Self-assembling hydrogel becomes a sanctuary for implanted stem cells
Stem cells hold huge potential in the world of regenerative medicine, but getting them where they need to go, and ensuring they do their job when they get there, is a real and complex challenge. Scientists in Australia have made a big breakthrough in this area, developing a hydrogel that acts as a “sanctuary” for transplanted stem cells in the brain, giving them the smooth start they need to survive in their new environment.
Over the last few years, we’ve seen advances in stem cell research that promise greater success in transplantation efforts. But whether these cells have been designed for injured hearts, muscles, skin or bone marrow, there is plenty of room for improvement when it comes to their overall survival numbers.
“In my opinion this is largely due to a focus on transplanted cells offering protection to remaining host tissue, rather than actual replacement of tissue,” Professor David Nisbet, study-co-author and biomaterials researcher at Australian National University, tells New Atlas.
Nisbet and his team have taken an approach to stem cell transplantation that places equal emphasis on preserving remaining tissue and picking up the slack created by tissue that has become damaged.
“This required a two-pronged strategy," he explains. "We first focused on generating a material that protects cells during their administration into tissue and second, and it turns out most importantly, that provides a biologically similar physical and chemical environment to support the cells post administration."
This chemical environment is a new type of artificial scaffold made up of a sequence of amino acids. By tuning the chemical properties of these building blocks, the scientists were able to have them self-assemble into peptides and ultimately a structure resembling a naturally occurring scaffold called an extracellular matrix. Conveniently, this scaffold entraps water to become a hydrogel, allowing fibrils that bond it together to be broken apart and reformed, as study co-author Richard Williams explains.
“We make the hydrogel outside of the body, load the cells in, and then, under the forces of injection, some of the fibrils lose a hold of each other, allowing the gel to flow, rather like lumps of ice in a stream,” Williams tells New Atlas. “The cells in the middle of the lumps are not exposed to the external forces, and once in the body, the lumps are able to come together and reform the hydrogel. The majority of the cells don't realize what they have been through, but they are now in the tissue in a hydrogel that fully supports them, and allows them to develop and mature.”
The researchers tested out the hydrogel on mouse brain cells and say it produced some impressive results, with experiments demonstrating the stem cells could be shielded from inflammation and begin to integrate with the neural circuitry. By self-assembling into a three-dimensional web that mimics the natural environment of the brain tissue, the hydrogel appears to give the transplanted cells a much greater chance of avoiding death.
“The hydrogel we have developed largely stops this,” says Nisbet. “It protects the cells during administration and provides an environment after their injection that greatly increases their survival.”
While the research has focused on repairing injured brain tissue and the diseases that cause it, such as Parkinson’s or stroke, the team members say that with some fine-tuning the technology could be applied to all kinds of damaged tissues.
“Essentially we examine the native proteins that are present within the desired tissue type and incorporate the most biologically relevant and cell instructive amino acids to form our cell transplantation vector,” says Nisbet. “They hydrogels are truly bio-inspired. This means that we could essentially use the platform to transplant most tissues types with slight modification to the amino acids that constitute it.”
The team’s research was published in the journal Advanced Functional Materials.
Source: Australian National University