Stroke

Stem Cells: A Promising Treatment for Stroke

Scientists have discovered that transplanting brain cells derived from stem cells can offer benefits beyond simply surviving a stroke, according to SciTechDaily.

Blood Vessel Repair

According to new research conducted by the University of Zurich and the University of Southern California, stem cell therapy helped mice recover from strokes by rebuilding damaged brain connections, repairing blood vessels, and improving movement. These findings bolster hopes that future treatments may one day repair the damage caused by strokes, which are currently considered permanent.

Long-Term Disability

Stroke remains a leading cause of long-term disability worldwide. When blood flow to a part of the brain is interrupted, oxygen-deprived cells die within minutes. Unlike skin or bone, the brain's ability to replace lost tissue is limited, leaving many survivors with lifelong paralysis, speech problems, or memory loss.

Neural Progenitor Cells

Scientists have spent years searching for ways to help the brain regenerate itself. In the new study, researchers used neural progenitor cells, which are early-stage cells capable of developing into various types of brain tissue. The cells were derived from induced pluripotent stem cells (iPSCs), adult human cells that have been reprogrammed to resemble stem cells.

One Week After Injury

During the research, the team implanted these cells into the brains of mice one week after they had suffered a stroke. This timing proved crucial. In previous transplants, the success rate was low because the damaged brain was still experiencing inflammation and toxic chemical signals. Waiting several days allowed conditions to stabilize sufficiently for the transplanted cells to grow. The researchers were surprised to find new neurons and rebuilt connections.

Stem Cells

Cells that Regulate Neural Activity

Over five weeks, the transplanted cells survived, spread into surrounding brain tissue, and most matured into functional neurons. Many became ganglionic neurons, specialized inhibitory brain cells that help regulate neural activity and whose numbers are drastically reduced after a stroke. These cells are essential for balancing brain signals, preventing over-excitability, and coordinating movement.

Actively Communicating Cells

The transplanted neurons were not simply present alongside the damaged brain tissue. Evidence indicated that these cells actively communicated with surrounding cells via molecular signaling systems associated with neuronal growth, synaptic formation, and tissue repair.

 Researchers identified several key pathways involved in this interaction, including signals related to rebuilding neural networks and directing axons to reconnect. Stem cell therapy also appeared to stimulate a broader healing response throughout the affected brain.

Blood-Brain Barrier

Mice that received the transplants developed a significantly greater number of blood vessels near the stroke site, improving blood flow to the damaged tissue. 

The treatment also reduced inflammatory activity and strengthened the blood-brain barrier, the protective membrane that normally prevents harmful substances from leaking from the bloodstream into the brain. Damage to this barrier is a major factor in swelling and worsening of the injury after a stroke.

The researchers also observed an increase in nerve fiber growth around the damaged area. Some of the transplanted neurons extended into regions associated with movement and sensory control, suggesting that the new cells may have begun to integrate into existing brain circuits. Improvements in movement and coordination were also noted.

Stem Cells

Other Regenerative Processes

"The results show that neural stem cells form new neurons and also stimulate other regenerative processes," says Christian Takenberg of the Institute for Regenerative Medicine at the University of Zurich. Several types of stem cell therapies have reached the initial stages of clinical trials in humans to treat neurological diseases, including Parkinson's, and stroke could become one of the next major targets.