Houston, Texas - United States citizens who had pinned hopes on a company being able to offer stem-cell treatments close to home will now have to travel a little further. Celltex Therapeutics of Houston, Texas, stopped treating patients in the US six months ago following a warning from the Food and Drug Administration.

An e-mail last week to Celltex customers indicated that the firm will follow in the footsteps of other companies offering unproven stem-cell therapies, and send patients abroad for treatment — but only to Mexico.

The controversial stem-cell treatments offered by the company involved extracting adult stem cells from a patient, culturing them, and then reinjecting them in a bid to replenish damaged tissue. Celltex had been offering the treatment for more than a year — with one of its high-profile customers being Texas governor, Rick Perry — when last September the FDA advised the company that "since the stem cells it harvested and grew were more than 'minimally manipulated' during their procedures, they were regarded as drugs and would require federal approval to inject them into patients."

The FDA also warned that Celltex had failed to address problems in its cell processing that inspectors from the agency had identified in an April 2012 inspection of its cell bank in Sugar Land, Texas. Shortly after it received the letter, Celltex stopped injecting stem cells into patients.

For customers who still had cells banked at Celltex and were wondering how to get them out, things became more chaotic when Celltex and RNL Bio - a company based in Seoul, South Korea, which operated the processing center and bank in Sugar Land - sued each other over financial disagreements. Celltex had to issue a restraining order just to gain access to the cells.

The January e-mail from Celltex reassures customers that their cells are safely stored in a facility in Houston and adds: "We anticipate that we will be able to offer our stem cell therapy services to physicians in Mexico starting very soon!"

The e-mail also says that the company is building a new laboratory in Houston, to be opened in March 2013. Its aim is to then begin an FDA-approved clinical trial and obtain the green-light to perform the procedure in the US. Because its culturing and banking technology was licensed from RNL Bio, there is some uncertainty about whether Celltex has the facilities and expertise to carry out the trial on its own.