Transplanted bone marrow generates new neurons in human brains

Area of Science:

• Stem Cell Biology
• Neuroscience
• Hematology

Background:

• Adult bone marrow stem cells (BMSCs) demonstrate plasticity, differentiating into various cell types in rodents.
• Previous studies showed BMSCs can enter the brain and differentiate into neurons in mice.
• Human BMSCs have regenerated tissues like myocardium and liver, indicating regenerative potential.

Purpose of the Study:

• To investigate whether adult human bone marrow cells can migrate to the brain and differentiate into neurons.
• To identify donor-derived cells in postmortem brain samples from female patients who received bone marrow transplants from male donors.

Main Methods:

• Postmortem brain samples from four female patients (transplanted with male bone marrow) were analyzed.
• Immunocytochemistry with neuron-specific antibodies was used to identify neurons.
• Fluorescent in situ hybridization histochemistry detected Y chromosome-positive cells, indicating donor origin.

Main Results:

• Y chromosome-positive cells were found in multiple brain regions of all four patients.
• While most donor cells were non-neuronal (endothelial, white matter), neurons were also labeled, particularly in the hippocampus and cerebral cortex.
• The youngest patient, who survived longest post-transplant, exhibited the highest frequency of donor-derived neurons (7 in 10,000).
• Clustering of Y-positive cells suggested clonal expansion and differentiation of single progenitor cells.

Conclusions:

• Adult human bone marrow cells can enter the brain and generate new neurons.
• This bone marrow-derived neurogenesis in humans mirrors findings in rodents.
• This phenomenon holds promise for future therapeutic applications in neurodegenerative diseases, infarction, and trauma repair.