You should be able to use that experience as long as it took place within the time period allowed by PMI and there was no overlapping of projects. I was able to use my project management related volunteer experience on my application. Good luck with your application.
On the PMP application, do undergraduate research projects and summer internships count as experiences if I am leading those projects? Thank you for your time.
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®