Isolation of bone marrow-derived stem cells using density-gradient separation.

Area of Science:

• Hematology
• Stem Cell Biology
• Immunology

Background:

• Established methods for isolating murine hematopoietic stem cells (HSCs) rely on functional characteristics like homing ability and aldehyde dehydrogenase (ALDH) activity.
• A key step in these protocols involves separating whole bone marrow into small-sized cells using counter-flow elutriation.

Purpose of the Study:

• To develop an alternative method for isolating functional HSCs by replacing counter-flow elutriation with density-gradient centrifugation.
• To validate the efficacy of density-gradient centrifugation in isolating HSCs with long-term reconstituting potential.

Main Methods:

• Whole bone marrow cells were separated using discontinuous density-gradient centrifugation.
• Fractions were assessed for their ability to home to bone marrow and provide long-term hematopoietic reconstitution in recipient mice.
• The ALDH protocol was combined with density-gradient centrifugation to evaluate the repopulation capacity of high-density bone marrow cells.

Main Results:

• Bone marrow cells isolated at a high-density interface (1.081/1.087 g/mL, fraction 3) demonstrated homing capacity and long-term hematopoietic reconstitution potential.
• Lineage-depleted, ALDH-bright cells from fraction three also successfully engrafted and provided long-term hematopoiesis.

Conclusions:

• Density-gradient centrifugation is a viable alternative to elutriation for isolating HSCs with long-term reconstitution ability.
• This simplified approach facilitates the study of HSCs isolated based on functional characteristics, promoting broader research in the field.