Hox11 Expressing Regional Skeletal Stem Cells Are Progenitors for Osteoblasts, Chondrocytes and Adipocytes Throughout Life

Multipotent mesenchymal stromal cells (MSCs) are required for skeletal formation, maintenance, and repair throughout life; however, current models posit that postnatally arising long-lived adult MSCs replace transient embryonic progenitor populations. We previously reported exclusive expression and function of the embryonic patterning transcription factor, Hoxa11, in adult skeletal progenitor-enriched MSCs. Here, using a newly generated Hoxa11-CreER T2 lineage-tracing system, we show Hoxa11 -lineage marked cells give rise to all skeletal lineages throughout the life of the animal and persist as MSCs. Hoxa11 lineage-positive cells give rise to previously described progenitor-enriched MSC populations marked by LepR-Cre and Osx-CreER , placing them upstream of these populations. Our studies establish that Hox-expressing cells are skeletal stem cells that arise from the earliest stages of skeletal development and self-renew throughout the life of the animal.