Lumican inhibits collagen deposition in tissue engineered cartilage.
Lumican is a glycoprotein that is found in the extracellular matrix of many connective tissues, including cartilage. It is a member of the small leucine-rich repeat proteoglycans family and along with two others, decorin and fibromodulin, has the capacity to bind to fibrillar collagens and limit their growth. Cartilage tissue engineering provides a potential method for the production of three-dimensional tissue for implantation into eroded joints. Many studies have demonstrated the growth of cartilage in vitro. However in all cases, biochemical analysis of the tissue revealed a significant deficit in the collagen content. We have now tested the hypothesis that the reduced collagen accumulation in engineered cartilage is a result of over-expression of decorin, fibromodulin or lumican. We have found that the lumican gene and protein are both over-expressed in engineered compared to natural cartilage whereas this is not the case for decorin or fibromodulin. Using a small hairpin lumican antisense sequence we were able to knockdown the lumican gene and protein expression in chondrocytes being used for tissue engineering. This resulted in increased accumulation of type II collagen (the major collagen of cartilage) whilst there was no significant alteration in the proteoglycan content. Furthermore, the antisense knockdown of lumican resulted in an increase in the average collagen fibril diameter measured by transmission electron microscopy. These results suggest that lumican plays a pivotal role in the development of tissue engineered cartilage and that regulation of this protein may be important for the production of high-quality implants.
Kafienah
Wael
W
Cellular and Molecular Medicine, School of Medical Sciences, University of Bristol, Bristol, UK.
Cheung
Frank L
FL
Sims
Trevor
T
Martin
Ivan
I
Miot
Sylvie
S
Von Ruhland
Chris
C
Roughley
Peter J
PJ
Hollander
Anthony P
AP
D000818:Animals; D002356:Cartilage / Q000166:cytology / Q000378:metabolism; D002417:Cattle; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism*; D003094:Collagen / Q000378:metabolism* / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D017353:Gene Deletion; D006801:Humans; D007632:Keratan Sulfate / Q000235:genetics / Q000378:metabolism*; D000071234:Lumican; D051379:Mice; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D023822:Tissue Engineering
D011508:Chondroitin Sulfate Proteoglycans; C000604306:LUM protein, human; C000604307:Lum protein, mouse; D000071234:Lumican; D011509:Proteoglycans; D034741:RNA, Small Interfering; D003094:Collagen; D007632:Keratan Sulfate