Much focus has been on fat graft concentration which is the singularly most studied factor on graft survival. Like fat graft collection, it is most often a device-driven part of the process. Three main techniques exist for graft concentration including gravity separation, washing, and centrifugation. Each method has their own advantages and disadvantages.
Centrifuges have been widely touted and there is no question of their ability to separate the various fat layers and obtain a cellular fraction. As long as the spin times are not too long and at too high revolutions per minute, the fat cells are not adversely affected. While gravity can create the same effect in a syringe or jar, centrifugation does it much faster. I started out years ago using a fine mesh metal sieve to separate the solid part of the fat graft from the liquid. Gravity can fairly quickly create that separation in a non-traumatic manner although it is a completely open system. Gravity can do the same thing in syringes given enough time and enough syringes and this works well if the fat grafting is done by syringe extraction. Filters exist in modified syringes and IV bags and keep the entire process in a closed system. Syringe filters are best suited for facial grafting with low volumes while bag filter systems are better for larger volume body injections.
Having used all methods of fat graft concentration, I have evolved back today to the ‘low tech’ approach of an open wash method through a sieve filter. The one difference from years ago is that I now do a double Lactated Ringer’s wash to obtain a better fat concentrate with less contaminants. Interestingly, I have placed such washed fat grafts in a centrifuge and compared them to purely centrifuged fat and they have very little layering, suggesting that it produces a similar degree of graft concentration.
The one area that remains enticing in improving fat graft survival is whether there is some biologic agent that can be added to the purified fat that can help it survive better after injection. Historically, insulin was the original’ fat activator’ decades ago based on the well known observation of fat lumps developing in chronically used abdominal injection sites in diabetics. While intuitively appealing it was never scientifically proven to have a positive effect. It was the alchemy of the early fat grafting days.
Today’s theoretical fat activator is PRP or platelet-rich plasma which is harvested and prepared from the same fat donor and recipient. Unlike insulin, autologous PRP does have some experimental studies and clinical work that provides some evidence for a positive effect on fat graft survival. But how it might work beyond the simple nourishing of the fat and the dosing for fat graft volume to be effective are issues open for ongoing study. But it is a simple and autologous agent to add to fat grafting that takes little extra time and expense to do.
Dr. Barry Eppley
Indianapolis, Indiana