Boston Scientific Corp. a medical device company now headquartered in Natick, said Thursday that it plans to move its headquarters and about 800 employees to Marlborough.

Separately, Boston Scientific said it has agreed to buy Vessix Vascular Inc., a California company specializing in balloon catheter technology. The deal that could be worth as much as $425 million.

As for Boston Scientific’s move to Marlborough, the consolidation will take place in phases, starting next spring. Boston Scientific, which purchased a building in Marlborough in 2004, said it expects that its employees will be essentially moved out of the Natick facility by mid 2014, when construction of an additional building on the Marlborough site is set to be completed. The two facilities are about 13 miles apart, Boston Scientific said.

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The company added that it is in final stages of negotiating a sale with MathWorks to buy Boston Scientific’s entire 500,000-square foot facility in Natick, which it has occupied since 1995.

In a statement, Boston Scientific president and chief executive Mike Mahoney said, “Consolidating our Natick and Marlborough facilities is expected to foster greater collaboration and efficiency, benefitting our employees, our customers, and, ultimately, the patients they treat.”

As for Vessix Vascular, Boston Scientific said in a separate press release that the planned acquistion will extend Boston Scientific’s reach into the “strategically critical renal denervation market.”

“Renal denervation represents a potential breakthrough therapy for the treatment of uncontrolled hypertension and is an important part of the Boston Scientific growth strategy,” chief executive Mahoney said in a statement.

The agreement calls for an upfront payment of $125 million, plus $300 million in additional clinical and sales-based milestones aggregating a maximum value of the transaction of $425 million, Vessix said in a press release.