Microglia-like macrophages support sensory axon regeneration after nerve injury

Edmund R. Hollis II, PhD
Associate Professor
Neuroscience
Brain and Mind Research Institute
Weill Cornell Medicine

Director
Circuit Repair Laboratory
Burke Neurological Institute (Academic Affiliate of Weill Cornell Medicine)
White Plains, NY, USA

This conference is hosted by Artur Kania, PhD. This conference is part of the 2025-2026 IRCM conference calendar.

About this conference
Peripheral nerve injury triggers complex, heterogeneous responses among dorsal root ganglion (DRG) neurons, ranging from successful axon regeneration to degeneration and cell death. In parallel, DRG macrophages proliferate and accumulate around injured neurons, where distinct macrophage states emerge. The identities of these injury-induced macrophage states—and how each state engages specific sensory neuron subtypes to shape divergent neuronal outcomes—remain unclear. We combined transgenic mouse models, sciatic nerve injury, high-resolution three-dimensional (3D) DRG imaging, and single-cell transcriptomic analysis to identify injury-induced pro-regenerative and phagocytic macrophage states driving subtype-specific neuron–macrophage interactions. Microglia-like, stellate macrophages tightly surround the somata of large-diameter regenerating DRG neurons, while amoeboid macrophages fully engulf cell bodies of degenerating neurons. Limiting interactions with stellate DRG macrophages in a genetically defined population of sensory neurons results in a selective reduction in axon regeneration. These selective cell–cell interactions represent a tractable neuroimmune axis to enhance repair and potentially limit maladaptive responses after nerve injury.

About Edmund R. Hollis II
Edmund Hollis, PhD, is Director of the Circuit Repair Laboratory at the Weill Cornell Medicine (WCM) affiliated Burke Neurological Institute (BNI) and Associate Professor of Neuroscience at WCM. He performed his graduate and postdoctoral training at the University of California, San Diego with Mark H. Tuszynski, MD, PhD and Yimin Zuo, PhD, respectively. He has received several research awards and was a recipient of a 2017 NIH Director’s New Innovator Award. Dr. Hollis served as the BNI Postdoctoral Advancement Advisor from 2021-2025, WCM IACUC Chair since 2025, and as a post-hoc member on multiple NIH study sections. His laboratory studies neural circuit control over movement using a variety of experimental approaches including genetic manipulations, 2-photon imaging, optogenetic and chemogenetic control, and novel behavioral paradigms. In collaboration with Justin Brown, MD, at Massachusetts General Hospital, he is building on his pre-clinical studies on peripheral nerve regeneration to improve motor recovery in individuals with nerve transfer surgery to treat chronic spinal cord injury.

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