Planarian flatworms regenerate lost body parts using stem cells steered by signals from far‑off tissues rather than nearby neighbors, research published in Cell Reports on October 15, 2025, suggests—reframing how niches regulate stem cells and hinting at future approaches to tissue repair.
Researchers at the Stowers Institute for Medical Research report that planarian stem cells defy the classic, contact‑based “niche” model. Led by postdoctoral researcher Frederick “Biff” Mann in the laboratory of Stowers President and Chief Scientific Officer Alejandro Sánchez Alvarado, the team combined spatial transcriptomics with imaging to map gene activity around stem cells and identified a previously undescribed cell type, dubbed hecatonoblasts, with many fingerlike projections—named after the many‑armed Hecatoncheires of Greek myth. The study appeared in Cell Reports on October 15, 2025. (stowers.org)
“Because they were located so close to stem cells, we were surprised to find that hecatonoblasts were not controlling their fate,” Mann said. Instead, the strongest instructive signals arose from intestinal cells located at a distance, indicating that long‑range cues, not immediate neighbors, orchestrate how planarian stem cells position and function during regeneration. Co‑corresponding author Blair Benham‑Pyle of Baylor College of Medicine described the system as “local versus global communication networks.” (stowers.org)
The findings challenge the prevailing view that most stem cells require a fixed, contact‑dependent niche for instructions on division and differentiation. Sánchez Alvarado said the work reframes the niche concept and could advance efforts to control stem cells’ capacity to restore damaged tissues. (sciencedaily.com)
Adult planarian stem cells are capable of generating any cell type; the authors propose that relative independence from a fixed niche may help explain the animals’ exceptional regenerative abilities, such as rebuilding a head or even an entire body from a small fragment. Coverage by The Scientist likewise highlights that distant intestinal signals, rather than nearest neighbors, govern regeneration. (medicalxpress.com)
Additional authors include Carolyn Brewster, Ph.D., and Dung Vuu, among others. The work was supported by the National Institute for General Medical Sciences of the NIH (award R37GM057260) and institutional support from Stowers. (sciencedaily.com)