Bioengineers have grown a mini-spinal cord and achieved its regeneration

Researchers from Northwestern University in the USA have made a significant step towards treating spinal cord injuries, which often lead to paralysis. In the laboratory, scientists grew tiny organoids from the human spinal cord, then damaged them and applied a therapy that stimulated tissue repair. The results are published in magazine Nature Biomedical Engineering.

“We created two injury models in a human spinal cord organoid and tested our therapy to see if the results would be similar to those seen in animals. After treatment, the glial scar paled and became almost invisible, and neurites began to grow in the same way as axonal branches in animals.

This gives hope for the successful use of the therapy in humans,” says biomedical engineer Samuel Stoop.

How are organelles arranged?

The organoids, about 3 millimeters in diameter, were grown from induced pluripotent stem cells from an adult donor. After a few months, they formed the main cell types of the spinal cord: neurons, astrocytes and organized layers of tissue.

After reaching maturity, some organoids were cut with a scalpel, while others were subjected to compression simulating crushing, like in a car accident. Both injuries cause nerve cell death, glial scar formation, and an inflammatory response similar to true spinal cord injuries.

“We could differentiate between normal astrocytes, which are part of normal tissue, and astrocytes in the glial scar—they are noticeably larger and very densely packed,” explains Stoop.

The researchers also identified chondroitin sulfate proteoglycans, molecules that respond to injury and prevent the growth of new nerve fibers.

The role of “dancing” molecules

Previously, the team developed the material IKVAV-PAused to restore mice after severe spinal cord injuries. The main component is supramolecular therapeutic peptides, nicknamed “dancing molecules”. They stimulate axonal growth by synchronizing the movement of receptors on the surface of nerve cells.

“Because cells and their receptors are constantly moving, molecules that collide with them faster are more effective at stimulating regeneration. Slow molecules may simply not contact the cells,” explains Stoop.

In experiments on organoids, IKVAV-PA was applied to damaged areas, where the liquid quickly solidified into a gel-like scaffold. Active molecules stimulated the growth of nerve cells, reducing inflammation and scarring. Control organoids without treatment showed less regeneration and more inflammation.

What does this mean for medicine?

The results show that the therapy works not only in mice, but also on human tissue in the laboratory. Stoop notes:

“Organoids allow us to test new methods on human cells without risk to patients. This is the only way to prepare for clinical trials.”

Actual application in humans may be several years away, but consistent results in animals and organoids provide significant hope for the future of spinal cord injury repair.