Researchers invent a needle that knows where to go

Syringes and hollow needles have been used to administer medication for more than a century. However, the precise implementation of these devices depends on the operator and it can be difficult to administer medications in delicate areas such as the suprachoroidal space at the back of the body. 39; eye. Investigators at Brigham and Women & # 39; s Hospital have developed a highly sensitive Smart Injector for Tissue Targeting (i2T2), which detects changes in resistance to safely and correctly deliver drugs in preclinical tests. Their results are published in Nature Biomedical Engineering.

"Targeting specific tissues with the help of a conventional needle can be difficult and often requires a highly qualified individual," said lead author Jeff Karp, Ph.D., professor of medicine at Brigham. "In the last century, the needles themselves had few innovations and we saw an opportunity to develop better and more accurate devices." We sought to improve the targeting of tissues while keeping design as simple as possible to make it easier to use. "

A difficult place to target with a standard needle is the suprachoroidal space (SCS), located between the sclera and the choroid at the back of the eye. The SCS has become an important place for the administration of drugs and is difficult to target because the needle has to stop after transition through the sclera, which has a thickness less than 1 millimeter (approximately half of the thickness of a US neighborhood), not to damage the retina. . Other common tissue targets include the epidural space around the spinal cord (used for epidural anesthesia to relieve pain during labor), the peritoneal space of the abdomen and the abdomen. subcutaneous tissue between the skin and the muscles.

The i2T2 device was manufactured using a standard hypodermic needle and parts from commercially available syringes. The body tissues have different densities and the smart injector exploits the pressure differences to allow the needle to move into the target tissue. The driving force, the maximum forces and the friction force of the injector were tested with the help of a universal testing machine. Feedback from the injector is instantaneous, which allows for better tissue targeting and minimal overshoot (injection beyond the target tissue) in an undesirable location.

The i2T2 has been tested on tissues from three animal models to examine the accuracy of delivery in suprachoroidal, epidural and peritoneal spaces, as well as subcutaneously. By using both extracted tissues and an animal model, the researchers found that i2T2 avoided passing injuries and accurately dispensed the drug in the desired location, without additional training or specialized technique.

In preclinical models, the researchers reported a strong coverage of contrast agent in the posterior part of the eye, indicating that the payload had been injected at the right place. The researchers also showed that the injector could deliver stem cells to the back of the eye, which could be useful for regenerative therapies.

"The stem cells injected into the SCS survived, indicating that the strength of the injection and the transit through the SCS were mild for the cells," said Kisuk Yang, co-author and postdoctoral fellow at Karp's lab. "This should open the door to regenerative therapies for patients with affections from the eye and beyond."

"This smart injector is a simple solution that could be quickly offered to patients in order to increase the accuracy of target tissues and reduce overuse injuries.We have completely transformed the needles with a small modification that makes it possible to better target the tissue, "said first author Girish Chitnis, Ph.D., a former postdoctoral fellow at Karp's lab. "This is a platform technology, so the uses could be widespread."

"The i2T2 will facilitate injections into hard-to-target places in the body," said Miguel Gonzalez-Andrades, MD, Ph.D., ophthalmologist co-author of the manuscript and a collaborator of Karp's lab. "The next step toward human use is to demonstrate the utility and safety of the technology in relevant preclinical disease models."

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Brigham and Women's Hospital