Discovery of new skeletal stem cells may improve regenerative therapies for osteoporosis

Researchers at Boston Children’s Hospital (MA, USA) and the Harvard Stem Cell Institute (MA, USA) have discovered a new group of skeletal stem cells (SCCs) that function during a discrete phase of transitional growth. This study may help scientists understand the physiological factors that affect bone formation – leading to improved regenerative therapies for bone injury and disease.

Their study was recently published in the journal Stem Cells.

“This is particularly important given that anything that interferes with the proper development of bone mass during childhood and adolescence has long-lasting effects on our health, including the development of osteoporosis in adults,” commented corresponding author Diana Carlone (Boston Children’s Hospital and the Harvard Stem Cell Institute).

Telomerase (tert) – an enzyme that helps keep cells alive by adding DNA to the ends of chromosomes as the cells divide – is required for the maintenance of many stem cells. M-Tert expression is present in embryonic stem cells, induced pluripotent stem cells and self-renewing tissue stem cells. However, until now it was unclear if telomerase expression is also a marker for skeletal stem cells.

In their study, the team investigated the role of mTert-expressing cells in postnatal mouse long bone, whose formation relies on skeletal progenitor/stem cells.

Previous studies have shown that discrete skeletal stem cell populations play a critical role in rapid bone growth and bone maintenance at specific time periods. To determine if mTert was active during these periods, Carlone and her team studied their mTert mouse model at 1, 3 and 12 weeks of age.

They discovered that low levels of mTert were detected at multiple time points, noting that the enzyme was upregulated at 3 weeks – suggesting that mTert positive cells mark a distinct time period between rapid bone growth and bone maintenance.

“We also show that mTert-expressing cells are a distinct skeletal stem cell population with enriched colony-forming capacity and contribute to multiple mesenchymal lineages in vitro. In contrast, in vivo lineage-tracing studies identified mTert+ cells as osteochondral progenitors and contribute to the bone-forming cell pool during endochondral bone growth, with a subset persisting into adulthood,” added Carlone.

“Taken together, our results show that mTert expression is temporally regulated and marks skeletal stem cells during a discrete phase of transitional growth between rapid bone growth and maintenance that corresponds to the adolescent growth spurt in humans. We believe this warrants future studies focused on understanding how alterations in this cell population during this growth period translate into disorders such as osteoporosis.”

Link: https://www.regmednet.com/discovery-of-new-skeletal-stem-cells-may-improve-regenerative-therapies-for-osteoporosis/