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Synchronized cell-cycle induction of engrafting long-term repopulating stem cells
S K Nilsson1, M S Dooner, P J Quesenberry
1Cancer Center, University of Massachusetts Medical Center, Worcester, MA, USA.
Blood
|December 31, 1997
Summary
Hematopoietic stem cells rapidly enter S-phase within 12 hours post-transplant to ensure long-term engraftment. These cells appear naturally synchronized, minimizing cell death when hydroxyurea is administered during this critical window.
Area of Science:
- Hematopoietic stem cell biology
- Transplantation immunology
- Cell cycle regulation
Background:
- Marrow stem cell homing is crucial for long-term hematopoiesis.
- The initial 24 hours post-transplant represent a critical window for stem cell homing.
- Understanding the cell-cycle status of engrafting cells is vital for optimizing transplantation outcomes.
Purpose of the Study:
- To determine the cell-cycle status of hematopoietic stem cells during the early homing window.
- To assess the impact of cell-cycle phase on long-term engraftment potential.
- To investigate if engrafting cells exhibit synchronized cell-cycle progression.
Main Methods:
- Bone marrow transplantation from male to female nonablated hosts.
- Administration of hydroxyurea (HU), an S-phase specific agent, at various time points (0-15 hours post-transplant).
- Analysis of donor cell engraftment in bone marrow and peripheral blood after 6 weeks.
Main Results:
- Over half of the engrafting cells are in S-phase by 12 hours post-transplant.
- Engrafting cells capable of long-term multilineage hematopoietic contribution are predominantly in S-phase early after transplantation.
- Donor cells demonstrated synchronized cell-cycle progression, with minimal cell death observed when HU was administered during the early homing window.
Conclusions:
- Engrafting hematopoietic stem cells actively enter S-phase within the first 12 hours post-transplant.
- This early S-phase entry is critical for successful long-term engraftment and hematopoietic reconstitution.
- The observed synchronization suggests a coordinated cellular response during the homing phase.