Cardiosolutions Inc. landed about half of what it hopes will amount to a $6.5 million fundraising round, pulling in $3.3 million from eight un-named investors, according to a regulatory filing.

The Stoughton, Mass.-based company is a spinout from contract manufacturer STD Med, which early last year bought a new, 32,000-square-foot cleanroom to house Cardiosolutions and sister firm Spirus Medical Inc.