Che Connon, Professor of Tissue Engineering at Newcastle University explains: The stem cells are surrounded by an alginate gel which protects them from the environment - a bit like frogspawn. We found them unchanged even after three days at room temperature.
This has lots of advantages and applications. For example, we have used them to make a bandage which contains human stem cells which could be applied to a wound such as an ulcer or burn to speed up the healing process.
Stem cells for healing
There is much scientific evidence showing stem cells from fatty tissue (adipose-derived mesenchymal stem cells) can be used to improve wound healing by reducing inflammation and speeding up wound closure. However, until now the problem has been that these stem cells have had to be stored and handled by experts under specialised conditions - limiting their practical use.
Rather than keeping them at 37 degrees Celsius, in atmospheric oxygen and 5% carbon dioxide, encasing the stem cells in an alginate gel is shown in the academic paper to prolong their life for up to three days at ambient temperatures. This offers an effective and simple solution to many of the challenges of transporting cell cultures.
Alginate is a natural material extracted from seaweed that is used in cosmetics, food manufacturing and more recently in healthcare. Alginate on its own without stem cells is used in wound dressings to keep burns moist.
The study found that after three days at a range of temperatures (between 4 and 21 degrees C) up to 90% of the stem cells were still viable and available for healing. Medically, 70% viability is considered acceptable.
The team think that the alginate encapsulation offers a degree of protection from the environment. They also believe it may be acting like a corset, preventing the stem cell from expanding and being destroyed, a process known as lysing - which would normally occur within a day when unprotected cells are stored in their liquid state.
Stem cell encapsulation method
Using the alginate solution the Newcastle University team have been able to develop stem cell beads and also a gel which can be put into a mould to form a jelly pad or film.
Dr Stephen Swioklo describes the process: The stem cells are grown from the standard frozen form and then mixed into the alginate solution. This is extracted from a type of brown algae, a seaweed commonly used in food and medical applications.
This can either be dropped into a vial of calcium chloride which forms cross-links making the alginate set, forming tiny beads. Or the gel can be placed into a mould to form a film which sets in a couple of minutes. We have used this to make plasters and bandages.
One circular disc just an inch diameter was demonstrated in our study to effectively preserve a million stem cells and could easily contain up to 10 million.
The 'Stem-gell' bandage has many potential uses from paramedics treating people at the scene of an accident to the army battlefield. Some of the work has been funded by the Defence Science and Technology Laboratory (Dstl), part of the Ministry of Defence.
The Newcastle University scientists say 'Stem-gell' offers many exciting opportunities for therapeutics, for ease of transport, in cell printing, in improving the results with injections of stem cells and for wound healing. They are now working to get 'Stem-gell' scaled up and into the clinic for trials.
Professor Connon said this new process offers many exciting opportunities: With this new technology we are able to put stem cells directly onto an open wound with a stem cell bandage. The gel retains the cells so that they don't leave the bandage - it's the chemicals these cells make that actually do the healing.
The product could also be used for cell printing, for example, a doctor's surgery could purchase a cartridge of stem cells in the alginate gel to keep in the fridge and when needed print tissues providing rapid personalised medicine there and then.
And we're not talking about far into the future - we're looking at this being something we can all be treated with in a few years.
Reference: Alginate-Encapsulation for the Improved Hypothermic Preservation of Human Adipose-Derived Stem Cells. Stephen Swioklo, Andrei Constantinescu, Che J. Connon. DOI:10.5966/sctm.2015-0131
Notes to editors:
Information on stem cell transportation: Current distribution solutions for cell cultures involve a combination of complex and high cost logistics, often with limited time windows. This 'Stem-gell' technology enables cell cultures to be delivered in an easy to use form, providing considerable cost and time efficiencies.
Stem cell manufacturers are generally limited to either cryopreservation of cells, warm cell shipping (ambient), cold chain shipping (2-8C), or co-localisation and coordination of manufacture and clinical procedures. Freezing cells leads to loss in cell viability, and adds expense and complications to transport and delivery, e.g. the need to maintain them at a low temperature, and facilities to safely store and thaw the cells at the destination. Cryopreservation also presents a hazard to handlers (asphyxiation risk, risk of cryogenic burns). Warm transport in the absence of hydrogels (alginate beads or gel) drastically limits transport times, is logistically complicated, potentially affects cell viability/quality, and has a higher risk of microbiological contamination. Warm transport is also vulnerable to delays in the distribution chain (flight delay/cancellation, traffic jams, customs hold-ups). Co-localisation of stem cell manufacture and clinical use limits business models and inconveniences patients. Neither of the current distribution solutions is ideal, involving a combination of complex, specialised logistics with high costs, limited delivery windows, and technical challenges.
Information on stem cell injections: Injection of stem cells is required for many therapies in development. It has been demonstrated that during injection forces acting on the cells cause membrane damage and loss of cell viability results. Encapsulating cells for injection in hydrogel has been shown to protect the cells from injection stresses, leading to increased cell viability.
Reference: PN 05-16
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