Here is the study I often mention I posted 5 years or so ago that proved donor regrowth using Dr. Gho’s old FM method. I’ve been shocked by the level of ignorance that abounds in the hair restoration industry when it comes to donor regrowth. This is a phenomenon shown to occur in the early work of Oliver/Jahoda many decades ago. Yet, to this day, 99.9% of hair transplant surgeons believe donor regrowth is impossible. It is imperative we begin to educate these people.
The donor regrowth is not an issue at all. The recipient regrowth was the difficult part to figure out. However, soaking the grafts in a special medium for 2 hours prior to implantation solves the problem. You also have to wait about a year for the donor to fully heal before the follicles can be reharvested for a second procedure.
The meat and potatoes of this study is:
“we harvest the upper two-thirds of the follicles and 76% of the follicles regenerate at the donor site. This ratio increases as the level of transection gets higher ( 98% for the upper one-thirds).” Here is the full study:
The limitations of the donor area reserve is the most important problem to be solved by all physicians dealing with hair restoration surgery. The studies for increasing the potential donor supply such as hair cell implantation and in vitro hair follicle regeneration are still under investigation due to their poor results. The only recent advance is the follicular unit extraction technique also known as FUE. This technique allows the surgeon to obtain an increased number of follicular groups from the scalp and other body areas. However, as the level of baldness advances the number of grafts needed is not sufficient for a satisfactory result.
Several authors have proved that follicular epithelial stem cells should be located in the bulbar region as well as the bulge area. In 1995 Kim et al1 and in 1999 Reynolds et al2 reported that the outer root sheath cells cultured from different parts of a hair follicle could regenerate into a differentiated hair follicles. Based on Dr. Kım and Dr. Reynold’s studies, we hypothesize that transecting the hair follicle from different levels should allow doctors to obtain several viable donor grafts from one donor hair. Therefore, the number of donor hairs available in a patient’s donor area would increase in comparison to the techniques used today. This manipulation will result not only in hair growth in the recipient site, but will also allow for hair regrowth from the remaining part of each follicle in the actual donor site.
In this clinical study, we transplanted different parts of transversly trisected hair follicles, harvested by the FUE technique, from the donor site. We then tested the hypothesis by duplicating the available donor hair grafts in hair transplantation. We then evaluated the efficiency of the transected follicles by checking the growth rate of each type of transection. This evaluaton is especially important for surgeons using FUE since transplanting the transected follicles is sometimes a problem.
MATERIAL AND METHODS
Using the follicular unit extraction technique, normal human occipital scalp hair follicles were obtained from 5 healthy male patients. A total of 45 hair follicles were isolated for each patient. The follicles were divided into three groups. Group A (N:15): The upper one third of the follicles were extracted from the donor site, leaving the remainıng two thirds of each follicle intact. Group B (N:15): The upper half of the follicles was extracted, leaving the remainıng lower half of each follicle ıntact. Group C (N:15): The upper two thirds of the follicles were extracted, leaving the lower one third of each follicle ıntact. Extracted follicles from each group were placed into the slits at the recipient site. To monitor the growth in each site, the area was divided into 1 cm2 boxes using permanent tatoos. Follicle count and thickness control was performed for one year by an independent third party
At the recipient site at the 15 follicles meanly 3 (2-4) of upper one thirds, 4.4 (2-6) of upper half and 6.2 (5-8) of upper two thirds were observed as fully grown after 1 year. The regenerated hairs were thinner than those from intact follicles. At the donor site a regrowth rate of meanly 12.6 (10-14) of extracted upper one thirds, 10.2 (8-13) of extracted half and 8 (7-12) of extracted upper two thirds was observed as emerging new follicles. The growth rate at the donor site and regrowth rate at the recipient site is given in Figure 1 and Figure 2 respectively.
Figure 1: UPPER 1/3 1/2 UPPER 2/3
Growth rate at the recipient sit
Figure 2: UPPER 1/3 1/2 UPPER 2/3
Regrowth rate at the donor site.
