Renal Solutions Inc., the Marshall-based provider of dialysis products, is being sold to a German firm that hopes to use its technology to develop wearable kidneys.

Fresenius Medical Care, a subsidiary of Fresenius SE, agreed to pay up to $190 million for Renal Solutions over a period of three years. It also will assume approximately $10 million of debt. Peter M. DeComo, Renal Solutions president and chief operating officer, will continue to lead operations both here and in the company's Oklahoma City office.

Renal Solutions specializes in the field of "sorbent dialysis therapy." Current dialysis procedures use an artificial kidney that requires large volumes of purified water to operate, typically hundreds of liters. Renal Solutions has developed a chemically treated cartridge to be used in conjunction with the artificial kidney that absorbs contaminants in ordinary tap water, making it usable for dialysis. That reduces the amount of water needed to a mere 1.5 gallons, or six liters, per treatment.

"As you reduce the volume of fluid you need, you can reduce the size of the electromechanical device that does the dialysis," Mr. DeComo said. "Then it becomes very conceivable to create a truly portable, truly wearable device."

The sale of Renal Solutions also is a landmark for the Pittsburgh Life Sciences Greenhouse, the public/private partnership formed in 2001 to nurture biosciences companies in southwestern Pennsylvania. After Renal Solutions moved to Pittsburgh from East Lafayette, Ind., in 2002, the Greenhouse made a $90,000 investment in the company, making it the first holding in the Greenhouse's portfolio. At the time, Mr. DeComo was the only employee. Now Renal Solutions employs 38 locally, 22 in Oklahoma City, and eight sales representatives scattered across the country.

Under the deal's terms, Fresenius Medical Care will pay $100 million at closing, $60 million after the first year, and up to $30 million in installments over the next three years, based on the achievement of specific milestones.