DNA-gold coated nanoparticles enable enriching of bone-healing stem cells
Scientists from the University of Southampton have demonstrated an innovative technique that uses fluorescent nanotechnology to identify and enrich skeletal stem cells.
The ground-breaking study, co-led by the School of Physics and Astronomy's Professor Antonios Kanaras, could lead to new treatments for major bone fractures and the repair of lost or damaged bone.
The interdisciplinary research builds upon over 15 years of investigations into bone stem cell based therapies by Professor Richard Oreffo.
The new technique, published this month in the international ACS Nano journal, uses specially designed gold nanoparticles to seek out specific human bone stem cells. This creates a fluorescent glow to reveal their presence among other types of cells, allowing them to be isolated or 'enriched'.
The researchers concluded their new technique is simpler and quicker than other methods and up to 50-500 times more effective at enriching stem cells.
Professor Kanaras and colleagues in the Quantum, Light and Matter Research Group are experts in the design of novel nanomaterials and the study of applications in the fields of biomedical sciences and energy.
"The appropriate design of materials is essential for their application in complex systems," he says. "Customizing the chemistry of nanoparticles we are able to program specific functions in their design.
"In this research project, we designed nanoparticles coated with short sequences of DNA, which are able to sense HSPA8 mRNA and Runx2 mRNA in skeletal stem cells and together with advanced FACS gating strategies, to enable the assortment of the relevant cells from human bone marrow.
"An important aspect of the nanomaterial design involves strategies to regulate the density of oligonucleotides on the surface of the nanoparticles, which help to avoid DNA enzymatic degradation in cells. Fluorescent reporters on the oligonucleotides enable us to observe the status of the nanoparticles at different stages of the experiment, ensuring the quality of the endocellular sensor."
Stem cells are cells that are not yet specialised and can develop to perform different functions. Identifying skeletal stems cells allows scientists to grow these cells in defined conditions to enable the growth and formation of bone and cartilage tissue - for example, to help mend broken bones.
Among the challenges posed by our ageing population is the need for novel and cost-effective approaches to bone repair. With one in three women and one in five men at risk of osteoporotic fractures worldwide, the costs are significant, with bone fractures alone costing the European economy €17 billion and the US economy $20 billion annually.
Professor Oreffo says: "Skeletal stem cell based therapies offer some of the most exciting and promising areas for bone disease treatment and bone regenerative medicine for an aging population. The current studies have harnessed unique DNA sequences from targets we believe would enrich the skeletal stem cell and, using Fluorescence Activated Cell Sorting (FACS) we have been able to enrich bone stem cells from patients.
"Identification of unique markers is the holy grail in bone stem cell biology and, while we still have some way to go; these studies offer a step change in our ability to target and identify human bone stem cells and the exciting therapeutic potential therein.
"Importantly, these studies show the advantages of interdisciplinary research to address a challenging problem with state of the art molecular/cell biology combined with nanomaterials chemistry platform technologies."
This latest research, which was advanced through a joint BBSRC project grant to Professor Oreffo and Professor Kanaras, was supported by experienced research fellows and PhD students as well as collaboration with Professor Tom Brown and Dr Afaf E-Sagheer of the University of Oxford.
The scientists are currently applying single cell RNA sequencing to the platform technology developed with partners in Oxford and the Institute for Life Sciences (IfLS) at Southampton to further refine and enrich bone stem cells and assess functionality. The team propose to then move to clinical application with preclinical bone formation studies to generate proof of concept studies.