Ali Jamil

Human bone is a dynamic tissue, which undergoes continues remodeling, that is the removal of old and damaged bone replaced by new bone matrix. The specialized cell types involved in bone formation are descendants of a pool of immature progenitor cells (BM-MSCs) residing within the bone marrow. These cells can be easily expanded in culture for which they gained a huge momentum for the treatment of degenerated bone diseases such as bone fractures and cartilage injuries.

However, the clinical outcomes of BM-MSC-based regenerative therapies have revealed varying results. This is presumably due to the injection of a heterogenous pool of cells since isolation of BM-MSCs is based on the cells ability to attach to tissue culture plastic, a property which is not unique to BM-MSCs. Thus, BM-MSC cultures can be contaminated with cells that do not contribute to or even hamper tissue regeneration. Our aim is to investigate how patient-derived BM-MSCs differ in their BM-MSC subpopulation composition as well as how these BM-MSC subpopulations differ in their tissue regenerative potential.

Unfortunately, the golden standard of identifying all progeny cell-types of a particular cell population is tracking the cell population by a method referred to as lineage tracing, which takes place in live mice. In lineage tracing, a single cell is labelled typically with a marker in such way that the marker transmits to the cell’s progeny. With this, a set of labelled clones allow tracking of the single cell during its lineage differentiation pathway in a microscope to reveal all progenitor cells.

A potential alternative to lineage tracing in mice is recruiting voluntary human donors to obtain and use their cells to build a regression model through another method called single-cell RNA sequencing. Then, this model can be benchmarked by comparing the results from the sequencing experiment with experimental results that shows differentiation and bone tissue regenerative abilities of investigated BM-MSC subpopulations. Proven successful, our alternative strategy may circumvent lineage tracing in mice while increasing the confidence level of the resulting regression model that predicts cellular differentiation potential based on BM-MSC sample composition. In summary, the outcome of our project may approve of an alternative strategy to the current golden standard of lineage tracing and differentiation investigation assays in living mice.