OAKLAND -- A Santa Clara county man is suing a Bay Area stem cell research and development company on allegations he was fired from a senior management job for voicing concerns about a manufacturing practices he says puts stem cell therapy patients' lives at risk.

Rob Williams' wrongful termination and retaliation lawsuit against StemCells was filed in Alameda County Superior Court this week and seeks punitive damages against the Newark-based, publicly traded company that receives millions in government and private grants.

StemCells hired Williams in December to oversee the facility where stem cells cultures are cultivated for clinical trials. The lawsuit alleges he was fired in May in retaliation for making complaints about "dangers/defective products that the company was releasing into the commerce stream for human clinical trials."

StemCells, Inc. spokeswoman Andrea Flynn said the allegations are without merit and Williams was terminated for performance deficiencies.

"The elements of manufacturing practices that concerned Mr. Williams were immediately and carefully reviewed by the company," Flynn wrote in an email. "The company's primary concern has always been, and will continue to be, the safety and tolerability of stem cell transplantation in its clinical trials.

"To date, no patients participating in the clinical studies have experienced any product related safety concerns," Flynn wrote.

Daniel Velton, Williams' Silicon Valley employment lawyer, wrote in the complaint, "Williams, in no uncertain words, complained to the company about flaws in its manufacturing process that created a substantial risk to public health and safety, including the threat of infection and even death of patients," Velton declined to comment on the lawsuit Thursday.

Williams says he noticed shortly after he was hired as senior manager for manufacturing that the company wasn't following good manufacturing practices, "substantial deficiencies" in its processing in central nervous system stem cell lines, and poor sterile technique.

The poor manufacturing processes led to therapies with dangerously high number of nonviable or damaged cells that, in addition to potentially harming patients, could skew test results and jeopardize data behind years of clinical trials and research, the lawsuit says.

When Williams reported his concerns to a longtime upper manager in March, she "directed her ire at him personally" and ignored "the underlying problem in the manufacturing process that he had brought to light," the lawsuit says. Williams allegedly was suspended pending an investigation into his working relationship with the unnamed supervisor, and then fired after emailing leadership about his concerns about the stem cell production line.

Contact Malaika Fraley at 925-234-1684. Follow her at Twitter.com/malaikafraley.