Experimental bone marrow transplantation 101 – part 1: Definitions

by Alexey Bersenev on October 23, 2011 · 0 comments

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In this series I’ll introduce and discuss the basic principles of experimental bone marrow transplantation.
Part 1 – Definitions.

Experimental bone marrow transplantation (BMT) – transfer of bone marrow (BM) cells from one animal to another via intravenous or intra-bone routes.

The main purposes:

  • Assessment of hematopoietic stem / progenitor cell function.
  • Quantification of hematopoietic stem cell number.
  • Model of hematological, immune and autoimmune diseases.

Donor (test) – the animal, which bone marrow cells will be tested for blood repopulation and engraftment.

Recipient (host) – the animal, which will receive bone marrow cells from donor.

Competitor – normal mouse with known bone marrow (stem cell) repopulation activity.
Competitor cells serve as:

  • radioprotector (to keep recipient survive) in case of unknown repopulation potential of test BM;
  • a competitor (standard) in competitive repopulation or limiting dilution assays.

Blood repopulation – contribution of donor-derived cells in blood lineages.

Engraftment – survival and persistence of donor-derived cells in host bone marrow and their functional contribution in host hematopoieisis (bone marrow and blood chimerism).

Percentage of chimerism – defined as % of donor test cells in the blood or bone marrow = (% of donor cells) / (% of donor cells + % of competitor + % of host) x 100.

Multilineage repopulation/ engraftment – contribution of donor cells in the most or all hematopoietic lineages in the host. Used as a marker of multipotent progenitors or stem cells. Usually simplified to tri-lineage (myeloid, B- and T- lymphoid) engraftment detection.

Long-term repopulation/ engraftment – persistence of donor-derived cells in the host blood or/and bone marrow more than 16 weeks after BMT. Used as a marker for long-term hematopoietic stem cell (HSC) function.

Short-term repopulation/ engraftment – persistence of donor-derived cells less than 16 weeks after BMT. Used as a marker of progenitors and short-term HSC function.

Congenic mouse model – inbred strains that differ at only a single locus through mutation. Antigenic difference in CD45 alleles used for donor cell detection after BMT.

Recipient conditioning – Pre-transplant recipient manipulation aimed to increase engraftment of donor cells in bone marrow. Lethal irradiation typically used for the most BMT experiments.

Competitive repopulation assay – mixing donor and competitor bone marrow cells with different ratios. Used for assessment of unknown hematopoietic stem/ progenotor cell function of donor (test) in comparison with known repopulating activity of competitor. Latter used as a reference standard of normal bone marrow.
The assay based on competition for engraftment in host bone marrow between a test cells and standard number of freshly isolated competitor BM cells.

Non-competitive repopulation assay – BMT of different donor cell numbers without competitor.

Repopulating units (RU) – quantitative assessment of donor repopulating ability = repopulating capacity of test donor cells relative to 1 x 105 of competitor cells. By definition 105 competitor bone marrow cells produced 1RU of functional ability (Harrison et al, 1993). Calculated as (% chimerism)(number of competitor cells) / (100-% chimerism) x 105.

Limiting dilution BMT – transplantation of graded decreasing donor cell numbers (titration) mixed with standard cell dose of competitor. Used for calculation of frequency donor (test) HSC (CRU). Competitor served as radioprotector and for CRU calculation.

Competitive repopulating units (CRU) – the number of repopulating cells (correlates with HSC number) in test donor cells. Determined by limiting dilution assay.

Serial BMT assay – transplantation of total bone marrow cells from primary recipient to the secondary, tertiary, quaternary (and so on) recipients with interval enough for long-term engraftment of donor cells. Used for assessment of HSC self-renewal function.

Please feel free to contribute to the project!

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