The February edition of Neurosurgery reports that animal experiments in brain-injured rats have shown that stem cells injected via the carotid artery travel directly to the brain, greatly enhancing functional recovery. The study demonstrates, according to leading researcher Dr Toshiya Osanai, of Hokkaido University Graduate School of Medicine in Sapporo, Japan, that the carotid artery injection technique could, together with some form of in-vivo optical imaging to track the stem cells after transplantation, potentially be part of a new approach for stem cell transplantation in human brain trauma injuries (TBI).

Dr. Osanai and team assessed a new “intra-arterial” technique of stem cell transplantation in rats, with the aim of delivering the stem cells directly to the brain without having to go through the general circulation. They induced TBI in the animals before injecting stem cells into the carotid artery seven days later.

The stem cells were obtained from the rats’ bone marrow and were labeled with “quantum dots” prior to being injected. Quantom dots are a biocompatible, fluorescent semiconductor created with nanotechnology that emit near-infrared light with much longer wavelengths that penetrate bone and skin, enabling a non-invasive method of monitoring the stem cells for a period of four weeks following transplantation.

This in vivo optical imaging technique enabled the scientists to observe that the injected stem cells entered the brain on the first attempt, without entering the general circulation. They observed that the stem cells started migrating from the capillaries into the injured part of the brain within three hours.

At week 4, the researchers noted that the rats in the stem cell transplant group achieved a substantial recovery of motor function, compared with the untreated animals that had no signs of recovery.

The team learnt, after examining the treated brains, that the stem cells had transformed into different brain cell types and aided in healing the injured brain area.

Over the last few years, the potential of stem cell therapy for curing and treating illnesses and conditions has been growing rapidly. Below is a list of some of its possible uses.

Stem cell treatments

Stem cells represent a potential, new important method of treatment for those who suffered brain injuries, TBI and stroke. But even though bone marrow stem cells, similar to the ones used in the new study, are a promising source of donor cells, many questions remain open regarding the optimal timing, dose and route of stem cell delivery.

In the new animal study, the rats were injected with the stem cells one week after TBI. This is a “clinically relevant” time, given that this is the minimum time it takes to develop stem cells from bone marrow.

Transplanting the stem cells into the carotid artery is a fairly simple procedure that delivers the cells directly to the brain.

The experiments have also provided key evidence that stem cell treatment can promote healing after TBI with a substantial recovery of function.

Dr. Osanai and team write that by using in vivo optical imaging:

“The present study was the first to successfully track donor cells that were intra-arterially transplanted into the brain of living animals over four weeks.”

A similar form of imaging technology could also prove beneficial for monitoring the effects of stem cell transplantation in humans, although the tracking will pose challenges, due to the human skull and scalp being much thicker than in rats.

The researchers conclude:

“Further studies are warranted to apply in vivo
optical imaging clinically.”

Written by Petra Rattue