It seems that is messing with charset!

[antoniocapuozzo]

UTF-8 character problem seems to be solved adding flag U to regular expression.
http://stackoverflow.com/questions/19629893/does-preg-replace-change-my-character-set

$re = '% # Collapse ws everywhere but in blacklisted elements.
(?> # Match all whitespans other than single space.
[^\S ]\s* # Either one [\t\r\n\f\v] and zero or more ws,
| \s{2,} # or two or more consecutive-any-whitespace.
) # Note: The remaining regex consumes no text at all...
(?= # Ensure we are not in a blacklist tag.
(?: # Begin (unnecessary) group.
(?: # Zero or more of...
[^<]++ # Either one or more non-"<"
| < # or a < starting a non-blacklist tag.
(?!/?(?:textarea|pre)\b)
)*+ # (This could be "unroll-the-loop"ified.)
) # End (unnecessary) group.
(?: # Begin alternation group.
< # Either a blacklist start tag.
(?>textarea|pre)\b
| \z # or end of file.
) # End alternation group.
) # If we made it here, we are not in a blacklist tag.
%ixu';