06/13/2025
By Gweneth Andersen

The Kennedy College of Sciences, Department of Physics and Applied Physics, invites you to attend a master’s thesis defense by Gweneth Andersen on “Relative sparing effects of carbon ion radiation on dendritic development in murine hippocampal neurons.”

Date: Tuesday, July 1, 2025
Time: 2 to 3:30 p.m.
Location: Virtual defense via Zoom. Those interested in attending should contact MS candidate Gweneth Andersen at Gweneth_Andersen@student.uml.edu at least 24 hours prior to the defense to request access to the meeting.

Committee Members:

  • Advisor: Jan Schümann, Ph.D., Associate Professor of Radiation Oncology, Mass General Research Institute and Harvard Medical School
  • Erno Sajo, Ph.D., Professor, Department of Physics and Applied Physics, UMass Lowell
  • Romy Guthier, Ph.D., Assistant Professor, Department of Physics and Applied Physics, UMass Lowell

Abstract:
While whole brain radiotherapy (WBRT) methods are effective at controlling brain tumor growth, the damage they deal to brain tissue often exacerbates cognitive decline in patients (iatrogenic brain injury, IBI). Hippocampal avoidance (HA-WBRT) planning and proton or ion beam therapies have reduced IBI in both palliative and pediatric patients, but the mechanistic basis is still unclear. Guided by biophysical models of synaptic integrity underlying affected cognitive domains (learning, memory, attention, etc.), this work explores the comparative effects of carbon ion and X-ray (photon) irradiation of immature hippocampal neurons on their morphological development through analysis of the yet unpublished results of murine experiments conducted at Gunma University in Japan. Neurons were collected from 16-day-old mouse embryos, cultured, irradiated, and then fixed and imaged at various stages throughout the course of their 3-week maturation period using immunofluorescence microscopy. Fluorescent markers (MAP2, DAPI, drebrin) visualized the cytoskeleton inside each neuron's dendrites and highlighted dendritic spines, permitting the use of morphometric algorithms that traced the extent and branching complexity of the dendritic arbor. Cohorts of neurons that were irradiated with 225 kV X-rays to doses of 0.5 Gy and 1 Gy and survived to maturity developed significantly shorter and less branched dendrites than the unirradiated controls. Similar trends were observed in cohorts irradiated with 290 MeV/u carbon ions to the same doses, but the effects were significantly less pronounced and appeared to saturate with increasing dose.

All interested students and faculty members are invited to attend.