Cresset Group converted an office and manufacturing building at 65 Grove St. into 120,000 square feet of lab space before selling it to BioMed Realty for $62.5 million in November.

A Harvard University biotech spinout is relocating in January from Cambridge to a Watertown property that was converted into office and lab space before being acquired by BioMed Realty last fall for $62.5 million.

Platelet BioGenesis leased nearly 18,000 square feet at 65 Grove St., a 120,000-square-foot complex whose tenant roster includes Bosch Thermotechnology, Lyndra Inc. and Markem-Imaje.

The 88-month lease in Watertown was signed less than a year after Platelet BioGenesis expanded into 14,000 square feet at Nest.Bio Labs, a life science incubator at 325 Vassar St. in Cambridge.

Platelet BioGenesis now has 25 employees in Cambridge and will expand to 40 by the end of the year, co-founder and chief business officer Sven Karlsson said. The company specializes in technologies to generate blood platelets from stem cells for transfusions and surgery, and expects to begin phase one clinical trials in 2021, Karlsson said.

It won an Amgen-sponsored “Golden Ticket” in 2016, entitling it to free lab space for six months at the LabCentral incubator in Kendall Square, before relocating to UMass-Boston’s Venture Development Center and then Nest.Bio Labs.

Since its founding in 2014, Platelet BioGenesis has attracted $14.6 million in funding, according to Crunchbase. Sources of funding have included the Massachusetts Life Science Center, the National Institute of Health and U.S. Department of Defense.

Karlsson said the company considered approximately 20 locations in Greater Boston before committing to the Watertown property.

“There’s a lot of biotech moving out to Watertown, the space was the right size for us, and BioMed is a landlord that we’re looking forward to working with,” he said.

The Watertown lease is the latest in a series of moves of life science companies expanding outside of Cambridge to new lab-ready buildings.

Boston-based Cresset Group bought the former GE Ionics property at 65 Grove St. in 2014 for $5 million and converted it into life science-ready space with new building systems and amenities before selling it to BioMed last year for $62.5 million.

This article has been updated with comment from Sven Karlsson, co-founder and chief business officer of Platelet BioGenesis.