Retro develops therapies for diseases driven by the biology of aging. We focus on cellular reprogramming and autophagy to rejuvenate cell and tissue function with the ultimate aim of adding 10 years to healthy human lifespan. We’re building a mission-driven team of accomplished and kind individuals who embrace our startup culture of rapid iteration, transparency, and versatility. We are hiring a new member of the team who will expand Retro’s capabilities by building, maintaining, and scaling custom bioreactor systems used for automated cell culture. This is a highly hands-on “builder” role at the intersection of precision assembly, fluidics, sensors, electronics, and automation. In this role, expect to be at the bioreactor—assembling hardware, improving designs, strengthening reliability, and enabling scientists to run more experiments confidently. About you: You are a hands-on engineer at heart—someone who loves building complex, reliable systems. You balance rigor and documentation with a bias toward unconventional approaches and rapid iteration. You’ve likely worked in environments like precision manufacturing, instrument assembly, or hardware-heavy R&D where you were close to the hardware—not just designing it, but building it, debugging it, and improving it. Ideally, you have a track record of transforming prototype systems into closed, production-ready platforms, within cGMP environments.