For two decades, Lawrence Rizzolo, the director of medical studies at the Yale School of Medicine, has been working toward a project that aims to transplant young, healthy retinal cells to replace diseased tissues in the eyes of patients who are going blind.

But now Rizzolo fears he may have to delay, or even stop, his research because of last week’s ruling by a federal judge that prevents federal funding for studies involving embryonic stem cells, the building blocks for human organs and tissues that Rizzolo needs for his project.

Rizzolo had applied for a grant from the National Institutes of Health to replace his funding from the nonprofit International Retinal Research Foundation, which ends in December. Rizzolo also has a three-year state grant from Rocky Hill, Conn.-based state holding company Connecticut Innovations, but he says he cannot continue his research without the federal funding.

Rizzolo’s laboratory is one of about a dozen facilities on campus that use stem cells. Haifan Lin, director of the Yale Stem Cell Center, said he did not yet know how the moratorium will affect Yale researchers.

“We’re all waiting for clarification on the implications of the judge’s ruling,” University President Richard Levin said.

But frozen funding could lead scientists to lose their jobs. Rizzolo said that although a fourth researcher will join his laboratory in October, he may soon have to fire his workers because the grants and not the University pay for his researchers’ salaries.

Although the U.S. Department of Justice has filed a motion seeking to delay the federal judge’s ban on funding, the relief would only be temporary, NIH spokesman Don Ralbovsky said. The Justice Department declined to comment Thursday.

Opponents of embryonic stem cell research have hailed the ruling.

“The American people should not be forced to pay for experiments — prohibited by federal law — that destroy human life,” said Steven Aden, the legal counsel for the Alliance Defense Fund, which advised the party that brought the lawsuit to court.

Most labs at Yale’s Stem Cell Center are supported primarily by state funds, which are not affected by the ruling, said Diane Krause, the center’s assistant director. But, she explained, those state grants were meant to be a springboard for acquiring federal funding.

“Discontinuation of NIH funding of work with human embryonic stem cells could be a disaster,” she said.

School of Medicine Dean Robert Alpern agreed, saying that halting the stem cell research would be a “loss to society.”

Krause and other Yale researchers met Aug. 26 with Connecticut attorney general and U.S. Senate candidate Richard Blumenthal LAW ’73, who told the News this week that he plans to file a brief in support of the appeal.

“It is incredibly important for our scientific and legislative leaders to come together and solve this issue quickly,” Blumenthal said in a statement. “We have already lost so many years of work to backwards-looking and bureaucratic federal policy.”

Linda McMahon, his Republican challenger for Chris Dodd’s Senate seat, also supports stem cell research, according to her website. The McMahon campaign did not respond to multiple phone requests for comment this week.

Even if the Justice Department successfully delays the ruling, NIH has not said whether it would accept new applications. That would be a problem for Yibing Qyang, an assistant professor of cardiology at the School of Medicine who currently has a $95,499 federal grant and had planned on applying for another in October.

“I cannot live without federal funding,” said Qyang, who is priming stem cells to become healthy heart cells in patients with heart disease.

Yale has received at least $17 million in state funding from a $100 million stem cell research pot funded in part by tobacco taxes. It also received $4.9 million in NIH stem cell research grants in 2009 and 2010. NIH gave $123 million to researchers in fiscal year 2010 for embryonic stem cell research, Ralbovsky said.

Rizzolo studies eye tissues called retinal pigment epithelia. Many eye diseases — including macular degeneration, from which more than 10 million Americans suffer — affect these tissues, which function as a support for the retina, the part of the eye responsible for sight. Doctors have tried to transplant retinal and epithelial cells to combat these diseases. But most of the transplants fail because they are risky and the patients who choose to undergo them are usually almost blind. Patients in the early stages of macular degeneration are unlikely to attempt a transplant; Rizzolo said he hopes that his research with stem cells, which he started to use about a year ago, would lead to other, less risky, treatments for the disease.

Rizzolo added that, in the past year, two Yale colleagues had entirely shut down their stem-cell research labs because of funding shortages.

“It’s pretty frustrating when you work so hard to see something go unfunded for political reasons,” he said.

The Yale Stem Cell Center, established in 2006, brings together more than 30 faculty members across the University.