The goal of a recent study published in Stem Cells International was to compare human periosteum and donor-matched iliac crest bone marrow (BM) multipotential stromal cell (MSC) content and to characterize MSCs in terms of colony formation, growth kinetics, phenotype, cell migration patterns and the trilineage differentiation capacity.

The results revealed the following:

• "Clinically accessible" periosteum had an intact outer fibrous layer, containing CD271+ candidate MSCs located perivasculary. The inner cambium was rarely present.
• After the enzymatic release of cells, periosteum formed significantly smaller fibroblastic colonies compared to BM (6.1 mm² versus 15.5 mm²).
• Periosteal colonies were more homogenous in size (range 2-30 mm² versus 2-54 mm²) and on an average 2500-fold more frequent (2.0% versus 0.0008%) relative to the total viable cells.
• When expanded in vitro, equivalent growth rates up to passage 0 (P0) were observed.
• Subsequently, BM MSCs proliferated significantly slower by P4 (4.3 PDs per day, periosteum versus 9.3 PDs per day, BM).
• In early culture, periosteum cells were less migratory at slower speeds than BM cells.
• Both MSC types exhibited MSC phenotype and trilineage differentiation capacity.
• Meanwhile, the periosteum MSCs showed significantly lower (2.7-fold) adipogenic potential based with reduced expression of adipogenesis-related transcripts PPAR-γ.

The findings indicated that periosteal samples represent a consistently rich source of highly proliferative MSCs compared to donor-matched BM and show similar osteochondral capacity and lower adipogenic potential. It was stated that live cell tracking allowed for the determination of unique morphological and migration characteristics of periosteal MSCs that can be used for the development of novel bone graft substitutes to be preferentially repopulated by these cells.

Source: Stem Cells International. 2019 Nov 21;2019:6074245. doi: 10.1155/2019/6074245. eCollection 2019