Our HeLa PCL Platform

Realizing the Promise of AAV Gene Therapy

The Challenge of AAV: Manufacturing

While the adeno-associated virus (AAV) is widely considered to be an ideal vector for gene therapy—because of its favorable tissue tropism (ability to infect a particular cell type), predictable gene expression, and low toxicity—it is notoriously challenging to manufacture AAV vectors.

The current industry-standard method for manufacturing AAV is inefficient and costly, and results in low product-yield. While gene therapy holds promise for diseases emanating from deficiencies in CNS and muscle tissues, these diseases can require much larger doses of therapy compared to liver-targeted approaches, which amplifies the problem. Many of these diseases also have higher prevalence rates, which could multiply the demand for manufacturing at scale.

The HeLa PCL Platform: A Line Toward the Future

At Ultragenyx, we have established a new manufacturing platform that can produce AAV vectors with increased efficiency and lower material costs than traditional methods, and at a scale that can help meet the rising demands of today’s gene therapy landscape.

At the heart of our platform is our proprietary HeLa Producer Cell Line (PCL), which we have engineered to stably produce high yields of viable, intact AAV vectors, while minimizing the production of empty AAV capsids.

Ultragenyx continues to invest in improvements to increase the capacity and efficiency of our HeLa PCL platform.

Breaking New Ground with AAV Manufacturing

Reflecting our commitment to developing and delivering more accessible AAV-based gene therapies, we have begun construction on a 100,000-square-foot manufacturing facility in Bedford, Massachusetts.

We believe this state-of-the-art facility, slated for completion in 2023, will provide us with a flexibility and control of process that can further optimize the HeLa PCL platform, ultimately broadening our future partnerships and advancing our own gene therapy pipeline.

HeLa PCL at Work Today

Through the strength of our HeLa PCL platform—greater efficiency, lower costs and commercial scalability—the great potential of AAV-based gene therapy is beginning to be realized today, as evidenced by our current partnerships:

  • Bayer is using our HeLa PCL platform to produce its hemophilia A gene therapy at a 2,000-liter scale.
  • Daiichi Sankyo has selected our proprietary AAV-based gene therapy manufacturing technologies, including our HeLa PCL platform, for its internal gene therapy programs.
  • Solid Biosciences is partnering with us to advance new AAV-based gene therapies for Duchenne muscular dystrophy.


We are interested in hearing from people who, like us, are focused on improving the lives of people living with serious rare and ultra-rare genetic diseases.

Want to get in touch? Contact us