 |
|
Dr. Bertram Medical Hair Transplant
眉 髮 醫 學 移 植 中 心 ( 香 港 ) |
( 852 ) 3421-1138
|
Research 5 - Is it Safe to Keep Grafts in the Refrigerator
So far the optimal temperature for graft storage had not been determined. Very often Dr Limber’s study was quoted - that grafts immersed in chilled saline at 4 0°C have a survival of 88% even after 8 hours. For years chilled saline has become the Gold Standard.
This is a very common practice to put grafts in saline and then keep in the refigerator. It is based on the assumptions that this will somehow keep the graft at 4°C.
However Dr Pathomvanich reported an incidence when all the grafts were frozen and then no growth. So how can we be so certain that this is a safe practice? Subzero freezing can cause intracellular crystallization. Can we risk any damage to the hair follicles by relying on just assumptions?
Objective:
- To compare the different methods in graft storage
- To evaluate whether it is safe to Keep Grafts in the Refrigerator
Materials:
- Domestic refrigerator (Sharp SJ-2984) with a digital thermometer installed to monitor the inside temperature
- Glass Petri Dish 12 inches in diameter
- A digital thermometer with a sensor probe
- Infra-red thermometer
- Rubbermaid Blue Ice Cooler
Methods and Results:
| |
Study 1
 |
|
< |
| Picture 1 - Study 1 |
|
Picture 2 - Study 2 |
The Petri Disc was first filled with chilled saline. The temperature of the saline was measured by a fully submerged temperature sensor probe ( picture 2 ) every 4 hours.
Result :Saline was over 10°C in less than 30 minutes, and stayed at 16 -18°C.
Study 2
The Petri Disc with chilled saline was then placed over the Blue Ice coolant ( picture 2 ) and test repeated.
Result :Saline stayed around 12°C for up to 8 hours
Study 3
The Petri Disc with chilled saline was then kept in the fridge. The temperature was set to MEDIUM, and then MAXIMUM, and test repeated.
Result :
- Fridge temperature reading did not reflect the saline temperature
- At medium temperature setting the saline was between 1.5 to 7 °C
- Once the setting increase to maximum, the saline temperature dropped to subzero.
|
The Principle of Hypothermic Storage
- Storage of tissue above 0°C but below normal body temperature of 37°C is known as hypothermic storage
- Rule of thumb in Cryobiology - Every 10°C reduction in temperature is accompanied by a 50% decrease in cellular oxygen consumption
- Theoretically this lowering of cellular biochemical activity and metabolic demands may reduce physiological damage to the isolated hair follicles
Storing the saline in refrigerator, when compared to over the Blue Ice coolant, only resulted in a further 7% of oxygen consumption. However there was a risk of subzero subzero freezing if the fridge temperature was set too low.
Studies On Chilling vs. Non-Chilling on Graft Survival
| |
Study by Raposio 1999
Comparing survival of grafts stored in normal saline at 10°C and 26°C. After 5 hours the hair were then cultured in Williams E media for 10 days
Results :
Hair shaft elongation rate between the two groups was similar. The final surviva ( without loss of normal follicular architecture ) was as following :
| Storage Temperature |
10°C |
26°C |
| Survival |
87 % |
88% |
Rapasio et al. Effects of Cooling Micrografts in Hair Transplantation Surgery, Dermatologic Surgery Vol 25:9 pages 705–707, September 1999 (3)
Study by Kim and Hwang
Results :
No significant difference in survival within 6 hours whether the grafts were stored in room temp or 4°C, but a significant difference after 24 hours.
Therefore temperature is not a major factor in survival in the first 5-6 hours.
Duration of preservation (hrs)
|
Graft Survival Rate (%)
|
|
4°C |
| Control |
85 % |
96 % |
| 6 |
92 % |
94 % |
| 24 |
40 % |
76% |
| 48 |
34 % |
50% |
The Effects of dehydration, preservation temperature and time, and Hydrogen Peroxide on hair grafts – Kim & Hwang
(Unger. Hair Transplantation 4th edition pp 285-286)
|
Possible Risks in Storing Grafts in Refrigerator:
| |
1. Cold injury as a result of acidosis; depressed sodium activity; and production of free radicals and ATP loss
2. Risk of subzero graft freezing and poorer graft survival.
3. Spilling of grafts when taking in and out of the refrigerator.
4. Rapid re-warming can lead to Ischemic Reperfusion Injury
|
Our Recommendation :
This study showed that saline stored over a Blue Ice coolant is effective in reducing oxygen consumption up to 6 hours. Keeping the saline in dish and stored in the refigerator is a good alternative but one must be careful about the setting as there is a risk of drop the temperature to below 0 °C. Also the other possible risks have to be considered.
 |
|
|
|
|
