Cells with promise

Medical RESEARCH

Artificial bone, created using stem cells and a new lightweight plastic, could soon be used to heal shattered limbs. The use of bone stem cells, combined with a degradable rigid material that inserts into broken bones and encourages real bone to regrow, has been developed at the Universities of Edinburgh and Southampton.

Researchers have developed the material with a honeycomb scaffold structure that allows blood to flow through it, enabling stem cells from the patient’s bone marrow to attach to the material and grow new bone. Over time, the plastic slowly degrades as the implant is replaced by newly grown bone.

Scientists developed the material by blending three types of plastics. They used a pioneering technique to blend and test hundreds of combinations of plastics, to identify a blend that was robust, lightweight, and able to support bone stem cells.

Successful results have been shown in the lab and in animal testing with the focus now moving towards human clinical evaluation. The study, published in the journal Advanced Functional Materials, was funded by the Biotechnology and Biological Sciences Research Council.

This new discovery is the result of a seven-year partnership between the University of Southampton and the University of Edinburgh. Richard Oreffo, Professor of Musculoskeletal Science at the University of Southampton, comments, “Fractures and bone loss due to trauma or disease are a significant clinical and socioeconomic problem. This collaboration between chemistry and medicine has identified unique candidate materials that support human bone stem cell growth and allow bone formation. Our collaborative strategy offers significant therapeutic implications.”

Professor Mark Bradley, of the University of Edinburgh’s School of Chemistry, adds, “We were able to make and look at hundreds of candidate materials and rapidly whittle these down to one which is strong enough to replace bone and is also a suitable surface upon which to grow new bone. “We are confident that this material could soon be helping to improve the quality of life for patients with severe bone injuries, and will help maintain the health of an ageing population.”

Printing process

A specialised 3D printing process, using human stem cells, could pave the way to purpose-built replacement organs for patients, eliminating the need for organ donation, immune suppression and the problem of transplant rejection.

The process, developed at Heriot-Watt University, in partnership with a stem cell firm, takes advantage of the fact that stem cells can now be grown in laboratory conditions from established cell lines, could also speed up and improve the process of drug testing by growing three-dimensional human tissues and structures for pharmaceuticals to be tested on.

A range of human stem cell cultures can now be grown, generation after generation, in laboratory conditions. Those cultures developed from cells from areas like bone marrow or skin are hardier but less flexible than those developed from embryonic material. While 3D printing of the tougher cell cultures has been achieved before, the new valve-based technique developed by Will Shu and his colleagues at Heriot-Watt’s Biomedical Microengineering group are the first to print the more delicate embryonic cell cultures, which have an ability to replicate indefinitely and differentiate into almost any cell type in the human body.

Shu said, “To the best of our knowledge, this is the first time that these cells have been 3D printed. The technique will allow us to create more accurate human tissue models which are essential to in vitro drug development and toxicity-testing. Since the majority of drug discovery is targeting human disease, it makes sense to use human tissues. “In the longer term, we envisage the technology being further developed to create viable 3D organs for medical implantation from a patient’s own cells, eliminating the need for organ donation, immune suppression and the problem of transplant rejection.”

Shu’s team is working with a stem cell technology company, which has a good track record of applying new technologies to human stem cell systems and will take the lead in developing 3D stem cell printing for commercial uses. Initially this will be in the areas of novel drug-testing products but in the longer term there is the goal of growing purpose-built replacement organs.