BRUSSELS (Reuters) - Belgian biotechnology firm TiGenix has recruited enough patients to start a mid-stage trial for its stem cell-based treatment for rheumatoid arthritis, it said on Wednesday.

"This is the most advanced stem cell therapy trial in rheumatoid arthritis in the world, and completing the enrolment on time confirms our leadership position in the field," said chief executive Eduardo Bravo in a statement.

"We anticipate reporting the results of the study no later than April 2013."

Recruiting enough test subjects for a mid-stage trial can be tricky as it is often the first time that a drug is tested on people who are ill.

TiGenix said it has recruited 53 patients who previously failed to respond to at least two biological treatments for the phase IIa trial of its stem cell treatment Cx611.

(Reporting By Ben Deighton; editing by Barbara Lewis)