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Ohashi. Plast Aesthet Res 2020;7:26 I http://dx.doi.org/10.20517/2347-9264.2020.15 Page 9 of 10

Improper cryopreservation techniques may compromise fat viability; however, with adequate
cryopreservation techniques such as slow cooling and fast thawing, preservation at -196 °C (below -85 °C)
and the addition of cryoprotective agents foster high fat viability [27-29] .

We trust the CPC (CellSource Co. in Tokyo) to use proper cryopreservation techniques. Our
responsibilities, therefore, only include packaging and sending residual fat. To use the cryopreserved fat,
we then recall the fat [refer to Figure 1]. This ordering system allows small clinics to use cryopreserved
fat without needing high-cost cell processing facilities on site. This makes it easier for clinics to start
using cryopreserved fat safely while ensuring the stable quality of the fat. Having specialists conduct cell
processing also benefits patients by preserving the quality of their fat for repeat injections.

Regarding volume and SVF count of cryopreserved fat, our results showed that the volume of fat decreased
after cryopreservation; however, the amount of SVF per mL increased. This may be attributed to the fact
that SVF (and adipose-derived stromal cells) is stronger than normal adipocytes in response to stress from
[6]
factors such as ischemia, mechanical damage (during transportation), and cryopreservation . According to
our results, cryopreserved fat is very useful for rejuvenation and fertilization/revitalization.

Lastly, our cases indicated that cryopreserved fat has comparable viability as fresh fat; however, further
studies are needed to compare the retention rate and regeneration effects of fresh and cryopreserved fat in
a pathological study.

In summary, we did not experience any severe complications in any of our 216 patients over three and
half years. Our results indicated that fat grafting with cryopreserved fat closely mimics that with fresh fat,
making cryopreserved fat a safe and useful source for repeat fat grafting injections.

DECLARATIONS
Acknowledgments
We thank Hidato Kaneshima, MD, PhD, Satoshi Tsunoda, and Syunsuke Tazumi from CellSource Co., Ltd.
for providing methods for cryopreservation and thawing.

Authors’ contributions
The author contributed solely to the article.

Availability of data and materials
Not applicable.

Financial support and sponsorship
None.

Conflicts of interest
The author declared that there are no conflicts of interest.

Ethical approval and consent to participate
In Japan, the Regenerative Medicine Safety Act came into effect as of November 25, 2014 under an
institutional framework for promoting the implementation of regenerative medicine. This act, which
covers clinical research and private practice, stipulates three risk-dependent standards and the procedures
for notification of plans for regenerative medicine as well as the standards of cell culture and processing
facilities and the licensing procedures to ensure the safety of regenerative medicine.