Implants against spinal cord injuries
Researchers at the University of California at San Diego and the Institute of Engineering in Medicine, working under the leadership of Professor Mark Tuszynski and Professor Shaochen Chen, used three-dimensional printing technology to create hydrogel skeletons of the spinal cord filled with nerve stem cells. Subsequently, these scaffolds were successfully implanted into areas of severe spinal cord injuries in rats.
The implant proposed by the authors is designed to stimulate nerve growth in the damaged area to restore nerve contacts and lost functions. It is permeated with dozens of the thinnest channels 200 microns wide (2 times thicker than a human hair), directing the growth of nerve stem cells and their axons along the spinal cord to close the damage zone. These channels are necessary for the formation of directed nerve fibers, since axons themselves are prone to chaotic growth in different directions.
A section of the implant used as a framework for the restoration of spinal cord injuries in rats. The circles around the H-shaped nucleus are hollow channels through which axons of implanted neural stem cells can penetrate into surrounding tissues.
As part of the study, implants filled with nerve stem cells with a length of 2 mm were placed in areas of severe spinal cord injury in rats. After a few months, the damage zones were filled with new nerve tissue connecting the edges of spinal cord defects. This provided a significant recovery of the motor functions of the hind legs of the animals.
According to the authors, in addition to directing the growth and ordering of nerve fibers, the framework provides a stable physical structure that promotes the engraftment and survival of nerve stem cells. It protects cells from the toxic inflammatory environment in the damaged area.
Further studies showed that blood vessels penetrated into the implants, forming a functioning vascular network that also contributes to the survival of stem cells. This indicates a high biocompatibility of the frame.
The three-dimensional printing technology used by the authors ensures the production of a 2 mm implant within 1.6 seconds. Traditionally used inkjet printers take several hours to complete much simpler structures.
The printing process can be scaled to the size of a human spinal cord. To test the concept, the authors printed a 4 cm implant modeled on the basis of images obtained by magnetic resonance imaging of real human spinal cord injuries. This task took the printer 10 minutes.
Currently, they are already working on practical scaling of the technology and testing it on larger animal models, considering the possibility of subsequent clinical trials. In addition, they plan to inject proteins into the scaffolds that provide additional support for the viability of stem cells and the growth of new axons.
Article by Jacob Koffler et al. Biomimetic 3D-printed scaffolds for spinal cord injury repair is published in the journal Nature Medicine.
Evgenia Ryabtseva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the University of California - San Diego: Biomimetic 3D-printed scaffolds for spinal cord injury repair.