Table 1 |.
Cre models applied for osteoblast lineage studies
| Cre model | Targeted cells | Advantages | Disadvantages | Refs |
|---|---|---|---|---|
| Sox9 | SSCs, osteochondroprogenitor cells | Overcomes embryonic lethality of Sox9 heterozygous mutant mice; expressed throughout the lifetime of mice from the neonatal stage to old age | Potential for off-target Cre-mediated recombination in intestines and pancreas | 203 |
| Grem1 | Osteochondroprogenitor cells, bone stromal cells | Expression of cells concentrated in metaphysis; distinct from mesenchymal stem cells | Potential for off-target Cre-mediated recombination in intestines; low level of fibroblast CFUs (~1%) in in vitro studies forself-renewal | 36 |
| Osx | SSCs, osteoblast progenitor cells | Expression is specific to osteoblasts; expression is associated with invading blood vessels during development | Unable to study precursor cells that have not committed to the osteoblast lineage fate | 204 |
| Prrxl | SSCs | Expressed throughout the lifetime of mice from the neonatal stage to old age; presence of self-renewal properties for bulk cell culture in vitro | Potential off-target effects around the eye | 205 |
| Sost | Mature osteocytes | Used a Sost gene within a BAC clone for better expression; no off-target effects present in osteoblasts or myocytes | Potential off-target effects in haematopoietic cells and osteoclasts | 206 |
| Pthrp (also known as Pthih) | SSCs, osteochondroprogenitor cells, bone stromal cells | Stromal contribution; expressed throughout the lifetime of mice from the neonatal stage to old age | Involved in long-term maintenance of skeletal integrity; predilection for chondrogenesis over osteogenesis | 42 |
| Runx2 | Mature osteoblasts | Can be used to determine gene function in mature osteoblasts; robust expression and recombination | Reporter leakage into cartilage cells | 204 |
| Ctsk | SSCs in the periosteum | Can be used to determine the function of SSCs found in the periosteum | Potential deletion of gene in germline cells | 43 |
| Hoxa11 | SSCs in the periosteum | Labelling of cells from development until adulthood allows cell lineage tracing | Hox11+ SSCs only mark a subset of the entire SSC population | 26,28,207 |
BAC, bacterial artificial chromosome; CFU, colony-forming unit; Cre, Cre recombinase; SSC, skeletal stem cell.