The human skeleton is an amalgam of diverse tissue types including bone, cartilage, and fat cells. Each tissue type in the skeleton is generated and maintained by the precise regulation of stem cells possessing the ability to replenish themselves via specific cell-lineages, with researchers looking for the elusive stem cell-type for bone and cartilage. Now, a study from researchers led by Stanford University isolates human skeletal stem cells from fetal and adult bones, capable of differentiating into bone or cartilage cells. The team states they were also able to derive the skeletal stem cells from human induced pluripotent stem cells, opening up a realm of therapeutic possibilities. The opensource study is published in the journal Cell.
Previous studies have shown skeletal dysfunction can lead to a broad spectrum of health conditions ranging from age-related diseases such as osteoporosis and osteoarthritis to non-healing skeletal injury, blood disorders, and even cancer. However, despite its significant impact on health and disease, treatment options aimed at improving skeletal function are currently limited. One major hurdle is stem cell regulation in the human skeletal system remains largely unexplored, with only rodent studies identifying skeletal stem cells. The current study identifies and characterizes human skeletal stem cells and downstream bone and cartilage progeny in a variety of tissues.
The current study analyzes cells from human tissue located in bone growth plate zones, able to produce cells for bone growth. Results, using single-cell analysis of RNA sequences, identify potential human skeletal stem cells with gene expression similar to that of previously characterized mouse skeletal stem cells. Data findings show these self-renewing and multipotent cells were present in both fetal and adult human bone marrow tissues and could be derived from induced pluripotent stem cells.
Results show a comparison of human skeletal stem cells with mouse skeletal stem cells provides insights into convergent and divergent skeletal evolution. The lab explains by comparing the molecular and functional differences in specific types of stem cells between different species of vertebrates, it may be possible to uncover convergent and divergent mechanisms underlying tissue growth and regeneration. They conclude applying this understanding will enhance health and rejuvenation in humans.
The team surmises they have successfully isolated human skeletal stem cells capable of self-renewal and multilineage differentiation into bone, cartilage, and stroma. For the future, the researchers state they envision a multitude of applications for their technique, including a time when readily available fat cells from liposuction could be turned into stem cells that could then be injected into joints to make new cartilage or stimulated to form new bone in the repair fractures.
Source: National Institutes of Health
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