Effects of coating a titanium alloy with fibronectin on the expression of osteoblast gene markers in the MC3T3 osteoprogenitor cell line.
OBJECTIVE
A number of environmental and patient-related factors contribute to implant failure. A significant fraction of these failures can be attributed to limited osseointegration resulting from poor bone healing responses. The overall goal of this study was to determine whether surface treatment of a titanium-aluminum-vanadium alloy (Ti-6Al-4V) implant material in combination with a biomimetic protein coating could promote the differentiation of attached osteoblastic cells. The specific aims of the study were to investigate whether osteoprogenitor cells cultured on a rigorously cleaned implant specimen showed a normal pattern of differentiation and whether preadsorbed fibronectin accelerated or enhanced osteoblast differentiation.


METHODS
Ti-6Al-4V disks were rigorously cleaned, passivated in nitric acid, and dry heat- sterilized; some of the disks were then coated with 1 nmol/L fibronectin. MC3T3 osteoprogenitor cells were then cultured on the pretreated disks for several weeks. Quantitative real-time polymerase chain reaction was performed to measure changes over time in the mRNA levels of osteoblast genes.


RESULTS
Fibronectin increased the peak expression of all analyzed osteoblast gene markers. "Early" genes that normally mark the proliferative phase (0 to 10 days) of osteoblastic development showed peak expression within the first 10 days after cell attachment to the titanium alloy. In contrast, "late" genes that normally mark the differentiation (10 to 20 days) and mineralization (20 to 36 days) phases of osteoblastogenesis achieved peak expression only after approximately 3 to 4 weeks of culture.


CONCLUSIONS
Osteoprogenitors cultured on a rigorously cleaned Ti-6Al-4V alloy were found to demonstrate a normal pattern of osteoblast differentiation. Preadsorbed fibronectin was observed to stimulate osteoblast differentiation during the mineralization phase of osteoblastogenesis.
Hospital for Special Sugery, Weill Medical College of Cornell University, New York, New York, USA.
Bruce E
BE
Rapuano
Kyle M
KM
Hackshaw
Hannes C
HC
Schniepp
Daniel E
DE
MacDonald
D000497:Alloys; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D005353:Fibronectins / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects* / Q000235:genetics; D005819:Genetic Markers; D006801:Humans; D016348:Osseointegration / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013499:Surface Properties; D014025:Titanium
D000497:Alloys; D005353:Fibronectins; D005819:Genetic Markers; D012333:RNA, Messenger; C031462:titanium alloy (TiAl6V4); D014025:Titanium