After a quick Google search, I found this
"Meaning of Barbed Wire Tattoo Designs
The Crown of Thorns
The barbed tattoo has taken its inspiration from the crown of thorns which Jesus was made to wear before being crucified. It is a symbol of strength and faith in the power of the almighty. It is also a symbol which represents the fact that the individual wearing the tattoo has seen much hardship in his life and has been able to withstand all hurdles and pain, because of his faith in the Lord. The fact that he too is one of the many children of God and he will be given peace after he passes through this life onto heaven, where he will face his final judgment, is one of the symbols that this tattoo represents.
Years Spent as a Convict
The barbed wire gained popularity among the Italians who used the barbed wire tattoo to symbolize the fact that they were weathered criminals and had spent years spending their term in jail. Usually the number of spikes on the barbed wire tattoo correlated to the number of years spent serving their jail sentence. While in Russia, this tattoo was etched on a convicts wrist to show that he had been put in for a lifelong term of imprisonment for an unforgivable crime.
I'm Not an Open Book
Many people prefer barbed wire tattoo designs because it represents a fence. These people like to believe that they are unapproachable and not easy to understand. They are not the most social people and prefer dwelling in their own solitude. Some are cold and cruel, and enjoy violence and seek sadistic pleasure in harming others. In reality, a barbed tattoo is looked upon as a criminal tattoo which establishes deviant behavior and lack of respect for societal rules and regulations."
This is from Buzzle.com