# An axolotl embryogenesis single-cell reference atlas to enable lineage-based developmental and regenerative studies

> **NIH NIH R03** · HARVARD UNIVERSITY · 2024 · $169,000

## Abstract

PROJECT SUMMARY
 Human patients who lose limbs due to injury or disease are faced with profound challenges for the rest
of their lives. Prostheses, while increasingly sophisticated, lack key functionalities, and amputees report
dissatisfaction with current prosthetic options. A long-term goal of regenerative medicine is to develop
therapeutic limb regeneration strategies. Yet, this goal remains in the distant future because of a fundamental
lack of scientific understanding of how to stimulate and guide a patient’s own cells to create a new limb. Animal
models are likely to be key in building this missing foundation in scientific understanding of how to regenerate a
limb. While mice offer many advantages in genetic studies, they are extremely limited in their limb regeneration
abilities—like humans, mice are only naturally capable of regenerating the extreme distal tip of their digits. Full,
natural limb regeneration has not been reported in any mammal to date. Frogs can naturally regenerate full
limbs but only as tadpoles before development is complete. In contrast, many (if not all) salamander species
studied to date can regenerate full limbs following amputation throughout life. Salamander limbs are
remarkably similar in tissue composition and anatomy to human limbs. Thus, salamanders are ideal models for
elucidating the fundamental biological processes required to regenerate limbs. Among salamanders, axolotls
have emerged as a premier model because many genetic and experimental tools have now been developed
for axolotl. An important missing piece of the overall puzzle is how stem cells are specified to form during
axolotl embryological development and how these relate to the axolotl’s ability to regenerate limbs later in life.
 Here, we propose to use modern molecular genetic tools to build a map of transcriptional control of
axolotl embryogenesis with single-cell resolution. This resource will enable us to identify the origin and nature
of stem cells in axolotl embryos, and it will enable other researchers to develop hypotheses about other cell
types as well. We will identify stem cells as they arise during development, along with the key transcripts that
distinguish these cells from other cells, which will be essential for future studies, including those directed at
understanding how limb regeneration may use stem cells. In parallel, in a complementary strategy, we will
interrogate the embryological origins of 8 putative fibroblast stem cell types we recently isolated from axolotl
limbs and demonstrated become activated to proliferate by amputation. We will extend this analysis to
developing limbs. This work is essential for understanding the contribution of stem cells to the diverse tissues
of the regenerate limb. It will also pave the way to experimentally manipulate specific stem cell populations in
future studies in order to rigorously define their activities and the factors they use to execute these functions.

## Key facts

- **NIH application ID:** 10952651
- **Project number:** 1R03HD115999-01
- **Recipient organization:** HARVARD UNIVERSITY
- **Principal Investigator:** JESSICA L. WHITED
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $169,000
- **Award type:** 1
- **Project period:** 2024-08-01 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10952651

## Citation

> US National Institutes of Health, RePORTER application 10952651, An axolotl embryogenesis single-cell reference atlas to enable lineage-based developmental and regenerative studies (1R03HD115999-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10952651. Licensed CC0.

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