeded on either uncoated or chitosan-coated cove rslips at 1 x 10(5)/cells per well. Cultures were incubated at 37 degrees C , 5% CO2 for a period of 7 days. Cell viability was assessed at that time u sing a fluorescent molecular probe. The phenotypic expression of osteoblast s and chondrocytes was analyzed by reverse transcriptase-polymerase chain r eaction and immunocytochemistry. Osteoblasts and chondrocytes appeared sphe rical and refractile on chitosan-coated coverslips. In contrast, greater th an 90% of cells on plastic coverslips were elongated and spindle shaped aft er 7 days of culture. Similar to cells propagated on uncoated control wells , greater than 90% of human osteoblasts and chondrocytes propagated on chit osan remained viable. Human osteoblasts propagated on chitosan films contin ued to express collagen type I whereas chondrocytes expressed collagen type II and aggrecan, as shown by reverse transcriptase-polymerase chain reacti on analysis and immunostaining. The present in vitro work demonstrates the biocompatibility of chitosan as a substrate for the growth and continued fu nction of human osteoblasts and chondrocytes. Chitosan may have potential u se as a tissue engineering tool for the repair of osseous and chondral defe cts. (C) 2000 John Wiley & Sons, Inc.