About us

About Excellos

Excellos accelerates gene therapies by improving the quality, breadth, and variance of donor samples, and providing end-to-end cell therapy services: from customized collection to engineered working cell banks. Our proprietary Excellos 360 technology provides deep characterization of cells to better match patient and therapeutic development needs.

The Excellos Story

Our team has extensive experience in cell banking, processing, and manufacturing. As a spin-out of the San Diego Blood Bank, we understand the challenges in collecting quality, consented material and that cell characterization is the foundation for a successful therapeutic. By teaming with Telegraph Hill Partners, we built the dream cell processing and manufacturing facility in downtown San Diego. We embrace our customers not as clients, but as partners- we are in this together!

Leadership Team

David Wellis

CEO, Board

David is a cell biologist with over 30 years’ experience in the life science industry. Prior experiences include CEO of San Diego Blood Bank, and key leadership roles at Ilumina, GenVault and Axon Instruments. David is on the Executive Committee of the Clinical and Translational Research Institute at UC San Diego and has held board and committee roles in several national blood bank organizations, the National Institutes of Health and local biotechnology companies. David received his B.S. from UC Irvine, an M.S. and Ph.D. from Emory University, postdoctoral training at Tufts University and UC Berkeley, and business training at Leavey Business School of Santa Clara University and Haas Business School at UC Berkeley. For two consecutive years, he was named to the SD500 list of Most Influential People in San Diego.

Rob Tressler


Robert has authored over 30 peer-reviewed articles and publications and is an inventor on numerous patents. Previously he was the CSO at the San Diego Blood Bank and has held executive scientific roles at Geron, Inc. and Cellerant Therapuetics. Robert’s scientific focus is stem cell biology, oncology, and anti-aging. Robert achieved is Ph.D. from University of Texas in Cancer Biology and has a Masters Degree in Microbiology. He is a member of the American Association of Blood Banks, The International Society of Cell Therapy, and the American Society of Hematology.

Sun Ra Bullins

VP Operations

Sun Ra is an operations leader with over 29 years of experience developing and managing high performing operations teams in multi-product GMP biotech facilities. His experience encompasses small- and large-scale clinical and commercial drug substance and gene therapy operations, and he has worked with several CDMO organizations during his tenure. Sun Ra systems focus and ability to develop collaborative relationships will ensure the needs of customers and patients are consistently met. Sun Ra’s priority will be to use his operations and GMP background to help Excellos become a leader in the ATMP and specialized medicine space, making significant differences in patient’s lives.

Heather Burnell

VP Quality

Heather is a Quality Professional with over 32 years of experience in the biotech industry, with over 7 years of experience in cell and gene therapy. She has experience leading Quality teams for large multi-product facilities and startup environments. Prior to Excellos, Heather held roles at CDMOs as Head of Manufacturing and MSAT for Abzena, and Head of Quality at SAFC (now Millipore Sigma). Heather held a variety of QC/QA roles at Amgen in her 22 years there, including leading regulatory inspections, both pre-approval and biennials for FDA, EMA, TGA, among others to successful outcomes and overseeing Corporate Quality Systems globally across all of Amgen’s sites.

Hillary Youngberg

VP Business Development

Hillary has over 15 years of experience in the cell and gene therapy space. Prior to her leadership role at Excellos, she led west coast business development at WuXi Advanced Therapies, focusing on the development, manufacturing and testing of cell and gene therapy products. Her experiences include 7 years at SAFC (now Millipore Sigma), a viral vector CDMO, in both program management and business development roles. Hillary received her B.S. in molecular, cellular, and developmental biology from UC Santa Barbara.

Bruna Bertsch

VP Finance

Bruna Bertsch is a finance leader with over 20 years of experience developing, scaling, and managing all aspects of finance. Her experience encompasses private and public companies, and she has worked with several start-up companies and their subsequent acquisitions. Prior companies include Certik, Luxtera, Sequenom, Qualcomm, and Accenture. Bruna’s emphasis is providing value-added data and analytics that delivers decision-making insights.

Virginia Bunnell

VP of People & Administration

Virginia Bunnell leads the people strategy for Excellos, including developing a high-performance culture that motivates and drives alignment of organization goals and initiatives. She is responsible for the development of a people focused culture and drives all aspects of the employee experience for Excellos. Prior to Excellos, Virginia previously held the Director of Administrative Services role at the San Diego Blood Bank where she lead, managed and motivated a multi-functional team to build a highly efficient culture and increased staff productivity. Virginia holds a Strategic Human Resources Leadership Certificate from Cornell University and Senior Certified Professional from the Society of Human Resource Management. Virginia gives back to the community by serving on several not-for-profit Boards.

Board of Directors

Paul Grossman

Telegraph Hill Partners

Deval Lashkari

Telegraph Hill Partners

Terry Kinninger

Robert (Bob) Finzi