Development of a Fat Extraction/Transfer Cannula for Greater Fat Particle Size Control

By Brian Lupish, CMI Fellow

The University of Pittsburgh CMI program has funded a translational research project to develop the PrecisionGraftTM lipotransfer cannula.  Lipotransfer is a reconstructive surgery procedure in which adipose (fat) tissue is surgically extracted from a patient and subsequently re-injected to an injury site in order to restore soft tissue mass.  It is often used for reconstruction after mastectomies, as well as in battlefield injuries.  However, an average of 50% (and as high as 90%) of the surgically transferred mass is lost in the weeks and months after the procedure, due to the implanted tissue being re-absorbed into the body.  As such, lipotransfers must often be repeated, at great cost to the patient.

Existing research has indicated that one of the primary drivers of adipose tissue re-absorption is the relatively large size of the fat particles extracted from the patient.  Because of their size, oxygen and nutrients from the patient's body can't penetrate the large droplets, leading to cell death and the formation of oil cysts, which prevent the surrounding fat from integrating into the surrounding area.  It was thus determined that extracting smaller fat particles from patients might help to prevent the events causing major re-absorption.  

In order to test their hypothesis, the team performed in vitro tests on fat particles of varying sizes, testing their cellular metabolism, stress responses, and signs of cell death.  The smaller particles showed improved metabolism and reduced inflammatory responses.  They also produced more growth factors required for integration into the patient.  Furthermore, in vivo studies where particles were implanted in rats demonstrated that larger particles led to greater oil cyst formation, indicating tissue death.

Having demonstrated the benefits of smaller fat particles, the team designed a new type of extraction cannula.  It had an adjustable opening size, enabling the surgeon to exert much greater control over the size of extracted particles.  Various tests confirmed that the new cannula provided a significant increase in control over extraction and implantation of fat particles.

The researchers on the team were:

Through a $20,000 grant from CMI in 2013, the team was able to develop a PrecisionGraftTM prototype and conduct pre-clinical experiments.  They are now exploring clinical trial and commercialization possibilities, as well as researching additional improvements to cannula systems to promote better lipotransfer outcomes.