delayed micrograft transplantation
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Delayed micrograft transplantation

The number and length of sessions a patient has to undergo to complete a hair transplant procedure depends largely on the donor hair density and proportionally the time involved in the process of dissection and insertion of the grafts. After the donor hair has been harvested, the patient has to wait a couple of hours before the follicular units are separated and the recipient site can be readied. In order to minimize the time delay, there are proposals from several surgeons to preserve donor hair using various techniques until the required number of follicular units can be readied and the transplantation performed in a single session.

One of the first proposals based on this idea was suggested by Kurata et al. in 1999. They tried to preserve the dissected hair follicles in a salt solution called DMEM at 4 deg C at varying lengths of time after which they were transplanted on the skin of athymic mice to evaluate the success of their technique. According to their observations, hair follicles were cultivatable for up to 7 days after excision and 60% of the transplanted hair in mice grew well even after 5 months post implantation. With this as background, Qian et al. from Institute of Dermatology, Peking Union Medical College and Chinese Academy of Medical Sciences, China have conducted further experiments in an attempt to identify better hair follicle preservation techniques.

Qian and colleagues harvested hair follicles from patients who had undergone face lift procedures and follicular units containing 1-2 hairs were only selected and preserved in Ringer’s and DMEM solution at 0 deg C for 24 h, 48 h, 3 days and 7 days respectively. Lactated Ringer’s solution, also known as Hartmann’s solution, is generally used for intravenous administration. It is a rich source of sodium, chloride, potassium and calcium ions obtained by combining sodium chloride, calcium chloride, potassium chloride and sodium lactate. DMEM or Dulbecco/Vogt modified Eagle’s minimal essential medium is a cell culture medium suitable for most types of animal cells including human, monkey, rat, hamster and chicken cells. It contains amino acids, vitamins such as ascorbic acid, folic acid, nicotinamide, riboflavin and B 12 along with glucose, salts and extra iron.

The hair follicles were pretreated with 0.3% trypsin for 3 mins and all extra connective tissue was removed. The follicles were then cultured in Petri dishes coated with gelatin and nurtured with DMEM and 10% FCS as a supplement and incubated at 37 deg C for 7 days in a CO2 water jacketed incubator with 5% CO2 and 95% air atmosphere. Using an inverted microscope, the cultures were studied for possible hair colony formation. Results from this experiment revealed that colonization of hair follicles decreased with increase in preservation time. That is hair follicles preserved for 24 h had better potential to form colonies as compared to follicles preserved for 48 h, 3 days and 7 days. The outer sheath cells also showed better growth with follicles preserved for 24 h. At this preservation time about 95.8% growth of outer sheath cells were seen in Ringer’s solution while about 86.7% in DMEM. With increase in preservation time, the rate of growth of outer sheath cells decreased but, the rate of growth in Ringer’s solution was significantly higher as compared to DMEM in all the experiment’s time frames. This formed the cell culture part of the experiment.

Another set of hair follicles preserved in DMEM and Ringer’s solution at 0 deg C were transplanted under the skin in a layer called the panniculus carnosus of 24, four-week old athymic mice. While two of the experimental animals died within a few days of transplantation the rest of them were allowed to grow for 5 months after which they were killed and the growth characteristics of the hair follicles studied. As compared to cell culture results, the hair survival rate in the mice seemed a little less with 84.8% in Ringer’s and 72.5% in DMEM when 24h treated hairs were transplanted. Those follicles with 48h and 3 days exposure to preservation showed a drastic decrease in survival rates and those of 7 days had practically no growth. Those hairs that re-grew were very thin as opposed to the normal hair thickness and the length ranged from 15-26 mm.

From these sets of experiments, it could be concluded that for long term preservation of hair follicles, the solutions maintained at 0 deg c are better than those at a temperature range of 1-4 deg C. Since the hair transplant was in the panniculus carsosus area and not on the skin as performed by Kurata et al., the possibility of follicle damage by mechanical means was nil. Since no specific solution or combination has been identified for hair preservation and culturing, the regularly used Ringer’s and DMEM solutions were made use of here. Despite DMEM being richer in all aspects in comparison with Ringer’s, the latter has been found to give better results. In accordance with the results, the authors have suggested that preserved hair follicles no more than 48 h of preservation is good for transplantation with those preserved for a maximum of 24 h giving the best results.

Delayed micrograft transplantation references

  • Qian JG, Li WZ, Zhang GC, Yan LB. Is delayed micro-graft hair transplantation possible?--evaluation of viabilities of hair follicles preserved in two storage media. Br J Plast Surg. 2005 Jan;58(1):38-41. PMID: 15629165
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