Is Stored Fat Safe to Use for Fat Transfer?

The longer fat is stored, the more of it dies, and the more temporary the results from fat injection are.
Many patients believe that when fat is taken from one part of the body and placed elsewhere, that fat will "take".
This is not true.
Most fat that is harvested from one are of the body is dead. Fat is delicate biologic tissue that exists in a complex biologic environment in the body. Fat injection technique works by first aspirating (sucking) the fat out of the body with a vacuum (syringe), purifying it in some fashion, and then injecting it back into the patient.
The percentage of live cells is debatable. In our research (which we have presented at national meetings and published in Plastic and Reconstructive Surgery journal), the viability is 20%. The rest of the fat cells are dead and are either metabolized away or walled off eventually. In other studies, the viability rates are as low as 3% if you measure the metabolism of the cells (ability to "breathe").
We prefer LiveFill grafts, nontraumatized fascial fat grafts, for volume augmentation in the face, since they are alive. The long term survival is far higher than that of traumatized grafts.
Also, the swelling at the time of insertion is less than that of fat injection because the body does not have to deal with metabolizing away a large amount of dead cells. The disadvantage of LiveFill is its greater cost than fat injection.
If you do choose to have the fat transplantation method, the more time the fat sits in the refrigerator, the more of it dies.
Another consideration:
Although unlikely, it is possible that the patient's fat samples could be mixed up with those of another patient. Such errors are possible even in the most highly monitored blood banks at the best institutions, so they are possible in an unmonitored doctor's office. For that reason, to minimize the risk to patients, we do not store patient's samples for reinjection.

Frozen Stored Fat Transfer - Probably not in your best interest
The options your doctor gave you are not standard, are experimental, and and in short are not in your best interest. Is he/she board certified by the American Board of Plastic Surgery - I doubt it. The reason is that as a rule, the longer the fat is outside your body the more of a chance there is of fat cell death, infection from contamination, and less chance of survival. The best chance for maximum fat survival is immediate fat transfer. Even then there is incomplete survival.

Remember there is Zeltiq CoolScultpting which essentially cools fat in your body externally to make fat cells die early. It therefore doesn't make sense that cooling fat will also increase the survival of fat. See a board certified plastic surgeon with experience in this technique

Fat grafting is fickle. Frozen fat would not be expected to have the same viability as freshly harvested fat.  A better strategy would be to harvest only the amount of fat that is being transferred in the same setting.

 

Fat can be frozen and re-injected with good results.  The method of cryopreservation of fat is very important.  A standard compact or household freezer stores fat at -20 degrees C which is not ideal for storage of fat.  For long-term storage of fat the ideal temperature is -75 to –80 degrees C.

There have been some interesting reports in the plastic surgery literature comparing the biologic activity of frozen/stored fat compared to freshly harvested fat. Based on these studies, fresh fat appears to be more biologically active.
However, clinically, frozen fat appears to perform almost as well as freshly harvested fat in the setting of facial fat grafting. In fact, its important to freeze some fat for later use because touch up injections are frequently needed.

Thanks for your question -
There have been several studies examining using cryo-preserved fat for tissue augmentation. It does seem that fat can be stored for a period of time and still be viable (though not as well as fresh fat).
Fat that has been cryopreserved has an even lower survivability.
Most surgeons who are performing autologous fat transfer are using the tissue immediately upon harvest for the most consistent results.
I hope this helps.

Some studies show that frozen fat may work even better than fresh fat, but this has not been reproduced by other studies.
Frozen fat has been used for many years, and when performed by a knowledgeable physician who takes the proper precautions and safety measures, including dealing with power outages, and verification that the product stored and to be reinjected is from the same patient, the procedure should be safe.

I feel it is always better to use fresh fat. These are living cells and you want your body to incorporate them. By freezing the cells, over time the cells denature. Please be careful.

Freezing fat in the doctors office frig and reusing it does not make any sense although there are people who advocate it. Simply put freezing and thawing ruptures  the cell membrane killing the cell unless it is done by freezing techniques used freeze embryos, eggs, etc in a proper lab setting. Other wise you are getting injected with dead oily glob which is  hopefully removed by your phahgocytes. You may also end up having a sterile abcess which calcifies leaving a hard lump

Several studies have suggested that frozen fat can survive without a problem. Unfortunately, the results will depend on the method for preserving the fat. As Dr. Lam points out, high standards should be observed to ensure sterility and viability are preserved. Unfortunately, most physicians offices are not monitored to ensure this reliability as it can be quite expensive to keep up the standard. Overall,  I prefer to simply harvest fat at each session as this has been shown to have a greater viability than preserved fat in any circumstance.