New Method Found To Improve Stem Cell Delivery

It turns out that delivery of transplanted stem cells to a specific site in rodents is improved by increasing the presence of chemicals that attract the introduced cells.

Non-destructive pulsed and focused ultrasound interacts with tissue to elevate levels of naturally produced chemicals (such as cytokines, chemokines, and growth factors) on target tissues. Transplanted stem cells have receptors for these chemicals, so an increased presence attracts more of them to the desired site.

“It's like your circulatory system is a series of highways. What makes you want to get off at New York City? We're putting an attraction in the middle of nowhere so the transplant cells will want to go there, to the target site,” said Joseph A. Frank, M.D., chief of the NIH Clinical Center Radiology and Imaging Sciences Laboratory of Diagnostic Radiology Research.

Regenerative medicine uses stem cells to replace damaged cells and tissues, and transplanting these cells intravenously is a noninvasive and easily replicated procedure. However, only 1 to 3 percent of intravenous transplanted cells make it to the desired target. By increasing the presence of chemically attractive factors, researchers in the laboratory saw 8 to 10 times more transplanted bone marrow stromal cells in a pulsed focused ultrasound-treated rodent kidney than a non-treated kidney.

An advantage of this improved delivery method is that the pulsed and focused ultrasound does not cause any adverse effects to the treated tissue.

Researchers also saw increased passage of stem cells into treated tissue and retention, and the focused ultrasound permeates deep so human body composition is not a limitation. Since the technique increases presence of more than 10 attractive chemical factors, the method is not cell specific and may be advantageous for a variety of cell products, such as neural cells or immune cells.

Adapted from the National Institutes of Health announcement.