CLEVELAND, Ohio (TheStreet) -- The verdict on an experimental stem-cell therapy developed by Athersys (ATHX) to assist the recovery of stroke patients is coming on April 19.

Athersys' future arguably hinges on the results of this mid-stage study. The company's stock price plunged last April when MultiStem, the stem cell therapy, failed to benefit ulcerative colitis patients. The MultiStem stroke study is Athersys' best and perhaps last chance for redemption. Athersys shares were trading around $3.10 before the market opened on Monday.

MultiStem is derived from adult bone marrow and is designed to promote tissue repair and reduce inflammation. As an off-the-shelf product, MultiStem can be mass produced and frozen for storage until needed.

The current study enrolled 140 patients suffering from a severe ischemic stroke caused by blockage of blood flow to the brain. Treatment of the patients is randomized, with an infusion of MultiStem or a placebo administered one or two days after the stroke occurred. Current clot-busting stroke therapies must be given within hours of occurrence in order to be effective.

Athersys' goal is to demonstrate that MultiStem can facilitate stroke recovery better than a placebo at 90 days following treatment.

A "global test analysis" encompassing three different stroke-recovery measures -- the modified Rankin Scale (mRS), the NIH Stroke Scale and the Barthel Index -- will be used to assess the study's primary efficacy endpoint. Combined, the stroke-recovery scales measure improvements in cognitive function, disability and daily living skills.

"The approach we are using for the trial is patterned after the approach that was used in the NINDS study to evaluate tissue plasminogen activator when it was approved approximately 20 years ago," said Athersys President B.J. Lehmann, referring to the class of clot-busting drugs used to treat stroke today.

The original design of the MultiStem study used only the modified Rankin Scale to measure the stroke recovery primary endpoint. Last December, Athersys changed the assessment method for stroke recovery by adding the two other scales. Changes were made to the study endpoints to evaluate the "total picture" of stroke recovery, which doctors who treat stroke patients consider most important, Athersys' Lehmann said.

Handicapping the outcome of the stroke study is a shot in the dark. Athersys has no prior clinical data using MultiStem in stroke patients. The company based the phase II study on preclinical experiments demonstrating neurological and functional improvement in mice with strokes treated with MultiStem. Detailed data from the failed MultiStem study in ulcerative colitis have not yet been disclosed.

Athersys' current stock price has recovered from the swoon last April following the failure of the ulcerative colitis study, but the company's market value is still a relatively small $240 million. 

In February, Japanese drug maker Chugai licensed MultiStem for stroke treatment in Japan. Chugai's willingness to make a deal so close to the study results could be seen as positive endorsement of the stem cell therapy except financial terms are back-end loaded. Chugai paid only $10 million upfront to Athersys for the MultiStem license and committed another $7 million depending on the phase II results. The deal gets much more lucrative for Athersys if MultiStem is eventually approved in Japan as a new stroke therapy. 

Athersys estimates approximately 1.75 million people in the U.S., Europe and Japan suffer ischemic strokes each year.

The MultiStem stroke study results will be announced during a presentation at the European Stroke Conference on April 19. 

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.