Storage of Hair Transplant Grafts outside of the body significantly impacts the quality of hair transplant procedures.
There are almost as many opinions on the best ex vivo storage media for follicle grafts during a hair transplant procedure as there are hair transplant surgeons.
Many surgeons have used the same protocol for years with great success, and there is always a tendency not to ‘rock the boat’ or mess with something that has worked in the past. But is your chosen hair graft storage solution as good as it could be? And how much impact does storage media have on the final quality of a transplant operation?
Which storage media offers the greatest protection to grafts during hair transplantation?
In a recent article for Hair Transplant International, renowned biopreservation expert Aby J. Mathew, Ph.D., argues that optimized intracellular-like solutions (such as HypoThermosol® FRS) are the best option for supporting grafts during ex vivo storage.
Dr. Mathew argues that these solutions offer the greatest level of protection and the lowest level of stress on the graft during its time outside of the body. This reduced stress increases the probability for improved survival and growth of follicular units post-transplantation, as can been seen in the image on the right.
How does an intracellular-like solution improve graft viability?
Most hair graft storage solutions in wide spread use represent ‘isotonic solutions’ composed of simple saline and modified cell culture media (Plasma-Lyte®, Lactated ringers®, DMEM, or Williams E), and were originally designed to support cells at normal body temperatures. Hair transplant grafts however are routinely stored in a hypothermic state (typically 2-8 °C) in order to reduce metabolic demand and gain the beneficial, protective effects of reduced temperature on the cells and tissues of the graft.
Unfortunately, the very same characteristics of hypothermia that confer graft protection also result in inactivation of the ATP-driven ion pumps that would normally maintain osmotic balance, leading to changes in cell membranes, instability of intracellular structures, free radical generation, abnormal water flux, and ultimately, cell death via apoptosis, necrosis, and/or secondary necrosis 8-21. These factors are all exacerbated in isotonic solutions that mimic the cells extracellular environment. While well suited to supporting an active cell at normal body temperature (where metabolic rates are normal and ATP-driven ion pumps are operational), isotonic solutions will actually accelerate the process of cell edema, lysis, and death under the hypothermic conditions experienced by hair grafts during ex vivo storage.
Maximizing the viability of hair transplant grafts following ex vivo storage.
To support a cell under hypothermic conditions and in order to reap maximum benefit from the stasis conferred by reduced temperature, we need a solution that maintains a balanced intracellular environment. An optimized intracellular-like solution (such as HypoThermosol® FRS) is formulated specifically to support tissue samples during hypothermic storage, and address the stresses of hypothermia with balanced ions and molecules, targeted pH buffering, and potent free radical scavengers that reduce hair follicle cell death via apoptosis and necrosis. Such a solution works to mitigate the overall cell stresses, buffering cells in each follicular unit, and increasing the potential for stronger and more rapid recovery of the graft post-transplantation.
The increased cell viability of tissue samples stored in an optimized intracellular-like solution versus those samples stored in a variety of isotonic solutions is clearly visible under fluorescent microscopy (figure 2 below).
Fig. 2. Fluorescent micrographs illustrating cell viability following hypothermic ex vivo storage in different storage solutions.
Enhancing the health and viability of the follicular unit grafts is essential to ensure the quality and success of a hair transplant procedure as measured by graft survival, hairline design, graft density, scalp irritation/edema, rate of regrowth, and hair shaft thickness. The optimization of ex vivo storage conditions is a practical and effective way to improve the health and viability of the follicular unit grafts.