Gene Inhibitor Plus Fish Fibrin Restore Nerve Function Lost After a Spinal Cord Injury


Scientists at UC Irvine’s Reeve-Irvine Research Center have discovered that injections of salmon fibrin injections into the injured spinal cord plus injections of a gene inhibitor into the brain restored voluntary motor function impaired by spinal cord injury.

Gail Lewandowski and Oswald Steward, director of the Reeve-Irvine Research Center at UCI, examined rodents that had received spinal cord injuries.  They were able to heal the damage by developmentally turning back the clock in a molecular pathway that is critical to the formation of the corticospinal nerve tract, and by providing a scaffold for the growing neurons so that the axons of these growing neurons could grow and make the necessary connections with other cells.  Their research was published in the July 23 issue of The Journal of Neuroscience.

The work of Steward and Lewandowski is an extension of previous research at UC Irvine from 2010.  Steward and his colleagues discovered that the axon of neurons grow quite well once an enzyme called PTEN is removed from the cells.  PTEN is short for “phosphatase and tensin homolog,” and it removes phosphate groups from specific proteins and lipids.  In doing so, PTEN signals to cells to stop dividing and it can also direct cells to undergo programmed cell death (a kind of self-destruct program).  PTEN also prevents damaged tissues from regenerating sometimes, because it is a protein that puts the brakes of cell division.  Mutations in PTEN are common in certain cancers, but the down-regulation of PTEN is required for severed axons to re-form, extend, migrate to their original site, and form new connections with their target cells.

PTEN function

 

After two years, team from U.C. Irvine discovered that injections of salmon fibrin into the damaged spinal cord or rats filled cavities at the injury site and provided the axons with a scaffolding upon which they could grow, reconnect and facilitate recovery. Fibrin produced by the blood system when the blood vessels are breached and it is a fibrous, insoluble protein produced by the blood clotting process.  Surgeons even use it as a kind of surgical glue.

“This is a major next step in our effort to identify treatments that restore functional losses suffered by those with spinal cord injury,” said Steward, professor of anatomy & neurobiology and director of the Reeve-Irvine Research Center. “Paralysis and loss of function from spinal cord injury has been considered irreversible, but our discovery points the way toward a potential therapy to induce regeneration of nerve connections.”

In their study, Steward and Lewandowski subjected rats to spinal cord injuries, and then assessed their defects.  Because these were upper back injuries, the rats all showed impaired forelimb (hand) movement.  Steward and Lewandowski then treated these animals with a combination of salmon fibrin at the site of injury and a modified virus that made a molecule that inhibited PTEN.  These viruses were genetically engineered adenovirus-associated viruses encoded a small RNA that inhibited translation of the PTEN gene (AAVshPTEN).  This greatly decreased the levels of PTEN protein in the neurons.  Other rodents received control treatments of only AAVshPTEN and no salmon fibrin.

The results were remarkable.  Those rats that received the PTEN inhibitor alone showed no improvement in their forelimb function, but those animals who were given AAVshPTEN plus the salmon fibrin recovered forelimb use (at least reaching and grasping).

“The data suggest that the combination of PTEN deletion and salmon fibrin injection into the lesion can significantly enhance motor skills by enabling regenerative growth of corticospinal tract axons,” Steward said.

Corticospinal Nerve tract

Statistics compiled by the Christopher & Dana Reeve Foundation suggests that approximately 2 percent of Americans have some form of paralysis that is the result of a spinal cord injury.  Spinal cord injuries break connections between nerves and muscles or nerves and other nerves.  Even injuries the size of a grape can cause complete loss of function below the level of the injury.  Injuries to the neck can cause paralysis of the arms and legs, an absence of sensation below the shoulders, bladder and bowel incontinence, sexual dysfunction, and secondary health risks such as susceptibility to urinary tract infections, pressure sores and blood clots due to an inability to move one’s legs.

Steward said the next objective is to learn how long after injury this combination treatment can be effectively administered. “It would be a huge step if it could be delivered in the chronic period weeks and months after an injury, but we need to determine this before we can engage in clinical trials,” he said.

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Human Umbilical Cord Mesenchymal Stem Cells Form Prostate Gland Tissues


Repairing the prostate gland is an important goal in regenerative medicine. However, finding the right cell for the job has proven to be a slow and tedious search.

To that end, Wei-Qiang Gao and his colleagues from Shanghai Jiao Tong University in Shanghai, China, used mesenchymal stem cells from human umbilical cord (hUC-MSCs) to test the ability of these cells to differentiate into prostate-specific cells. They combined hUC-MSCs with rat urogenital sinus stromal cells (rUGSSs) and then transplanted these cells into the renal capsule of BLB/c nude mice for two months. Cells tend to grow very well under the kidney capsule because this particular microenvironment has a very rich blood supply. Also the rUGSSs provide soluble, secreted factors that induce the hUC-MSCs to differentiate into prostate-specific cells.

After removing the implanted tissue, analyses of the implanted cells showed that the hUC-MSCs differentiated into prostate epithelial-like cells. This was confirmed by the presence of prostate specific antigen on the surfaces of these hUC-MSCs. Prostate specific antigen is only found on prostate cells, which is the reason why this protein is such a good indicator of prostate cancer. Also, the hUC-MSCs formed prostatic glandular structures that had the same cellular architecture as a normal prostate (see figure F below). Additionally, the human origin of the hUC-MSCs was further confirmed by the detection of a protein called human nuclear antigen, which is specific to human cells.

Human UC-MSCs combined with rUGSSs can generate prostate glands. Mice were sacrificed 2 months after co-transplantation surgery, and the kidneys from the cell implanted nude mice were collected. (A) Graft initiated with hUC-MSCs alone and (B) rUGSSs alone were used as negative control, respectively. (C) Graft derived with hUC-MSCs and rUGSSs. (D–F) Histological analyses of the sections of the graft stained for haematoxylin and eosin (H&E). (D) Note that while hUC-MSCs alone and (E) rUGSSs single cell type transplantation fail to regenerate prostate glandular structures. (F) co-transplantation of hUC-MSCs and rUGSSs gives rise to prostate glandular structures. Scale bar 50 mm.
Human UC-MSCs combined with rUGSSs can generate prostate glands. Mice were sacrificed 2 months after co-transplantation surgery, and the kidneys from the cell implanted nude mice were collected. (A) Graft initiated with hUC-MSCs alone and (B) rUGSSs alone were used as negative control, respectively. (C) Graft derived with hUC-MSCs and rUGSSs. (D–F) Histological analyses of the sections of the graft stained for haematoxylin and eosin (H&E). (D) Note that while hUC-MSCs alone and (E) rUGSSs single cell type transplantation fail to regenerate prostate glandular structures. (F) co-transplantation of hUC-MSCs and rUGSSs gives rise to prostate glandular structures. Scale bar 50 mm.

This interesting paper shows that hUC-MSCs can differentiate into epithelial-like cells that are normally derived from embryonic endodermal tissue. This implies that MSCs from umbilical cord can be used to repair not only prostate glands, but also other endodermally-derived tissues.