The hair follicle is a complex organism. It contains stem cells that not only govern the rate of cell loss, but also the regeneration of the hair during its life cycle. These stem cells are located at the bulb and outer sheath close to the erector pili muscle which is called the“bulge” as well. Oliver Et Al showed that rat vibrissae can still regenerate after removing the lowest one-third of the follicle. Similarly, Inaba Et Al, Kim and Choi proved that grafted hair follicles can regenerate after removal from the bulb. This data showed that the upper half of the follicle can regenerate outside of the bulb area. In our study we observed a growth rate of 29.3 % in the upper half of the follicles after 1 year. The regrowth rate was 76% at the donor site during the time period.
Recently, Rochat and Kobayashi proved the bulge hypothesis as true by isolating keratinocyte colony-forming cells from human hair follicles. They determined that cells were located in the follicular bulge area. This area is the outer root sheath to which the erector pili muscle is attached. This muscle is located nearly at the midportion of the follicle. Raposio Et Al identified these cells as follicular stem cells. Therefore, theoretically each half of the follicle should contain a stem cell reservoir and allow for new shaft production and hair growth which means an unlimited donor supply. They also transected hair follicles from the level immediately below the bulge area. They proved that the lower half of the follicle had the same growth rate as the intact follicle but that the upper half exhibited a reduced shaft production capacity. Although, the upper half of the follicle exhibited a reduced capacity for shaft production, it still had the capacity to form a hair shaft which means that it still contained some follicular stem cells. We have observed similar results ın our studies; just 13% of the upper one-third of the follicle can regenerate as a new follicle after transplantation. the upper half resulted in 20% and the upper two-thirds resulted in 33%. So we have observed that if only the bulge area is included in the graft the survival rate increases. If the transection level goes lower and the number of outer root sheath cells included in the graft increases, the survival rate will also increase, just like in the success rate in the extraction of the upper two-thirds of the follicles. This data supports the bulge hypothesis that implicates that the stem cell circulation begins in the upper outer root sheath and moves downward through the bulb area. Therefore, it is logical to include both stem cell locations and as much outer sheath as possible to increase the graft yield after the transplantation.
To our knowledge our clinical study is the first written study that compares trisected hair follicle growth and donor regrowth with single follicle extraction system. The most important problem in FUE procedures is the unacceptable levels of transection (damage due to cut hair follicles) in some patients. Sometimes surgeons are not careful enough when inserting the transected grafts into the slits. The results of our study reveals these transected new follicle can emerge in the recipient site. However, the number of new follicles depends on the transection level. New follicles are thinner than the original ones and they cannot cover the recipient site sufficiently. We think the bulge area stem cells can regenerate to build a new follicle, but without the bulb, the new follicle is thinner than the original one. We suggest that surgeons reconsider placing any transected follicle in the recipient site and maybe it is better to switch to strip surgery or to cancel the operation if the transection rate is above 10% in any patient.
We have also observed that in all FUE patients new hair follicles can regrow in the donor site. So we thought a kind of in vivo multiplication can be achieved so that the donor site can be harvested several times. This is basically true because we harvest the upper two-thirds of the follicles and 76% of the follicles regenerate at the donor site. This ratio increases as the level of transection gets higher ( 98% for the upper one-thirds). Also, new hairs emerge from 33% of these transplanted follicles in the recipient site. However, if a surgeon tries to extract the same follicle again it is really very difficult to extract the follicle intact. The punch suddenly buries into the skin and extracting the same follicle gets practically impossible.
In conclusion, the survival and growth rate of transversly sectioned human hair follicle increases as the level of transection decreases. However, we don’t recommend the surgeon to transplant the sectioned parts because the growth rate is not more than 33% and new follicles are so thin that they have no coverage effect. Also, at the donor site new follicle growth is observed but it is not possible to extract them again; therefore, the surgeon should be very careful with the patients whose transection rate is high during FUE procedures.