Astellas Pharma said today that it has extended into next month its tender offer to acquire all outstanding shares of Ocata Therapeutics for $379 million.

Astellas’ offer has been extended nearly three weeks, from January 21 to February 9 at 5 pm ET. The offer period began on November 25 and was originally set to end on December 17.

Astellas hopes the second extension will give it the time it needs to persuade Ocata shareholder Gary Aronson—a co-founder of Targa Therapeutics—and other shareholders to go along with the deal.

Aronson and allies have contended that the acquisition undervalues Ocata, with Aronson telling The Boston Globe in December: “My impression is the value should be at least double.”

That month, Aronson also told the Boston Business Journal that he has suggested Ocata instead pursue a “merger of equals” with regenerative medicine company BioTime—a company in which he owns 2.2 million shares, accounting for more than 5% of the company.

Under the tender offer, Astellas’ indirect wholly owned subsidiary Laurel Acquisition is acquiring all issued and outstanding shares of Ocata common stock for $8.50 per share. Astellas said all terms and conditions of the tender offer remain unchanged during the extended offering period.

Astellas and Ocata announced the deal in November, saying the combination would benefit the buyer by giving it a presence in ophthalmology and cell therapy. Astellas now focuses on immunology, nephrology, neuroscience, oncology, and urology.

Ocata—which changed its name in 2014 from Advanced Cell Technology—focuses on regenerative medicine and cell therapy technologies for eye diseases.

“We remain very excited about the combination of Astellas and Ocata and are fully committed to achieving a successful completion of the transaction,” Astellas President and CEO Yoshihiko Hatanaka said in a statement. “We highly value Ocata's R&D capabilities, where we plan to make further investments, and expect Ocata to take a key role within Astellas' R&D in ophthalmology and cell therapy.”