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Canine cyclic haematopoiesis: bone marrow adherent cell influence of CFU-C formation
Insights
Canine cyclic haematopoiesis involves a stem cell defect affecting marrow cells. These cells show cyclical inhibition and stimulation of normal canine granulopoiesis in vitro.
Area of Science:
- Hematology
- Stem Cell Biology
- Canine Medicine
Background:
- Canine cyclic haematopoiesis (CH) is a condition characterized by cyclical neutropenia and other blood cell abnormalities.
- The underlying cause of CH is suspected to be a defect in multipotential hematopoietic stem cells within the bone marrow.
Purpose of the Study:
- To investigate the role of in vitro adherent bone marrow cells from CH dogs in regulating normal canine granulopoiesis.
- To determine if CH adherent cells exhibit cyclical regulatory activity on hematopoietic progenitor cells.
Main Methods:
- Bone marrow adherent cells from CH dogs were cultured as underlayers.
- Normal dog nonadherent marrow cells, containing granulocyte-committed colony-forming units (CFU-C), were cultured on top of the CH adherent cell underlayers.
- CFU-C formation was assessed on different days of the CH cycle.
Main Results:
- CH adherent cells demonstrated cyclical influence on normal dog CFU-C formation.
- Adherent cells from days 9-10 post-neutropenia onset inhibited CFU-C formation.
- Adherent cells from day 6 stimulated significant CFU-C formation (up to 108 colonies).
- Other cycle days showed variable stimulation, with day 3 being inconsistently stimulatory.
Conclusions:
- Canine cyclic haematopoiesis involves an intrinsic bone marrow defect affecting adherent cells.
- CH adherent cells exhibit a cyclical pattern of both stimulating and inhibiting normal canine granulopoiesis in vitro.
- These findings suggest a complex regulatory mechanism involving bone marrow stromal cells in the pathogenesis of CH.
Abstract:
Canine cyclic haematopoiesis (CH) appears to be a multipotential stem cell defect, possibly due to an intrinsic marrow defect. The in vitro adherent marrow cells of the cyclic haematopoietic (CH) dog were cultured as underlayers beneath normal dog nonadherent marrow cells. The marrow granulocyte-committed colony forming units (CFU-C0 of the normal dog nonadherent cells were cyclically influenced by the CH adherent cell underlayers. The CH adherent cells collected on the ninth or tenth day following the onset of neutropenia did not stimulate CFU-C formation while those collected on the sixth day stimulated as many as 108 colonies. The CH adherent cells collected on other cycle days supported increased CFU-C formation with the exception of cycle day 3 which inconsistently stimulated growth. These data show that the CH marrow in vitro adherent cells alternately stimulate and inhibit in vitro granulopoiesis of normal dog marrows.