TECH FRONT
(0.007 inches) for cells to survive. In these studies, a baby- sized ear structure (38 mm) survived and showed signs of vascularization at one and two months after implantation. “Our results indicate that the bio-ink combination we used, combined with the micro-channels, provides the right environment to keep the cells alive and to support cell and tissue growth,” said Atala.
Another advantage of the ITOP system is its ability to use
data from CT and MRI scans to “tailor-make” tissue for pa- tients. For a patient missing an ear, for example, the system could print a matching structure. Several proof-of-concept experiments demonstrated the capabilities of ITOP. To show that ITOP can generate complex 3D structures, printed, human-sized external ears were implanted un- der the skin of mice. Two months later, the shape of the implanted ear was well-maintained and car- tilage tissue and blood vessels had formed. To demonstrate that ITOP can generate organized soft tissue structures, printed muscle tissue was implanted in rats. After two weeks, tests con- firmed that the muscle was robust enough to maintain its structural characteristics, become vascularized and induce nerve formation.
And, to show that construction of a human-sized bone
structure, jaw bone fragments were printed using human stem cells. The fragments were the size and shape needed for facial reconstruction in humans. To study the maturation of bioprinted bone in the body, printed segments of skull bone were implanted in rats. After five months, the bioprinted structures had formed vascularized bone tissue.
N
Thought-Controlled Prosthetic Arm Moves Fingers
ow this is a digital breakthrough: Physicians and bio- medical engineers from Johns Hopkins University (Balti-
more, MD) report what they believe is the first successful effort to wiggle fingers individually and independently of each other using a mind-controlled artificial arm to control the movement.
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AdvancedManufacturing.org | April 2016 The proof-of-concept feat, described online this week in
the Journal of Neural Engineering, represents a potential advance in technologies to restore refined hand function to those who have lost arms to injury or disease, the research- ers say. The young man on whom the experiment was performed was outfitted with a device that essentially took advantage of a brain-mapping procedure to bypass control of his own arm and hand. “We believe this is the first time a person using a mind- controlled prosthesis has immediately performed individual digit
Illustration of the electrode array on the subject’s brain, including a representation of what part of the brain controls each finger.
movements without extensive training,” says senior author Na- than Crone of the Johns Hopkins University School of Medicine. For the experiment, the research team recruited a young man with epilepsy already scheduled to undergo brain map- ping at The Johns Hopkins Hospital’s Epilepsy Monitoring Unit to pinpoint the origin of his seizures. While brain record- ings were made using electrodes surgically implanted for clinical reasons, the signals also control a modular prosthetic limb developed by the Johns Hopkins University Applied Physics Laboratory.
Prior to connecting the prosthesis, the researchers mapped and tracked the specific parts of the subject’s brain responsible for moving each finger, then programmed the prosthesis to move the corresponding finger. First, the patient’s neurosurgeon placed an array of 128
electrode sensors—all on a single rectangular sheet of film the size of a credit card—on the part of the man’s brain that normally controls hand and arm movements. Each sensor measured a circle of brain tissue 1 mm in diameter.
Image courtesy Johns Hopkins University
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