Now That's Healthy Recycling: Donated Fat Could Play Key Role in Neurosurgery

Donated fat removed during liposuction and chemically treated to prevent rejection could become a viable source of repair tissue during neurological and other types of surgeries.


University of Wisconsin neurosurgeon Dr. John S. Kuo and colleagues report in a new study on taking fat from donor rabbits, chemically treating it, and then implanting it into recipient rabbits. Those who received the processed fat grafts showed good wound healing and little immune rejection, compared with those that received untreated fat grafts. The transplanted processed fat was accepted in recipients as well as, or better than, transplants of their own fat removed from elsewhere in the body.


Dr. Kuo, assistant professor of neurosurgery and director of the comprehensive brain tumor program at the UW School of Medicine and Public Health, reported the findings online in the December 4, 2009, edition of the Journal of Neurosurgery.


Kuo and other neurosurgeons often harvest fat from patients to help repair cerebrospinal fluid leaks. These leaks are often caused by trauma or in the course of surgeries near the skull base to remove tumors such as pituitary tumors, acoustic neuromas or meningiomas.


Although fat can be harvested from other parts of a patient's body (e.g. abdomen), it would require another incision, more time on the operating table and increased infection risk. There are also more expensive, artificial means of enhancing wound healing and repair available now, but none from human sources.


Kuo said the idea came from Dr. Martin Weiss, his mentor and former chair of neurosurgery at the University of Southern California, who noted that the fat removed during liposuction was routinely discarded.


"We thought, there is all this fat going to waste, is there a way to make it useful?'' Kuo said. "If you could clean, process and make fat non-immunogenic, it could be an inexpensive off the shelf product for clinical use."


The key was treating the fat to reduce immune rejection by reducing grafts to an acellular matrix that is more easily taken up by the host. While the processed fat was well-incorporated into the wounds during healing, untreated fat incited an acute immune response that also damaged adjacent host tissue.


In addition to neurosurgery, Kuo said that plastic surgeons also implant fat tissue for a variety of defects from traumatic injury, following tumor removal or for enhancement, and that it might be useful for multiple purposes in wound healing, as well. While more work needs to be done before testing in humans, the vision is to create a "tissue bank" of fat that has been processed to remove infectious and antigenic factors for use. There are tissues such as tendon, bone, and skin grafts treated in a similar manner already clinically in use.


One of Kuo's colleagues in plastic surgery, Dr. Summer E. Hanson, mentions that there are several applications for fat grafts, and that plastic surgeons have been using the patients' own fat for over a century.


"We certainly have access to fat from healthy donors and having an artificial 'off-the-shelf graft' could potentially save a patient from an additional procedure and the associated risks," said Hanson.


In addition to Weiss, Kuo's co-authors on the study were Drs. Cynthia Hawkins and James Rutka, both of the University of Toronto.