Human embryonic stem cell -- derived bone tissue closes massive skull injury

Dec 02, 2007

There are mice in Baltimore whose skulls were made whole again by bone tissue grown from human embryonic stem cells (hESCs).

Healing critical-size defects (defects that would not otherwise heal on their own) in intramembraneous bone, the flat bone type that forms the skull, is a vivid demonstration of new techniques devised by researchers at John Hopkins University to use hESCs for tissue regeneration.

Using mesenchymal precursor cells isolated from hESCs, the Hopkins team steered them into bone regeneration by using “scaffolds,” tiny, three-dimensional platforms made from biomaterials.

Physical context, it turns out, is a powerful influence on cell fate. Nathaniel S. Hwang, Jennifer Elisseeff, and colleagues at Hopkins demonstrated that by changing the scaffold materials, they could shift mesenchymal precursor cells into either of the body’s osteogenic pathways: intramembraneous, which makes skull, jaw, and clavicle bone; or endochondral, which builds the “long” bones and involves initial formation of cartilage, which is then transformed into bone by mineralization.

Mesenchymal precursor cells grown on an all-polymer, biodegradable scaffold followed the endochondral lineage. Those grown on a composite scaffold made of biodegradable polymers and a hard, gritty mineral called hydroxyapatite went to the intramembraneous side.

Biomaterial scaffolds provide a three-dimensional framework on which cells can proliferate and differentiate, secrete extracellular matrix, and form functional tissues, says Hwang. In addition, their known composition allowed the researchers to characterize the extracellular microenvironmental cues that drive the lineage specification.

The promise of pluripotent embryonic stem cells for regenerative medicine hangs on the development of such control techniques. Left to themselves, hESCs in culture differentiate wildly, forming a highly mixed population of cell types, which is of little use for cell-based therapy or for studying particular lineages.

Conventional hESC differentiation protocols rely on growth factors, co-culture, or genetic manipulation, say the researchers. The scaffolds offer a much more efficient method.

As a proof of principle, Hwang and colleagues seeded hESC-derived mesenchymal cells onto hydroxyapatite-composite scaffolds and used the resulting intramembraneous bone cells to successfully heal large skull defects in mice. The Hopkins researchers believe that this is the first study to demonstrate a potential application of hESC-derived mesenchymal cells in a musculoskeletal tissue regeneration application.

Source: American Society for Cell Biology

Explore further: Free the seed: OSSI nurtures growing plants without patent barriers

add to favorites email to friend print save as pdf

Related Stories

Stem-cell disruption induces skull deformity, study shows

May 25, 2010

University of Rochester Medical Center scientists discovered a defect in cellular pathways that provides a new explanation for the earliest stages of abnormal skull development in newborns, known as craniosynostosis.

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers successfully clone adult human stem cells

Apr 18, 2014

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

User comments : 0

More news stories

Easter morning delivery for space station

Space station astronauts got a special Easter treat: a cargo ship full of supplies. The shipment arrived Sunday morning via the SpaceX company's Dragon cargo capsule.