Researchers have developed a new way for bone cell regeneration. More precise way to control the differentiation of stem cells into bone cells shows promise for bone regeneration, growth and healing.
The problem with only tuning the stiffness of a cell’s microenvironment, also known as the extracellular matrix, is that it assumes the environment behaves like an elastic material (rubber).
But in nature, extracellular matrices are not elastic but viscoelastic like chewing gum that relaxes with stress and dissipates energy over time when a strain is applied.
The research team decided to mimic the viscoelasticity of living tissue by developing hydrogels with different stress relaxation responses.
When they put stem cells into this viscoelastic microenvironment and tuned the rate at which the gel relaxed, they observed dramatic changes in the behaviour and differentiation of the cells.
With increased stress relaxation, there was also a decrease in the differentiation into fat cells.
This is the first time that the team observed how matrix stress relaxation impacts stem cell differentiation in 3D. The enhanced stress relaxation dramatically increases early osteogenic differentiation.
These cells continued to grow as bone cells weeks after their initial differentiation and formed an interconnected mineralised matrix rich in collagen- key structural features of bone.
It may seem counter intuitive that bone cells need fast-relaxing environments to grow into bone which is very stiff and elastic.
However, the team observed that the microenvironment around bone fractures is very similar to the fastest-relaxing hydrogel the team developed in the lab.
“This may be an indication that in the natural environment, when a bone fracture is healing, it needs a really fast stress relaxation matrix to assist in bone formation,” they added. The findings were published in the journal Nature Materials.